registry.ts

/*-----------------------------------------------------------------------------
| Copyright (c) Jupyter Development Team.
| Distributed under the terms of the Modified BSD License.
|----------------------------------------------------------------------------*/
import { Contents, Session } from '@jupyterlab/services';

import { IRenderMime } from '@jupyterlab/rendermime-interfaces';

import { PathExt, URLExt } from '@jupyterlab/coreutils';

import {
  IClientSession,
  ISanitizer,
  defaultSanitizer
} from '@jupyterlab/apputils';

import { ReadonlyJSONObject } from '@phosphor/coreutils';

import { MimeModel } from './mimemodel';

import { IRenderMimeRegistry } from './tokens';

/**
 * An object which manages mime renderer factories.
 *
 * This object is used to render mime models using registered mime
 * renderers, selecting the preferred mime renderer to render the
 * model into a widget.
 *
 * #### Notes
 * This class is not intended to be subclassed.
 */
export class RenderMimeRegistry implements IRenderMimeRegistry {
  /**
   * Construct a new rendermime.
   *
   * @param options - The options for initializing the instance.
   */
  constructor(options: RenderMimeRegistry.IOptions = {}) {
    // Parse the options.
    this.resolver = options.resolver || null;
    this.linkHandler = options.linkHandler || null;
    this.latexTypesetter = options.latexTypesetter || null;
    this.sanitizer = options.sanitizer || defaultSanitizer;

    // Add the initial factories.
    if (options.initialFactories) {
      for (let factory of options.initialFactories) {
        this.addFactory(factory);
      }
    }
  }

  /**
   * The sanitizer used by the rendermime instance.
   */
  readonly sanitizer: ISanitizer;

  /**
   * The object used to resolve relative urls for the rendermime instance.
   */
  readonly resolver: IRenderMime.IResolver | null;

  /**
   * The object used to handle path opening links.
   */
  readonly linkHandler: IRenderMime.ILinkHandler | null;

  /**
   * The LaTeX typesetter for the rendermime.
   */
  readonly latexTypesetter: IRenderMime.ILatexTypesetter | null;

  /**
   * The ordered list of mimeTypes.
   */
  get mimeTypes(): ReadonlyArray<string> {
    return this._types || (this._types = Private.sortedTypes(this._ranks));
  }

  /**
   * Find the preferred mime type for a mime bundle.
   *
   * @param bundle - The bundle of mime data.
   *
   * @param safe - How to consider safe/unsafe factories. If 'ensure',
   *   it will only consider safe factories. If 'any', any factory will be
   *   considered. If 'prefer', unsafe factories will be considered, but
   *   only after the safe options have been exhausted.
   *
   * @returns The preferred mime type from the available factories,
   *   or `undefined` if the mime type cannot be rendered.
   */
  preferredMimeType(
    bundle: ReadonlyJSONObject,
    safe: 'ensure' | 'prefer' | 'any' = 'ensure'
  ): string | undefined {
    // Try to find a safe factory first, if preferred.
    if (safe === 'ensure' || safe === 'prefer') {
      for (let mt of this.mimeTypes) {
        if (mt in bundle && this._factories[mt].safe) {
          return mt;
        }
      }
    }

    if (safe !== 'ensure') {
      // Otherwise, search for the best factory among all factories.
      for (let mt of this.mimeTypes) {
        if (mt in bundle) {
          return mt;
        }
      }
    }

    // Otherwise, no matching mime type exists.
    return undefined;
  }

  /**
   * Create a renderer for a mime type.
   *
   * @param mimeType - The mime type of interest.
   *
   * @returns A new renderer for the given mime type.
   *
   * @throws An error if no factory exists for the mime type.
   */
  createRenderer(mimeType: string): IRenderMime.IRenderer {
    // Throw an error if no factory exists for the mime type.
    if (!(mimeType in this._factories)) {
      throw new Error(`No factory for mime type: '${mimeType}'`);
    }

    // Invoke the best factory for the given mime type.
    return this._factories[mimeType].createRenderer({
      mimeType,
      resolver: this.resolver,
      sanitizer: this.sanitizer,
      linkHandler: this.linkHandler,
      latexTypesetter: this.latexTypesetter
    });
  }

  /**
   * Create a new mime model.  This is a convenience method.
   *
   * @options - The options used to create the model.
   *
   * @returns A new mime model.
   */
  createModel(options: MimeModel.IOptions = {}): MimeModel {
    return new MimeModel(options);
  }

  /**
   * Create a clone of this rendermime instance.
   *
   * @param options - The options for configuring the clone.
   *
   * @returns A new independent clone of the rendermime.
   */
  clone(options: IRenderMimeRegistry.ICloneOptions = {}): RenderMimeRegistry {
    // Create the clone.
    let clone = new RenderMimeRegistry({
      resolver: options.resolver || this.resolver || undefined,
      sanitizer: options.sanitizer || this.sanitizer || undefined,
      linkHandler: options.linkHandler || this.linkHandler || undefined,
      latexTypesetter: options.latexTypesetter || this.latexTypesetter
    });

    // Clone the internal state.
    clone._factories = { ...this._factories };
    clone._ranks = { ...this._ranks };
    clone._id = this._id;

    // Return the cloned object.
    return clone;
  }

  /**
   * Get the renderer factory registered for a mime type.
   *
   * @param mimeType - The mime type of interest.
   *
   * @returns The factory for the mime type, or `undefined`.
   */
  getFactory(mimeType: string): IRenderMime.IRendererFactory | undefined {
    return this._factories[mimeType];
  }

