import type { LoadPinballOptions, PinballInstance } from './types.js';

export type { LoadPinballOptions, PinballInstance } from './types.js';
export { attachTouchControls } from './touch-controls.js';
export type { TouchControlsOptions, TouchControlsHandle } from './touch-controls.js';

const DEFAULT_TABLE_PATH = '/tables/default.vpx';
const UPLOADED_TABLE_PATH = '/tables/uploaded.vpx';

/**
 * Instantiates the WebAssembly build of Visual Pinball against the given
 * canvas and returns a handle to control its lifecycle.
 */
export async function loadPinball(options: LoadPinballOptions): Promise<PinballInstance> {
	// Resolved to an absolute URL against the *page's* location up front,
	// rather than used as-is: a bare relative baseUrl works for
	// Module.locateFile and wireDownloadProgress's fetch() (both resolve
	// relative to the page), but not for the dynamic import() below, whose
	// relative-specifier resolution is against *this module's own* URL
	// (dist/index.js) instead - the two disagree for any page location that
	// doesn't happen to cancel the difference out (as examples/basic/'s
	// '../../dist' accidentally does). Resolving once here, to an absolute
	// URL, makes every use of it agree.
	const baseUrl = new URL(options.baseUrl ?? '.', document.baseURI).href.replace(/\/$/, '');
	let tablePath = DEFAULT_TABLE_PATH;

	const moduleArgs: Record<string, unknown> = {
		canvas: options.canvas,
		locateFile: (path: string) => `${baseUrl}/${path}`,
	};

	if (options.onProgress) {
		await wireDownloadProgress(moduleArgs, baseUrl, options.onProgress);
	}

	// dist/vpinball.js is built with -sMODULARIZE=1 -sEXPORT_NAME=VPinballModule,
	// so importing it yields a factory function, not a module with side effects.
	const factory = (await import(/* @vite-ignore */ `${baseUrl}/vpinball.js`)).default as (
		moduleArgs: Record<string, unknown>
	) => Promise<EmscriptenModule>;

	const module = await factory(moduleArgs);
	options.onProgress?.(1);

	if (options.tableData) {
		module.FS.writeFile(UPLOADED_TABLE_PATH, new Uint8Array(options.tableData));
		tablePath = UPLOADED_TABLE_PATH;
	}

	return {
		loadTable(vpxBytes: ArrayBuffer) {
			module.FS.writeFile(UPLOADED_TABLE_PATH, new Uint8Array(vpxBytes));
			tablePath = UPLOADED_TABLE_PATH;
		},
		loadRom(gameName: string, romZipBytes: ArrayBuffer) {
			module.FS.mkdirTree(PINMAME_ROMS_DIR);
			module.FS.writeFile(`${PINMAME_ROMS_DIR}/${gameName}.zip`, new Uint8Array(romZipBytes));
		},
		start() {
			module.ccall?.('vpinball_wasm_start', 'number', ['string'], [tablePath]);
		},
		stop() {
			module.ccall?.('vpinball_wasm_stop', null, [], []);
		},
		dispose() {
			module.ccall?.('vpinball_wasm_dispose', null, [], []);
		},
		requestFullscreen() {
			return options.canvas.requestFullscreen();
		},
		evalScript(script: string) {
			return Boolean(module.ccall?.('vpinball_wasm_eval_script', 'number', ['string'], [script]));
		},
	};
}

/**
 * Best-effort byte-level download progress: manually fetches vpinball.wasm
 * with a streaming reader (assigning the result to Module.wasmBinary so the
 * factory doesn't re-fetch it), weighted against Module's own coarse
 * "Downloading data..." status callback for the preloaded asset package.
 * Emscripten's own dependency counter (monitorRunDependencies) doesn't give
 * byte-level granularity, hence fetching the .wasm by hand instead.
 */
async function wireDownloadProgress(
	moduleArgs: Record<string, unknown>,
	baseUrl: string,
	onProgress: (fraction: number) => void
): Promise<void> {
	// Roughly half the total download is the wasm binary, half the data
	// package - this is an estimate (see README's size-tuning roadmap item),
	// not a guarantee, so progress may jump at the wasm/data boundary.
	const WASM_WEIGHT = 0.5;

	try {
		const response = await fetch(`${baseUrl}/vpinball.wasm`);
		const total = Number(response.headers.get('Content-Length') ?? 0);
		const reader = response.body?.getReader();
		if (!reader || !total) {
			return;
		}
		const chunks: Uint8Array[] = [];
		let received = 0;
		for (;;) {
			const { done, value } = await reader.read();
			if (done) break;
			chunks.push(value);
			received += value.length;
			onProgress((received / total) * WASM_WEIGHT);
		}
		const wasmBinary = new Uint8Array(received);
		let offset = 0;
		for (const chunk of chunks) {
			wasmBinary.set(chunk, offset);
			offset += chunk.length;
		}
		moduleArgs.wasmBinary = wasmBinary;
	} catch {
		// Streaming progress is best-effort; fall through to the factory's
		// own default fetch if this fails for any reason (e.g. no CORS
		// Content-Length exposed, older browser).
	}

	moduleArgs.setStatus = (text: string) => {
		if (text) onProgress(WASM_WEIGHT + (1 - WASM_WEIGHT) * 0.5);
	};
}

interface EmscriptenModule {
	FS: {
		writeFile(path: string, data: Uint8Array): void;
		mkdirTree(path: string): void;
	};
	ccall?: (name: string, returnType: string | null, argTypes: string[], args: unknown[]) => unknown;
}

const PINMAME_ROMS_DIR = '/tables/pinmame/roms';