GoogleEarthEnterpriseMetadata.js

import * as protobuf from "protobufjs/dist/minimal/protobuf.js";
import buildModuleUrl from "./buildModuleUrl.js";
import Check from "./Check.js";
import Credit from "./Credit.js";
import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import GoogleEarthEnterpriseTileInformation from "./GoogleEarthEnterpriseTileInformation.js";
import isBitSet from "./isBitSet.js";
import loadAndExecuteScript from "./loadAndExecuteScript.js";
import CesiumMath from "./Math.js";
import Request from "./Request.js";
import Resource from "./Resource.js";
import RuntimeError from "./RuntimeError.js";
import TaskProcessor from "./TaskProcessor.js";

function stringToBuffer(str) {
  const len = str.length;
  const buffer = new ArrayBuffer(len);
  const ui8 = new Uint8Array(buffer);
  for (let i = 0; i < len; ++i) {
    ui8[i] = str.charCodeAt(i);
  }

  return buffer;
}

// Decodes packet with a key that has been around since the beginning of Google Earth Enterprise
const defaultKey = stringToBuffer(
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);

/**
 * <div class="notice">
 * To construct GoogleEarthEnterpriseMetadata, call {@link GoogleEarthEnterpriseMetadata.fromUrl}. Do not call the constructor directly.
 * </div>
 *
 * Provides metadata using the Google Earth Enterprise REST API. This is used by the GoogleEarthEnterpriseImageryProvider
 *  and GoogleEarthEnterpriseTerrainProvider to share metadata requests.
 *
 * @alias GoogleEarthEnterpriseMetadata
 * @constructor
 *
 * @see GoogleEarthEnterpriseImageryProvider
 * @see GoogleEarthEnterpriseTerrainProvider
 *
 */
function GoogleEarthEnterpriseMetadata(resourceOrUrl) {
  /**
   * True if imagery is available.
   * @type {boolean}
   * @default true
   */
  this.imageryPresent = true;

  /**
   * True if imagery is sent as a protocol buffer, false if sent as plain images. If undefined we will try both.
   * @type {boolean}
   * @default undefined
   */
  this.protoImagery = undefined;

  /**
   * True if terrain is available.
   * @type {boolean}
   * @default true
   */
  this.terrainPresent = true;

  /**
   * Exponent used to compute constant to calculate negative height values.
   * @type {number}
   * @default 32
   */
  this.negativeAltitudeExponentBias = 32;

  /**
   * Threshold where any numbers smaller are actually negative values. They are multiplied by -2^negativeAltitudeExponentBias.
   * @type {number}
   * @default EPSILON12
   */
  this.negativeAltitudeThreshold = CesiumMath.EPSILON12;

  /**
   * Dictionary of provider id to copyright strings.
   * @type {object}
   * @default {}
   */
  this.providers = {};

  /**
   * Key used to decode packets
   * @type {ArrayBuffer}
   */
  this.key = undefined;

  this._resource = undefined;
  this._quadPacketVersion = 1;
  this._tileInfo = {};
  this._subtreePromises = {};
}

Object.defineProperties(GoogleEarthEnterpriseMetadata.prototype, {
  /**
   * Gets the name of the Google Earth Enterprise server.
   * @memberof GoogleEarthEnterpriseMetadata.prototype
   * @type {string}
   * @readonly
   */
  url: {
    get: function () {
      return this._resource.url;
    },
  },

  /**
   * Gets the proxy used for metadata requests.
   * @memberof GoogleEarthEnterpriseMetadata.prototype
   * @type {Proxy}
   * @readonly
   */
  proxy: {
    get: function () {
      return this._resource.proxy;
    },
  },

  /**
   * Gets the resource used for metadata requests.
   * @memberof GoogleEarthEnterpriseMetadata.prototype
   * @type {Resource}
   * @readonly
   */
  resource: {
    get: function () {
      return this._resource;
    },
  },
});