  /**
   * Add a renderer factory to the rendermime.
   *
   * @param factory - The renderer factory of interest.
   *
   * @param rank - The rank of the renderer. A lower rank indicates
   *   a higher priority for rendering. If not given, the rank will
   *   defer to the `defaultRank` of the factory.  If no `defaultRank`
   *   is given, it will default to 100.
   *
   * #### Notes
   * The renderer will replace an existing renderer for the given
   * mimeType.
   */
  addFactory(factory: IRenderMime.IRendererFactory, rank?: number): void {
    if (rank === undefined) {
      rank = factory.defaultRank;
      if (rank === undefined) {
        rank = 100;
      }
    }
    for (let mt of factory.mimeTypes) {
      this._factories[mt] = factory;
      this._ranks[mt] = { rank, id: this._id++ };
    }
    this._types = null;
  }

  /**
   * Remove a mime type.
   *
   * @param mimeType - The mime type of interest.
   */
  removeMimeType(mimeType: string): void {
    delete this._factories[mimeType];
    delete this._ranks[mimeType];
    this._types = null;
  }

  /**
   * Get the rank for a given mime type.
   *
   * @param mimeType - The mime type of interest.
   *
   * @returns The rank of the mime type or undefined.
   */
  getRank(mimeType: string): number | undefined {
    let rank = this._ranks[mimeType];
    return rank && rank.rank;
  }

  /**
   * Set the rank of a given mime type.
   *
   * @param mimeType - The mime type of interest.
   *
   * @param rank - The new rank to assign.
   *
   * #### Notes
   * This is a no-op if the mime type is not registered.
   */
  setRank(mimeType: string, rank: number): void {
    if (!this._ranks[mimeType]) {
      return;
    }
    let id = this._id++;
    this._ranks[mimeType] = { rank, id };
    this._types = null;
  }

  private _id = 0;
  private _ranks: Private.RankMap = {};
  private _types: string[] | null = null;
  private _factories: Private.FactoryMap = {};
}

/**
 * The namespace for `RenderMimeRegistry` class statics.
 */
export namespace RenderMimeRegistry {
  /**
   * The options used to initialize a rendermime instance.
   */
  export interface IOptions {
    /**
     * Initial factories to add to the rendermime instance.
     */
    initialFactories?: ReadonlyArray<IRenderMime.IRendererFactory>;

    /**
     * The sanitizer used to sanitize untrusted html inputs.
     *
     * If not given, a default sanitizer will be used.
     */
    sanitizer?: IRenderMime.ISanitizer;

    /**
     * The initial resolver object.
     *
     * The default is `null`.
     */
    resolver?: IRenderMime.IResolver;

    /**
     * An optional path handler.
     */
    linkHandler?: IRenderMime.ILinkHandler;

    /**
     * An optional LaTeX typesetter.
     */
    latexTypesetter?: IRenderMime.ILatexTypesetter;
  }

  /**
   * A default resolver that uses a session and a contents manager.
   */
  export class UrlResolver implements IRenderMime.IResolver {
    /**
     * Create a new url resolver for a console.
     */
    constructor(options: IUrlResolverOptions) {
      this._session = options.session;
      this._contents = options.contents;
    }

    /**
     * Resolve a relative url to an absolute url path.
     */
    resolveUrl(url: string): Promise<string> {
      if (this.isLocal(url)) {
        const cwd = encodeURI(PathExt.dirname(this._session.path));
        url = PathExt.resolve(cwd, url);
      }
      return Promise.resolve(url);
    }

    /**
     * Get the download url of a given absolute url path.
     *
     * #### Notes
     * This URL may include a query parameter.
     */
    getDownloadUrl(url: string): Promise<string> {
      if (this.isLocal(url)) {
        // decode url->path before passing to contents api
        return this._contents.getDownloadUrl(decodeURI(url));
      }
      return Promise.resolve(url);
    }

    /**
     * Whether the URL should be handled by the resolver
     * or not.
     *
     * #### Notes
     * This is similar to the `isLocal` check in `URLExt`,
     * but it also checks whether the path points to any
     * of the `IDrive`s that may be registered with the contents
     * manager.
     */
    isLocal(url: string): boolean {
      const path = decodeURI(url);
      return URLExt.isLocal(url) || !!this._contents.driveName(path);
    }

    private _session: Session.ISession | IClientSession;
    private _contents: Contents.IManager;
  }

  /**
   * The options used to create a UrlResolver.
   */
  export interface IUrlResolverOptions {
    /**
     * The session used by the resolver.
     */
    session: Session.ISession | IClientSession;

    /**
     * The contents manager used by the resolver.
     */
    contents: Contents.IManager;
  }
}

/**
 * The namespace for the module implementation details.
 */
namespace Private {
  /**
   * A type alias for a mime rank and tie-breaking id.
   */
  export type RankPair = { readonly id: number; readonly rank: number };

  /**
   * A type alias for a mapping of mime type -> rank pair.
   */
  export type RankMap = { [key: string]: RankPair };

  /**
   * A type alias for a mapping of mime type -> ordered factories.
   */
  export type FactoryMap = { [key: string]: IRenderMime.IRendererFactory };

  /**
   * Get the mime types in the map, ordered by rank.
   */
  export function sortedTypes(map: RankMap): string[] {
    return Object.keys(map).sort((a, b) => {
      let p1 = map[a];
      let p2 = map[b];
      if (p1.rank !== p2.rank) {
        return p1.rank - p2.rank;
      }
      return p1.id - p2.id;
    });
  }
}