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

import type {
    FetchGetUrlFunc, 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 function createGetUrl(options?: Record<string, any>): FetchGetUrlFunc {

    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(protocol === "https" || !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
        };
    }

    return getUrl;
}

// @TODO: remove in v7; provided for backwards compat
const defaultGetUrl: FetchGetUrlFunc = createGetUrl({ });

export async function getUrl(req: FetchRequest, _signal?: FetchCancelSignal): Promise<GetUrlResponse> {
    return defaultGetUrl(req, _signal);
}