local api = vim.api

local libformat = require 'lib/format'
local format = libformat.format_tree
local highlight = libformat.highlight_buffer

local stateutils = require 'lib/state'
local get_tree = stateutils.get_tree

local bindings = require 'lib/config'.bindings

local M = {
  BUF_NAME = 'LuaTree'
}

function M.get_buf()
  local regex = '.*'..M.BUF_NAME..'$';

  for _, win in pairs(api.nvim_list_wins()) do
    local buf = api.nvim_win_get_buf(win)
    local buf_name = api.nvim_buf_get_name(buf)

    if string.match(buf_name, regex) ~= nil then return buf end
  end

  return nil
end

function M.get_win()
  local regex = '.*'..M.BUF_NAME..'$';

  for _, win in pairs(api.nvim_list_wins()) do
    local buf_name = api.nvim_buf_get_name(api.nvim_win_get_buf(win))
    if string.match(buf_name, regex) ~= nil then return win end
  end

  return nil
end

local BUF_OPTIONS = {
  'nowrap', 'sidescroll=5', 'nospell', 'nolist', 'nofoldenable',
  'foldmethod=manual', 'foldcolumn=0', 'nonumber', 'norelativenumber',
  'winfixwidth', 'winfixheight', 'noswapfile', 'splitbelow', 'noruler',
  'noshowmode', 'noshowcmd'
}

local WIN_WIDTH = 30
local SIDE = 'H'

if api.nvim_call_function('exists', { 'g:lua_tree_width' }) == 1 then
  WIN_WIDTH = api.nvim_get_var('lua_tree_width')
end

if api.nvim_call_function('exists', { 'g:lua_tree_side' }) == 1 then
  if api.nvim_get_var('lua_tree_side') == 'right' then
    SIDE = 'L'
  end
end

function M.open()
  local options = {
    bufhidden = 'wipe';
    buftype = 'nowrite';
    modifiable = false;
  }

  local buf = api.nvim_create_buf(false, true)
  api.nvim_buf_set_name(buf, M.BUF_NAME)
  api.nvim_buf_set_option(buf, 'filetype', M.BUF_NAME)

  for opt, val in pairs(options) do
    api.nvim_buf_set_option(buf, opt, val)
  end

  api.nvim_command('vsplit')
  api.nvim_command('wincmd '..SIDE)
  api.nvim_command('vertical resize '..WIN_WIDTH)
  api.nvim_win_set_buf(0, buf)

  api.nvim_command('setlocal winhighlight=EndOfBuffer:LuaTreeEndOfBuffer,Normal:LuaTreeNormal,CursorLine:LuaTreeCursorLine,VertSplit:LuaTreeVertSplit')
  for _, opt in pairs(BUF_OPTIONS) do
    api.nvim_command('setlocal '..opt)
  end
  if SIDE == 'L' then
    api.nvim_command('setlocal nosplitright')
  else
    api.nvim_command('setlocal splitright')
  end
end

function M.replace_tree()
  local win = M.get_win()
  if not win then return end

  local tree_position = api.nvim_win_get_position(win)
  local win_width = api.nvim_win_get_width(win)
  if win_width == WIN_WIDTH then
    if SIDE == 'H' and tree_position[2] == 0 then return end
    local columns = api.nvim_get_option('columns')
    if SIDE == 'L' and tree_position[2] ~= columns - win_width then return end
  end

  local current_win = api.nvim_get_current_win()

  api.nvim_set_current_win(win)
  api.nvim_command('wincmd '..SIDE)
  api.nvim_command('vertical resize '..WIN_WIDTH)

  api.nvim_set_current_win(current_win)
end

function M.close()
  local win = M.get_win()
  if not win then return end

  api.nvim_win_close(win, true)
end

function M.update_view(update_cursor)
  local buf = M.get_buf();
  if not buf then return end

  local cursor = api.nvim_win_get_cursor(0)
  local tree = get_tree()

  api.nvim_buf_set_option(buf, 'modifiable', true)
  api.nvim_buf_set_lines(buf, 0, -1, false, format(tree))
  highlight(buf, tree)
  api.nvim_buf_set_option(buf, 'modifiable', false)

  if update_cursor == true then
    api.nvim_win_set_cursor(0, cursor)
  end
end

function M.set_mappings()
  local buf = M.get_buf()
  if not buf then return end

  local mappings = {
    ['<2-LeftMouse>'] = 'open_file("edit")';
    ['<2-RightMouse>'] = 'open_file("chdir")';
    [bindings.edit] = 'open_file("edit")';
    [bindings.edit_vsplit] = 'open_file("vsplit")';
    [bindings.edit_split] = 'open_file("split")';
    [bindings.edit_tab] = 'open_file("tabnew")';
    [bindings.cd] = 'open_file("chdir")';
    [bindings.create] = 'edit_file("create")';
    [bindings.remove] = 'edit_file("remove")';
    [bindings.rename] = 'edit_file("rename")';
  }

  for k,v in pairs(mappings) do
    api.nvim_buf_set_keymap(buf, 'n', k, ':lua require"tree".'..v..'<cr>', {
        nowait = true, noremap = true, silent = true
      })
  end
end

function M.is_win_open()
  return M.get_buf() ~= nil
end

return M