local lock_path = vim.fs.joinpath(vim.fn.stdpath('config'), 'paq-lock.json')
local paq_removed_status = 3

local function clone_paq()
  local path = vim.fn.stdpath('data') .. '/site/pack/paqs/opt/paq-nvim'
  if not vim.uv.fs_stat(path) then
    local repo = 'https://github.com/savq/paq-nvim.git'
    local result = vim.system({ 'git', 'clone', '--depth=1', repo, path }):wait()
    if result.code == 0 then
      print('Package manager installed correctly')
    end
  end
end

local function load_paq()
  vim.cmd.packadd('paq-nvim')
  local paq = require('paq')
  local packages = require('setup.packages').get()
  paq:setup({ lock = lock_path })(packages)
  return paq
end

local function run_paq(event, operation)
  local done = false
  vim.api.nvim_create_autocmd('User', {
    pattern = event,
    once = true,
    callback = function()
      done = true
    end,
  })

  operation()

  vim.wait(60000, function()
    return done
  end, 200)

  return done
end

local function install_packages()
  clone_paq()

  local paq = load_paq()
  if not run_paq('PaqDoneInstall', paq.install) then
    print('Paq installation timeout or failed')
  else
    print('Paq installation completed')
  end
end

local function assert_no_unlisted_package_dirs(paq)
  local expected_dirs = {}
  for _, filter in ipairs({ 'installed', 'to_install' }) do
    for _, pkg in ipairs(paq.query(filter)) do
      expected_dirs[pkg.dir] = true
    end
  end

  local stale_dirs = {}
  local paq_path = vim.fs.joinpath(vim.fn.stdpath('data'), 'site', 'pack', 'paqs')
  for _, packdir in ipairs({ 'start', 'opt' }) do
    local path = vim.fs.joinpath(paq_path, packdir)
    if vim.uv.fs_stat(path) then
      for name, type in vim.fs.dir(path) do
        local dir = vim.fs.joinpath(path, name)
        if type == 'directory' and not expected_dirs[dir] then
          table.insert(stale_dirs, dir)
        end
      end
    end
  end

  if #stale_dirs > 0 then
    error('Paq cleanup left unlisted package directories:\n' .. table.concat(stale_dirs, '\n'))
  end
end

local function prune_removed_lock_entries()
  if vim.fn.filereadable(lock_path) == 0 then
    return
  end

  local raw = table.concat(vim.fn.readfile(lock_path), '\n')
  local lock = vim.json.decode(raw)
  local changed = false

  for name, pkg in pairs(lock) do
    if pkg.status == paq_removed_status then
      lock[name] = nil
      changed = true
    end
  end

  if changed then
    vim.fn.writefile({ vim.json.encode(lock) }, lock_path)
  end
end

local function reconcile_packages()
  clone_paq()

  local paq = load_paq()
  if not run_paq('PaqDoneRemove', paq.clean) then
    print('Paq cleanup timeout or failed')
    return
  end
  assert_no_unlisted_package_dirs(paq)
  prune_removed_lock_entries()

  if not run_paq('PaqDoneInstall', paq.install) then
    print('Paq installation timeout or failed')
  else
    print('Paq packages reconciled')
  end
end

local function install_languages()
  vim.cmd.packadd('mason.nvim')
  require('mason').setup()

  local lm = require('plugins.language-manager')
  lm.invalidate_cache()
  lm.load_specs()
  lm.install()
end

local function sync_packages()
  clone_paq()
  local paq = load_paq()
  if not run_paq('PaqDoneSync', function()
    paq:sync()
  end) then
    print('Paq sync timeout or failed')
  else
    print('Paq sync completed')
  end
end

local function fetch_lsp_configs()
  local base_url = 'https://raw.githubusercontent.com/neovim/nvim-lspconfig/refs/heads/master/lsp/'

  local lm = require('plugins.language-manager')
  lm.invalidate_cache()
  local general = lm.load_specs()

  local lsp_dir = vim.fs.joinpath(vim.fn.stdpath('config'), 'lsp')
  vim.fn.mkdir(lsp_dir, 'p')

  for _, name in ipairs(general.language_servers or {}) do
    local file = vim.fs.joinpath(lsp_dir, name .. '.lua')
    if vim.fn.filereadable(file) == 0 then
      local url = base_url .. name .. '.lua'
      local cmd = string.format('curl -fsSL -o %q %q', file, url)
      vim.fn.system(cmd)
      if vim.v.shell_error ~= 0 then
        vim.notify('Failed to fetch ' .. name .. '.lua', vim.log.levels.ERROR)
        vim.fn.delete(file)
      else
        vim.notify('Fetched ' .. name .. '.lua', vim.log.levels.INFO)
      end
    else
      vim.notify('Skipped existing ' .. name .. '.lua', vim.log.levels.INFO)
    end
  end
end

local function create_command(name, callback, desc)
  vim.api.nvim_create_user_command(name, callback, { desc = desc })
end

create_command('Setup', function()
  print('> Reconciling packages...')
  reconcile_packages()
  print('\n> Installing languages: treesitter parsers, language servers, linters, formatters...')
  install_languages()
  print('\n=== Setup Finished ===\n')
end, 'Install packages and language tooling (first-time setup)')

create_command('InstallPackages', function()
  print('> Installing packages...')
  install_packages()
  print('\n=== Package Install Finished ===\n')
end, 'Install packages via Paq')

create_command('InstallLanguages', function()
  print('> Installing languages: treesitter parsers, language servers, linters, formatters...')
  install_languages()
  print('\n=== Language Install Finished ===\n')
end, 'Install treesitter, LSP, linter, and formatter tooling')

create_command('Sync', sync_packages, 'Sync packages with Paq')
create_command('FetchLspConfigs', fetch_lsp_configs, 'Fetch default LSP configs into lsp/')