import { getConfig } from './config';
import { dispatchRequest } from './request';

/**
 * File support for the client. This interface establishes the contract for
 * uploading files to the server and transforming the input to replace file
 * objects with URLs.
 */
export interface StorageSupport {
  /**
   * Upload a file to the server. Returns the URL of the uploaded file.
   * @param file the file to upload
   * @param options optional parameters, such as custom file name
   * @returns the URL of the uploaded file
   */
  upload: (file: Blob) => Promise<string>;

  /**
   * Transform the input to replace file objects with URLs. This is used
   * to transform the input before sending it to the server and ensures
   * that the server receives URLs instead of file objects.
   *
   * @param input the input to transform.
   * @returns the transformed input.
   */
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  transformInput: (input: Record<string, any>) => Promise<Record<string, any>>;
}

function isDataUri(uri: string): boolean {
  // avoid uri parsing if it doesn't start with data:
  if (!uri.startsWith('data:')) {
    return false;
  }
  try {
    const url = new URL(uri);
    return url.protocol === 'data:';
  } catch (_) {
    return false;
  }
}

type InitiateUploadResult = {
  file_url: string;
  upload_url: string;
};

type InitiateUploadData = {
  file_name: string;
  content_type: string | null;
};

function getRestApiUrl(): string {
  const { host } = getConfig();
  return host.replace('gateway', 'rest');
}

/**
 * Get the file extension from the content type. This is used to generate
 * a file name if the file name is not provided.
 *
 * @param contentType the content type of the file.
 * @returns the file extension or `bin` if the content type is not recognized.
 */
function getExtensionFromContentType(contentType: string): string {
  const [_, fileType] = contentType.split('/');
  return fileType.split(/[-;]/)[0] ?? 'bin';
}

/**
 * Initiate the upload of a file to the server. This returns the URL to upload
 * the file to and the URL of the file once it is uploaded.
 *
 * @param file the file to upload
 * @returns the URL to upload the file to and the URL of the file once it is uploaded.
 */
async function initiateUpload(file: Blob): Promise<InitiateUploadResult> {
  const contentType = file.type || 'application/octet-stream';
  const filename =
    file.name || `${Date.now()}.${getExtensionFromContentType(contentType)}`;
  return await dispatchRequest<InitiateUploadData, InitiateUploadResult>(
    'POST',
    `https://${getRestApiUrl()}/storage/upload/initiate`,
    {
      content_type: contentType,
      file_name: filename,
    }
  );
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
type KeyValuePair = [string, any];

export const storageImpl: StorageSupport = {
  upload: async (file: Blob) => {
    const { upload_url: uploadUrl, file_url: url } = await initiateUpload(file);
    const response = await fetch(uploadUrl, {
      method: 'PUT',
      body: file,
      headers: {
        'Content-Type': file.type || 'application/octet-stream',
      },
    });
    const { responseHandler } = getConfig();
    await responseHandler(response);
    return url;
  },

  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  transformInput: async (input: Record<string, any>) => {
    const promises = Object.entries(input).map(async ([key, value]) => {
      if (
        value instanceof Blob ||
        (typeof value === 'string' && isDataUri(value))
      ) {
        let blob = value;
        // if string is a data uri, convert to blob
        if (typeof value === 'string' && isDataUri(value)) {
          const response = await fetch(value);
          blob = await response.blob();
        }
        const url = await storageImpl.upload(blob as Blob);
        return [key, url];
      }
      return [key, value] as KeyValuePair;
    });
    const results = await Promise.all(promises);
    return Object.fromEntries(results);
  },
};