#include <lua.h>
#include <stdlib.h>
#include <unistd.h>

#include "log.h"
#include "lua_state.h"
#include "state.h"
#include "str.h"

lua_State *L = NULL;
bool L_is_loaded = false;

static void lua_path_push(const char *new_path) {
	lua_getglobal(L, "package");
	lua_getfield(L, -1, "path");

	const char *current_path = lua_tostring(L, -1);
	if (!current_path)
		current_path = "";
	lua_pop(L, 1);

	lua_pushfstring(L, "%s;%s", current_path, new_path);
	lua_setfield(L, -2, "path");

	lua_pop(L, 1);
}

#define HANDLE_LUA_ERROR                                                       \
	do {                                                                       \
		log_error("lua: %s", lua_tostring(L, -1));                             \
		lua_pop(L, 1);                                                         \
		return false;                                                          \
	} while (0)

bool init_lua_state(void) {
	if (L_is_loaded)
		return true;

	L = luaL_newstate();
	luaL_openlibs(L);

	str lua_path = str_format("%.*s/?.lua", str_fmt(&config.dir));
	lua_path_push(lua_path.data);

	if (luaL_loadfile(L, config.init_path.data) || lua_pcall(L, 0, 1, 0)) {
		log_error("cannot run configuration script: %s", lua_tostring(L, -1));
		log_pkgit("to generate a configuration file, head into the");
		log_pkgit(
			"root directory of the pkgit source and run `make defconfig`");
		lua_close(L);
		return false;
	}

	if (!lua_istable(L, -1)) {
		log_error("top-level configuration is not a table");
		lua_pop(L, 1);
		lua_close(L);
		return false;
	}

	str_free(&lua_path);
	L_is_loaded = true;
	return true;
}

static void setup_base_dirs(void) {
	int uid = getuid(), euid = geteuid();

	config.is_root = false;

	if (uid < 0 || uid != euid) {
		config.is_root = true;
		config.dir = mstr("/etc/pkgit");
	} else {
		char *tmp = getenv("XDG_CONFIG_HOME");
		if (tmp) {
			config.dir = str_format("%s/pkgit", tmp);
		} else {
			config.dir = str_format("%s/.config/pkgit", getenv("HOME"));
		}
	}

	config.init_path = str_format(
		"%.*s/init.lua",
		str_fmt(&config.dir)
	);
	config.autogenerated_path = str_format(
		"%.*s/autogenerated.lua",
		str_fmt(&config.dir)
	);
}

#define lua_get_field_type(name, type, file)                                   \
	do {                                                                       \
		lua_getfield(L, -1, name);                                             \
		if (!lua_is##type(L, -1)) {                                            \
			log_error("lua: expected type " #type " for " name " in %.*s",     \
					  str_fmt(file));                                          \
			lua_pop(L, 1);                                                     \
			return false;                                                      \
		}                                                                      \
	} while (0)

static bool load_init_lua(void) {
	lua_setglobal(L, "__PkgitUserConfig");
	lua_getglobal(L, "__PkgitUserConfig");

	lua_get_field_type("dirs", table, &config.init_path);

#define X(field)                                                               \
	do {                                                                       \
		lua_get_field_type(#field, string, &config.init_path);                 \
		config.inst_dirs.field = str_adopt((char *)lua_tostring(L, -1));       \
		lua_pop(L, 1);                                                        \
	} while (0)

	X(prefix);
	X(bin);
	X(include);
	X(lib);
	X(src);

#undef X

	return true;
}

bool init_lua_config(void) {
	setup_base_dirs();

	if (!init_lua_state())
		return false;

	if (!load_init_lua())
		return false;

	return true;
}

void free_lua_state(void) {
	if (L != NULL) {
		lua_close(L);
		L = NULL;
	}
	L_is_loaded = false;
}

void free_lua_config(void) {
	free_lua_state();
}