/**
 * 地名注记数据提供者，通过改变LSGlobe实现地名注记数据的加载。
 *
 * * @alias CesiumTerrainProvider
 * @constructor
 *
 * @param {LSGlobe} LSGlobe  The result of LSGlobe.js
 * @param {Object} options  The options include:
 * @param {String} options.url 地形服务的url。
 * @param {Proxy} [options.proxy] 请求的代理。
 * @param {String} [options.tileUrlTemplate] url模板。
 * @param {Ellipsoid} [options.ellipsoid] 椭球体，默认为WGS84椭球体。
 * @param {String} [options.metadataUrl] 元数据文件路径。
 */
var VTPMarkerProvider = function (LSGlobe, options) {
    "use strict"; // 进入严格模式

    if (typeof LSGlobe === 'undefined') {
        throw 'LSGlobe must be defined for this plugin to work.';
    }
    if (typeof LSGlobe.defined === 'undefined' || !LSGlobe.defined(LSGlobe.GlobeSurfaceTile)) {
        throw 'Your version of LSGlobe is out of date, please upgrade LSGlobe.';
    }
    this.LSGlobe = LSGlobe;

    // Provider自有的内容
    if (!LSGlobe.defined(options) || !LSGlobe.defined(options.url)) {
        throw new LSGlobe.DeveloperError('options.url is required.');
    }

    this.viewer = undefined;

    // 字体设置
    this.fontSize = LSGlobe.defaultValue(options.fontSize, 16);
    this.fontFamily = LSGlobe.defaultValue(options.fontFamily, "Microsoft YaHei");

    this._url = options.url;
    this._proxy = options.proxy;
    this.fatherGroup = options.fatherGroup;
    var tileUrlTemplate = this._url + '/ReadTerrainLrp?layer=' + options.layer + '&x={row}&y={col}&z={level}';
    this._tileUrlTemplate = LSGlobe.defaultValue(options.tileUrlTemplate, tileUrlTemplate);

    this._tilingScheme = new LSGlobe.GeographicTilingScheme({
        numberOfLevelZeroTilesX: 2,
        numberOfLevelZeroTilesY: 1,
        ellipsoid: options.ellipsoid
    });

    this._errorEvent = new LSGlobe.Event();
    this._availability = undefined;

    this._ready = false;
    this._readyPromise = LSGlobe.when.defer();

    var metadataUrl = this._url + '/CreateTerrainLrc?layer=' + options.layer;
    if (LSGlobe.defined(this._proxy)) {
        metadataUrl = this._proxy.getURL(metadataUrl);
    }
    metadataUrl = LSGlobe.defaultValue(options.metadataUrl, metadataUrl);
    var metadataError;

    var that = this;

    /**
     * 元数据请求成功函数，用于解析元数据文件。
     * @param {#document} xml 元数据文件
     * @private
     */
    function metadataSuccess(xml) {
        that._minimumLevel = parseInt(xml.getElementsByTagName('LevelBegin')[0].childNodes[0].nodeValue);
        that._maximumLevel = parseInt(xml.getElementsByTagName('LevelEnd')[0].childNodes[0].nodeValue);

        var west = LSGlobe.Math.toRadians(xml.getElementsByTagName('West')[0].childNodes[0].nodeValue);
        var south = LSGlobe.Math.toRadians(xml.getElementsByTagName('South')[0].childNodes[0].nodeValue);
        var east = LSGlobe.Math.toRadians(xml.getElementsByTagName('East')[0].childNodes[0].nodeValue);
        var north = LSGlobe.Math.toRadians(xml.getElementsByTagName('North')[0].childNodes[0].nodeValue);
        that._rectangle = new LSGlobe.Rectangle(west, south, east, north);

        that._ready = true;
        that._readyPromise.resolve(true);
    }

    /**
     * 元数据请求失败函数。
     * @private
     */
    function metadataFailure(data) {
        var message = 'An error occurred while accessing ' + metadataUrl + '.';
        metadataError = TileProviderError.handleError(metadataError, that, that._errorEvent, message, undefined, undefined, undefined, requestMetadata);
    }

