const express = require('express');
const fs = require('fs');
const path = require('path');
const http = require('http');
const { exec } = require('child_process');
const multer = require('multer');

const app = express();
const PORT = process.env.PORT || 4080;
const TILE_CACHE_URL = (process.env.TILE_CACHE_URL || '').trim();

const ROOT_DIR = path.join(__dirname, '..');
const CONFIG_DIR = process.env.CONFIG_DIR || null;
const TARGETS_CSV = CONFIG_DIR ? path.join(CONFIG_DIR, 'targets.csv') : null;

const upload = multer({ storage: multer.memoryStorage() });

// 内存模式（与 central-server 一起跑、无挂载时）：存一份 targets 的解析结果
const DEFAULT_HEADER = ['type', 'ip', 'name', 'role', 'parent', 'uplink_type', 'network', 'device_type', 'model', 'location', 'username', 'password', 'onvif_port', 'lat', 'lon'];
let memoryStore = {
  comments: ['# 统一监控 + 拓扑目标配置文件\n', '# 格式: type,ip,name,role,parent,uplink_type,...\n'],
  header: DEFAULT_HEADER,
  rows: [],
};

function isFileMode() {
  return CONFIG_DIR && TARGETS_CSV && fs.existsSync(TARGETS_CSV);
}

app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

function parseCsv(text) {
  const lines = text.split(/\r?\n/);
  const comments = [];
  let headerLineIndex = -1;

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i].trim();
    if (!line || line.startsWith('#')) {
      comments.push(lines[i]);
      continue;
    }
    headerLineIndex = i;
    break;
  }

  if (headerLineIndex === -1) {
    return { comments: lines, header: DEFAULT_HEADER, rows: [] };
  }

  const header = lines[headerLineIndex].split(',').map(s => s.trim());
  const rows = [];

  for (let i = headerLineIndex + 1; i < lines.length; i++) {
    const raw = lines[i];
    if (!raw || raw.trim().startsWith('#')) continue;
    const parts = raw.split(',');
    const obj = {};
    header.forEach((h, idx) => {
      obj[h] = (parts[idx] || '').trim();
    });
    if (Object.values(obj).every(v => v === '')) continue;
    rows.push(obj);
  }

  return { comments, header, rows };
}

function stringifyCsv(comments, header, rows) {
  const lines = [];
  if (comments && comments.length) {
    lines.push(...comments);
  }
  if (header && header.length) {
    lines.push(header.join(','));
  }
  for (const row of rows) {
    const line = header.map(h => (row[h] || '').replace(/,/g, ' ')).join(',');
    lines.push(line);
  }
  return lines.join('\n') + '\n';
}

function loadTargets() {
  if (isFileMode()) {
    const text = fs.readFileSync(TARGETS_CSV, 'utf8');
    return parseCsv(text);
  }
  return { ...memoryStore, rows: [...memoryStore.rows] };
}

function saveTargets(parsed) {
  if (isFileMode()) {
    const text = stringifyCsv(parsed.comments, parsed.header, parsed.rows);
    fs.writeFileSync(TARGETS_CSV, text, 'utf8');
    return;
  }
  memoryStore = {
    comments: parsed.comments || memoryStore.comments,
    header: parsed.header || memoryStore.header,
    rows: parsed.rows || memoryStore.rows,
  };
}

function rebuildConfigs() {
  if (!CONFIG_DIR) return;
  const cmd = `cd "${CONFIG_DIR}" && ./update-configs.sh && ./csv-to-topology-geojson.sh targets.csv topology.geojson`;
  exec(cmd, (err, stdout, stderr) => {
    if (err) {
      console.error('重建配置失败:', err.message);
      if (stderr) console.error(stderr);
      return;
    }
    if (stdout) console.log(stdout);
  });
}

app.get('/api/targets', (req, res) => {
  try {
    const parsed = loadTargets();
    res.json(parsed.rows);
  } catch (e) {
    console.error(e);
    res.status(500).json({ error: '读取 targets 失败' });
  }
});

