-- lua/nuwiki/ftplugin.lua — per-buffer hookup invoked by
-- `ftplugin/nuwiki.vim`. Centralises the Lua side of the per-buffer
-- glue so the VimL ftplugin stays a one-liner regardless of which subgroups are
-- enabled.

local M = {}

local function setup_folding(bufnr, folding_mode)
  if folding_mode == 'off' then
    return
  end
  -- `foldmethod` / `foldexpr` / `foldtext` are window-local options.
  -- The ftplugin runs during BufRead → FileType, by which time the
  -- buffer is displayed in the current window. `vim.opt_local` writes
  -- to the current window's view of the option.
  -- The LSP foldexpr is wrapped via `nuwiki.folding.lsp_expr` so a
  -- transient client failure (e.g. server still starting, buffer not
  -- yet attached) degrades to the regex variant instead of spamming
  -- the user with E5108 errors per line.
  local apply = function()
    if folding_mode == 'expr'
       or not (vim.fn.has('nvim-0.11') == 1 and vim.lsp.foldexpr)
    then
      vim.opt_local.foldmethod = 'expr'
      vim.opt_local.foldexpr = 'v:lua.require("nuwiki.folding").expr()'
      vim.opt_local.foldtext = 'v:lua.require("nuwiki.folding").foldtext()'
    else
      vim.opt_local.foldmethod = 'expr'
      vim.opt_local.foldexpr = 'v:lua.require("nuwiki.folding").lsp_expr()'
      vim.opt_local.foldtext = 'v:lua.require("nuwiki.folding").foldtext()'
    end
  end

  -- Set on the current window first (the one that triggered the
  -- ftplugin). Also re-apply on any future split that views this
  -- buffer, so `<C-w>v` / `:split` preserves the fold method.
  apply()
  -- Start with every heading-block fold open. `foldlevel` is window-local
  -- but only sets the initial state; once the user closes folds with `zc`
  -- those stay closed, so we don't re-apply this on BufWinEnter.
  vim.opt_local.foldlevel = 99
  vim.api.nvim_create_autocmd('BufWinEnter', {
    buffer = bufnr,
    group = vim.api.nvim_create_augroup('nuwiki_folding_' .. bufnr, { clear = true }),
    callback = apply,
  })
end

-- vimwiki `autowriteall`: while this wiki buffer is current, mirror the option
-- into Vim's global 'autowriteall' (auto-save on switch/make), restoring the
-- prior value on leave.
local function setup_autowriteall(bufnr, enabled)
  if not enabled then
    return
  end
  if bufnr == 0 then
    bufnr = vim.api.nvim_get_current_buf()
  end
  local grp = vim.api.nvim_create_augroup('nuwiki_awa_' .. bufnr, { clear = true })
  local function enter()
    vim.b[bufnr].nuwiki_awa_saved = vim.o.autowriteall
    vim.o.autowriteall = true
  end
  local function leave()
    local saved = vim.b[bufnr].nuwiki_awa_saved
    if saved ~= nil then
      vim.o.autowriteall = saved
    end
  end
  vim.api.nvim_create_autocmd('BufEnter', { buffer = bufnr, group = grp, callback = enter })
  vim.api.nvim_create_autocmd('BufLeave', { buffer = bufnr, group = grp, callback = leave })
  -- FileType fires after the initial BufEnter, so apply once now too.
  enter()
end

-- vimwiki `table_auto_fmt`: re-align the table under the cursor on InsertLeave.
local function setup_table_auto_fmt(bufnr, enabled)
  if not enabled then
    return
  end
  if bufnr == 0 then
    bufnr = vim.api.nvim_get_current_buf()
  end
  local grp = vim.api.nvim_create_augroup('nuwiki_taf_' .. bufnr, { clear = true })
  vim.api.nvim_create_autocmd('InsertLeave', {
    buffer = bufnr,
    group = grp,
    callback = function()
      -- Cheap guard: only round-trip to the server on a table row.
      if vim.api.nvim_get_current_line():find('|', 1, true) then
        require('nuwiki.commands').table_align()
      end
    end,
  })
end

-- vimwiki `auto_chdir`: `:lcd` into the owning wiki's root while this buffer
-- is current.
local function setup_auto_chdir(bufnr, enabled)
  if not enabled then
    return
  end
  if bufnr == 0 then
    bufnr = vim.api.nvim_get_current_buf()
  end
  local function chdir()
    local file = vim.api.nvim_buf_get_name(bufnr)
    local root = require('nuwiki.config').wiki_root_for(file)
    if root then
      vim.cmd('lcd ' .. vim.fn.fnameescape(root))
    end
  end
  local grp = vim.api.nvim_create_augroup('nuwiki_chdir_' .. bufnr, { clear = true })
  vim.api.nvim_create_autocmd({ 'BufEnter', 'BufWinEnter' }, {
    buffer = bufnr,
    group = grp,
    callback = chdir,
  })
  chdir()
end

function M.attach(bufnr)
  bufnr = bufnr or 0
  local config = require('nuwiki.config')
  local opts = config.options or config.defaults

  if opts.mappings and opts.mappings.enabled ~= false then
    require('nuwiki.keymaps').attach(bufnr, opts.mappings)
    if opts.mappings.text_objects ~= false then
      require('nuwiki.textobjects').attach(bufnr)
    end
  end

  setup_folding(bufnr, opts.folding or 'lsp')
  setup_autowriteall(bufnr, opts.autowriteall ~= false)
  setup_table_auto_fmt(bufnr, opts.table_auto_fmt ~= false)
  setup_auto_chdir(bufnr, opts.auto_chdir == true)
end

return M