import express from 'express';
import fs from 'fs/promises';
import { existsSync } from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import {
  deleteDocumentByFileName,
  getDatabasePath,
  getDocumentByFileName,
  getDocumentById,
  getVocabCards,
  initDatabase,
  listDocuments,
  migrateSavesToDatabase,
  sanitizeSaveName,
  saveDocument,
} from './db.js';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const PROJECT_ROOT = path.resolve(__dirname, '..');
const PORT = Number(process.env.PORT || 3002);
const HOST = process.env.HOST || '0.0.0.0';
const DIST_DIR = path.resolve(PROJECT_ROOT, 'dist');
const SAVES_DIR = path.resolve(process.env.SAVES_DIR || path.join(PROJECT_ROOT, 'saves'));

const app = express();

app.use((req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', process.env.CORS_ORIGIN || '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET,POST,DELETE,OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (req.method === 'OPTIONS') {
    res.sendStatus(204);
    return;
  }

  next();
});

app.use(express.json({ limit: '10mb' }));

const ensureSavesDir = async () => {
  await fs.mkdir(SAVES_DIR, { recursive: true });
};

const getSaveFilePath = (name) => path.join(SAVES_DIR, sanitizeSaveName(name));

app.get('/api/health', (_req, res) => {
  res.json({
    ok: true,
    savesDir: SAVES_DIR,
    database: getDatabasePath(),
  });
});

app.get('/api/saves', async (_req, res) => {
  try {
    await ensureSavesDir();
    const files = await listDocuments();
    res.json({ files });
  } catch (error) {
    console.error('Failed to list save files', error);
    res.status(500).json({ error: 'Failed to list save files' });
  }
});

app.get('/api/saves/:fileName', async (req, res) => {
  try {
    await ensureSavesDir();
    const document = await getDocumentByFileName(req.params.fileName);
    if (document) {
      res.json(document);
      return;
    }

    const filePath = getSaveFilePath(req.params.fileName);
    if (!existsSync(filePath)) {
      res.status(404).json({ error: 'Save file not found' });
      return;
    }

    const content = await fs.readFile(filePath, 'utf-8');
    res.type('application/json').send(content);
  } catch (error) {
    console.error('Failed to read save file', error);
    res.status(500).json({ error: 'Failed to read save file' });
  }
});

app.post('/api/saves', async (req, res) => {
  try {
    await ensureSavesDir();
    const fileName = sanitizeSaveName(req.body?.name || 'current');
    const document = req.body?.document;

    if (!document || typeof document !== 'object') {
      res.status(400).json({ error: 'Missing document payload' });
      return;
    }

    const filePath = path.join(SAVES_DIR, fileName);
    await fs.writeFile(filePath, JSON.stringify(document, null, 2), 'utf-8');
    const file = await saveDocument({ name: fileName, document });
    res.json({ file });
  } catch (error) {
    console.error('Failed to save document', error);
    res.status(500).json({ error: 'Failed to save document' });
  }
});

app.delete('/api/saves/:fileName', async (req, res) => {
  try {
    await ensureSavesDir();
    const filePath = getSaveFilePath(req.params.fileName);
    if (!existsSync(filePath)) {
      res.status(404).json({ error: 'Save file not found' });
      return;
    }

    await fs.unlink(filePath);
    await deleteDocumentByFileName(req.params.fileName);
    res.json({ ok: true });
  } catch (error) {
    console.error('Failed to delete save file', error);
    res.status(500).json({ error: 'Failed to delete save file' });
  }
});

app.get('/api/documents', async (_req, res) => {
  try {
    const files = await listDocuments();
    res.json({ files });
  } catch (error) {
    console.error('Failed to list documents', error);
    res.status(500).json({ error: 'Failed to list documents' });
  }
});

app.get('/api/documents/:id', async (req, res) => {
  try {
    const document = await getDocumentById(req.params.id);
    if (!document) {
      res.status(404).json({ error: 'Document not found' });
      return;
    }
    res.json(document);
  } catch (error) {
    console.error('Failed to read document', error);
    res.status(500).json({ error: 'Failed to read document' });
  }
});

app.post('/api/documents', async (req, res) => {
  try {
    const document = req.body?.document;
    if (!document || typeof document !== 'object') {
      res.status(400).json({ error: 'Missing document payload' });
      return;
    }

    const file = await saveDocument({ name: req.body?.name || document.title || 'current', document });
    await ensureSavesDir();
    await fs.writeFile(path.join(SAVES_DIR, file.name), JSON.stringify(document, null, 2), 'utf-8');
    res.json({ file });
  } catch (error) {
    console.error('Failed to save document', error);
    res.status(500).json({ error: 'Failed to save document' });
  }
});

app.get('/api/vocab', async (_req, res) => {
  try {
    const cards = await getVocabCards();
    res.json({ cards });
  } catch (error) {
    console.error('Failed to list vocab cards', error);
    res.status(500).json({ error: 'Failed to list vocab cards' });
  }
});

app.get('/api/vocab/:term', async (req, res) => {
  try {
    const cards = await getVocabCards();
    const card = cards.find((item) => item.normalizedText === req.params.term || item.text === req.params.term);
    if (!card) {
      res.status(404).json({ error: 'Vocab card not found' });
      return;
    }
    res.json({ card });
  } catch (error) {
    console.error('Failed to read vocab card', error);
    res.status(500).json({ error: 'Failed to read vocab card' });
  }
});

if (existsSync(DIST_DIR)) {
  app.use(express.static(DIST_DIR));
  app.get('*', (req, res, next) => {
    if (req.path.startsWith('/api/')) {
      next();
      return;
    }
    res.sendFile(path.join(DIST_DIR, 'index.html'));
  });
} else {
  app.get('*', (_req, res) => {
    res.status(503).send('Frontend dist not found. Run `npm run build` before starting the server.');
  });
}

await initDatabase();
await ensureSavesDir();
const migratedFiles = await migrateSavesToDatabase(SAVES_DIR);

app.listen(PORT, HOST, () => {
  console.log(`Kotonoha server listening on http://${HOST}:${PORT}`);
  console.log(`Serving frontend from: ${DIST_DIR}`);
  console.log(`Using saves directory: ${SAVES_DIR}`);
  console.log(`Using SQLite database: ${getDatabasePath()}`);
  console.log(`Indexed save files: ${migratedFiles.length}`);
});