    /**
     * 元数据请求函数。
     * @private
     */
    function requestMetadata() {
        function getxmlDoc(xmlFile) {
            var xmlDoc;
            if (window.ActiveXObject) {
                xmlDoc = new ActiveXObject('Microsoft.XMLDOM'); //IE
                xmlDoc.async = false;
                xmlDoc.load(xmlFile);
            } else if (navigator.userAgent.indexOf("Firefox") > 0) { //火狐
                try {
                    xmlDoc = document.implementation.createDocument('', '', null);
                    xmlDoc.load(xmlFile);
                } catch (e) {
                    var xmlhttp = new window.XMLHttpRequest();
                    xmlhttp.open("GET", xmlFile, false);
                    xmlhttp.send(null);
                    if (xmlhttp.readyState == 4) {
                        xmlDoc = xmlhttp.responseXML.documentElement;
                    }
                }
            } else { //谷歌
                var xmlhttp = new window.XMLHttpRequest();
                xmlhttp.open("GET", xmlFile, false);
                xmlhttp.send(null);
                if (xmlhttp.readyState == 4) {
                    xmlDoc = xmlhttp.responseXML.documentElement;
                }
            }

            return xmlDoc;
        }
        //加载XML
        var metadata = getxmlDoc(metadataUrl);
        //var metadata = LSGlobe.loadXML(metadataUrl);
        LSGlobe.when(metadata, metadataSuccess, metadataFailure);
    }

    // 请求元数据
    requestMetadata();

    /**
     * Modifying the passed in LSGlobe to allow for loading VTP markers...
     */
    // 使用新的 processStateMachine 函数，增加对地名注记的处理
    LSGlobe.GlobeSurfaceTile._oldProcessStateMachine = LSGlobe.GlobeSurfaceTile.processStateMachine;
    LSGlobe.GlobeSurfaceTile.processStateMachine = function (tile, frameState,
        terrainLayerCollection, imageryLayerCollection, vertexArraysToDestroy) {
        var priorityFunc = tile._priorityFunction; // _oldProcessStateMachine可能会改变tile._priorityFunction，提前备份。

        LSGlobe.GlobeSurfaceTile._oldProcessStateMachine(tile, frameState,
            terrainLayerCollection, imageryLayerCollection, vertexArraysToDestroy);

        // 地名注记的处理
        var surfaceTile = tile.data;
        var tileEntity = surfaceTile.tileEntity;
        if (!LSGlobe.defined(tileEntity)) {
            tileEntity = new TileEntity(that);
            surfaceTile.tileEntity = tileEntity;
        }
        // 地名注记没有加载完成，修改tile的状态不为QuadtreeTileLoadState.DONE
        var isDoneLoading = tileEntity.processStateMachine(frameState, that, tile.x, tile.y, tile.level, tile._priorityFunction);
        if (!isDoneLoading && tile.state === LSGlobe.QuadtreeTileLoadState.DONE) {
            tile.state = LSGlobe.QuadtreeTileLoadState.LOADING;
            tile._priorityFunction = priorityFunc;
        }
    };

    // 使用新的 freeResources 函数，增加对 tileEntity 的释放。
    LSGlobe.GlobeSurfaceTile.prototype._oldFreeResources = LSGlobe.GlobeSurfaceTile.prototype.freeResources;
    LSGlobe.GlobeSurfaceTile.prototype.freeResources = function () {
        this._oldFreeResources();

        if (LSGlobe.defined(this.tileEntity)) {
            this.tileEntity.freeResources();
            this.tileEntity = undefined;
        }
    };

