import tailwindcss from '@tailwindcss/vite';
import { sveltekit } from '@sveltejs/kit/vite';
import * as fflate from 'fflate';
import { readFileSync, writeFileSync, existsSync } from 'fs';
import { resolve } from 'path';
import { defineConfig } from 'vite';
import devtoolsJson from 'vite-plugin-devtools-json';
import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';

const GUIDE_FOR_FRONTEND = `
<!--
  This is a single file build of the frontend.
  It is automatically generated by the build process.
  Do not edit this file directly.
  To make changes, refer to the "Web UI" section in the README.
-->
`.trim();

const MAX_BUNDLE_SIZE = 2 * 1024 * 1024;

/**
 * the maximum size of an embedded asset in bytes,
 * e.g. maximum size of embedded font (see node_modules/katex/dist/fonts/*.woff2)
 */
const MAX_ASSET_SIZE = 32000;

/** public/index.html.gz minified flag */
const ENABLE_JS_MINIFICATION = true;

function llamaCppBuildPlugin() {
	return {
		name: 'llamacpp:build',
		apply: 'build' as const,
		closeBundle() {
			// Ensure the SvelteKit adapter has finished writing to ../public
			setTimeout(() => {
				try {
					const indexPath = resolve('../public/index.html');
					const gzipPath = resolve('../public/index.html.gz');

					if (!existsSync(indexPath)) {
						return;
					}

					let content = readFileSync(indexPath, 'utf-8');

					const faviconPath = resolve('static/favicon.svg');
					if (existsSync(faviconPath)) {
						const faviconContent = readFileSync(faviconPath, 'utf-8');
						const faviconBase64 = Buffer.from(faviconContent).toString('base64');
						const faviconDataUrl = `data:image/svg+xml;base64,${faviconBase64}`;

						content = content.replace(/href="[^"]*favicon\.svg"/g, `href="${faviconDataUrl}"`);

						console.log('✓ Inlined favicon.svg as base64 data URL');
					}

					content = content.replace(/\r/g, '');
					content = GUIDE_FOR_FRONTEND + '\n' + content;

					const compressed = fflate.gzipSync(Buffer.from(content, 'utf-8'), { level: 9 });

					compressed[0x4] = 0;
					compressed[0x5] = 0;
					compressed[0x6] = 0;
					compressed[0x7] = 0;
					compressed[0x9] = 0;

					if (compressed.byteLength > MAX_BUNDLE_SIZE) {
						throw new Error(
							`Bundle size is too large (${Math.ceil(compressed.byteLength / 1024)} KB).\n` +
								`Please reduce the size of the frontend or increase MAX_BUNDLE_SIZE in vite.config.ts.\n`
						);
					}

					writeFileSync(gzipPath, compressed);
					console.log('✓ Created index.html.gz');
				} catch (error) {
					console.error('Failed to create gzip file:', error);
				}
			}, 100);
		}
	};
}

export default defineConfig({
	resolve: {
		alias: {
			'katex-fonts': resolve('node_modules/katex/dist/fonts')
		}
	},
	build: {
		assetsInlineLimit: MAX_ASSET_SIZE,
		chunkSizeWarningLimit: 3072,
		minify: ENABLE_JS_MINIFICATION
	},
	css: {
		preprocessorOptions: {
			scss: {
				additionalData: `
					$use-woff2: true;
					$use-woff: false;
					$use-ttf: false;
				`
			}
		}
	},
	plugins: [tailwindcss(), sveltekit(), devtoolsJson(), llamaCppBuildPlugin()],
	test: {
		projects: [
			{
				extends: './vite.config.ts',
				test: {
					name: 'client',
					environment: 'browser',
					browser: {
						enabled: true,
						provider: 'playwright',
						instances: [{ browser: 'chromium' }]
					},
					include: ['src/**/*.svelte.{test,spec}.{js,ts}'],
					exclude: ['src/lib/server/**'],
					setupFiles: ['./vitest-setup-client.ts']
				}
			},
			{
				extends: './vite.config.ts',
				test: {
					name: 'server',
					environment: 'node',
					include: ['src/**/*.{test,spec}.{js,ts}'],
					exclude: ['src/**/*.svelte.{test,spec}.{js,ts}']
				}
			},
			{
				extends: './vite.config.ts',
				test: {
					name: 'ui',
					environment: 'browser',
					browser: {
						enabled: true,
						provider: 'playwright',
						instances: [{ browser: 'chromium', headless: true }]
					},
					include: ['src/**/*.stories.{js,ts,svelte}'],
					setupFiles: ['./.storybook/vitest.setup.ts']
				},
				plugins: [
					storybookTest({
						storybookScript: 'pnpm run storybook --no-open'
					})
				]
			}
		]
	},

	server: {
		proxy: {
			'/v1': 'http://localhost:8080',
			'/props': 'http://localhost:8080',
			'/slots': 'http://localhost:8080'
		},
		headers: {
			'Cross-Origin-Embedder-Policy': 'require-corp',
			'Cross-Origin-Opener-Policy': 'same-origin'
		}
	}
});
