#!/usr/bin/env node

import { createServer } from 'node:http';
import { readFile } from 'node:fs/promises';
import { extname, relative, resolve, sep } from 'node:path';
import { fileURLToPath } from 'node:url';
import {
  DEFAULT_BASE_URL,
  ExternalAgentParser,
  blockedResult
} from './external-agent-client.mjs';

const rootDir = resolve(import.meta.dirname);
const port = Number(process.env.PORT || 8765);

const contentTypes = {
  '.css': 'text/css; charset=utf-8',
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.md': 'text/markdown; charset=utf-8',
  '.mjs': 'text/javascript; charset=utf-8',
  '.png': 'image/png'
};

export function createExternalParserFromEnv({ fetchImpl = globalThis.fetch } = {}) {
  return new ExternalAgentParser({
    baseUrl: process.env.DEERFLOW_BASE_URL || DEFAULT_BASE_URL,
    apiKey: process.env.DEERFLOW_OPEN_API_KEY,
    fetchImpl,
    timeoutMs: parseTimeout(process.env.PARSER_REQUEST_TIMEOUT_MS),
    totalTimeoutMs: parseTimeout(process.env.PARSER_TOTAL_TIMEOUT_MS || '180000')
  });
}

export function createBusinessServer({ parser = createExternalParserFromEnv() } = {}) {
  return createServer(async (req, res) => {
    try {
      const requestUrl = new URL(req.url || '/', `http://${req.headers.host || '127.0.0.1'}`);
      if (req.method === 'GET' && requestUrl.pathname === '/api/status') {
        const aiProbe = typeof parser.checkConnection === 'function'
          ? await parser.checkConnection()
          : {
            ok: Boolean(process.env.DEERFLOW_OPEN_API_KEY),
            configured: Boolean(process.env.DEERFLOW_OPEN_API_KEY),
            reachable: false,
            error_code: 'status_probe_unavailable'
          };
        sendJson(res, 200, {
          ok: true,
          service: 'external_parse_api',
          ai_configured: Boolean(aiProbe.configured),
          ai_connected: Boolean(aiProbe.ok),
          ai_probe: aiProbe
        });
        return;
      }
      if (req.method === 'POST' && requestUrl.pathname === '/api/parse') {
        const payload = await readRequestJson(req);
        const result = await parser.parse({
          rawText: payload.raw_text,
          taskId: payload.task_id,
          receivedAt: payload.received_at
        });
        sendJson(res, 200, result);
        return;
      }
      if (req.method !== 'GET' && req.method !== 'HEAD') {
        sendJson(res, 405, { error: 'method_not_allowed' });
        return;
      }
      await serveStatic(req, res, requestUrl);
    } catch (error) {
      if (error?.code === 'invalid_json') {
        sendJson(res, 400, blockedResult(['请求体不是有效 JSON。'], { error_code: error.code }));
        return;
      }
      sendJson(res, 500, {
        error: 'server_error',
        message: error.message || String(error)
      });
    }
  });
}

export async function readRequestJson(req) {
  const chunks = [];
  for await (const chunk of req) chunks.push(chunk);
  const body = Buffer.concat(chunks).toString('utf8');
  if (!body.trim()) return {};
  try {
    return JSON.parse(body);
  } catch (error) {
    const invalidJsonError = new Error('request body must be valid JSON');
    invalidJsonError.code = 'invalid_json';
    throw invalidJsonError;
  }
}

async function serveStatic(req, res, requestUrl) {
  const pathname = decodeURIComponent(requestUrl.pathname || '/');
  const requestedPath = pathname === '/' ? 'index.html' : pathname.replace(/^\/+/, '');
  const filePath = resolve(rootDir, requestedPath);
  const relativePath = relative(rootDir, filePath);
  if (relativePath.startsWith('..') || relativePath.includes(`..${sep}`)) {
    res.writeHead(403);
    res.end('Forbidden');
    return;
  }
  try {
    const body = await readFile(filePath);
    res.writeHead(200, {
      'Content-Type': contentTypes[extname(filePath)] || 'application/octet-stream',
      'Content-Length': body.byteLength
    });
    if (req.method === 'HEAD') res.end();
    else res.end(body);
  } catch (error) {
    res.writeHead(404, { 'Content-Type': 'text/plain; charset=utf-8' });
    res.end('Not found');
  }
}

function sendJson(res, status, data) {
  const body = `${JSON.stringify(data, null, 2)}\n`;
  res.writeHead(status, {
    'Content-Type': 'application/json; charset=utf-8',
    'Content-Length': Buffer.byteLength(body)
  });
  res.end(body);
}

function parseTimeout(value) {
  const timeout = Number(value);
  return Number.isFinite(timeout) && timeout > 0 ? timeout : 120_000;
}

function isMainModule() {
  return process.argv[1] && resolve(process.argv[1]) === fileURLToPath(import.meta.url);
}

if (isMainModule()) {
  const server = createBusinessServer();
  server.listen(port, '127.0.0.1', () => {
    console.log(`Business system listening on http://127.0.0.1:${port}/`);
    if (!process.env.DEERFLOW_OPEN_API_KEY) {
      console.warn('External parsing service is not configured: set DEERFLOW_OPEN_API_KEY in the server environment.');
    }
  });
}