import { normalizeProxyUrl } from "../net/proxy.ts";

export interface FetchContentParams {
	url?: unknown;
	urls?: unknown;
	mode?: unknown;
	proxy?: unknown;
}

export interface NormalizedFetchContentParams {
	urlList: string[];
	options: {
		mode?: "readable" | "raw";
		proxy?: string;
	};
}

export function normalizeFetchContentParams(params: FetchContentParams): NormalizedFetchContentParams {
	const urls = Array.isArray(params.urls)
		? params.urls.flatMap(normalizeUrl)
		: [];
	const urlList = [...new Set(urls.length > 0 ? urls : normalizeUrl(params.url))];
	const mode = normalizeMode(params.mode);
	const proxy = normalizeProxy(params.proxy);
	return {
		urlList,
		options: {
			...(mode ? { mode } : {}),
			...(proxy !== undefined ? { proxy } : {}),
		},
	};
}

function normalizeUrl(value: unknown): string[] {
	if (typeof value !== "string") return [];
	const url = value.trim();
	return url ? [url] : [];
}

function normalizeMode(value: unknown): "readable" | "raw" | undefined {
	if (value === undefined) return undefined;
	if (value === "readable" || value === "raw") return value;
	throw new Error('mode must be "readable" or "raw"');
}

function normalizeProxy(value: unknown): string | undefined {
	if (value === undefined || value === false) return undefined;
	if (value === null) throw new Error("proxy must be an HTTP(S) proxy URL string");
	return normalizeProxyUrl(value, "proxy") ?? "";
}