import { existsSync } from "node:fs";
import { readdir, readFile } from "node:fs/promises";
import { join, relative, resolve } from "node:path";
import { pathToFileURL } from "node:url";
import { transform } from "@astrojs/compiler";
import { experimental_AstroContainer as AstroContainer } from "astro/container";
import ts from "typescript";
import type { Integration, IntegrationContext } from "muddle/contracts";

export interface AstroIntegrationOptions {
	dir?: string;
	partials?: boolean;
}

function routeFor(root: string, file: string): string {
	const path = relative(root, file)
		.replace(/\\/g, "/")
		.replace(/\.astro$/, "");
	return `/${path.replace(/index$/, "").replace(/\/+/g, "/") || ""}` || "/";
}

export function astroIntegration(
	options: AstroIntegrationOptions = {},
): Integration {
	return {
		name: "astro",
		async setup(context: IntegrationContext) {
			context.loader("astro", {
				name: "astro",
				extensions: [".astro"],
				async load(file) {
					return {
						data: {},
						content: await renderAstro(file.source, undefined, file.path),
					};
				},
			});
			const dir = resolve(context.config.root, options.dir ?? "src/pages");
			if (!existsSync(dir)) return;
			for (const file of await astroFiles(dir)) {
				const route = routeFor(dir, file);
				context.route(
					"GET",
					route,
					async (request) =>
						new Response(
							await renderAstro(await readFile(file, "utf8"), request, file),
							{
								headers: {
									"content-type": "text/html; charset=utf-8",
								},
							},
						),
				);
			}
		},
	};
}

async function astroFiles(dir: string): Promise<string[]> {
	const files: string[] = [];
	for (const entry of await readdir(dir, { withFileTypes: true })) {
		const path = join(dir, entry.name);
		if (entry.isDirectory()) files.push(...(await astroFiles(path)));
		else if (entry.name.endsWith(".astro")) files.push(path);
	}
	return files;
}

export async function renderAstro(
	source: string,
	request = new Request("http://localhost/"),
	filename = resolve("inline.astro"),
): Promise<string> {
	const component = await compileAstro(source, filename);
	const container = await AstroContainer.create();
	return container.renderToString(component, { request });
}

async function compileAstro(
	source: string,
	filename: string,
	ancestors: string[] = [],
): Promise<any> {
	if (ancestors.includes(filename)) {
		throw new Error(`Circular Astro import ${filename}`);
	}
	const result = await transform(source, {
		filename,
		internalURL: "astro/runtime/server/index.js",
	});
	let code = result.code
		.replace(/,\s*createMetadata as \$\$createMetadata/, "")
		.replace(/export const \$\$metadata = [^\n]+\n/g, "");
	for (const match of [...code.matchAll(/from\s+["']([^"']+)["']/g)]) {
		const specifier = match[1]!;
		let url: string;
		if (specifier.endsWith(".astro")) {
			const file = resolve(filename, "..", specifier);
			const child = await compileAstro(await readFile(file, "utf8"), file, [
				...ancestors,
				filename,
			]);
			const key = `__muddle_astro_${crypto.randomUUID().replaceAll("-", "")}`;
			(globalThis as Record<string, unknown>)[key] = child;
			url = `data:text/javascript;base64,${Buffer.from(
				`export default globalThis[${JSON.stringify(key)}]`,
			).toString("base64")}`;
		} else {
			url = specifier.startsWith(".")
				? pathToFileURL(resolve(filename, "..", specifier)).href
				: import.meta.resolve(specifier);
		}
		code = code
			.replaceAll(`"${specifier}"`, JSON.stringify(url))
			.replaceAll(`'${specifier}'`, JSON.stringify(url));
	}
	code = ts.transpileModule(code, {
		compilerOptions: {
			module: ts.ModuleKind.ESNext,
			target: ts.ScriptTarget.ES2022,
		},
	}).outputText;
	return (
		await import(
			`data:text/javascript;base64,${Buffer.from(code).toString("base64")}`
		)
	).default;
}

/** Import into TemplateContext with `.import("Card", astroComponent("./Card.astro"))`. */
export function astroComponent(file: string) {
	return {
		async render(
			props: Record<string, unknown>,
			context: {
				params: Record<string, string>;
				locals: Record<string, unknown>;
			},
		) {
			const path = resolve(file);
			const component = await compileAstro(await readFile(path, "utf8"), path);
			const container = await AstroContainer.create();
			const slots: Record<string, string> = {};
			for (const [key, value] of Object.entries(props)) {
				if (typeof value === "function") {
					slots[key === "content" ? "default" : key] = await value();
				}
			}
			return container.renderToString(component, {
				props,
				params: context.params,
				locals: context.locals,
				slots,
			});
		},
	};
}