added bare pluginsHEADmaster

1 files changed, 2128 insertions, 0 deletions

diff --git a/.config/vis/plugins/vis-lspc/init.lua b/.config/vis/plugins/vis-lspc/init.lua
new file mode 100644
index 0000000..52f8d08
--- /dev/null
+++ b/.config/vis/plugins/vis-lspc/init.lua
@@ -0,0 +1,2128 @@
+-- Copyright (c) 2021-2024 Florian Fischer. All rights reserved.
+--
+-- This file is part of vis-lspc.
+--
+-- vis-lspc is free software: you can redistribute it and/or modify it under the
+-- terms of the GNU General Public License as published by the Free Software
+-- Foundation, either version 3 of the License, or (at your option) any later
+-- version.
+--
+-- vis-lspc is distributed in the hope that it will be useful, but WITHOUT ANY
+-- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+-- FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License along with
+-- vis-lspc found in the LICENSE file. If not, see <https://www.gnu.org/licenses/>.
+--
+-- We require vis compiled with the communicate patch
+if not vis.communicate then
+  vis:info('LSPC Error: language server support requires vis communicate patch')
+  return {}
+end
+
+local source_str = debug.getinfo(1, 'S').source:sub(2)
+local source_path = source_str:match('(.*/)')
+
+-- state of our language server client
+local lspc = dofile(source_path .. 'lspc.lua')
+
+-- initialise the logging system
+lspc.logger = dofile(source_path .. 'log.lua').lazyNew('lspc', lspc)
+
+local parser = dofile(source_path .. 'parser.lua')
+
+-- initialise the util module
+local util = dofile(source_path .. 'util.lua').init(lspc)
+
+-- initialise the settings module
+local settings = dofile(source_path .. 'settings.lua').init(lspc)
+
+-- load a suitable json module
+lspc.json = dofile(source_path .. 'json.lua')
+
+local jsonrpc = {}
+jsonrpc.error_codes = {
+  -- json rpc errors
+  ParseError = -32700,
+  InvalidRequest = -32600,
+  MethodNotFound = -32601,
+  InvalidParams = -32602,
+  InternalError = -32603,
+
+  ServerNotInitialized = -32002,
+  UnknownErrorCode = -32001,
+
+  -- lsp errors
+  ContentModified = -32801,
+  RequestCancelled = -32800,
+}
+
+-- get vis's pid to pass it to the language servers
+local vis_pid
+do
+  local vis_proc_file = io.open('/proc/self/stat', 'r')
+  if vis_proc_file then
+    vis_pid = vis_proc_file:read('*n')
+    vis_proc_file:close()
+
+  else -- fallback if /proc/self/stat
+    local out = util.capture_cmd('sh -c "echo $PPID"')
+    vis_pid = tonumber(out)
+  end
+end
+assert(vis_pid)
+
+-- mapping function between vis lexer names and LSP languageIds
+local function syntax_to_languageId(syntax)
+  -- LuaFormatter off
+  local map = {
+    ansi_c = 'c',
+    javascript = 'jsx',
+    typescript = 'tsx',
+  }
+  -- LuaFormatter on
+
+  return map[syntax] or syntax
+end
+
+-- map of known language servers per syntax
+lspc.ls_map = dofile(source_path .. 'supported-servers.lua')
+
+--- Return the name of the language server for this syntax
+-- @param syntax the syntax the language server should support
+-- @return the name of the languauge server configured for syntax
+local function get_ls_name_for_syntax(syntax)
+  local ls_def = lspc.ls_map[syntax]
+  if not ls_def then
+    return nil, 'No language server available for ' .. syntax
+  end
+  return ls_def.name
+end
+
+-- Document position code
+-- https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocumentPositionParams
+
+-- We use the following position/location/file related types in  vis-lspc:
+-- pos - like in vis a 0-based byte offset into the file.
+-- path - posix path used by vis
+-- uri - file uri used by LSP
+
+-- lsp_position - 0-based tuple (line, character)
+-- lsp_document_position - aka. LSP TextDocumentPosition, tuple of (uri, lsp_position)
+
+-- vis_selection - 1-based tuple (line, cul) (character)
+--              Can be used with with Selection:to
+-- vis_document_position - 1-based tuple of (path, line, cul)
+
+-- vis_range - tuple of 0-based byte offsets (finish, start)
+-- lsp_range - aka. Range, tuple of two lsp_positions (start, end)
+
+-- There exist helper function to convert from one type into another
+-- aswell as helper to retrieve the current primary selection from a vis.window
+
+local function path_to_uri(path)
+  return 'file://' .. path
+end
+
+-- uri decode logic taken from
+-- https://stackoverflow.com/questions/20405985/lua-decodeuri-luvit
+local uri_decode_table = {}
+for i = 0, 255 do
+  uri_decode_table[string.format('%02x', i)] = string.char(i)
+  uri_decode_table[string.format('%02X', i)] = string.char(i)
+end
+
+local function decode_uri(s)
+  return (s:gsub('%%(%x%x)', uri_decode_table))
+end
+
+local function uri_to_path(uri)
+  return decode_uri(uri:gsub('file://', ''))
+end
+
+-- get the vis_selection from current primary selection
+local function get_selection(win)
+  return {line = win.selection.line, col = win.selection.col}
+end
+
+-- convert lsp_position to vis_selection
+local function lsp_pos_to_vis_sel(pos)
+  return {line = pos.line + 1, col = pos.character + 1}
+end
+
+-- convert vis_selection to lsp_position
+local function vis_sel_to_lsp_pos(pos)
+  return {line = pos.line - 1, character = pos.col - 1}
+end
+
+-- convert our vis_document_position to lsp_document_position aka. TextDocumentPosition
+local function vis_doc_pos_to_lsp(doc_pos)
+  return {
+    textDocument = {uri = path_to_uri(doc_pos.file)},
+    position = vis_sel_to_lsp_pos({line = doc_pos.line, col = doc_pos.col}),
+  }
+end
+
+-- convert lsp_document_position to vis_document_position
+local function lsp_doc_pos_to_vis(doc_pos)
+  local pos = lsp_pos_to_vis_sel(doc_pos.position)
+  return {
+    file = uri_to_path(doc_pos.textDocument.uri),
+    line = pos.line,
+    col = pos.col,
+  }
+end
+
+-- get document position of the main curser
+local function vis_get_doc_pos(win)
+  return {
+    file = win.file.path,
+    line = win.selection.line,
+    col = win.selection.col,
+  }
+end
+
+--- Convert a lsp_range to a vis_range
+-- @param file the file in which the range lies
+-- @param lsp_range the LSP range that should be converted
+-- @return the according vis range
+local function lsp_range_to_vis_range(file, lsp_range)
+  local start = lsp_pos_to_vis_sel(lsp_range.start)
+  local finish = lsp_pos_to_vis_sel(lsp_range['end'])
+
+  local positions = util.vis_sorted_selections_to_pos(file, {start, finish})
+  local start_pos = positions[1]
+  local finish_pos = positions[2]
+
+  return {start = start_pos, finish = finish_pos}
+end
+
+--- Check if a lsp_position lies before another.
+-- @param p1 first lsp_position to compare
+-- @param p2 second lsp_position to compare
+-- @return true if p1 lies before p2
+local function lsp_pos_before(p1, p2)
+  return p1.line < p2.line or (p1.line == p2.line and p1.character < p2.character)
+end
+
+--- Check if a lsp_range starts before another.
+-- The ranges may overlap since only their start positions are compared.
