import { assert } from "./errors.js";

import type { FetchRequest, FetchCancelSignal, GetUrlResponse } from "./fetch.js";


declare global {
    class Headers {
        constructor(values: Array<[ string, string ]>);
        forEach(func: (v: string, k: string) => void): void;
    }

    class Response {
        status: number;
        statusText: string;
        headers: Headers;
        arrayBuffer(): Promise<ArrayBuffer>;
    }

    type FetchInit = {
        method?: string,
        headers?: Headers,
        body?: Uint8Array
    };

    function fetch(url: string, init: FetchInit): Promise<Response>;
}

// @TODO: timeout is completely ignored; start a Promise.any with a reject?

export async function getUrl(req: FetchRequest, _signal?: FetchCancelSignal): Promise<GetUrlResponse> {
    const protocol = req.url.split(":")[0].toLowerCase();

    assert(protocol === "http" || protocol === "https", `unsupported protocol ${ protocol }`, "UNSUPPORTED_OPERATION", {
        info: { protocol },
        operation: "request"
    });

    assert(!req.credentials || req.allowInsecureAuthentication, "insecure authorized connections unsupported", "UNSUPPORTED_OPERATION", {
        operation: "request"
    });

    let signal: undefined | AbortSignal = undefined;
    if (_signal) {
        const controller = new AbortController();
        signal = controller.signal;
        _signal.addListener(() => { controller.abort(); });
    }

    const init = {
        method: req.method,
        headers: new Headers(Array.from(req)),
        body: req.body || undefined,
        signal
    };

    const resp = await fetch(req.url, init);

    const headers: Record<string, string> = { };
    resp.headers.forEach((value, key) => {
        headers[key.toLowerCase()] = value;
    });

    const respBody = await resp.arrayBuffer();
    const body = (respBody == null) ? null: new Uint8Array(respBody);

    return {
        statusCode: resp.status,
        statusMessage: resp.statusText,
        headers, body
    };
}