local map = vim.keymap.set
local last_file_buf
local previous_file_buf

local function is_real_file_buffer(buf)
  return vim.api.nvim_buf_is_valid(buf)
    and vim.bo[buf].buflisted
    and vim.bo[buf].buftype == ''
    and vim.bo[buf].filetype ~= 'netrw'
    and vim.api.nvim_buf_get_name(buf) ~= ''
end

local function is_netrw_buffer(buf)
  if not vim.api.nvim_buf_is_valid(buf) then
    return false
  end

  return vim.bo[buf].filetype == 'netrw' or vim.api.nvim_buf_get_name(buf):match('NetrwTreeListing$') ~= nil
end

local function switch_to_buffer(buf)
  vim.cmd('buffer ' .. buf)
end

local function switch_to_native_alternate()
  pcall(vim.cmd, 'buffer #')
end

local function jump_to_alternate_file()
  local alternate = vim.fn.bufnr('#')

  if is_real_file_buffer(alternate) then
    switch_to_buffer(alternate)
    return
  end

  if is_netrw_buffer(alternate) and is_real_file_buffer(previous_file_buf) then
    switch_to_buffer(previous_file_buf)
    return
  end

  switch_to_native_alternate()
end

-- Netrw configuration for file browsing
-- Native Neovim file explorer (no plugins required)

-- Hide the banner (that annoying help text at the top)
vim.g.netrw_banner = 0

-- Tree view by default (3 = tree style)
-- Options: 0=thin, 1=long, 2=wide, 3=tree
vim.g.netrw_liststyle = 3

-- Preview in horizontal split (underneath)
vim.g.netrw_preview = 0

-- Open preview splits below (1=below, 0=above)
vim.g.netrw_alto = 0

-- Window size for preview splits (percentage for preview window)
-- 50% split when pressing 'p'
vim.g.netrw_winsize = 50

-- Keep working directory unchanged when browsing (1 = don't change directory)
-- Setting to 1 prevents netrw from changing vim's working directory
vim.g.netrw_keepdir = 1

-- Open files in the same window (replace netrw buffer)
-- Options: 0=same window, 1=horizontal split, 2=vertical split, 3=new tab, 4=previous window
-- Using 0 so Enter opens file in netrw window itself
vim.g.netrw_browse_split = 0

-- Sort order: name (empty), time (t), size (s), exten (e)
vim.g.netrw_sort_by = 'name'

-- Hide dotfiles by default (toggle with 'gh' in netrw)
vim.g.netrw_list_hide = [[^\.\.\=/\=$]]

-- Use human-readable file sizes
vim.g.netrw_sizestyle = 'H'

-- Netrw file explorer keymaps
-- Open netrw in new tab at current file's directory
map('n', '<leader>nt', function()
  local current_file_dir = vim.fn.expand('%:p:h')
  vim.cmd('tabnew')
  vim.cmd('Explore ' .. vim.fn.fnameescape(current_file_dir))
end, { desc = 'Netrw: Tab at current file dir', silent = true })

-- Open netrw in new tab at project root (stored at startup)
map('n', '<leader>nT', function()
  vim.cmd('tabnew')
  vim.cmd('Explore ' .. vim.fn.fnameescape(vim.g.project_root))
end, { desc = 'Netrw: Tab at project root', silent = true })

-- Open netrw in current window at project root (stored at startup)
map('n', '<leader>nr', function()
  vim.cmd('Explore ' .. vim.fn.fnameescape(vim.g.project_root))
end, { desc = 'Netrw: Open at project root', silent = true })

map('n', '<C-6>', jump_to_alternate_file, { desc = 'Buffer: Alternate file skipping netrw', silent = true })
map('n', '<C-^>', jump_to_alternate_file, { desc = 'Buffer: Alternate file skipping netrw', silent = true })

vim.api.nvim_create_autocmd('BufEnter', {
  desc = 'Track recent real file buffers for alternate-buffer jumps',
  callback = function(args)
    local buf = args.buf

    if is_real_file_buffer(buf) and buf ~= last_file_buf then
      previous_file_buf = last_file_buf
      last_file_buf = buf
    end
  end,
})

-- Enable line numbers in netrw buffers
vim.api.nvim_create_autocmd('FileType', {
  pattern = 'netrw',
  desc = 'Configure netrw buffer-local options',
  callback = function()
    vim.bo.buflisted = false
    vim.opt_local.number = true
    vim.opt_local.relativenumber = true
  end,
})