+-- @param r1 first lsp_range to compare
+-- @param r2 second lsp_range to compare
+-- @return true if r1 is starts before r2
+local function lsp_range_starts_before(r1, r2)
+  return lsp_pos_before(r1.start, r2.start)
+end
+
+-- concatenate all numeric values in choices and pass it on stdin to lspc.menu_cmd
+local function lspc_select(choices)
+  local menu_input = ''
+  local i = 0
+  for _, c in ipairs(choices) do
+    i = i + 1
+    menu_input = menu_input .. c .. '\n'
+  end
+
+  -- select the only possible choice
+  if i < 2 then
+    return choices[1]
+  end
+
+  local fullscreen = lspc.menu_cmd == 'fzf'
+  local status, output = util.vis_pipe(menu_input, lspc.menu_cmd, fullscreen)
+
+  local choice = nil
+  if status == 0 then
+    -- trim newline from selection
+    if output:sub(-1) == '\n' then
+      choice = output:sub(1, -2)
+    else
+      choice = output
+    end
+  end
+
+  vis:redraw()
+  return choice
+end
+
+local function lspc_select_location(locations)
+  -- Collect all paths with a list of their locations so we
+  -- can sort the locations before calling file_line_iterator_to_n
+  local collected = {}
+
+  for _, location in ipairs(locations) do
+    local path = uri_to_path(location.uri or location.targetUri)
+    local range = location.range or location.targetSelectionRange
+    local position = lsp_pos_to_vis_sel(range.start)
+
+    if collected[path] == nil then
+      table.insert(collected, path)
+      collected[path] = {}
+    end
+
+    table.insert(collected[path], {
+      ['location'] = location,
+      ['position'] = position,
+    })
+  end
+
+  local choices = {}
+  local cwd_components = util.capture_cmd('pwd')
+  -- Strip trailing newline
+  cwd_components = util.split_path_into_components(cwd_components:sub(1, #cwd_components - 1))
+
+  for _, path in ipairs(collected) do
+    -- Sort positions
+    table.sort(collected[path], function(a, b)
+      return a['position'].line < b['position'].line
+    end)
+
+    local rel_path = util.get_relative_path(cwd_components, path)
+    -- Use the already open file if present to get accurate line content for references
+    local line_iter
+    if lspc.open_files[path] ~= nil then
+      line_iter = function(n)
+        if n == -1 then
+          return nil
+        end
+
+        return lspc.open_files[path].file.lines[n]
+      end
+    else
+      line_iter = util.file_line_iterator_to_n(path)
+    end
+
+    for _, val in ipairs(collected[path]) do
+      local position = val['position']
+      local location = val['location']
+
+      local choice = rel_path .. ':' .. ('%.0f'):format(position.line) .. ':' ..
+                         ('%.0f'):format(position.col) .. ':' .. (line_iter(position.line) or '')
+      table.insert(choices, choice)
+      choices[choice] = location
+    end
+
+    -- close the iterator
+    line_iter(-1)
+  end
+
+  -- select a location
+  local choice = lspc_select(choices)
+  if not choice then
+    return nil
+  end
+
+  return choices[choice]
+end
+
+-- get a user confirmation
+-- return true if user selected yes, false otherwise
+local function lspc_confirm(prompt)
+  local choices = 'no\nyes'
+
+  local cmd = lspc.confirm_cmd
+
+  if prompt then
+    cmd = cmd .. ' -p \'' .. prompt .. '\''
+  end
+
+  lspc:log('get confirmation using: ' .. cmd)
+
+  local choice = nil
+  local status, output = util.vis_pipe(choices, cmd)
+  if status == 0 then
+    -- trim newline from selection
+    if output:sub(-1) == '\n' then
+      choice = output:sub(1, -2)
+    else
+      choice = output
+    end
+  end
+
+  vis:redraw()
+  return choice == 'yes'
+end
+
+local function vis_open_file(file, cmd)
+  vis:command(('%s %s'):format(cmd, file:gsub('[\\\t "\']', '\\%1'):gsub('\n', '\\n')))
+end
+
+-- open a doc_pos using the vis command <cmd>
+local function vis_open_doc_pos(doc_pos, cmd, win)
+  if win and win ~= vis.win then
+    vis.win = win
+  end
+  assert(cmd)
+  if vis.win.file.path ~= doc_pos.file then
+    if vis.win.file.modified and cmd == 'e' then
+      if lspc_confirm('Save currently open file:') then
+        vis:command('w')
+      else
+        vis:info('Not opening new file, current file has unsaved changes')
+        return
+      end
+    end
+    vis_open_file(doc_pos.file, cmd)
+    if doc_pos.line then
+      vis.win.selection:to(doc_pos.line, doc_pos.col or 0)
+    end
+    vis:command('lspc-open')
+  else
+    vis.win.selection:to(doc_pos.line, doc_pos.col)
+  end
+end
+
+-- Support jumping between document positions
+-- Stack of edited document positions
+local doc_pos_history = {}
+
+local function vis_push_doc_pos(win)
+  local old_doc_pos = vis_get_doc_pos(win)
+  table.insert(doc_pos_history, old_doc_pos)
+end
+
+-- open a new doc_pos remembering the old if it is replaced
+local function vis_open_new_doc_pos(doc_pos, cmd, win)
+  win = win or vis.win
+  if cmd == 'e' then
+    vis_push_doc_pos(win)
+  end
+
+  vis_open_doc_pos(doc_pos, cmd, win)
+end
+
+lspc.open_file = function(win, path, line, col, cmd)
+  vis_open_new_doc_pos({file = path, line = line, col = col}, cmd or 'e', win)
+end
+
+local function vis_pop_doc_pos(win)
+  local last_doc_pos = table.remove(doc_pos_history)
+  if not last_doc_pos then
+    return 'Document history is empty'
+  end
+
+  vis_open_doc_pos(last_doc_pos, 'e', win)
+end
+
+-- apply a textEdit received from the language server
+local function vis_apply_textEdit(win, file, textEdit)
+  assert(win.file == file)
+
+  local range = lsp_range_to_vis_range(file, textEdit.range)
+
+  file:delete(range)
+  file:insert(range.start, textEdit.newText)
+
+  win.selection.anchored = false
+  win.selection.pos = range.start + string.len(textEdit.newText)
+
+  win:draw()
+end
+
+-- apply a list of textEdits received from the language server
+local function vis_apply_textEdits(win, file, textEdits)
+  assert(win.file == file)
+
+  local edits = {}
+  for _, textEdit in ipairs(textEdits) do
+    local range = lsp_range_to_vis_range(file, textEdit.range)
+    table.insert(edits, {
+      mark = file:mark_set(range.start),
+      len = range.finish - range.start,
+      newText = textEdit.newText,
+    })
+  end
+  for _, edit in ipairs(edits) do
+    local pos = file:mark_get(edit.mark)
+    file:delete(pos, edit.len)
+    file:insert(pos, edit.newText)
+  end
+  win:draw()
+end
+
+--- Close the message window
+-- TODO: close the dedicated lspc message window
+local function lspc_close_message_win()
+  if lspc.show_message == 'message' then
+    vis:message('')
+    vis:command('q')
+  end
+end
+
+--- Present a message to the user
+-- TODO: use a dedicated lspc message window
+local function lspc_show_message(msg, hdr, syntax)
+  local current_win = vis.win
+
+  if lspc.show_message == 'message' then
+    local to_show = (hdr or '') .. msg .. '\n'
+    vis:message(to_show)
+    vis.win.selection = vis.win.file.size - #to_show
+    vis:feedkeys('zt')
+
+  elseif lspc.show_message == 'open' then
+    vis:command('open')
+    if syntax then
+      vis:command('set syntax ' .. syntax)
+    end
+
+    vis.win.file:insert(0, msg)
+    vis.win.selection.pos = 0
+  else
+    lspc:err('invalid message configuration "' .. lspc.show_message .. '".')
+  end
+
+  -- reset the focus to the current window
+  vis.win = current_win
+end
+
+-- apply a WorkspaceEdit received from the language server
+local function vis_apply_workspaceEdit(_, _, workspaceEdit)
+  local file_edits = workspaceEdit.changes
+  assert(file_edits or workspaceEdit.documentChanges)
+
+  -- try to convert NOT SUPPORTED TextDocumentEdit[]
+  -- We do not announce support for versioned DocumentChanges in our
+  -- client capabilities, but some LSP servers ignore our capabilities
+  -- sending them anyway.
