local M = {}
local api = vim.api

local merge_tb = vim.tbl_deep_extend

M.close_buffer = function(bufnr)
  if vim.bo.buftype == "terminal" then
    vim.cmd(vim.bo.buflisted and "set nobl | enew" or "hide")
  elseif vim.bo.modified then
    print "save the file bruh"
  else
    bufnr = bufnr or api.nvim_get_current_buf()
    require("core.utils").tabuflinePrev()
    vim.cmd("bd" .. bufnr)
  end
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)
  -- set mapping function with/without whichkey
  local set_maps
  local whichkey_exists, wk = pcall(require, "which-key")

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

  mappings = mappings or vim.deepcopy(M.load_config().mappings)
  mappings.lspconfig = nil

  for _, section in pairs(mappings) do
    for mode, mode_values in pairs(section) do
      for keybind, mapping_info in pairs(mode_values) 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

        set_maps(keybind, mapping_info, opts)
      end
    end
  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] or {}
  user_table = type(user_table) == "table" and user_table or user_table()
  return merge_tb("force", default_table, user_table)
end

M.packer_sync = function(...)
  local git_exists, git = pcall(require, "nvchad.utils.git")
  local defaults_exists, defaults = pcall(require, "nvchad.utils.config")
  local packer_exists, packer = pcall(require, "packer")

  if git_exists and defaults_exists then
    local current_branch_name = git.get_current_branch_name()

    -- warn the user if we are on a snapshot branch
    if current_branch_name:match(defaults.snaps.base_snap_branch_name .. "(.+)" .. "$") then
      vim.api.nvim_echo({
        { "WARNING: You are trying to use ", "WarningMsg" },
        { "PackerSync" },
        {
          " on a NvChadSnapshot. This will cause issues if NvChad dependencies contain "
            .. "any breaking changes! Plugin updates will not be included in this "
            .. "snapshot, so they will be lost after switching between snapshots! Would "
            .. "you still like to continue? [y/N]\n",
          "WarningMsg",
        },
      }, false, {})

      local ans = vim.trim(string.lower(vim.fn.input "-> "))

      if ans ~= "y" then
        return
      end
    end
  end

  if packer_exists then
    packer.sync(...)
  else
    error "Packer could not be loaded!"
  end
end

M.bufilter = function()
  local bufs = vim.t.bufs

  for i = #bufs, 1, -1 do
    if not vim.api.nvim_buf_is_valid(bufs[i]) then
      table.remove(bufs, i)
    end
  end

  return bufs
end

M.tabuflineNext = function()
  local bufs = M.bufilter() or {}

  for i, v in ipairs(bufs) do
    if api.nvim_get_current_buf() == v then
      vim.cmd(i == #bufs and "b" .. bufs[1] or "b" .. bufs[i + 1])
      break
    end
  end
end

M.tabuflinePrev = function()
  local bufs = M.bufilter() or {}

  for i, v in ipairs(bufs) do
    if api.nvim_get_current_buf() == v then
      vim.cmd(i == 1 and "b" .. bufs[#bufs] or "b" .. bufs[i - 1])
      break
    end
  end
end

-- closes tab + all of its buffers
M.closeAllBufs = function(action)
  local bufs = vim.t.bufs

  if action == "closeTab" then
    vim.cmd "tabclose"
  end

  for _, buf in ipairs(bufs) do
    M.close_buffer(buf)
  end

  if action ~= "closeTab" then
    vim.cmd "enew"
  end
end

return M