import {
  Entry,
  AssetProxy,
  PersistOptions,
  User,
  Config,
  Implementation,
  ImplementationFile,
  EditorialWorkflowError,
  APIError,
} from 'netlify-cms-lib-util';
import AuthenticationPage from './AuthenticationPage';

const serializeAsset = async (assetProxy: AssetProxy) => {
  const base64content = await assetProxy.toBase64!();

  return { path: assetProxy.path, content: base64content, encoding: 'base64' };
};

type MediaFile = {
  id: string;
  content: string;
  encoding: string;
  name: string;
  path: string;
};

const deserializeMediaFile = ({ id, content, encoding, path, name }: MediaFile) => {
  let byteArray = new Uint8Array(0);
  if (encoding !== 'base64') {
    console.error(`Unsupported encoding '${encoding}' for file '${path}'`);
  } else {
    const decodedContent = atob(content);
    byteArray = new Uint8Array(decodedContent.length);
    for (let i = 0; i < decodedContent.length; i++) {
      byteArray[i] = decodedContent.charCodeAt(i);
    }
  }
  const file = new File([byteArray], name);
  const url = URL.createObjectURL(file);
  return { id, name, path, file, size: file.size, url, displayURL: url };
};

export default class ProxyBackend implements Implementation {
  proxyUrl: string;
  mediaFolder: string;
  options: { initialWorkflowStatus?: string };
  branch: string;

  constructor(config: Config, options = {}) {
    if (!config.backend.proxy_url) {
      throw new Error('The Proxy backend needs a "proxy_url" in the backend configuration.');
    }

    this.branch = config.backend.branch || 'master';
    this.proxyUrl = config.backend.proxy_url;
    this.mediaFolder = config.media_folder;
    this.options = options;
  }

  authComponent() {
    return AuthenticationPage;
  }

  restoreUser() {
    return this.authenticate();
  }

  authenticate() {
    return (Promise.resolve() as unknown) as Promise<User>;
  }

  logout() {
    return null;
  }

  getToken() {
    return Promise.resolve('');
  }

  async request(payload: { action: string; params: Record<string, unknown> }) {
    const response = await fetch(this.proxyUrl, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json; charset=utf-8' },
      body: JSON.stringify({ branch: this.branch, ...payload }),
    });

    const json = await response.json();
    if (response.ok) {
      return json;
    } else {
      throw new APIError(json.message, response.status, 'Proxy');
    }
  }

  entriesByFolder(folder: string, extension: string, depth: number) {
    return this.request({
      action: 'entriesByFolder',
      params: { branch: this.branch, folder, extension, depth },
    });
  }

  entriesByFiles(files: ImplementationFile[]) {
    return this.request({
      action: 'entriesByFiles',
      params: { branch: this.branch, files },
    });
  }

  getEntry(path: string) {
    return this.request({
      action: 'getEntry',
      params: { branch: this.branch, path },
    });
  }

  unpublishedEntries() {
    return this.request({
      action: 'unpublishedEntries',
      params: { branch: this.branch },
    });
  }

  async unpublishedEntry(collection: string, slug: string) {
    try {
      const entry = await this.request({
        action: 'unpublishedEntry',
        params: { branch: this.branch, collection, slug },
      });

      const mediaFiles = entry.mediaFiles.map(deserializeMediaFile);
      return { ...entry, mediaFiles };
    } catch (e) {
      if (e.status === 404) {
        throw new EditorialWorkflowError('content is not under editorial workflow', true);
      }
      throw e;
    }
  }

  deleteUnpublishedEntry(collection: string, slug: string) {
    return this.request({
      action: 'deleteUnpublishedEntry',
      params: { branch: this.branch, collection, slug },
    });
  }

  async persistEntry(entry: Entry, assetProxies: AssetProxy[], options: PersistOptions) {
    const assets = await Promise.all(assetProxies.map(serializeAsset));
    return this.request({
      action: 'persistEntry',
      params: {
        branch: this.branch,
        entry,
        assets,
        options: { ...options, status: options.status || this.options.initialWorkflowStatus },
      },
    });
  }

  updateUnpublishedEntryStatus(collection: string, slug: string, newStatus: string) {
    return this.request({
      action: 'updateUnpublishedEntryStatus',
      params: { branch: this.branch, collection, slug, newStatus },
    });
  }

  publishUnpublishedEntry(collection: string, slug: string) {
    return this.request({
      action: 'publishUnpublishedEntry',
      params: { branch: this.branch, collection, slug },
    });
  }

  async getMedia(mediaFolder = this.mediaFolder) {
    const files: MediaFile[] = await this.request({
      action: 'getMedia',
      params: { branch: this.branch, mediaFolder },
    });

    return files.map(deserializeMediaFile);
  }

  async getMediaFile(path: string) {
    const file = await this.request({
      action: 'getMediaFile',
      params: { branch: this.branch, path },
    });
    return deserializeMediaFile(file);
  }

  async persistMedia(assetProxy: AssetProxy, options: PersistOptions) {
    const asset = await serializeAsset(assetProxy);
    const file: MediaFile = await this.request({
      action: 'persistMedia',
      params: { branch: this.branch, asset, options: { commitMessage: options.commitMessage } },
    });

    return deserializeMediaFile(file);
  }

  deleteFile(path: string, commitMessage: string) {
    return this.request({
      action: 'deleteFile',
      params: { branch: this.branch, path, options: { commitMessage } },
    });
  }

  getDeployPreview(collection: string, slug: string) {
    return this.request({
      action: 'getDeployPreview',
      params: { branch: this.branch, collection, slug },
    });
  }
}