+  if not file_edits then
+    file_edits = {}
+    for _, edit in ipairs(workspaceEdit.documentChanges) do
+      file_edits[edit.textDocument.uri] = edit.edits
+    end
+  end
+
+  if not lspc.autoconfirm_edits then
+    -- generate change summary
+    local summary = '--- workspace edit summary ---\n'
+    for uri, edits in pairs(file_edits) do
+      local path = uri_to_path(uri)
+      summary = summary .. path .. ':\n'
+      for i, edit in ipairs(edits) do
+        summary = summary .. '\t' .. i .. '.: ' .. lspc.json.encode(edit) .. '\n'
+      end
+    end
+
+    lspc_show_message(summary)
+    vis:redraw()
+
+    -- get user confirmation
+    local confirmation = lspc_confirm('apply changes:')
+
+    -- close summary window
+    lspc_close_message_win()
+
+    if not confirmation then
+      return
+    end
+  end
+
+  -- apply changes to open files
+  for uri, edits in pairs(file_edits) do
+    local path = uri_to_path(uri)
+
+    -- search all open windows for this uri
+    local win_with_file
+    for win in vis:windows() do
+      if win.file and win.file.path == path then
+        win_with_file = win
+        break
+      end
+    end
+
+    -- The file is not currently opened -> open it
+    local opened
+    if not win_with_file then
+      vis_open_file(path, 'o')
+      win_with_file = vis.win
+      opened = true
+    end
+
+    -- Remember the current primary cursor position
+    local old_pos = win_with_file.selection.pos
+
+    for _, edit in ipairs(edits) do
+      vis_apply_textEdit(win_with_file, win_with_file.file, edit)
+    end
+
+    -- Restore the remembered primary cursor position
+    if lspc.workspace_edit_remember_cursor then
+      win_with_file.selection.pos = old_pos
+    end
+
+    -- save changes and close the opened window
+    if opened then
+      vis:command('wq')
+    end
+  end
+end
+
+-- translate file line number to the relative row the line is displayed in the view of a window
+-- returns an integer relative to the window if line is in view (starting at 1)
+-- returns nil otherwise
+local function file_lineno_to_viewport_lineno(win, file_lineno)
+  -- The line is not in the current viewport
+  if file_lineno < win.viewport.lines.start or file_lineno > win.viewport.lines.finish then
+    return nil
+  end
+
+  -- The line is in the viewport and there is no wrapped line
+  if win.viewport.lines.finish - win.viewport.lines.start == win.viewport.height then
+    return file_lineno - win.viewport.lines.start
+  else -- Determine the position in the viewport considering possible prior wrapped lines
+    local view_lineno = 0
+    for n = win.viewport.lines.start, file_lineno do
+      view_lineno = view_lineno + 1
+      -- Wrapped lines shift our displayed line down
+      local line_len = #win.file.lines[n]
+      if not win.options.expandtab then
+        line_len = util.visual_chars_in_line(win, win.file.lines[n], line_len)
+      end
+
+      if line_len >= win.viewport.width then
+        view_lineno = view_lineno + math.floor(line_len / win.viewport.width)
+      end
+    end
+    return view_lineno
+  end
+end
+
+local function lspc_highlight_server_diagnostics(win, server_diagnostics, style)
+  if not style then
+    style = lspc.diagnostic_style_id or win.STYLE_LEXER_MAX
+  end
+
+  local level_mapping = {
+    [1] = lspc.diagnostic_styles.error,
+    [2] = lspc.diagnostic_styles.warning,
+    [3] = lspc.diagnostic_styles.information,
+    [4] = lspc.diagnostic_styles.hint,
+  }
+
+  for _, diagnostic in ipairs(server_diagnostics) do
+    local diagnostic_style = level_mapping[diagnostic.severity] or level_mapping[1]
+    assert(win:style_define(style, diagnostic_style))
+
+    if lspc.highlight_diagnostics == 'range' then
+      local range = diagnostic.vis_range
+
+      -- LSP ranges use an exclusive finish
+      local finish = range.finish - 1
+
+      -- make sure to highlight only ranges which actually contain the diagnostic
+      if diagnostic.content == win.file:content(range) then
+        win:style(style, range.start, finish)
+      end
+
+    elseif lspc.highlight_diagnostics == 'line' then
+      if not win.style_pos then
+        lspc:err('Vis build does not support style_pos')
+        return
+      end
+
+      local start_line = diagnostic.range.start.line
+      local end_line = diagnostic.range['end'].line
+      for line = start_line, end_line, 1 do
+        local row = file_lineno_to_viewport_lineno(win, line)
+        if row then
+          -- Heuristic how many cells need to be styled
+          -- (at least one plus the decimal places of the line number).
+          for i = 0, #('' .. line) do
+            win:style_pos(style, i, row)
+          end
+        end
+      end
+    end
+  end
+end
+
+local function lspc_highlight_diagnostics(win, diagnostics, style)
+  for _, server_diagnostics in pairs(diagnostics) do
+    lspc_highlight_server_diagnostics(win, server_diagnostics, style)
+  end
+end
+
+--- LanguageServer class metatable
+local LanguageServer = {}
+
+--- send a RPC message to the language server
+-- @param req The request to send
+function LanguageServer:rpc(req)
+  req.jsonrpc = '2.0'
+
+  local content_part = lspc.json.encode(req)
+  local content_len = string.len(content_part)
+
+  local header_part = 'Content-Length: ' .. tostring(content_len)
+  local msg = header_part .. '\r\n\r\n' .. content_part
+  lspc:log('LSPC Sending -> ' .. self.name .. ': ' .. msg)
+
+  self.fd:write(msg)
+  self.fd:flush()
+end
+
+--- Send a RPC notification to the language server
+-- @param name the name of the notification
+-- @param params the parameters to send
+function LanguageServer:send_notification(name, params)
+  self:rpc({method = name, params = params})
+end
+
+--- Send a textDocument/didChange notification to the language server
+-- @param the vis file object which changed
+function LanguageServer:send_did_change(file)
+  lspc:log('send didChange')
+  local new_version = assert(lspc.open_files[file.path]).version + 1
+  lspc.open_files[file.path].version = new_version
+
+  local document = {uri = path_to_uri(file.path), version = new_version}
+  local changes = {{text = file:content(0, file.size)}}
+  local params = {textDocument = document, contentChanges = changes}
+  self:send_notification('textDocument/didChange', params)
+end
+
+function LanguageServer:request_diagnostics(win)
+  -- check if the language server has a provider for this method
+  if self.capabilities['diagnosticProvider'] then
+    local params = {textDocument = {uri = path_to_uri(win.file.path)}}
+    self:call_method('textDocument/diagnostic', params, win, params.textDocument)
+  end
+end
+
+--- Send a rpc method call to the language server.
+-- @param method name of remote procedure to call
+-- @param params the parameter passed to the remote procedure
+-- @param win the related vis window object
+-- @param ctx a opaque context value stored with the request
+function LanguageServer:call_method(method, params, win, ctx)
+  local id = self.id
+  self.id = self.id + 1
+
+  local req = {id = id, method = method, params = params}
+  self.inflight[id] = req
+
+  self:rpc(req)
+  -- remember the current window to apply the effects of a
+  -- method call in the original window
+  self.inflight[id].win = win
+
+  -- remember the user provided ctx value
+  -- ctx can be used to remember arbitrary data from method invocation till
+  -- method response handling
+  -- The goto-location methods remember in ctx how to open the location
+  self.inflight[id].ctx = ctx
+end
+
+--- Call textDocument/<method> of the server
+-- We send a didChange notification upfront to make sure the server sees our
+-- current state. This is not ideal since we are sending more data than needed
+-- and the server has less time to parse the new file content and do its work
+-- resulting in longer stalls after method invocation.
+-- @param method the name of LSP textDocument method
+-- @param params the parameters of the method call
+-- @param win the related vis window object
+-- @param ctx a opaque context value stored with the request
+function LanguageServer:call_text_document_method(method, params, win, ctx)
+  self:send_did_change(win.file)
+  self:call_method('textDocument/' .. method, params, win, ctx)
+  self:request_diagnostics(win)
+end
+
+--- Call the textDocument/symbol method of the server if provided
+function LanguageServer:request_symbols(win, ctx)
+  if self.capabilities['documentSymbolProvider'] then
+    local params = {textDocument = {uri = path_to_uri(win.file.path)}}
+    self:call_text_document_method('documentSymbol', params, win, ctx)
+  end
+end
+
+local function lspc_handle_goto_method_response(req, result)
+  if not result or type(result) ~= 'table' or next(result) == nil then
+    lspc:warn(req.method .. ' found no results')
+    return
+  end
+
+  local location
+  -- result actually a list of results
+  if type(result) == 'table' then
+    location = lspc_select_location(result)
+    if not location then
+      return
+    end
+  else
+    location = result
+  end
+  assert(location)
+
+  -- location is a Location
+  local lsp_doc_pos
+  if location.uri then
+    lspc:log('Handle location: ' .. lspc.json.encode(location))
+    lsp_doc_pos = {
+      textDocument = {uri = location.uri},
+      position = {
+        line = location.range.start.line,
+        character = location.range.start.character,
+      },
+    }
+    -- location is a LocationLink
+  elseif location.targetUri then
+    lspc:log('Handle locationLink: ' .. lspc.json.encode(location))
+    lsp_doc_pos = {
+      textDocument = {uri = location.targetUri},
+      position = {
+        line = location.targetSelectionRange.start.line,
+        character = location.targetSelectionRange.start.character,
+      },
+    }
+  else
+    lspc:warn('Unknown location type: ' .. lspc.json.encode(location))
+  end
+
+  local doc_pos = lsp_doc_pos_to_vis(lsp_doc_pos)
+  vis_open_new_doc_pos(doc_pos, req.ctx, req.win)
+end
+
+local function lspc_handle_completion_method_response(win, result, old_pos)
+  if not result or type(result) ~= 'table' or not result.items then
+    lspc:warn('no completion available')
+    return
+  end
+
+  local completions = result
+  if result.isIncomplete ~= nil then
+    completions = result.items
+  end
+
+  local choices = {}
+  for _, completion in ipairs(completions) do
+    table.insert(choices, completion.label)
+    choices[completion.label] = completion
+  end
+
+  -- select a completion
+  local choice = lspc_select(choices)
+  if not choice then
+    return
+  end
+
+  local completion = choices[choice]
+
+  if completion.textEdit then
+    vis_apply_textEdit(win, win.file, completion.textEdit)
+    return
+  end
+
+  if completion.insertText or completion.label then
+    -- Does our current state correspont to the state when the completion method
+    -- was called.
