import * as fs from "jsr:@std/fs@^1.0.0";

/**
 * Options
 */
export interface Options {
  /** write documents to FILE */
  outputDocument?: string;
  /** Proxy, Certificate, etc */
  client?: Deno.CreateHttpClientOptions;
}

/**
 * Result
 */
export interface Result {
  response?: Response;
  outputDocument?: string;
}

/**
 * wget
 *
 * @param url
 * @param options
 * @returns result
 */
export async function wget(
  url: string,
  options?: Options,
): Promise<Result> {
  const init = options?.client
    ? { client: Deno.createHttpClient(options.client) }
    : undefined;
  const response = await fetch(url, init);

  let outputDocument = options?.outputDocument?.trim();
  if (!outputDocument) {
    // response.headers.get("Content-Disposition") // TODO
    const array = new URL(url).pathname.split("/");
    outputDocument = array[array.length - 1].trim();
    if (!outputDocument) {
      outputDocument = "index.html";
    }
  }
  const writable = getWritable(outputDocument);
  await response.body?.pipeTo(writable);
  return { response, outputDocument };
}

function getWritable(outputDocument: string) {
  if (outputDocument === "-") {
    return Deno.stdout.writable;
  } else {
    const original = outputDocument;
    for (let i = 1; i < Number.MAX_SAFE_INTEGER; i++) {
      if (!fs.existsSync(outputDocument)) {
        break;
      }
      outputDocument = `${original}.${i}`;
    }
    return Deno.createSync(outputDocument).writable;
  }
}