local M = {}

local context = require('chatgpt_nvim.context')
local handler = require('chatgpt_nvim.handler')
local config = require('chatgpt_nvim.config')

local ok_yaml, lyaml = pcall(require, "lyaml")

local function copy_to_clipboard(text)
  vim.fn.setreg('+', text)
end

local function parse_response(raw)
  local conf = config.load()
  if not ok_yaml then
    vim.api.nvim_err_writeln("lyaml not available. Install with `luarocks install lyaml`.")
    return nil
  end
  local ok, data = pcall(lyaml.load, raw)
  if not ok or not data then
    vim.api.nvim_err_writeln("Failed to parse YAML response.")
    if conf.debug then
      vim.api.nvim_out_write("[chatgpt_nvim:init] RAW response that failed parsing:\n" .. raw .. "\n")
    end
    return nil
  end
  if conf.debug then
    vim.api.nvim_out_write("[chatgpt_nvim:init] Successfully parsed YAML response.\n")
  end
  return data
end

-- A simple token estimation function (approx. 4 chars per token)
local function estimate_tokens(text)
  local approx_chars_per_token = 4
  local length = #text
  return math.floor(length / approx_chars_per_token)
end

local function is_subpath(root, path)
  local root_abs = vim.fn.fnamemodify(root, ":p")
  local target_abs = vim.fn.fnamemodify(path, ":p")
  return target_abs:sub(1, #root_abs) == root_abs
end

-- We'll store requested files in a global variable for now, though a more robust solution might be needed.
local requested_files = {}

function M.run_chatgpt_command()
  local conf = config.load()
  if conf.debug then
    vim.api.nvim_out_write("[chatgpt_nvim:init] Running :ChatGPT command.\n")
  end
  local user_input = vim.fn.input("Message for O1 Model: ")
  if user_input == "" then
    print("No input provided.")
    return
  end

  local dirs = conf.directories or {"."}
  local project_structure = context.get_project_structure(dirs)

  local initial_sections = {
    conf.initial_prompt .. "\n" .. user_input,
    "\n\nProject name: " .. (conf.project_name or "") .. "\n",
    "\n\nProject Structure:\n",
    project_structure,
    "\n\nPlease respond with a YAML listing which files you need from the project. For example:\n",
    "project_name: " .. (conf.project_name or "") .. "\nfiles:\n  - path: \"relative/path/to/file\"\n\n"
  }

  local prompt = table.concat(initial_sections, "\n")

  local token_limit = conf.token_limit or 8000
  local token_count = estimate_tokens(prompt)

  if conf.debug then
    vim.api.nvim_out_write("[chatgpt_nvim:init] Prompt token count: " .. token_count .. "\n")
  end

  if token_count > token_limit then
    print("Too many files in project structure. The request exceeds the O1 model limit of " .. token_limit .. " tokens.")
    return
  end

  copy_to_clipboard(prompt)
  print("Prompt (requesting needed files) copied to clipboard! Paste it into the ChatGPT O1 model.")
end

function M.run_chatgpt_paste_command()
  local conf = config.load()
  if conf.debug then
    vim.api.nvim_out_write("[chatgpt_nvim:init] Running :ChatGPTPaste command.\n")
  end
  print("Reading ChatGPT YAML response from clipboard...")
  local raw = handler.get_clipboard_content()
  if raw == "" then
    vim.api.nvim_err_writeln("Clipboard is empty. Please copy the YAML response from ChatGPT first.")
    return
  end

  local data = parse_response(raw)
  if not data then
    return
  end

  if data.project_name and data.files then
    if conf.debug then
      vim.api.nvim_out_write("[chatgpt_nvim:init] Received project_name and files from response.\n")
    end
    local is_final = false
    for _, fileinfo in ipairs(data.files) do
      if fileinfo.content or fileinfo.delete == true then
        is_final = true
        break
      end
    end

    if is_final then
      if data.project_name ~= conf.project_name then
        vim.api.nvim_err_writeln("Project name mismatch. The provided changes are for project '" ..
          (data.project_name or "unknown") .. "' but current project is '" ..
          (conf.project_name or "unconfigured") .. "'. Aborting changes.")
        return
      end

      local root = vim.fn.getcwd()

      for _, fileinfo in ipairs(data.files) do
        if not fileinfo.path then
          vim.api.nvim_err_writeln("Invalid file entry. Must have 'path'.")
          goto continue
        end

        if not is_subpath(root, fileinfo.path) then
          vim.api.nvim_err_writeln("Invalid file path outside project root: " .. fileinfo.path)
          goto continue
        end

        if fileinfo.delete == true then
          if conf.debug then
            vim.api.nvim_out_write("[chatgpt_nvim:init] Deleting file: " .. fileinfo.path .. "\n")
          end
          handler.delete_file(fileinfo.path)
          print("Deleted file: " .. fileinfo.path)
        elseif fileinfo.content then
          if conf.debug then
            vim.api.nvim_out_write("[chatgpt_nvim:init] Writing file: " .. fileinfo.path .. "\n")
          end
          handler.write_file(fileinfo.path, fileinfo.content)
          print("Wrote file: " .. fileinfo.path)
        else
          vim.api.nvim_err_writeln("Invalid file entry. Must have 'content' or 'delete' set to true for final changes.")
        end
        ::continue::
      end

      return
    else
      -- Not final: the model is requesting these files. We must gather and send them.
      local dirs = conf.directories or {"."}
      local all_files = context.get_project_files(dirs)
      local requested_paths = {}
      for _, fileinfo in ipairs(data.files) do
        if fileinfo.path then
          table.insert(requested_paths, fileinfo.path)
        end
      end

      local file_sections = {}
      local root = vim.fn.getcwd()

      for _, f in ipairs(requested_paths) do
        local full_path = root .. "/" .. f
        local fd = vim.loop.fs_open(full_path, "r", 438)
        if fd then
          local stat = vim.loop.fs_fstat(fd)
          if stat then
            local content = vim.loop.fs_read(fd, stat.size, 0)
            vim.loop.fs_close(fd)
            if content then
              table.insert(file_sections, "\nFile: `" .. f .. "`\n```\n" .. content .. "\n```\n")
            end
          else
            vim.loop.fs_close(fd)
          end
        else
          table.insert(file_sections, "\nFile: `" .. f .. "`\n```\n(Could not read file)\n```\n")
        end
      end

      local sections = {
        conf.initial_prompt,
        "\n\nProject name: " .. (conf.project_name or ""),
        "\n\nBelow are the requested files from the project, each preceded by its filename in backticks and enclosed in triple backticks.\n",
        table.concat(file_sections, "\n"),
        "\n\nIf you need more files, please respond again in YAML listing additional files. If you have all information you need, provide the final YAML with `project_name` and `files` (with `content` or `delete`) to apply changes.\n"
      }

      local prompt = table.concat(sections, "\n")

      local token_limit = conf.token_limit or 8000
      local token_count = estimate_tokens(prompt)

      if conf.debug then
        vim.api.nvim_out_write("[chatgpt_nvim:init] Returning requested files. Token count: " .. token_count .. "\n")
      end

      if token_count > token_limit then
        vim.api.nvim_err_writeln("Too many requested files. Exceeds token limit.")
        return
      end

      copy_to_clipboard(prompt)
      print("Prompt (with requested files) copied to clipboard! Paste it into the ChatGPT O1 model.")
    end
  else
    vim.api.nvim_err_writeln("Invalid response. Expected 'project_name' and 'files'.")
  end
end

return M