const express = require('express');
const fs = require('fs');
const path = require('path');
const { success } = require('../response-helpers');
const { ValidationError, NotFoundError } = require('../errors');

/**
 * Themes routes factory
 * @param {Object} deps - Explicit dependencies
 * @param {Function} deps.asyncHandler - Async route handler wrapper
 * @param {Object} deps.log - Logger instance
 * @returns {express.Router}
 */
module.exports = function({ asyncHandler, log }) {
  const router = express.Router();
  const THEMES_DIR = process.env.THEMES_DIR || path.join(path.dirname(process.env.SERVICES_FILE || '/app/services.json'), 'themes');

  // Ensure themes directory exists
  if (!fs.existsSync(THEMES_DIR)) {
    fs.mkdirSync(THEMES_DIR, { recursive: true });
  }

  function readAllThemes() {
    const themes = {};
    try {
      const files = fs.readdirSync(THEMES_DIR).filter(f => f.endsWith('.json'));
      for (const file of files) {
        const slug = path.basename(file, '.json');
        const data = JSON.parse(fs.readFileSync(path.join(THEMES_DIR, file), 'utf8'));
        themes[slug] = data;
      }
    } catch (e) {
      log.error('themes', 'Failed to read themes', { error: e.message });
    }
    return themes;
  }

  // Get all user themes
  router.get('/themes', (req, res) => {
    success(res, { themes: readAllThemes() });
  });

  // Save a theme (create or update)
  router.post('/themes/:slug', asyncHandler(async (req, res) => {
    const { slug } = req.params;
    const { name, colors, lightBg } = req.body;

    if (!slug || !name || !colors) {
      throw new ValidationError('Missing slug, name, or colors');
    }

    if (!/^[a-z0-9-]+$/.test(slug)) {
      throw new ValidationError('Invalid slug format (use lowercase letters, numbers, and hyphens only)', 'slug');
    }

    const themeData = { name, ...colors };
    if (lightBg) themeData.lightBg = true;
    fs.writeFileSync(path.join(THEMES_DIR, slug + '.json'), JSON.stringify(themeData, null, 2), 'utf8');

    success(res, { message: name + ' theme saved' });
  }));

  // Delete a theme
  router.delete('/themes/:slug', asyncHandler(async (req, res) => {
    const { slug } = req.params;
    const filePath = path.join(THEMES_DIR, slug + '.json');

    if (!fs.existsSync(filePath)) {
      throw new NotFoundError(`Theme ${slug}`);
    }

    const data = JSON.parse(fs.readFileSync(filePath, 'utf8'));
    const name = data.name || slug;
    fs.unlinkSync(filePath);

    success(res, { message: name + ' theme deleted' });
  }));

  return router;
};