+    -- Otherwise we don't have a good way to apply the 'insertText' completion
+    if win.selection.pos ~= old_pos then
+      lspc:warn('can not apply textInsert because the cursor position changed')
+    end
+
+    local new_word = completion.insertText or completion.label
+    local old_word_range = win.file:text_object_word(old_pos)
+    local old_word = win.file:content(old_word_range)
+
+    lspc:log(string.format('Completion old_pos=%d, old_range={start=%d, finish=%d}, old_word=%s',
+                           old_pos, old_word_range.start, old_word_range.finish,
+                           old_word:gsub('\n', '\\n')))
+
+    -- update old_word_range and old_word and return if old_word is a prefix of the completion
+    local function does_completion_apply_to_pos(pos)
+      old_word_range = win.file:text_object_word(pos)
+      old_word = win.file:content(old_word_range)
+
+      local is_prefix = new_word:sub(1, string.len(old_word)) == old_word
+      return is_prefix
+    end
+
+    -- search for a possible completion token which we should replace with this insertText
+    local matches = does_completion_apply_to_pos(old_pos)
+    if not matches then
+      lspc:log('Cursor looks like its not on the completion token')
+
+      -- try the common case the cursor is behind its completion token: fooba┃
+      local next_pos_candidate = old_pos - 1
+      matches = does_completion_apply_to_pos(next_pos_candidate)
+      if matches then
+        old_pos = next_pos_candidate
+      end
+    end
+
+    local completion_start
+    -- we found a completion token -> replace it
+    if matches then
+      lspc:log('replace the token: ' .. old_word .. '  we found being a prefix of the completion')
+      win.file:delete(old_word_range)
+      completion_start = old_word_range.start
+    else
+      completion_start = old_pos
+    end
+    -- apply insertText
+    win.file:insert(completion_start, new_word)
+    win.selection.pos = completion_start + string.len(new_word)
+    win:draw()
+    return
+  end
+
+  -- neither insertText nor textEdit where present
+  lspc:err('Unsupported completion')
+end
+
+local function lspc_handle_hover_method_response(win, result, old_pos)
+  if not result or type(result) ~= 'table' or not result.contents then
+    lspc:warn('no hover available')
+    return
+  end
+
+  local sel = util.vis_pos_to_sel(win, old_pos)
+
+  local hover_header =
+      '--- hover: ' .. (win.file.path or '') .. ': ' .. sel.line .. ', ' .. sel.col .. ' ---\n'
+  local hover_msg = ''
+  -- The most common markup kind in LSP is markdown
+  local markup_kind = 'markdown'
+
+  -- result is MarkedString[]
+  if type(result.contents) == 'table' and #result.contents > 0 then
+    lspc:log('hover returned list of length ' .. #result.contents)
+
+    for i, marked_string in ipairs(result.contents) do
+      if i == 1 then
+        hover_msg = marked_string.value or marked_string
+      else
+        hover_msg = hover_msg .. '\n---\n' .. (marked_string.value or marked_string)
+      end
+    end
+  else -- result is either MarkedString or MarkupContent
+    hover_msg = result.contents.value or result.contents
+    if result.contents.kind and result.contents.kind == 'plaintext' then
+      markup_kind = 'text'
+    end
+  end
+  lspc_show_message(hover_msg, hover_header, markup_kind)
+end
+
+local function lspc_handle_signature_help_method_response(win, result, call_pos)
+  if not result or type(result) ~= 'table' or not result.signatures or #result.signatures == 0 then
+    lspc:warn('no signature help available')
+    return
+  end
+
+  local signatures = result.signatures
+
+  local sel = util.vis_pos_to_sel(win, call_pos)
+  local help_header = '--- signature help: ' .. (win.file.path or '') .. ': ' .. sel.line .. ', ' ..
+                          sel.col .. ' ---\n'
+
+  -- local help_msg = lspc.json.encode(result)
+  local help_msg = ''
+  for _, signature in ipairs(signatures) do
+    local sig_msg = signature.label
+    if signature.documentation then
+      local doc = signature.documentation.value or signature.documentation
+      sig_msg = sig_msg .. '\n\tdocumentation: ' .. doc
+    end
+    help_msg = help_msg .. '\n' .. sig_msg
+  end
+  -- strip first new line from the message
+  help_msg = help_msg:sub(2)
+  lspc_show_message(help_msg, help_header)
+end
+
+local function lspc_handle_rename_method_response(win, result)
+  -- result must always be valid because otherwise we would caught the error
+  -- in LanguageServer:handle_method_response
+  vis_apply_workspaceEdit(win, win.file, result)
+end
+
+local function lspc_handle_formatting_method_response(win, result)
+  -- The result of textDocument/formatting is defined as TextEdit[] | null
+  if result then
+    vis_apply_textEdits(win, win.file, result)
+  end
+end
+
+local lspc_handle_publish_diagnostics
+
+local function lspc_handle_diagnostic_method_response(ls, result, ctx)
+  if result then
+    lspc_handle_publish_diagnostics(ls, ctx.uri, result.items)
+  end
+end
+
+local function lspc_handle_initialize_response(ls, result)
+  ls.initialized = true
+  ls.capabilities = result.capabilities
+
+  local params = {}
+  setmetatable(params, {__jsontype = 'object'})
+  ls:send_notification('initialized', params)
+
+  -- According to nvim-lspconfig sendig the lsp server settings shortly after
+  -- initialization is an undocumented convention.
+  -- See https://github.com/neovim/nvim-lspconfig/blob/ed88435764d8b00442e66d39ec3d9c360e560783/CONTRIBUTING.md
+  lspc:log('Loading settings for ' .. ls.name)
+  ls:send_default_settings()
+
+  vis.events.emit(lspc.events.LS_INITIALIZED, ls)
+end
+
+local function lspc_handle_symbol_method_response(result, ctx)
+  if ctx.callback and type(ctx.callback) == 'function' then
+    ctx.callback(result, ctx)
+  end
+end
+
+--- Send didChangeConfiguration notification with the default settings
+function LanguageServer:send_default_settings()
+  -- Use the rootUri or the open file's path as scope for the initial settings
+  local scope = self.rootUri or vis.win.file and vis.win.file.path
+  local effective_ls_settings = settings.effective_settings(self, nil, scope)
+  if next(effective_ls_settings) then
+    self:send_notification('workspace/didChangeConfiguration', {
+      settings = effective_ls_settings,
+    })
+  end
+end
+
+--- Dispatch method response from the server
+-- @param method_response the response send from the server
+-- @param req the request causing this response
+function LanguageServer:handle_method_response(method_response, req)
+  local win = req.win
+
+  local method = req.method
+
+  local err = method_response.error
+  if err then
+    local err_msg = err.message
+    local err_code = err.code
+    lspc:err(err_msg .. ' (' .. err_code .. ') occurred during ' .. method)
+    -- Don't try to handle error responses any further
+    return
+  end
+
+  local result = method_response.result
+
+  -- LuaFormatter off
+  if method == 'textDocument/definition' or
+     method == 'textDocument/declaration' or
+     method == 'textDocument/typeDefinition' or
+     method == 'textDocument/implementation' or
+     method == 'textDocument/references' then
+    -- LuaFormatter on
+    lspc_handle_goto_method_response(req, result)
+
+  elseif method == 'initialize' then
+    lspc_handle_initialize_response(self, result)
+
+  elseif method == 'textDocument/completion' then
+    lspc_handle_completion_method_response(win, result, req.ctx)
+
+  elseif method == 'textDocument/hover' then
+    lspc_handle_hover_method_response(win, result, req.ctx)
+
+  elseif method == 'textDocument/signatureHelp' then
+    lspc_handle_signature_help_method_response(win, result, req.ctx)
+
+  elseif method == 'textDocument/rename' then
+    lspc_handle_rename_method_response(win, result)
+
+  elseif method == 'textDocument/formatting' then
+    lspc_handle_formatting_method_response(win, result)
+
+  elseif method == 'textDocument/diagnostic' then
+    lspc_handle_diagnostic_method_response(self, result, req.ctx)
+
+  elseif method == 'textDocument/documentSymbol' then
+    lspc_handle_symbol_method_response(result, req.ctx)
+
+  elseif method == 'shutdown' then
+    self:send_notification('exit')
+    self.fd:close()
+
+    -- remove the ls from lspc.running
+    for ls_name, rls in pairs(lspc.running) do
+      if self == rls then
+        lspc.running[ls_name] = nil
+        break
+      end
+    end
+  else
+    lspc:warn('received unknown method ' .. method)
+  end
+
+  self.inflight[method_response.id] = nil
+end
+
+--- Handle a workspace/configuration request from a server
+-- @param params the parameters send with the request
+-- @param response the response we are about to send
+local function lspc_handle_workspace_configuration_call(ls, params, response)
+  local results = {}
+  for _, item in ipairs(params.items) do
+    local scope = item.scopeUri and uri_to_path(item.scopeUri)
+    local effective_settings = settings.effective_settings(ls, item.section, scope)
+    -- If we can not provide any settings LSP requires that null is present in the result array.
