local M = {}

local merge_tb = vim.tbl_deep_extend

M.close_buffer = function(force)
   if vim.bo.buftype == "terminal" then
      vim.api.nvim_win_hide(0)
      return
   end

   local fileExists = vim.fn.filereadable(vim.fn.expand "%p")
   local modified = vim.api.nvim_buf_get_option(vim.fn.bufnr(), "modified")

   -- if file doesnt exist & its modified
   if fileExists == 0 and modified then
      print "no file name? add it now!"
      return
   end

   force = force or not vim.bo.buflisted or vim.bo.buftype == "nofile"

   -- if not force, change to prev buf and then close current
   local close_cmd = force and ":bd!" or ":bp | bd" .. vim.fn.bufnr()
   vim.cmd(close_cmd)
end

M.load_config = function()
   local config = require "core.default_config"
   local chadrc_exists, chadrc = pcall(require, "custom.chadrc")

   if chadrc_exists then
      -- merge user config if it exists and is a table; otherwise display an error
      if type(chadrc) == "table" then
         M.remove_default_keys()
         config = merge_tb("force", config, chadrc)
      else
         error "chadrc must return a table!"
      end
   end

   config.mappings.disabled = nil
   return config
end

M.remove_default_keys = function()
   local chadrc = require "custom.chadrc"
   local user_mappings = chadrc.mappings or {}
   local user_keys = {}
   local user_sections = vim.tbl_keys(user_mappings)

   -- push user_map keys in user_keys table
   for _, section in ipairs(user_sections) do
      user_keys = vim.tbl_deep_extend("force", user_keys, user_mappings[section])
   end

   local function disable_key(mode, keybind, mode_mapping)
      local keys_in_mode = vim.tbl_keys(user_keys[mode] or {})

      if vim.tbl_contains(keys_in_mode, keybind) then
         mode_mapping[keybind] = nil
      end
   end

   local default_mappings = require("core.default_config").mappings

   -- remove user_maps from default mapping table
   for _, section_mappings in pairs(default_mappings) do
      for mode, mode_mapping in pairs(section_mappings) do
         for keybind, _ in pairs(mode_mapping) do
            disable_key(mode, keybind, mode_mapping)
         end
      end
   end
end

M.load_mappings = function(mappings, mapping_opt)
   mappings = mappings or M.load_config().mappings

   -- set mapping function with/without whichkye
   local map_func
   local whichkey_exists, wk = pcall(require, "which-key")

   if whichkey_exists then
      map_func = function(keybind, mapping_info, opts)
         wk.register({ [keybind] = mapping_info }, opts)
      end
   else
      map_func = function(keybind, mapping_info, opts)
         local mode = opts.mode
         opts.mode = nil
         vim.keymap.set(mode, keybind, mapping_info[1], opts)
      end
   end

   for section, section_mappings in pairs(mappings) do
      if section ~= "lspconfig" then
         -- skip mapping this as its mapppings are loaded in lspconfiguti
         for mode, mode_mappings in pairs(section_mappings) do
            for keybind, mapping_info in pairs(mode_mappings) do
               -- merge default + user opts

               local default_opts = merge_tb("force", { mode = mode }, mapping_opt or {})
               local opts = merge_tb("force", default_opts, mapping_info.opts or {})

               if mapping_info.opts then
                  mapping_info.opts = nil
               end

               map_func(keybind, mapping_info, opts)
            end
         end
      end
   end
end

-- load plugin after entering vim ui
M.packer_lazy_load = function(plugin, timer)
   if plugin then
      timer = timer or 0
      vim.defer_fn(function()
         require("packer").loader(plugin)
      end, timer)
   end
end

-- remove plugins defined in chadrc
M.remove_default_plugins = function(plugins)
   local removals = M.load_config().plugins.remove or {}

   if not vim.tbl_isempty(removals) then
      for _, plugin in pairs(removals) do
         plugins[plugin] = nil
      end
   end

   return plugins
end

-- merge default/user plugin tables
M.merge_plugins = function(default_plugins)
   local user_plugins = M.load_config().plugins.user

   -- merge default + user plugin table
   default_plugins = merge_tb("force", default_plugins, user_plugins)

   local final_table = {}

   for key, _ in pairs(default_plugins) do
      default_plugins[key][1] = key

      final_table[#final_table + 1] = default_plugins[key]
   end

   return final_table
end

M.load_override = function(default_table, plugin_name)
   local user_table = M.load_config().plugins.override[plugin_name]

   if type(user_table) == "table" then
      default_table = merge_tb("force", default_table, user_table)
   else
      default_table = default_table
   end

   return default_table
end

return M