//#region src/middleware/cors/index.ts
/**
* CORS Middleware for Hono.
*
* @see {@link https://hono.dev/docs/middleware/builtin/cors}
*
* @param {CORSOptions} [options] - The options for the CORS middleware.
* @param {string | string[] | ((origin: string, c: Context) => Promise<string | undefined | null> | string | undefined | null)} [options.origin='*'] - The value of "Access-Control-Allow-Origin" CORS header.
* @param {string[] | ((origin: string, c: Context) => Promise<string[]> | string[])} [options.allowMethods=['GET', 'HEAD', 'PUT', 'POST', 'DELETE', 'PATCH', 'QUERY']] - The value of "Access-Control-Allow-Methods" CORS header.
* @param {string[]} [options.allowHeaders=[]] - The value of "Access-Control-Allow-Headers" CORS header.
* @param {number} [options.maxAge] - The value of "Access-Control-Max-Age" CORS header.
* @param {boolean} [options.credentials] - The value of "Access-Control-Allow-Credentials" CORS header.
* @param {string[]} [options.exposeHeaders=[]] - The value of "Access-Control-Expose-Headers" CORS header.
* @returns {MiddlewareHandler} The middleware handler function.
*
* @example
* ```ts
* const app = new Hono()
*
* app.use('/api/*', cors())
* app.use(
*   '/api2/*',
*   cors({
*     origin: 'http://example.com',
*     allowHeaders: ['X-Custom-Header', 'Upgrade-Insecure-Requests'],
*     allowMethods: ['POST', 'GET', 'OPTIONS'],
*     exposeHeaders: ['Content-Length', 'X-Kuma-Revision'],
*     maxAge: 600,
*     credentials: true,
*   })
* )
*
* app.all('/api/abc', (c) => {
*   return c.json({ success: true })
* })
* app.all('/api2/abc', (c) => {
*   return c.json({ success: true })
* })
* ```
*/
const cors = (options) => {
	const opts = {
		origin: "*",
		allowMethods: [
			"GET",
			"HEAD",
			"PUT",
			"POST",
			"DELETE",
			"PATCH",
			"QUERY"
		],
		allowHeaders: [],
		exposeHeaders: [],
		...options
	};
	const exposeHeadersStr = opts.exposeHeaders?.length ? opts.exposeHeaders.join(",") : void 0;
	const allowHeadersStr = opts.allowHeaders?.length ? opts.allowHeaders.join(",") : void 0;
	const findAllowOrigin = ((optsOrigin) => {
		if (typeof optsOrigin === "string") {
			if (optsOrigin === "*") return () => optsOrigin;
			else return (origin) => optsOrigin === origin ? origin : null;
		} else if (typeof optsOrigin === "function") return optsOrigin;
		else return (origin) => optsOrigin.includes(origin) ? origin : null;
	})(opts.origin);
	const findAllowMethods = ((optsAllowMethods) => {
		if (typeof optsAllowMethods === "function") return async (origin, c) => (await optsAllowMethods(origin, c)).join(",");
		else if (Array.isArray(optsAllowMethods)) {
			const methodsStr = optsAllowMethods.join(",");
			return () => methodsStr;
		} else return () => "";
	})(opts.allowMethods);
	return async function cors(c, next) {
		function set(key, value) {
			c.res.headers.set(key, value);
		}
		const allowOrigin = await findAllowOrigin(c.req.header("origin") || "", c);
		if (allowOrigin) set("Access-Control-Allow-Origin", allowOrigin);
		if (opts.credentials) set("Access-Control-Allow-Credentials", "true");
		if (exposeHeadersStr) set("Access-Control-Expose-Headers", exposeHeadersStr);
		if (c.req.method === "OPTIONS") {
			if (opts.origin !== "*") c.res.headers.append("Vary", "Origin");
			if (opts.maxAge != null) set("Access-Control-Max-Age", opts.maxAge.toString());
			const allowMethods = await findAllowMethods(c.req.header("origin") || "", c);
			if (allowMethods) set("Access-Control-Allow-Methods", allowMethods);
			let headersStr = allowHeadersStr;
			if (!headersStr) {
				const requestHeaders = c.req.header("Access-Control-Request-Headers");
				if (requestHeaders) headersStr = requestHeaders.split(",").map((h) => h.trim()).join(",");
			}
			if (headersStr) {
				set("Access-Control-Allow-Headers", headersStr);
				c.res.headers.append("Vary", "Access-Control-Request-Headers");
			}
			c.res.headers.delete("Content-Length");
			c.res.headers.delete("Content-Type");
			return new Response(null, {
				headers: c.res.headers,
				status: 204,
				statusText: "No Content"
			});
		}
		await next();
		if (opts.origin !== "*") c.header("Vary", "Origin", { append: true });
	};
};
//#endregion
export { cors };