import * as Koa from "koa";

export = cors;

/**
 * CORS middleware factory.
 * @param options - Configuration options.
 * @returns cors middleware
 */
declare function cors(options?: cors.Options): Koa.Middleware;

declare namespace cors {
    /**
     * Middleware configuration options.
     */
    interface Options {
        /**
         * `Access-Control-Allow-Origin`, default is '*'
         *
         * @remarks
         * If `credentials` set and return `true`, the `origin` default value will set to the request `Origin` header
         *
         * @remarks
         * If a function is provided, it will be called for each request with
         * the koa context object. It may return a string or a promise that
         * will resolve with a string.
         */
        origin?: ((ctx: Koa.Context) => string) | ((ctx: Koa.Context) => PromiseLike<string>) | string | undefined;

        /**
         * `Access-Control-Allow-Methods`, default is
         * 'GET,HEAD,PUT,POST,DELETE,PATCH'
         */
        allowMethods?: string[] | string | undefined;

        /**
         * `Access-Control-Expose-Headers`
         */
        exposeHeaders?: string[] | string | undefined;

        /**
         * `Access-Control-Allow-Headers`
         */
        allowHeaders?: string[] | string | undefined;

        /**
         * `Access-Control-Max-Age` in seconds
         */
        maxAge?: number | string | undefined;

        /**
         * `Access-Control-Allow-Credentials`
         *
         * @remarks
         * If a function is provided, it will be called for each request with
         * the koa context object. It may return a boolean or a promise that
         * will resolve with a boolean.
         */
        credentials?:
            | ((ctx: Koa.Context) => boolean)
            | ((ctx: Koa.Context) => PromiseLike<boolean>)
            | boolean
            | undefined;

        /**
         * Add set headers to `err.header` if an error is thrown
         */
        keepHeadersOnError?: boolean | undefined;

        /**
         * Add `Cross-Origin-Opener-Policy` & `Cross-Origin-Embedder-Policy` to response headers, default is `false`
         *
         * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer/Planned_changes
         */
        secureContext?: boolean | undefined;

        /**
         * Handle `Access-Control-Request-Private-Network` request by return `Access-Control-Allow-Private-Network`, default is `false`
         *
         * @see https://wicg.github.io/private-network-access/
         */
        privateNetworkAccess?: boolean | undefined;
    }
}