+    if next(effective_settings) then
+      table.insert(results, effective_settings)
+    else
+      table.insert(results, nil)
+    end
+  end
+  response.result = results
+end
+
+--- Handle a method call from the server
+-- @param method_call the received method call
+function LanguageServer:handle_method_call(method_call)
+  local method = method_call.method
+  local response = {id = method_call.id}
+  if method == 'workspace/configuration' then
+    lspc_handle_workspace_configuration_call(self, method_call.params, response)
+  else
+    lspc:log('Unknown method call ' .. method)
+    response['error'] = {
+      code = jsonrpc.error_codes.MethodNotFound,
+      message = method .. ' not implemented',
+    }
+  end
+  self:rpc(response)
+end
+
+-- save the diagnostics received for a file uri
+lspc_handle_publish_diagnostics = function(ls, uri, diagnostics)
+  local file_path = uri_to_path(uri)
+  local file = lspc.open_files[file_path]
+  if file then
+    for _, diagnostic in ipairs(diagnostics) do
+      -- We convert the lsp_range to a vis_range here to do it only once.
+      -- It's an expensive operation that involves counting all newlines.
+      diagnostic.vis_range = lsp_range_to_vis_range(file.file, diagnostic.range)
+
+      -- In some instances the range defined by the diagnostic starts
+      -- and ends at the same position. Highlight the exact position.
+      if diagnostic.vis_range.finish == diagnostic.vis_range.start then
+        -- We fake a one char range to retrieve its content.
+        -- In highlight_diagnostics we inconditionally decrement finish anyway.
+        diagnostic.vis_range.finish = diagnostic.vis_range.finish + 1
+      end
+
+      -- Remember the content of the diagnostic to only highlight it if the content
+      -- did not change
+      diagnostic.content = vis.win.file:content(diagnostic.vis_range)
+    end
+
+    file.diagnostics[ls] = diagnostics
+
+    lspc:log('remembered ' .. #diagnostics .. ' diagnostics for ' .. file_path)
+  else
+    lspc:log('Diagnostics for not opened file' .. file_path)
+  end
+end
+
+local lsp_message_types = {'Error', 'Warning', 'Info', 'Log'}
+-- show a message from the server in the UI
+local function lspc_handle_show_message(show_message_params)
+  if show_message_params.type > lspc.message_level then
+    return
+  end
+
+  vis:message('--- language server message ---')
+  local level = lsp_message_types[show_message_params.type] or 'Unknown'
+  vis:message(level .. ': ' .. show_message_params.message)
+end
+
+--- Handle a notification received from the server
+-- @param notification the received notification
+function LanguageServer:handle_notification(notification)
+  local method = notification.method
+  if method == 'textDocument/publishDiagnostics' then
+    lspc_handle_publish_diagnostics(self, notification.params.uri, notification.params.diagnostics)
+  elseif method == 'window/showMessage' then
+    lspc_handle_show_message(notification.params)
+  end
+end
+
+--- Dispatch between a method call and a message response
+-- Those are distinquiable because for a message response we have a req
+-- remembered in the inflight table
+-- @param method the method message received from the server
+function LanguageServer:handle_method(method)
+  local req = self.inflight[method.id]
+  if req and not method.method then
+    self:handle_method_response(method, req)
+  else
+    self:handle_method_call(method)
+  end
+end
+
+--- Dispatch between a method call/response and a notification from the server
+-- @param msg the message received from the server
+function LanguageServer:handle_msg(msg)
+  if msg.id then
+    self:handle_method(msg)
+  else
+    self:handle_notification(msg)
+  end
+end
+
+-- Parse the data send by the language server
+-- Note the chunks received may not end with the end of a message.
+-- In the worst case a data chunk contains two partial messages on at the beginning
+-- and one at the end
+function LanguageServer:recv_data(data)
+  local err = self.parser:add(data)
+  if err then
+    lspc:err(err)
+    return
+  end
+
+  local msgs = self.parser:get_msgs()
+  if not msgs then
+    return
+  end
+
+  for _, msg in ipairs(msgs) do
+    local resp = lspc.json.decode(msg)
+    self:handle_msg(resp)
+  end
+end
+
+--- Return a running language server
+-- @param win the window for which the language server might be running
+-- @param explicit_syntax the syntax if different from win.syntax
+-- @return a running language server or nil and an error message
+function lspc.get_running_ls(win, explicit_syntax)
+  local ls
+  local syntax = explicit_syntax or (win and win.syntax)
+  -- try to use the first language server managing the current file
+  if not syntax then
+    if win and win.file and lspc.open_files[win.file.path] and
+        next(lspc.open_files[win.file.path].language_servers) then
+      ls = next(lspc.open_files[win.file.path].language_servers)
+
+    else -- there is no language server with this file open and we have no syntax to guess
+      return nil, 'No syntax provided and no server is running'
+    end
+
+  else -- Use the syntax to guess the language server
+    local ls_name, err = get_ls_name_for_syntax(syntax)
+    if err then
+      return nil, err
+    end
+
+    ls = lspc.running[ls_name]
+    if not ls then
+      return nil, 'No language server running for ' .. syntax
+    end
+  end
+
+  return ls
+end
+
+--- Return a running and initialized language server
+-- @param win the window for which the language server might be running
+-- @param explicit_syntax the syntax if different from win.syntax
+-- @return a running and initialized language server or nil and an error message
+local function lspc_get_usable_ls(win, explicit_syntax)
+  local ls, err = lspc.get_running_ls(win, explicit_syntax)
+
+  if err then
+    return nil, err
+  end
+
+  assert(ls)
+  if not ls.initialized then
+    return nil, 'Language server ' .. ls.name .. ' not initialized yet. Please try again'
+  end
+
+  return ls
+end
+
+local function lspc_new_file_handle(file)
+  return {file = file, version = 0, diagnostics = {}, language_servers = {}}
+end
+
+--- Detect if a file is already opened by the language server
+-- @param file the vis file object to check
+-- @return true if the file is already opened by the language server
+function LanguageServer:is_file_opened(file)
+  return lspc.open_files[file.path] and lspc.open_files[file.path].language_servers[self]
+end
+
+-- close the file if associated with the language server
+local function lspc_close(ls, file)
+  if not ls:is_file_opened(file) then
+    return (file.path or '[No Name]') .. ' not open in ' .. ls.name
+  end
+  ls:send_notification('textDocument/didClose', {
+    textDocument = {uri = path_to_uri(file.path)},
+  })
+  lspc.open_files[file.path].language_servers[ls] = nil
+  if not next(lspc.open_files[file.path].language_servers) then
+    lspc.open_files[file.path] = nil
+  end
+end
+
+-- register a file as open with a language server and setup close and save event handlers
+-- A file must be opened before any textDocument functions can be used with it.
