discordeno/rest/createRequestBody.ts

import { FileContent } from "../types/discordeno.ts";
import { decode } from "../util/base64.ts";
import { USER_AGENT } from "../util/constants.ts";
import { RequestMethod } from "./rest.ts";
import { RestManager } from "./restManager.ts";

/** Creates the request body and headers that are necessary to send a request. Will handle different types of methods and everything necessary for discord. */
export function createRequestBody(rest: RestManager, options: CreateRequestBodyOptions) {
  const headers: Record<string, string> = {
    "user-agent": USER_AGENT,
  };

  if (!options.unauthorized) headers["authorization"] = `Bot ${rest.token}`;

  // SOMETIMES SPECIAL HEADERS (E.G. CUSTOM AUTHORIZATION) NEED TO BE USED
  if (options.headers) {
    for (const key in options.headers) {
      headers[key.toLowerCase()] = options.headers[key];
    }
  }

  // GET METHODS SHOULD NOT HAVE A BODY
  if (options.method === "GET") {
    options.body = undefined;
  }

  // IF A REASON IS PROVIDED ENCODE IT IN HEADERS
  if (options.body?.reason) {
    headers["X-Audit-Log-Reason"] = encodeURIComponent(options.body.reason as string);
    options.body.reason = undefined;
  }

  // IF A FILE/ATTACHMENT IS PRESENT WE NEED SPECIAL HANDLING
  if (options.body?.file) {
    const files = findFiles(options.body.file);

    const form = new FormData();

    // WHEN CREATING A STICKER, DISCORD WANTS FORM DATA ONLY
    if (options.url?.endsWith("/stickers") && options.method === "POST") {
      form.append(`file`, files[0].blob, files[0].name);
      form.append(`name`, options.body.name as string);
      form.append(`description`, options.body.description as string);
      form.append(`tags`, options.body.tags as string);
    } else {
      for (let i = 0; i < files.length; i++) {
        form.append(`file${i}`, files[i].blob, files[i].name);
      }

      form.append("payload_json", JSON.stringify({ ...options.body, file: undefined }));
    }

    options.body.file = form;
  } else if (options.body && !["GET", "DELETE"].includes(options.method)) {
    headers["Content-Type"] = "application/json";
  }

  return {
    headers,
    body: (options.body?.file ?? JSON.stringify(options.body)) as FormData | string,
    method: options.method,
  };
}

export interface CreateRequestBodyOptions {
  headers?: Record<string, string>;
  method: RequestMethod;
  body?: Record<string, unknown>;
  unauthorized?: boolean;
  url?: string;
}

function findFiles(file: unknown): FileContent[] {
  if (!file) {
    return [];
  }

  const files: unknown[] = Array.isArray(file) ? file : [file];
  return files.filter(coerceToFileContent);
}

function coerceToFileContent(value: unknown): value is FileContent {
  if (!value || typeof value !== "object") {
    return false;
  }

  const file = value as Record<string, unknown>;
  if (typeof file.name !== "string") {
    return false;
  }

  switch (typeof file.blob) {
    case "string": {
      const match = file.blob.match(/^data:(?<mimeType>[a-zA-Z0-9\/]*);base64,(?<content>.*)$/);
      if (match?.groups === undefined) {
        return false;
      }
      const { mimeType, content } = match.groups;
      file.blob = new Blob([decode(content)], { type: mimeType });
      return true;
    }
    case "object":
      return file.blob instanceof Blob;
    default:
      return false;
  }
}