overlay.lua

local Overlay = {}

function Overlay:new(events)
  local instance = {
    _events = events,
    _logger = require('diffusion.utils.logger'):child('Overlay'),
    chat_buf = nil,
    input_buf = nil,
    chat_win = nil,
    input_win = nil,
    layout = nil,
  }
  setmetatable(instance, { __index = self })
  return instance
end

function Overlay:_create_buffers()
  if not self.chat_buf or not vim.api.nvim_buf_is_valid(self.chat_buf) then
    self.chat_buf = vim.api.nvim_create_buf(false, true)
    vim.api.nvim_buf_set_option(self.chat_buf, 'buftype', 'nofile')
    vim.api.nvim_buf_set_option(self.chat_buf, 'swapfile', false)
    vim.api.nvim_buf_set_name(self.chat_buf, 'Diffusion Output')
  end
  if not self.input_buf or not vim.api.nvim_buf_is_valid(self.input_buf) then
    self.input_buf = vim.api.nvim_create_buf(false, true)
    vim.api.nvim_buf_set_option(self.input_buf, 'buftype', 'prompt')
    vim.api.nvim_buf_set_option(self.input_buf, 'swapfile', false)
    vim.fn.prompt_setprompt(self.input_buf, '› ')
  end
end

function Overlay:_open_windows()
  local ui = vim.api.nvim_list_uis()[1]
  local width = math.floor(ui.width * 0.5)
  local height = math.floor(ui.height * 0.4)
  local col = math.floor((ui.width - width) / 2)
  local row = math.floor(ui.height - height - 2)

  -- Chat window (top part)
  self.chat_win = vim.api.nvim_open_win(self.chat_buf, false, {
    relative = 'editor', width = width, height = height - 3,
    row = row, col = col, style = 'minimal', border = 'rounded'
  })
  vim.api.nvim_win_set_option(self.chat_win, 'wrap', true)
  vim.api.nvim_win_set_option(self.chat_win, 'cursorline', false)

  -- Input window (bottom line)
  self.input_win = vim.api.nvim_open_win(self.input_buf, true, {
    relative = 'editor', width = width, height = 1,
    row = row + height - 2, col = col, style = 'minimal', border = 'rounded'
  })
end

function Overlay:show()
  self:_create_buffers()
  self:_open_windows()

  -- Map <CR> on prompt buffer to send message
  vim.keymap.set('n', '<CR>', function()
    self:submit_input()
  end, { buffer = self.input_buf, nowait = true })

  vim.keymap.set('i', '<CR>', function()
    self:submit_input()
  end, { buffer = self.input_buf, nowait = true })
end

function Overlay:append_output(prefix, text)
  if not (self.chat_buf and vim.api.nvim_buf_is_valid(self.chat_buf)) then return end
  local lines = vim.split(text or '', '\n', { plain = true })
  local prefixed = {}
  for _, l in ipairs(lines) do table.insert(prefixed, string.format('%s %s', prefix, l)) end
  local last = vim.api.nvim_buf_line_count(self.chat_buf)
  vim.api.nvim_buf_set_lines(self.chat_buf, last, last, false, prefixed)
  if self.chat_win and vim.api.nvim_win_is_valid(self.chat_win) then
    vim.api.nvim_win_set_cursor(self.chat_win, { vim.api.nvim_buf_line_count(self.chat_buf), 0 })
  end
end

function Overlay:submit_input()
  local line = table.concat(vim.api.nvim_buf_get_lines(self.input_buf, 0, -1, false), '\n')
  line = line:gsub('^›%s*', '')
  if line == '' then return end
  self:append_output('You:', line)
  -- Clear prompt buffer
  vim.api.nvim_buf_set_lines(self.input_buf, 0, -1, false, { '' })
  -- Send to provider
  local ok, mod = pcall(require, 'diffusion')
  if ok and mod then
    mod.send_message(line)
  end
end

function Overlay:close()
  if self.input_win and vim.api.nvim_win_is_valid(self.input_win) then pcall(vim.api.nvim_win_close, self.input_win, true) end
  if self.chat_win and vim.api.nvim_win_is_valid(self.chat_win) then pcall(vim.api.nvim_win_close, self.chat_win, true) end
  self.input_win, self.chat_win = nil, nil
  if self.input_buf and vim.api.nvim_buf_is_valid(self.input_buf) then pcall(vim.api.nvim_buf_delete, self.input_buf, { force = true }) end
  if self.chat_buf and vim.api.nvim_buf_is_valid(self.chat_buf) then pcall(vim.api.nvim_buf_delete, self.chat_buf, { force = true }) end
  self.input_buf, self.chat_buf = nil, nil
end

return Overlay