app.get('/api/mode', (req, res) => {
  res.json({ mode: isFileMode() ? 'file' : 'memory' });
});

app.get('/api/map-config', (req, res) => {
  res.json({ cacheBaseUrl: TILE_CACHE_URL ? '/tiles' : '' });
});

function proxyToTileCache(pathname, res) {
  const url = TILE_CACHE_URL + pathname;
  const u = new URL(url);
  const client = u.protocol === 'https:' ? require('https') : require('http');
  client.get(url, (proxyRes) => {
    res.status(proxyRes.statusCode || 200);
    if (proxyRes.headers['content-type']) res.setHeader('Content-Type', proxyRes.headers['content-type']);
    if (proxyRes.headers['cache-control']) res.setHeader('Cache-Control', proxyRes.headers['cache-control']);
    proxyRes.pipe(res);
  }).on('error', (err) => {
    res.status(502).json({ error: 'Tile cache unreachable: ' + err.message });
  });
}

app.get('/tiles/vec/:z/:x/:y', (req, res) => {
  if (!TILE_CACHE_URL) return res.status(503).send('Tile cache not configured');
  proxyToTileCache(`/vec/${req.params.z}/${req.params.x}/${req.params.y}`, res);
});

app.get('/tiles/cva/:z/:x/:y', (req, res) => {
  if (!TILE_CACHE_URL) return res.status(503).send('Tile cache not configured');
  proxyToTileCache(`/cva/${req.params.z}/${req.params.x}/${req.params.y}`, res);
});

app.get('/api/download', (req, res) => {
  try {
    const parsed = loadTargets();
    const text = stringifyCsv(parsed.comments, parsed.header, parsed.rows);
    res.setHeader('Content-Type', 'text/csv; charset=utf-8');
    res.setHeader('Content-Disposition', 'attachment; filename=targets.csv');
    res.send(text);
  } catch (e) {
    console.error(e);
    res.status(500).json({ error: '生成下载失败' });
  }
});

app.post('/api/upload', upload.single('file'), (req, res) => {
  try {
    if (!req.file || !req.file.buffer) {
      return res.status(400).json({ error: '请选择 CSV 文件上传' });
    }
    const text = req.file.buffer.toString('utf8');
    const parsed = parseCsv(text);
    if (!isFileMode()) {
      memoryStore = parsed;
    } else {
      saveTargets(parsed);
    }
    res.json({ ok: true, rows: parsed.rows.length });
  } catch (e) {
    console.error(e);
    res.status(500).json({ error: '解析 CSV 失败' });
  }
});

app.post('/api/targets', (req, res) => {
  try {
    const {
      type = '',
      ip = '',
      name = '',
      role = '',
      parent = '',
      uplink_type = '',
      network = '',
      device_type = '',
      model = '',
      location = '',
      username = '',
      password = '',
      onvif_port = '',
      lat = '',
      lon = '',
    } = req.body || {};

    if (!type || !name) {
      return res.status(400).json({ error: 'type 与 name 为必填字段' });
    }

    const parsed = loadTargets();
    const { header, rows } = parsed;

    const idx = rows.findIndex((r) => r.name === name);
    const row = {};
    header.forEach((h) => {
      row[h] = '';
    });

    Object.assign(row, {
      type,
      ip,
      name,
      role,
      parent,
      uplink_type,
      network,
      device_type,
      model,
      location,
      username,
      password,
      onvif_port,
      lat,
      lon,
    });

    if (idx >= 0) {
      rows[idx] = row;
    } else {
      rows.push(row);
    }

    saveTargets({ ...parsed, rows });
    rebuildConfigs();

    res.json({ ok: true, row });
  } catch (e) {
    console.error(e);
    res.status(500).json({ error: '写入失败' });
  }
});

app.listen(PORT, '0.0.0.0', () => {
  console.log(`Topology editor listening on http://0.0.0.0:${PORT}`);
  if (CONFIG_DIR) {
    console.log(`CONFIG_DIR=${CONFIG_DIR} (file mode)`);
  } else {
    console.log('Running in memory mode: use Upload CSV / Download CSV');
  }
});