import adapter from '@sveltejs/adapter-static';
import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
import fs from 'fs';
import path from 'path';

/** @type {import('@sveltejs/kit').Config} */
const config = {
	// Consult https://svelte.dev/docs/kit/integrations
	// for more information about preprocessors
	preprocess: vitePreprocess(),
	kit: {
		// fallback: the SPA shell served for routes that were not prerendered
		// (unlisted cities, GPS coordinate routes); the universal load then
		// resolves the location client-side. Most static hosts serve 404.html
		// for unknown paths automatically.
		adapter: adapter({ fallback: '404.html' }),
		// Pregenerate city pages to improve SEO during static build
		prerender: {
			// dynamic per-location routes (14-day, compare, unlisted cities) are
			// served by the SPA fallback instead of being prerendered
			handleUnseenRoutes: 'ignore',
			// a transient geocoding failure for one city should skip that page
			// (the fallback still serves it), not abort the whole build
			handleHttpError: ({ path, message }) => {
				console.warn(`prerender skipped ${path}: ${message}`);
			},
			entries: (() => {
				try {
					const citiesPath = path.resolve('src/routes/weather/locations/city-names100.json');
					const raw = fs.readFileSync(citiesPath, 'utf-8');
					const cities = JSON.parse(raw);
					if (Array.isArray(cities)) {
						const cityEntries = cities.map((c) => `/weather/week/${c}`);
						// Keep the default wildcard to include other routes
						return ['*', ...cityEntries];
					}
				} catch {
					// If anything goes wrong, fall back to default behavior
				}
				return ['*'];
			})()
		}
	}
};

export default config;