+local function lspc_open(ls, win, file)
+  -- already opened
+  if ls:is_file_opened(file) then
+    return file.path .. ' already open in ' .. ls.name
+  end
+
+  local lspc_file_handle = lspc.open_files[file.path] or lspc_new_file_handle(file)
+  lspc_file_handle.language_servers[ls] = true
+  lspc.open_files[file.path] = lspc_file_handle
+
+  local params = {
+    textDocument = {
+      uri = 'file://' .. file.path,
+      languageId = syntax_to_languageId(win.syntax),
+      version = 0,
+      text = file:content(0, file.size),
+    },
+  }
+
+  ls:send_notification('textDocument/didOpen', params)
+
+  vis.events.emit(lspc.events.LS_DID_OPEN, ls, file)
+end
+
+--- Initiate the shutdown of the language server
+-- Sending the exit notification and closing the file handle are done in
+-- the shutdown response handler.
+function LanguageServer:shutdown()
+  self:call_method('shutdown')
+end
+
+--- Find the root project URI for a specific file
+-- @param ls the language server
+-- @param file_path the path to the file to find the root project of
+-- @return the URI of the root project or nil if none was found
+local function find_root_uri(ls, file_path)
+  local globs = ''
+
+  local roots = ls.roots
+  if roots then
+    for _, glob in ipairs(roots) do
+      globs = globs .. glob .. '\n'
+    end
+  end
+
+  if lspc.universal_root_globs then
+    for _, glob in ipairs(lspc.universal_root_globs) do
+      globs = globs .. glob .. '\n'
+    end
+  end
+
+  local root_path = util.find_upwards(globs, file_path)
+  if not root_path and lspc.fallback_dirname_as_root then
+    root_path = util.dirname(file_path)
+  end
+  return root_path and path_to_uri(root_path)
+end
+
+local function ls_start(ls, init_options)
+  ls.fd = vis:communicate(ls.name, 'exec ' .. ls.conf.cmd)
+
+  -- detect the workspace root
+  ls.rootUri = vis.win.file and find_root_uri(ls, vis.win.file.path)
+
+  -- register the response handler
+  vis.events.subscribe(vis.events.PROCESS_RESPONSE, function(name, event, code, msg)
+    if name ~= ls.name then
+      return
+    end
+
+    if event == 'EXIT' or event == 'SIGNAL' then
+      if event == 'EXIT' then
+        vis:info('language server exited with: ' .. code)
+      else
+        vis:info('language server received signal: ' .. code)
+      end
+
+      lspc.running[ls.name] = nil
+      return
+    end
+
+    lspc:log(ls.name .. ' response(' .. event .. '): ' .. msg)
+    if event == 'STDERR' then
+      return
+    end
+
+    ls:recv_data(msg)
+  end)
+
+  local params = {
+    processId = vis_pid,
+    clientInfo = {name = lspc.name, version = lspc.version},
+    rootUri = ls.rootUri or lspc.json.null,
+    capabilities = lspc.client_capabilites,
+  }
+
+  if init_options then
+    params.initializationOptions = init_options
+  end
+
+  ls:call_method('initialize', params)
+end
+
+function LanguageServer.new(ls_conf)
+  local ls = {
+    name = ls_conf.name,
+    conf = ls_conf,
+
+    initialized = false,
+    id = 0,
+    inflight = {},
+    parser = parser.new(),
+    capabilities = {},
+  }
+  setmetatable(ls, {__index = LanguageServer})
+
+  return ls
+end
+
+local function lspc_start_server(syntax)
+  local ls_conf = lspc.ls_map[syntax]
+  if not ls_conf then
+    return nil, 'No language server available for ' .. syntax
+  end
+
+  local exe = ls_conf.cmd:gmatch('%S+')()
+  if not os.execute('type ' .. exe .. '>/dev/null 2>/dev/null') then
+    -- remove the configured language server
+    lspc.ls_map[syntax] = nil
+    local msg = string.format('Language server for %s configured but %s not found', syntax, exe)
+    -- the warning will be visual if the language server was automatically startet
+    -- if the user tried to start teh server manually they will see msg as error
+    lspc:warn(msg)
+    return nil, msg
+  end
+
+  if lspc.running[ls_conf.name] then
+    return nil, 'Already a language server running for ' .. syntax
+  end
+
+  local ls = LanguageServer.new(ls_conf)
+  lspc.running[ls_conf.name] = ls
+  ls_start(ls, ls_conf.init_options)
+
+  return ls
+end
+
+-- generic stub implementation for all textDocument methods taking
+-- a textDocumentPositionParams parameter
+local function lspc_method_doc_pos(ls, method, win, argv, additional_params)
+  -- check if the language server has a provider for this method
+  if not ls.capabilities[method .. 'Provider'] then
+    return 'language server ' .. ls.name .. ' does not provide ' .. method
+  end
+
+  if not ls:is_file_opened(win.file) then
+    lspc_open(ls, win, win.file)
+  end
+
+  local params = vis_doc_pos_to_lsp(vis_get_doc_pos(win))
+  if additional_params then
+    for k, v in pairs(additional_params) do
+      params[k] = v
+    end
+  end
+
+  ls:call_text_document_method(method, params, win, argv)
+end
+
+local lspc_goto_location_methods = {
+  declaration = function(ls, win, open_cmd)
+    return lspc_method_doc_pos(ls, 'declaration', win, open_cmd)
+  end,
+  definition = function(ls, win, open_cmd)
+    return lspc_method_doc_pos(ls, 'definition', win, open_cmd)
+  end,
+  typeDefinition = function(ls, win, open_cmd)
+    return lspc_method_doc_pos(ls, 'typeDefinition', win, open_cmd)
+  end,
+  implementation = function(ls, win, open_cmd)
+    return lspc_method_doc_pos(ls, 'implementation', win, open_cmd)
+  end,
+  references = function(ls, win, open_cmd)
+    return lspc_method_doc_pos(ls, 'references', win, open_cmd,
+                               {context = {includeDeclaration = false}})
+  end,
+}
+
+local function has_diagnostics(file)
+  if not file or not file.diagnostics then
+    return false
+  end
+
+  -- detect if at least one server has published diagnostics
+  for _, d in pairs(file.diagnostics) do
+    if #d then
+      return true
+    end
+  end
+
+  return false
+end
+
+local function lspc_goto_next_diagnostic(win, reverse)
+  if not lspc.open_files[win.file.path] then
+    vis:command('lspc-open')
+  end
+
+  local open_file = lspc.open_files[win.file.path]
+
+  if not has_diagnostics(open_file) then
+    return (win.file.path or 'window') .. ' has no available diagnostics'
+  end
+
+  -- merge diagnostics
+  -- TODO: come up with more efficient algorithm
+  local diagnostics = {}
+  for _, server_diagnostics in pairs(open_file.diagnostics) do
+    for _, diagnostic in ipairs(server_diagnostics) do
+      table.insert(diagnostics, diagnostic)
+    end
+  end
+  -- sort the merged diagnostics
+  table.sort(diagnostics, function(d1, d2)
+    return lsp_range_starts_before(d1.range, d2.range)
+  end)
+
+  local sel = get_selection(win)
+
+  local previous_diagnostic
+  for _, diagnostic in ipairs(diagnostics) do
+    local start = lsp_pos_to_vis_sel(diagnostic.range.start)
+    local fin = lsp_pos_to_vis_sel(diagnostic.range['end'])
+
+    -- reverse
+    if reverse and
+        (start.line > sel.line or
+            (start.line == sel.line and (start.col >= sel.col or sel.col <= fin.col))) then
+
+      -- wrap around
+      if not previous_diagnostic then
+        previous_diagnostic = lsp_pos_to_vis_sel(diagnostics[#diagnostics].range.start)
+      end
+
+      win.selection:to(previous_diagnostic.line, previous_diagnostic.col)
+      return
+    end
+
+    -- forward
+    if start.line > sel.line or (start.line == sel.line and start.col > sel.col) then
+      win.selection:to(start.line, start.col)
+      return
+    end
+
+    previous_diagnostic = start
+  end
+
+  -- wrap around
+  if #diagnostics > 0 then
+    local first = lsp_pos_to_vis_sel(diagnostics[1].range.start)
+    win.selection:to(first.line, first.col)
+  end
+end
+
+local function lspc_show_diagnostic(win, line)
+  if not lspc.open_files[win.file.path] then
+    vis:command('lspc-open')
+  end
+  local file = lspc.open_files[win.file.path]
+
+  if not has_diagnostics(file) then
+    return win.file.path .. ' has no diagnostics available'
+  end
+  local diagnostics = file.diagnostics
+
+  line = line or get_selection(win).line
+  lspc:log('Show diagnostics for ' .. line)
+  local diagnostics_to_show = {}
+  for ls, server_diagnostics in pairs(diagnostics) do
+    for _, diagnostic in ipairs(server_diagnostics) do
+      local start = lsp_pos_to_vis_sel(diagnostic.range.start)
+      if start.line == line then
+        diagnostic.start = start
+        diagnostic.server = ls.name
+        table.insert(diagnostics_to_show, diagnostic)
+      end
+    end
+  end
+
+  local diagnostics_fmt = '%s: %d:%d %s:%s\n'
+  local diagnostics_msg = ''
+  for _, diagnostic in ipairs(diagnostics_to_show) do
+    diagnostics_msg = diagnostics_msg ..
