-- lua/plugins/pdf-viewer.lua
-- PDF viewer using pdftoppm + image.nvim (kitty/magick backend)
-- Requires: poppler (brew install poppler), kitty terminal

return {
  '3rd/image.nvim',
  opts = {
    backend = 'kitty',
    processor = 'magick_cli',
    integrations = {
      markdown = { enabled = true },
    },
  },
  config = function(_, opts)
    local image = require 'image'
    image.setup(opts)

    local pdf_state = {}

    -- Open PDF: convert all pages to PNG via pdftoppm, then display page 1
    vim.api.nvim_create_autocmd('BufReadPost', {
      pattern = '*.pdf',
      callback = function()
        local pdf_path = vim.fn.expand '%:p'
        local temp_dir = vim.fn.tempname()
        vim.fn.mkdir(temp_dir, 'p')
        local bufnr = vim.api.nvim_get_current_buf()

        vim.notify('Converting PDF…', vim.log.levels.INFO)

        vim.fn.jobstart({ 'pdftoppm', '-png', pdf_path, temp_dir .. '/page' }, {
          on_exit = function(_, code)
            vim.schedule(function()
              if code ~= 0 then
                vim.notify('Failed to convert PDF', vim.log.levels.ERROR)
                return
              end

              -- Count pages
              local handle = vim.loop.fs_scandir(temp_dir)
              local page_count = 0
              if handle then
                while true do
                  local name = vim.loop.fs_scandir_next(handle)
                  if not name then break end
                  if name:match '^page%-%d+%.png$' then page_count = page_count + 1 end
                end
              end

              pdf_state[bufnr] = { temp_dir = temp_dir, current_page = 1, total_pages = page_count }

              local function show_page(page_num)
                local state = pdf_state[bufnr]
                if not state then return end
                image.clear()
                vim.bo[bufnr].modifiable = true
                vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, { '' })
                vim.bo[bufnr].modifiable = false
                local page_file = string.format('%s/page-%02d.png', state.temp_dir, page_num)
                local img = image.from_file(page_file, { buffer = bufnr })
                if img then
                  img:render()
                  vim.notify(string.format('Page %d / %d', page_num, state.total_pages), vim.log.levels.INFO)
                else
                  vim.notify('Failed to load page ' .. page_num, vim.log.levels.ERROR)
                end
              end

              local function change_page(delta)
                local state = pdf_state[bufnr]
                if not state then return end
                local new_page = state.current_page + delta
                if new_page < 1 or new_page > state.total_pages then return end
                state.current_page = new_page
                show_page(new_page)
              end

              -- Buffer-local navigation keys
              local map = function(lhs, fn, desc)
                vim.keymap.set('n', lhs, fn, { buffer = bufnr, desc = desc })
              end
              map('j',       function() change_page(1) end,  'PDF: next page')
              map('k',       function() change_page(-1) end, 'PDF: previous page')
              map('<Right>', function() change_page(1) end,  'PDF: next page')
              map('<Left>',  function() change_page(-1) end, 'PDF: previous page')
              map('q', '<cmd>bd!<cr>', 'PDF: close')

              show_page(1)
            end)
          end,
        })
      end,
    })

    -- Cleanup temp files on buffer close
    vim.api.nvim_create_autocmd('BufDelete', {
      pattern = '*.pdf',
      callback = function(args)
        if pdf_state[args.buf] then
          image.clear()
          vim.fn.delete(pdf_state[args.buf].temp_dir, 'rf')
          pdf_state[args.buf] = nil
        end
      end,
    })
  end,
}