local M = {}
local config = require('chatgpt_nvim.config')
local conf = config.load()

local debug_bufnr = nil
if conf.improved_debug then
  debug_bufnr = vim.api.nvim_create_buf(false, true)
  vim.api.nvim_buf_set_name(debug_bufnr, "ChatGPT_Debug_Log")
  vim.api.nvim_buf_set_option(debug_bufnr, "filetype", "log")
end

function M.debug_log(msg)
  if conf.improved_debug and debug_bufnr then
    vim.api.nvim_buf_set_lines(debug_bufnr, -1, -1, false, { msg })
  else
    if conf.debug then
      vim.api.nvim_out_write("[chatgpt_nvim:debug] " .. msg .. "\n")
    end
  end
end

function M.pick_directories(dirs)
  local selected_dirs = {}
  local lines = { "Delete lines for directories you do NOT want, then :wq" }
  for _, d in ipairs(dirs) do
    table.insert(lines, d)
  end

  local bufnr = vim.api.nvim_create_buf(false, false)
  vim.api.nvim_buf_set_name(bufnr, "ChatGPT_File_Selection")
  vim.api.nvim_buf_set_option(bufnr, "filetype", "markdown")
  vim.api.nvim_buf_set_option(bufnr, "bufhidden", "wipe")
  vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines)

  local function on_write()
    local new_lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
    local final_dirs = {}
    for _, l in ipairs(new_lines) do
      if l ~= "" and not l:match("^Delete lines") and not l:match("^#") then
        table.insert(final_dirs, l)
      end
    end
    selected_dirs = final_dirs
    vim.api.nvim_buf_set_option(bufnr, "modified", false)
  end

  vim.api.nvim_create_autocmd("BufWriteCmd", {
    buffer = bufnr,
    once = true,
    callback = on_write
  })

  vim.cmd("split")
  vim.cmd("buffer " .. bufnr)

  -- Wait up to 30s for user to close
  vim.wait(30000, function()
    local winids = vim.api.nvim_tabpage_list_wins(0)
    for _, w in ipairs(winids) do
      local b = vim.api.nvim_win_get_buf(w)
      if b == bufnr then
        return false
      end
    end
    return true
  end)

  return selected_dirs
end

-- A function to chunk a long string if it exceeds token_limit
-- We'll just do rough splits by lines or paragraphs.
function M.chunkify(text, estimate_tokens_fn, token_limit)
  local lines = vim.split(text, "\n")
  local chunks = {}
  local current_chunk = {}
  local current_text = ""

  for _, line in ipairs(lines) do
    local test_text = (current_text == "") and line or (current_text .. "\n" .. line)
    local est_tokens = estimate_tokens_fn(test_text)
    if est_tokens > token_limit then
      -- push current chunk
      table.insert(chunks, current_text)
      -- start a new chunk
      current_text = line
    else
      current_text = test_text
    end
  end

  if current_text ~= "" then
    table.insert(chunks, current_text)
  end

  return chunks
end

return M