+                          string.format(diagnostics_fmt, diagnostic.server, diagnostic.start.line,
+                                        diagnostic.start.col, diagnostic.code or 'diagnostic',
+                                        diagnostic.message)
+  end
+
+  if diagnostics_msg ~= '' then
+    lspc_show_message(diagnostics_msg)
+  else
+    lspc:warn('No diagnostics available for line: ' .. line)
+  end
+end
+
+local lsp_symbol_kinds = {
+  'File',
+  'Module',
+  'Namespace',
+  'Package',
+  'Class',
+  'Method',
+  'Property',
+  'Field',
+  'Constructor',
+  'Enum',
+  'Interface',
+  'Function',
+  'Variable',
+  'Constant',
+  'String',
+  'Number',
+  'Boolean',
+  'Array',
+  'Object',
+  'Key',
+  'Null',
+  'EnumMember',
+  'Struct',
+  'Event',
+  'Operator',
+  'TypeParameter',
+}
+
+local function recursive_bfs_symbols_flatten(symbols, indent)
+  local ranges = {}
+  local str = ''
+  for _, s in ipairs(symbols) do
+    local range = s.selectionRange or s.location.range
+    table.insert(ranges, range)
+    str = str .. string.format(lspc.navwin_symbol_format, indent, lsp_symbol_kinds[s.kind], s.name,
+                               range.start.line + 1, range.start.character + 1)
+    -- Remember DocumentSymbol.selectionRange or SymbolInformation.location.range
+    if s.children then
+      local cstr, cranges = recursive_bfs_symbols_flatten(s.children, indent .. '  ')
+      str = str .. cstr
+      for _, v in ipairs(cranges) do
+        table.insert(ranges, v)
+      end
+    end
+  end
+  return str, ranges
+end
+
+--- Scroll the code window to the definition of the symbol selected in the navigation window.
+local function navwin_scroll_codewin(self, switch_win)
+  local line = self.navwin.selection.line
+  -- No valid selection in the navigation window
+  if line > #self.ranges then
+    return
+  end
+  local sel = lsp_pos_to_vis_sel(self.ranges[line].start)
+
+  -- Set the selection in the code window to the selected symbol
+  self.codewin.selection:to(sel.line, sel.col)
+
+  if switch_win then
+    vis.win = self.codewin
+  end
+end
+
+--- Instantiate a new navigation context from the received symbols.
+local function lspc_navwin_from_symbols(symbols, ctx)
+  local symbols_outline, ranges = recursive_bfs_symbols_flatten(symbols, '')
+
+  local old_layout = vis.ui.layout
+  if lspc.navwin_layout:sub(1, 1) == 'v' then
+    vis.ui.layout = vis.ui.layouts.VERTICAL
+  elseif lspc.navwin_layout:sub(1, 1) == 'h' then
+    vis.ui.layout = vis.ui.layouts.HORIZONTAL
+  end
+
+  local navwin
+  local codewin
+  -- The right or bottom (old) window is our navigation window
+  if lspc.navwin_layout:sub(2) == 'r' or lspc.navwin_layout:sub(2) == 'b' then
+    vis:command('o ' .. ctx.win.file.path)
+    navwin = ctx.win
+    navwin.file = ''
+    navwin.file:delete(0, navwin.file.size)
+    codewin = vis.win
+    -- The new (old) window is our navigation window
+  else
+    vis:command('o')
+    navwin = vis.win
+    codewin = ctx.win
+  end
+
+  -- Remove syntax highlighting from the symbols
+  navwin:set_syntax(nil)
+
+  assert(navwin)
+  assert(codewin)
+  ctx = {
+    navwin = navwin,
+    codewin = codewin,
+    ranges = ranges,
+    old_layout = old_layout,
+  }
+
+  lspc.navwins[navwin] = ctx
+  lspc.navwins[codewin] = ctx
+
+  -- Prepare window to be our symbol navigation window
+  navwin.file:insert(0, symbols_outline)
+  navwin:draw()
+
+  navwin:map(vis.modes.NORMAL, '<Enter>', function()
+    navwin_scroll_codewin(ctx, true)
+  end, 'jump to the selected symbol')
+  navwin:map(vis.modes.NORMAL, 'p', function()
+    navwin_scroll_codewin(ctx, false)
+  end, 'scroll to the selected symbol')
+  navwin:map(vis.modes.NORMAL, 'q', function()
+    navwin:close(true)
+  end, 'close this window')
+
+  -- Jump to navigation window
+  vis.win = navwin
+
+  -- Remove the event handlers.
+  local nav_win_close_handler
+  nav_win_close_handler = function(win)
+    -- Not our windows
+    if win ~= navwin and win ~= codewin then
+      return true
+      -- The code windows was closed, therefore we can also close the navigation window
+    elseif win == codewin then
+      lspc:log('Code window closed. Force close the navigation window.')
+      navwin:close(true)
+      return
+    end
+    -- reset vis' layout
+    vis.ui.layout = lspc.navwins[codewin].old_layout
+
+    -- remove the navigation window
+    lspc.navwins[navwin] = nil
+    lspc.navwins[codewin] = nil
+    lspc:log('unsubscribe navwin event handler')
+    vis.events.unsubscribe(vis.events.WIN_CLOSE, nav_win_close_handler)
+    return true
+  end
+
+  vis.events.subscribe(vis.events.WIN_CLOSE, nav_win_close_handler)
+end
+
+local function lspc_nav_symbols(ls, win)
+  local ctx = {win = win, callback = lspc_navwin_from_symbols}
+  ls:request_symbols(win, ctx)
+end
+
+-- vis-lspc commands
+
+vis:command_register('lspc-back', function()
+  local err = vis_pop_doc_pos()
+  if err then
+    lspc:err(err)
+  end
+end)
+
+for name, func in pairs(lspc_goto_location_methods) do
+  vis:command_register('lspc-' .. name, function(argv, _, win)
+    local ls, err = lspc_get_usable_ls(win, argv[1])
+    if err then
+      lspc:err(err)
+      return
+    end
+    assert(ls)
+
+    -- vis cmd how to open the new location
+    -- 'e' (default): in same window
+    -- 'vsplit': in a vertical split window
+    -- 'hsplit': in a horizontal split window
+    local open_cmd = argv[1] or 'e'
+    err = func(ls, win, open_cmd)
+    if err then
+      lspc:err(err)
+    end
+  end)
+end
+
+vis:command_register('lspc-hover', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- remember the position where hover was called
+  err = lspc_method_doc_pos(ls, 'hover', win, win.selection.pos)
+  if err then
+    lspc:err(err)
+  end
+end)
+
+vis:command_register('lspc-signature-help', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- remember the position where signatureHelp was called
+  err = lspc_method_doc_pos(ls, 'signatureHelp', win, win.selection.pos)
+  if err then
+    lspc:err(err)
+  end
+end)
+
+vis:command_register('lspc-rename', function(argv, _, win)
+  local new_name = argv[1]
+  if not new_name then
+    lspc:err('lspc-rename usage: <new name> [syntax]')
+    return
+  end
+
+  local ls, err = lspc_get_usable_ls(win, argv[2])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- check if the language server has a provider for this method
+  if not ls.capabilities['renameProvider'] then
+    lspc:err('language server ' .. ls.name .. ' does not provide rename')
+    return
+  end
+
+  if not ls:is_file_opened(win.file.path) then
+    lspc_open(ls, win, win.file)
+  end
+
+  local params = vis_doc_pos_to_lsp(vis_get_doc_pos(win))
+  params.newName = new_name
+
+  ls:call_text_document_method('rename', params, win)
+end)
+
+vis:command_register('lspc-format', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- check if the language server has a provider for this method
+  if not ls.capabilities['documentFormattingProvider'] then
+    lspc:err('language server ' .. ls.name .. ' does not provide formatting')
+    return
+  end
+
+  if not lspc.open_files[win.file.path] then
+    lspc_open(ls, win, win.file)
+  end
+
+  local params = {
+    textDocument = {uri = path_to_uri(win.file.path)},
+    options = ls.conf.formatting_options,
+  }
+  if params.options == nil then