/**
 * Creates a metadata object using the Google Earth Enterprise REST API. This is used by the GoogleEarthEnterpriseImageryProvider
 * and GoogleEarthEnterpriseTerrainProvider to share metadata requests.
 *
 * @param {Resource|String} resourceOrUrl The url of the Google Earth Enterprise server hosting the imagery.
 *
 * @returns {Promise<GoogleEarthEnterpriseMetadata>} A promise which resolves to the created GoogleEarthEnterpriseMetadata instance/
 */
GoogleEarthEnterpriseMetadata.fromUrl = async function (resourceOrUrl) {
  //>>includeStart('debug', pragmas.debug);
  Check.defined("resourceOrUrl", resourceOrUrl);
  //>>includeEnd('debug');
  let url = resourceOrUrl;

  if (typeof url !== "string" && !(url instanceof Resource)) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("resourceOrUrl.url", resourceOrUrl.url);
    //>>includeEnd('debug');

    url = resourceOrUrl.url;
  }

  const resource = Resource.createIfNeeded(url);
  resource.appendForwardSlash();

  const metadata = new GoogleEarthEnterpriseMetadata();
  metadata._resource = resource;

  try {
    await requestDbRoot(metadata);
    await metadata.getQuadTreePacket("", metadata._quadPacketVersion);
  } catch (error) {
    const message = `An error occurred while accessing ${
      getMetadataResource(metadata, "", 1).url
    }: ${error}`;

    throw new RuntimeError(message);
  }

  return metadata;
};

/**
 * Converts a tiles (x, y, level) position into a quadkey used to request an image
 * from a Google Earth Enterprise server.
 *
 * @param {number} x The tile's x coordinate.
 * @param {number} y The tile's y coordinate.
 * @param {number} level The tile's zoom level.
 *
 * @see GoogleEarthEnterpriseMetadata#quadKeyToTileXY
 */
GoogleEarthEnterpriseMetadata.tileXYToQuadKey = function (x, y, level) {
  let quadkey = "";
  for (let i = level; i >= 0; --i) {
    const bitmask = 1 << i;
    let digit = 0;

    // Tile Layout
    // ___ ___
    //|   |   |
    //| 3 | 2 |
    //|-------|
    //| 0 | 1 |
    //|___|___|
    //

    if (!isBitSet(y, bitmask)) {
      // Top Row
      digit |= 2;
      if (!isBitSet(x, bitmask)) {
        // Right to left
        digit |= 1;
      }
    } else if (isBitSet(x, bitmask)) {
      // Left to right
      digit |= 1;
    }

    quadkey += digit;
  }
  return quadkey;
};

/**
 * Converts a tile's quadkey used to request an image from a Google Earth Enterprise server into the
 * (x, y, level) position.
 *
 * @param {string} quadkey The tile's quad key
 *
 * @see GoogleEarthEnterpriseMetadata#tileXYToQuadKey
 */
GoogleEarthEnterpriseMetadata.quadKeyToTileXY = function (quadkey) {
  let x = 0;
  let y = 0;
  const level = quadkey.length - 1;
  for (let i = level; i >= 0; --i) {
    const bitmask = 1 << i;
    const digit = +quadkey[level - i];

    if (isBitSet(digit, 2)) {
      // Top Row
      if (!isBitSet(digit, 1)) {
        // // Right to left
        x |= bitmask;
      }
    } else {
      y |= bitmask;
      if (isBitSet(digit, 1)) {
        // Left to right
        x |= bitmask;
      }
    }
  }
  return {
    x: x,
    y: y,
    level: level,
  };
};

GoogleEarthEnterpriseMetadata.prototype.isValid = function (quadKey) {
  let info = this.getTileInformationFromQuadKey(quadKey);
  if (defined(info)) {
    return info !== null;
  }

  let valid = true;
  let q = quadKey;
  let last;
  while (q.length > 1) {
    last = q.substring(q.length - 1);
    q = q.substring(0, q.length - 1);
    info = this.getTileInformationFromQuadKey(q);
    if (defined(info)) {
      if (!info.hasSubtree() && !info.hasChild(parseInt(last))) {
        // We have no subtree or child available at some point in this node's ancestry
        valid = false;
      }

      break;
    } else if (info === null) {
      // Some node in the ancestry was loaded and said there wasn't a subtree
      valid = false;
      break;
    }
  }

  return valid;
};

const taskProcessor = new TaskProcessor("decodeGoogleEarthEnterprisePacket");

