import { NEWLINE, TAB } from '../src/lib/constants/code';
import { APPLE_DEVICES, BUILD_CONFIG, REGEX_PATTERNS, SPLASH_LINK } from '../src/lib/constants/pwa';
import { SplashOrientation } from '../src/lib/enums/splash.enums';
import type { SplashDimensions } from '../src/lib/types';
import { existsSync, readdirSync, readFileSync, writeFileSync } from 'node:fs';
import { resolve } from 'path';
import type { Plugin } from 'vite';

let processed = false;

const OUTPUT_DIR = process.env.LLAMA_UI_OUT_DIR ?? BUILD_CONFIG.OUTPUT_DIR;

/**
 * Generate iOS splash screen <link> tags from generated apple-splash-*.png files.
 * Returns an array of HTML link strings to be injected into the page head.
 */
export function generateSplashScreenLinks(outDir: string): string[] {
	const files = readdirSync(outDir).filter((f) => f.match(REGEX_PATTERNS.SPLASH_FILE));

	if (files.length === 0) return [];

	const dimMap = new Map<string, SplashDimensions>();

	for (const [dims, spec] of Object.entries(APPLE_DEVICES)) {
		const [w, h] = dims.split('x').map(Number);

		// logical-point dimensions
		dimMap.set(`${w}x${h}`, { deviceH: spec.height, deviceW: spec.width, dpr: spec.dpr });
		dimMap.set(`${h}x${w}`, { deviceH: spec.height, deviceW: spec.width, dpr: spec.dpr });
		// pixel dimensions (used by actual generated splash files)
		dimMap.set(`${w * spec.dpr}x${h * spec.dpr}`, {
			deviceH: spec.height,
			deviceW: spec.width,
			dpr: spec.dpr
		});
		dimMap.set(`${h * spec.dpr}x${w * spec.dpr}`, {
			deviceH: spec.height,
			deviceW: spec.width,
			dpr: spec.dpr
		});
	}

	const lightLinks: string[] = [];
	const darkLinks: string[] = [];

	for (const file of files) {
		const match = file.match(REGEX_PATTERNS.SPLASH_FILE);

		if (!match) continue;

		const orientation = match[1] as SplashOrientation;
		const isDark = !!match[2];
		const pixelW = parseInt(match[3]);
		const pixelH = parseInt(match[4]);
		const key = `${pixelW}x${pixelH}`;
		const spec = dimMap.get(key);

		if (!spec) {
			console.warn(`Unknown splash screen dimensions: ${key} (${file})`);

			continue;
		}

		const { deviceH, deviceW, dpr } = spec;
		const media = `screen and (device-width: ${deviceW}px) and (device-height: ${deviceH}px) and (-webkit-device-pixel-ratio: ${dpr}) and (orientation: ${orientation})`;
		const href = `./${file}`;

		if (isDark) {
			darkLinks.push(
				`${SPLASH_LINK.HTML} media="${media}${SPLASH_LINK.DARK_MEDIA_SUFFIX}" href="${href}">`
			);
		} else {
			lightLinks.push(`${SPLASH_LINK.HTML} media="${media}" href="${href}">`);
		}
	}

	return [...lightLinks, ...darkLinks];
}

export function splashScreenPlugin(): Plugin {
	return {
		apply: 'build',
		closeBundle() {
			setTimeout(() => {
				try {
					if (processed) return;

					processed = true;

					const outDir = resolve(OUTPUT_DIR);
					const indexPath = resolve(outDir, 'index.html');

					if (!existsSync(indexPath)) return;

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

					// Inject iOS splash screen <link> tags into <head>.
					// The @vite-pwa/assets-generator generates apple-splash-*.png files;
					// this scans them and creates the <link> tags SvelteKit needs.
					const splashLinks = generateSplashScreenLinks(outDir);

					if (splashLinks.length > 0) {
						console.log(`Generated ${splashLinks.length} apple-splash link tags`);
						const splashHtml = splashLinks.map((l) => TAB + TAB + l).join(NEWLINE);

						content = content.replace(
							REGEX_PATTERNS.HEAD_CLOSE,
							splashHtml + NEWLINE + TAB + TAB + '</head>'
						);
					}

					// Remove trailing \r from Windows line endings
					content = content.replace(/\r/g, '');
					content = BUILD_CONFIG.GUIDE_COMMENT + NEWLINE + content;

					writeFileSync(indexPath, content, 'utf-8');
					console.log('Updated index.html');
				} catch (error) {
					console.error('Failed to process build output:', error);
				}
			}, 100);
		},
		name: 'llamacpp:splash-screen'
	};
}
