import express from "express";
import fs from "fs";
import path from "path";
import { fileURLToPath } from "url";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();

// Trust proxy - CRITICAL for reverse proxy setup
app.set('trust proxy', true);

app.use(express.json());

// Logging middleware
app.use((req, res, next) => {
  console.log(`${req.method} ${req.url} - ${req.headers['x-forwarded-proto'] || 'http'}`);
  next();
});

// CRITICAL: Serve static files with proper headers
app.use(express.static(path.join(__dirname, "public"), {
  setHeaders: (res, filepath) => {
    if (filepath.endsWith('.js')) {
      res.setHeader('Content-Type', 'application/javascript; charset=utf-8');
    }
    if (filepath.endsWith('.json')) {
      res.setHeader('Content-Type', 'application/json; charset=utf-8');
    }
    if (filepath.endsWith('service-worker.js')) {
      res.setHeader('Service-Worker-Allowed', '/');
      res.setHeader('Cache-Control', 'no-cache');
    }
  }
}));

const stateFile = path.join(__dirname, "state.json");

// --------------------
// Konfiguration
// --------------------
const CONFIG = {
  A: {
    name: "Marc",
    color: 0x2ecc71,
    icon: "a.png"
  },
  B: {
    name: "Laila",
    color: 0xe74c3c,
    icon: "b.png"
  }
};

const PUBLIC_BASE_URL = process.env.PUBLIC_BASE_URL || "http://localhost:3000";
const DISCORD_WEBHOOK_URL = process.env.DISCORD_WEBHOOK_URL || "https://discord.com/api/webhooks/1450872860607381515/zRbiXOykKPUfLJ_H87wD2OxQJPLdro6yQzU2T48Pg4fxSNaXEqBFgxdHGTiIDmmKGHIF";

// --------------------
// State Handling
// --------------------
function getState() {
  if (!fs.existsSync(stateFile)) {
    fs.writeFileSync(
      stateFile,
      JSON.stringify({ current: "A", lastReason: null }, null, 2)
    );
  }
  return JSON.parse(fs.readFileSync(stateFile, "utf-8"));
}

function setState(newState) {
  fs.writeFileSync(stateFile, JSON.stringify(newState, null, 2));
}

// --------------------
// Discord Webhook
// --------------------
async function sendDiscordEmbed(previousKey, currentKey, reason) {
  const previous = CONFIG[previousKey];
  const current = CONFIG[currentKey];

  if (!DISCORD_WEBHOOK_URL) return;

  const fields = [
    {
      name: "Von",
      value: previous.name,
      inline: true
    },
    {
      name: "Zu",
      value: current.name,
      inline: true
    }
  ];

  if (reason) {
    fields.push({
      name: "📝 Grund",
      value: reason,
      inline: false
    });
  }

  const embed = {
    title: "💸 Zahl-Wechsel",
    description: `**${current.name}** ist jetzt dran zu zahlen`,
    color: current.color,
    thumbnail: {
      url: `${PUBLIC_BASE_URL}/img/${current.icon}`
    },
    fields: fields,
    footer: {
      text: new Date().toLocaleString("de-DE")
    }
  };

  try {
    await fetch(DISCORD_WEBHOOK_URL, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ embeds: [embed] })
    });
    console.log("✅ Discord Benachrichtigung gesendet");
  } catch (err) {
    console.error("❌ Discord Webhook Fehler:", err.message);
  }
}

// --------------------
// API Routes
// --------------------

app.get("/status", (req, res) => {
  res.json(getState());
});

app.post("/toggle", async (req, res) => {
  const state = getState();
  const previousKey = state.current;
  const reason = req.body?.reason;

  state.current = state.current === "A" ? "B" : "A";
  state.lastReason = reason || null;
  setState(state);

  const logMessage = reason
    ? `Zahl-Wechsel: ${CONFIG[previousKey].name} → ${CONFIG[state.current].name} (Grund: ${reason})`
    : `Zahl-Wechsel: ${CONFIG[previousKey].name} → ${CONFIG[state.current].name}`;
  
  console.log(logMessage);

  await sendDiscordEmbed(previousKey, state.current, reason);

  res.json({
    current: state.current,
    name: CONFIG[state.current].name,
    lastReason: state.lastReason
  });
});

app.get("/health", (req, res) => {
  res.json({ status: "ok" });
});

// --------------------
// SPA Fallback - NO CRASH
// --------------------
// Only serve index.html for navigation requests, not for missing static files
app.use((req, res, next) => {
  // If request already handled by static middleware, skip
  if (res.headersSent) return;
  
  // If it's an API route that wasn't matched, 404
  if (req.url.startsWith('/api/')) {
    return res.status(404).json({ error: 'Not found' });
  }
  
  // If Accept header indicates browser navigation (HTML), serve index.html
  const acceptsHtml = req.accepts('html');
  if (acceptsHtml) {
    return res.sendFile(path.join(__dirname, "public/index.html"));
  }
  
  // Otherwise 404
  res.status(404).send('Not found');
});

// Error handler to prevent crashes
app.use((err, req, res, next) => {
  console.error('Server error:', err);
  res.status(500).json({ error: 'Internal server error' });
});

// --------------------
// Start
// --------------------
const PORT = process.env.PORT || 3000;
app.listen(PORT, "0.0.0.0", () => {
  console.log(`\n✅ WhoPays läuft auf http://0.0.0.0:${PORT}\n`);
  console.log(`📁 Static files directory: ${path.join(__dirname, "public")}`);
  console.log(`🔒 Trust proxy: enabled (for reverse proxy support)`);
  
  // Verify critical files exist
  const criticalFiles = [
    'public/index.html',
    'public/service-worker.js',
    'public/manifest.json'
  ];
  
  console.log('\n🔍 Checking critical files:');
  criticalFiles.forEach(file => {
    const fullPath = path.join(__dirname, file);
    const exists = fs.existsSync(fullPath);
    console.log(`   ${exists ? '✅' : '❌'} ${file}`);
  });
  
  console.log('\n📝 Test URLs (adjust domain for your setup):');
  console.log(`   http://localhost:${PORT}/`);
  console.log(`   http://localhost:${PORT}/service-worker.js`);
  console.log(`   http://localhost:${PORT}/manifest.json\n`);
});