/**
 * Retrieves a Google Earth Enterprise quadtree packet.
 *
 * @param {string} [quadKey=''] The quadkey to retrieve the packet for.
 * @param {number} [version=1] The cnode version to be used in the request.
 * @param {Request} [request] The request object. Intended for internal use only.
 *
 * @private
 */
GoogleEarthEnterpriseMetadata.prototype.getQuadTreePacket = function (
  quadKey,
  version,
  request
) {
  version = defaultValue(version, 1);
  quadKey = defaultValue(quadKey, "");
  const resource = getMetadataResource(this, quadKey, version, request);

  const promise = resource.fetchArrayBuffer();

  if (!defined(promise)) {
    return undefined; // Throttled
  }

  const tileInfo = this._tileInfo;
  const key = this.key;
  return promise.then(function (metadata) {
    const decodePromise = taskProcessor.scheduleTask(
      {
        buffer: metadata,
        quadKey: quadKey,
        type: "Metadata",
        key: key,
      },
      [metadata]
    );

    return decodePromise.then(function (result) {
      let root;
      let topLevelKeyLength = -1;
      if (quadKey !== "") {
        // Root tile has no data except children bits, so put them into the tile info
        topLevelKeyLength = quadKey.length + 1;
        const top = result[quadKey];
        root = tileInfo[quadKey];
        root._bits |= top._bits;

        delete result[quadKey];
      }

      // Copy the resulting objects into tileInfo
      // Make sure we start with shorter quadkeys first, so we know the parents have
      //  already been processed. Otherwise we can lose ancestorHasTerrain along the way.
      const keys = Object.keys(result);
      keys.sort(function (a, b) {
        return a.length - b.length;
      });
      const keysLength = keys.length;
      for (let i = 0; i < keysLength; ++i) {
        const key = keys[i];
        const r = result[key];
        if (r !== null) {
          const info = GoogleEarthEnterpriseTileInformation.clone(result[key]);
          const keyLength = key.length;
          if (keyLength === topLevelKeyLength) {
            info.setParent(root);
          } else if (keyLength > 1) {
            const parent = tileInfo[key.substring(0, key.length - 1)];
            info.setParent(parent);
          }
          tileInfo[key] = info;
        } else {
          tileInfo[key] = null;
        }
      }
    });
  });
};

/**
 * Populates the metadata subtree down to the specified tile.
 *
 * @param {number} x The tile X coordinate.
 * @param {number} y The tile Y coordinate.
 * @param {number} level The tile level.
 * @param {Request} [request] The request object. Intended for internal use only.
 *
 * @returns {Promise<GoogleEarthEnterpriseTileInformation>} A promise that resolves to the tile info for the requested quad key
 *
 * @private
 */
GoogleEarthEnterpriseMetadata.prototype.populateSubtree = function (
  x,
  y,
  level,
  request
) {
  const quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
  return populateSubtree(this, quadkey, request);
};

function populateSubtree(that, quadKey, request) {
  const tileInfo = that._tileInfo;
  let q = quadKey;
  let t = tileInfo[q];
  // If we have tileInfo make sure sure it is not a node with a subtree that's not loaded
  if (defined(t) && (!t.hasSubtree() || t.hasChildren())) {
    return t;
  }

  while (t === undefined && q.length > 1) {
    q = q.substring(0, q.length - 1);
    t = tileInfo[q];
  }

  let subtreeRequest;
  const subtreePromises = that._subtreePromises;
  let promise = subtreePromises[q];
  if (defined(promise)) {
    return promise.then(function () {
      // Recursively call this in case we need multiple subtree requests
      subtreeRequest = new Request({
        throttle: request.throttle,
        throttleByServer: request.throttleByServer,
        type: request.type,
        priorityFunction: request.priorityFunction,
      });
      return populateSubtree(that, quadKey, subtreeRequest);
    });
  }

  // t is either
  //   null so one of its parents was a leaf node, so this tile doesn't exist
  //   exists but doesn't have a subtree to request
  //   undefined so no parent exists - this shouldn't ever happen once the provider is ready
  if (!defined(t) || !t.hasSubtree()) {
    return Promise.reject(
      new RuntimeError(`Couldn't load metadata for tile ${quadKey}`)
    );
  }

  // We need to split up the promise here because when will execute syncronously if getQuadTreePacket
  //  is already resolved (like in the tests), so subtreePromises will never get cleared out.
  //  Only the initial request will also remove the promise from subtreePromises.
  promise = that.getQuadTreePacket(q, t.cnodeVersion, request);
  if (!defined(promise)) {
    return undefined;
  }
  subtreePromises[q] = promise;

  return promise
    .then(function () {
      // Recursively call this in case we need multiple subtree requests
      subtreeRequest = new Request({
        throttle: request.throttle,
        throttleByServer: request.throttleByServer,
        type: request.type,
        priorityFunction: request.priorityFunction,
      });
      return populateSubtree(that, quadKey, subtreeRequest);
    })
    .finally(function () {
      delete subtreePromises[q];
    });
}

