import tailwindcss from '@tailwindcss/vite';
import react from '@vitejs/plugin-react';
import fs from 'fs/promises';
import { existsSync } from 'fs';
import path from 'path';
import { defineConfig, Plugin } from 'vite';
import {
  deleteDocumentByFileName,
  getDocumentByFileName,
  getDocumentById,
  getVocabCards,
  initDatabase,
  listDocuments,
  migrateSavesToDatabase,
  saveDocument,
} from './server/db.js';

const SAVES_DIR = path.resolve(__dirname, 'saves');

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

const sanitizeSaveName = (name: string) => {
  const cleaned = name
    .replace(/\.json$/i, '')
    .replace(/[<>:"/\\|?*\x00-\x1F]/g, '_')
    .trim();
  return `${cleaned || `save-${Date.now()}`}.json`;
};

const readJsonBody = async (req: any) => {
  const chunks: Buffer[] = [];
  for await (const chunk of req) {
    chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
  }
  const raw = Buffer.concat(chunks).toString('utf-8');
  return raw ? JSON.parse(raw) : {};
};

const sendJson = (res: any, statusCode: number, payload: unknown) => {
  res.statusCode = statusCode;
  res.setHeader('Content-Type', 'application/json; charset=utf-8');
  res.end(JSON.stringify(payload));
};

const localSavesPlugin = (): Plugin => ({
  name: 'local-saves-api',
  configureServer(server) {
    const ready = (async () => {
      await initDatabase();
      await ensureSavesDir();
      await migrateSavesToDatabase(SAVES_DIR);
    })();

    server.middlewares.use(async (req, res, next) => {
      if (!req.url?.startsWith('/api/saves') && !req.url?.startsWith('/api/documents') && !req.url?.startsWith('/api/vocab')) {
        next();
        return;
      }

      try {
        await ready;
        await ensureSavesDir();
        const url = new URL(req.url, 'http://localhost');
        const fileNameFromPath = decodeURIComponent(url.pathname.replace(/^\/api\/saves\/?/, ''));

        if (req.method === 'GET' && url.pathname === '/api/saves') {
          const files = await listDocuments();
          sendJson(res, 200, { files });
          return;
        }

        if (req.method === 'GET' && url.pathname.startsWith('/api/saves/') && fileNameFromPath) {
          const fileName = sanitizeSaveName(fileNameFromPath);
          const document = await getDocumentByFileName(fileName);
          if (document) {
            sendJson(res, 200, document);
            return;
          }

          const filePath = path.join(SAVES_DIR, fileName);
          if (!existsSync(filePath)) {
            sendJson(res, 404, { error: 'Save file not found' });
            return;
          }

          const content = await fs.readFile(filePath, 'utf-8');
          sendJson(res, 200, JSON.parse(content));
          return;
        }

        if (req.method === 'POST' && url.pathname === '/api/saves') {
          const body = await readJsonBody(req);
          const fileName = sanitizeSaveName(String(body.name || 'current'));
          const document = body.document;
          if (!document || typeof document !== 'object') {
            sendJson(res, 400, { 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 });
          sendJson(res, 200, { file });
          return;
        }

        if (req.method === 'DELETE' && url.pathname.startsWith('/api/saves/') && fileNameFromPath) {
          const fileName = sanitizeSaveName(fileNameFromPath);
          const filePath = path.join(SAVES_DIR, fileName);
          if (!existsSync(filePath)) {
            sendJson(res, 404, { error: 'Save file not found' });
            return;
          }
          await fs.unlink(filePath);
          await deleteDocumentByFileName(fileName);
          sendJson(res, 200, { ok: true });
          return;
        }

        if (req.method === 'GET' && url.pathname === '/api/documents') {
          const files = await listDocuments();
          sendJson(res, 200, { files });
          return;
        }

        if (req.method === 'GET' && url.pathname.startsWith('/api/documents/')) {
          const id = decodeURIComponent(url.pathname.replace(/^\/api\/documents\/?/, ''));
          const document = await getDocumentById(id);
          if (!document) {
            sendJson(res, 404, { error: 'Document not found' });
            return;
          }
          sendJson(res, 200, document);
          return;
        }

        if (req.method === 'POST' && url.pathname === '/api/documents') {
          const body = await readJsonBody(req);
          const document = body.document;
          if (!document || typeof document !== 'object') {
            sendJson(res, 400, { error: 'Missing document payload' });
            return;
          }
          const file = await saveDocument({ name: String(body.name || document.title || 'current'), document });
          await fs.writeFile(path.join(SAVES_DIR, file.name), JSON.stringify(document, null, 2), 'utf-8');
          sendJson(res, 200, { file });
          return;
        }

        if (req.method === 'GET' && url.pathname === '/api/vocab') {
          const cards = await getVocabCards();
          sendJson(res, 200, { cards });
          return;
        }

        if (req.method === 'GET' && url.pathname.startsWith('/api/vocab/')) {
          const term = decodeURIComponent(url.pathname.replace(/^\/api\/vocab\/?/, ''));
          const cards = await getVocabCards();
          const card = cards.find((item: any) => item.normalizedText === term || item.text === term);
          if (!card) {
            sendJson(res, 404, { error: 'Vocab card not found' });
            return;
          }
          sendJson(res, 200, { card });
          return;
        }

        sendJson(res, 405, { error: 'Unsupported saves API request' });
      } catch (error) {
        console.error(error);
        sendJson(res, 500, { error: 'Local saves API failed' });
      }
    });
  },
});

export default defineConfig(() => {
  return {
    base: './',
    plugins: [react(), tailwindcss(), localSavesPlugin()],
    resolve: {
      alias: {
        '@': path.resolve(__dirname, '.'),
      },
    },
    server: {
      // HMR is disabled in AI Studio via DISABLE_HMR env var.
      // Do not modify—file watching is disabled to prevent flickering during agent edits.
      hmr: process.env.DISABLE_HMR !== 'true',
      // Disable file watching when DISABLE_HMR is true to save CPU during agent edits.
      watch: process.env.DISABLE_HMR === 'true' ? null : {},
    },
  };
});