+    params.options = {
+      tabSize = win.options.tabwidth,
+      insertSpaces = win.options.expandtab,
+    }
+  end
+
+  ls:call_text_document_method('formatting', params, win)
+end)
+
+vis:command_register('lspc-diagnostic', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- check if the language server has a provider for this method
+  if not ls.capabilities['diagnosticProvider'] then
+    lspc:err('language server ' .. ls.name .. ' does not provide document diagnostics')
+    return
+  end
+
+  if not lspc.open_files[win.file.path] then
+    lspc_open(ls, win, win.file)
+  end
+
+  ls:request_diagnostics(win)
+end)
+
+vis:command_register('lspc-completion', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  -- remember the position where completions were requested
+  -- to apply insertText completions
+  err = lspc_method_doc_pos(ls, 'completion', win, win.selection.pos)
+  if err then
+    lspc:err(err)
+  end
+end)
+
+vis:command_register('lspc-start-server', function(argv, _, win)
+  local syntax = argv[1] or win.syntax
+  if not syntax then
+    lspc:err('no language specified')
+  end
+
+  local _, err = lspc_start_server(syntax)
+  if err then
+    lspc:err(err)
+  end
+end)
+
+vis:command_register('lspc-shutdown-server', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err('no language server running: ' .. err)
+    return
+  end
+  assert(ls)
+
+  ls:shutdown()
+end)
+
+vis:command_register('lspc-close', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  lspc_close(ls, win.file)
+end)
+
+vis:command_register('lspc-open', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+
+  lspc_open(ls, win, win.file)
+end)
+
+local function _lspc_next_diagnostic(win, reverse)
+  local err = lspc_goto_next_diagnostic(win, reverse)
+  if err then
+    lspc:err(err)
+  end
+end
+
+vis:command_register('lspc-next-diagnostic', function(_, _, win)
+  _lspc_next_diagnostic(win, false)
+end)
+
+vis:command_register('lspc-prev-diagnostic', function(_, _, win)
+  _lspc_next_diagnostic(win, true)
+end)
+
+vis:command_register('lspc-show-diagnostics', function(argv, _, win)
+  local err = lspc_show_diagnostic(win, argv[1])
+  if err then
+    lspc:err(err)
+  end
+end)
+
+vis:command_register('lspc-navigate-symbols', function(argv, _, win)
+  local ls, err = lspc_get_usable_ls(win, argv[1])
+  if err then
+    lspc:err(err)
+    return
+  end
+  assert(ls)
+  if not ls:is_file_opened(win.file.path) then
+    lspc_open(ls, win, win.file)
+  end
+  if lspc.navwins[win] then
+    lspc.navwins[win].navwin:close(true)
+  else
+    lspc_nav_symbols(ls, win)
+  end
+end, 'toggle the symbol navigation')
+
+vis:command_register('lspc-navwin-jump', function(_, _, win)
+  local navwin = lspc.navwins[win]
+  if not navwin then
+    lspc:err('no associated navigation window')
+  else
+    navwin_scroll_codewin(navwin, true)
+  end
+end, 'jump to the selected symbol')
+
+vis:command_register('lspc-navwin-scroll', function(_, _, win)
+  local navwin = lspc.navwins[win]
+  if not navwin then
+    lspc:err('no associated navigation window')
+  else
+    navwin_scroll_codewin(navwin, false)
+  end
+end, 'scroll the code window to the selected symbol')
+
+vis:command_register('lspc-navwin-close', function(_, _, win)
+  local navwin = lspc.navwins[win]
+  if not navwin then
+    lspc:err('no associated navigation window')
+  else
+    navwin.navwin:close(true)
+  end
+end, 'close the navigation window')
+
+-- vis-lspc event hooks
+vis.events.subscribe(vis.events.WIN_OPEN, function(win)
+  if lspc.autostart and win.syntax then
+    lspc_start_server(win.syntax)
+  end
+end)
+
+local function highlight_event()
+  local win = vis.win
+  if not win or not win.file then
+    return
+  end
+
+  local open_file = lspc.open_files[win.file.path]
+  if open_file and open_file.diagnostics and lspc.highlight_diagnostics then
+    lspc_highlight_diagnostics(win, open_file.diagnostics)
+  end
+end
+
+vis.events.subscribe(vis.events.WIN_HIGHLIGHT, highlight_event)
+vis.events.subscribe(vis.events.UI_DRAW, highlight_event)
+
+vis.events.subscribe(vis.events.FILE_OPEN, function(file)
+  local win = vis.win
+  -- the only window we can access is not our window
+  if not win or win.file ~= file then
+    return
+  end
+
+  local ls = lspc_get_usable_ls(win)
+  if not ls then
+    return
+  end
+
+  lspc_open(ls, win, file)
+end)
+
+vis.events.subscribe(vis.events.FILE_SAVE_POST, function(file, path)
+  if not vis.win or vis.win.file ~= file then
+    return
+  end
+
+  local file_handle = lspc.open_files[path]
+  if not file_handle then
+    return
+  end
+
+  for ls in pairs(file_handle.language_servers) do
+    ls:send_did_change(file)
+    -- the server is interested in didSave notifications
+    if ls.capabilities.textDocumentSync and type(ls.capabilities.textDocumentSync) == 'table' and
+        ls.capabilities.textDocumentSync.save then
+      local did_save_params = {textDocument = {uri = path_to_uri(file.path)}}
+      ls:send_notification('textDocument/didSave', did_save_params)
+    end
+    ls:request_diagnostics(vis.win)
+  end
+end)
+
+vis.events.subscribe(vis.events.FILE_CLOSE, function(closed_file)
+  local file_handle = lspc.open_files[closed_file.path]
+  if not file_handle then
+    return
+  end
+
+  for ls in pairs(file_handle.language_servers) do
+    lspc_close(ls, closed_file)
+  end
+end)
+
+vis.events.subscribe(lspc.events.LS_INITIALIZED, function(ls)
+  if vis.win and vis.win.file and lspc_get_usable_ls(vis.win) == ls then
+    lspc_open(ls, vis.win, vis.win.file)
+  end
+end)
+
+vis.events.subscribe(vis.events.QUIT, function()
+  for _, ls in pairs(lspc.running) do
+    -- attempt to gracefully shutdown the language server
+    ls:shutdown()
+    -- close the fd handle to terminate the subprocess because
+    -- a potential method response from the server will not be read after the
+    -- QUIT event
+    ls.fd:close()
+  end
+end)
+
+vis:option_register('lspc-highlight-diagnostics', 'string', function(value)
+  lspc.highlight_diagnostics = value
+  return true
+end, 'How should lspc highlight available diagnostics')
+
+vis:option_register('lspc-menu-cmd', 'string', function(value)
+  lspc.menu_cmd = value
+  return true
+end, 'External tool vis-lspc uses to present choices in a menu')
+
+vis:option_register('lspc-confirm-cmd', 'string', function(value)
+  lspc.confirm_cmd = value
+  return true
+end, 'External tool vis-lspc uses to ask the user for confirmation')
+
+vis:option_register('lspc-message-level', 'number', function(value)
+  lspc.message_level = value
+  return true
+end, 'Message level to show in UI (for server messages)')
+
+vis:option_register('lspc-diagnostic-style-error', 'string', function(value)
+  lspc.diagnostic_styles.error = value
+end, 'Style for diagnostic errors')
+
+vis:option_register('lspc-diagnostic-style-warning', 'string', function(value)
+  lspc.diagnostic_styles.warning = value
+end, 'Style for diagnostic warnings')
+
+vis:option_register('lspc-diagnostic-style-information', 'string', function(value)
+  lspc.diagnostic_styles.information = value
+end, 'Style for diagnostic information')
+
+vis:option_register('lspc-diagnostic-style-hint', 'string', function(value)
+  lspc.diagnostic_styles.hint = value
+end, 'Style for diagnostic hints')
+
+dofile(source_path .. 'bindings.lua')
+return lspc