/**
 * Gets information about a tile
 *
 * @param {number} x The tile X coordinate.
 * @param {number} y The tile Y coordinate.
 * @param {number} level The tile level.
 * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
 *
 * @private
 */
GoogleEarthEnterpriseMetadata.prototype.getTileInformation = function (
  x,
  y,
  level
) {
  const quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
  return this._tileInfo[quadkey];
};

/**
 * Gets information about a tile from a quadKey
 *
 * @param {string} quadkey The quadkey for the tile
 * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
 *
 * @private
 */
GoogleEarthEnterpriseMetadata.prototype.getTileInformationFromQuadKey = function (
  quadkey
) {
  return this._tileInfo[quadkey];
};

function getMetadataResource(that, quadKey, version, request) {
  return that._resource.getDerivedResource({
    url: `flatfile?q2-0${quadKey}-q.${version.toString()}`,
    request: request,
  });
}

let dbrootParser;
let dbrootParserPromise;
function requestDbRoot(that) {
  const resource = that._resource.getDerivedResource({
    url: "dbRoot.v5",
    queryParameters: {
      output: "proto",
    },
  });

  if (!defined(dbrootParserPromise)) {
    const url = buildModuleUrl("ThirdParty/google-earth-dbroot-parser.js");
    const oldValue = window.cesiumGoogleEarthDbRootParser;
    dbrootParserPromise = loadAndExecuteScript(url).then(function () {
      dbrootParser = window.cesiumGoogleEarthDbRootParser(protobuf);
      if (defined(oldValue)) {
        window.cesiumGoogleEarthDbRootParser = oldValue;
      } else {
        delete window.cesiumGoogleEarthDbRootParser;
      }
    });
  }

  return dbrootParserPromise
    .then(function () {
      return resource.fetchArrayBuffer();
    })
    .then(function (buf) {
      const encryptedDbRootProto = dbrootParser.EncryptedDbRootProto.decode(
        new Uint8Array(buf)
      );

      let byteArray = encryptedDbRootProto.encryptionData;
      let offset = byteArray.byteOffset;
      let end = offset + byteArray.byteLength;
      const key = (that.key = byteArray.buffer.slice(offset, end));

      byteArray = encryptedDbRootProto.dbrootData;
      offset = byteArray.byteOffset;
      end = offset + byteArray.byteLength;
      const dbRootCompressed = byteArray.buffer.slice(offset, end);
      return taskProcessor.scheduleTask(
        {
          buffer: dbRootCompressed,
          type: "DbRoot",
          key: key,
        },
        [dbRootCompressed]
      );
    })
    .then(function (result) {
      const dbRoot = dbrootParser.DbRootProto.decode(
        new Uint8Array(result.buffer)
      );
      that.imageryPresent = defaultValue(
        dbRoot.imageryPresent,
        that.imageryPresent
      );
      that.protoImagery = dbRoot.protoImagery;
      that.terrainPresent = defaultValue(
        dbRoot.terrainPresent,
        that.terrainPresent
      );
      if (defined(dbRoot.endSnippet) && defined(dbRoot.endSnippet.model)) {
        const model = dbRoot.endSnippet.model;
        that.negativeAltitudeExponentBias = defaultValue(
          model.negativeAltitudeExponentBias,
          that.negativeAltitudeExponentBias
        );
        that.negativeAltitudeThreshold = defaultValue(
          model.compressedNegativeAltitudeThreshold,
          that.negativeAltitudeThreshold
        );
      }
      if (defined(dbRoot.databaseVersion)) {
        that._quadPacketVersion = defaultValue(
          dbRoot.databaseVersion.quadtreeVersion,
          that._quadPacketVersion
        );
      }
      const providers = that.providers;
      const providerInfo = defaultValue(dbRoot.providerInfo, []);
      const count = providerInfo.length;
      for (let i = 0; i < count; ++i) {
        const provider = providerInfo[i];
        const copyrightString = provider.copyrightString;
        if (defined(copyrightString)) {
          providers[provider.providerId] = new Credit(copyrightString.value);
        }
      }
    })
    .catch(function () {
      // Just eat the error and use the default values.
      console.log(`Failed to retrieve ${resource.url}. Using defaults.`);
      that.key = defaultKey;
    });
}
export default GoogleEarthEnterpriseMetadata;