    // 是否需要隐藏当前没有渲染的tile对应的地标，待确认.
    LSGlobe.GlobeSurfaceTileProvider.prototype._oldEndUpdate = LSGlobe.GlobeSurfaceTileProvider.prototype.endUpdate;
    LSGlobe.GlobeSurfaceTileProvider.prototype.endUpdate = function (frameState) {
        // Call the original update
        this._oldEndUpdate(frameState);

        // 先把所有的设置为不可见，然后把所有要渲染的瓦片设置可见。
        // 会晚一帧，因为给其添加command在这之前已经做了
        // var entities = that.viewer.entities;
        // for (var i = 0, len = entities.length; i < len; ++i) {
        //     entities[i]._show = false;
        // }
        //
        // var tilesToRenderByTextureCount = this._tilesToRenderByTextureCount;
        // for (var textureCountIndex = 0, textureCountLength = tilesToRenderByTextureCount.length; textureCountIndex < textureCountLength; ++textureCountIndex) {
        //     var tilesToRender = tilesToRenderByTextureCount[textureCountIndex];
        //     if (!LSGlobe.defined(tilesToRender)) {
        //         continue;
        //     }
        //
        //     for (var tileIndex = 0, tileLength = tilesToRender.length; tileIndex < tileLength; ++tileIndex) {
        //         var tileEntity = tilesToRender[tileIndex].data.tileEntity;
        //         for (var i = 0, len = tileEntity.dataList.length; i < len; ++i) {
        //             entities.getById(tileEntity.dataList[i])._show = true;
        //         }
        //     }
        // }
    };

};

/**
 * 为给定瓦片请求几何数据。 
 *
 * @param {Number} x x坐标。
 * @param {Number} y y坐标。
 * @param {Number} level tile等级。
 *
 * @returns {Promise.<TerrainData>|undefined} 地形数据对象。
 *
 * @exception {DeveloperError} 函数必须在{@link DTPTerrainProvider#ready}为ture之后调用。
 */
VTPMarkerProvider.prototype.requestEntityData = function (x, y, level, request) {
    if (!this._ready) {
        return undefined; //throw new DeveloperError('requestTileGeometry must not be called before the terrain provider is ready.');
    }

    var urlTemplate = this._tileUrlTemplate;
    if (!isatCesium.defined(urlTemplate)) {
        return undefined;
    }

    if (!this.getTileDataAvailable(x, y, level)) {
        return undefined;
    }

    // 计算瓦片对应的地标块范围（一个瓦片可能对应多个地标块数据）
    var yTiles = this._tilingScheme.getNumberOfYTilesAtLevel(level) * 2;
    var minXY = new isatCesium.Cartesian2(-1, -1);
    var maxXY = new isatCesium.Cartesian2(-1, -1);
    calcMinMaxRowCol(this, x, y, level, minXY, maxXY);
    if (maxXY.x >= yTiles) {
        maxXY.x = yTiles - 1;
    }
    if (maxXY.y >= yTiles) {
        maxXY.y = yTiles - 1;
    }
    if (minXY.y >= yTiles || maxXY.x >= yTiles || // 无效范围
        minXY.y < 0 || maxXY.y < 0 || minXY.x < 0 || maxXY.x < 0) {
        return undefined;
    }
    // 数据请求数组
    var promiseArray = [];
    for (var i = minXY.y; i <= maxXY.y; ++i) {
        for (var j = minXY.x; j <= maxXY.x; ++j) {
            var url = buildUrl(this, j, yTiles - i - 1, level + 1);
            var promise = isatCesium.loadArrayBuffer(url);
            if (!isatCesium.defined(promise)) {
                return undefined;
            }
            promiseArray.push(promise);
        }
    }

    var that = this;
    return isatCesium.when.all(promiseArray, function (buffers) {
        return buffers;
    }, function () {
        return isatCesium.when.reject();
    });
};

/**
 * 判断瓦片数据是否可以加载。
 *
 * @param {Number} x 列号.
 * @param {Number} y 行号.
 * @param {Number} level 层号.
 * @returns {Boolean} Undefined if not supported, otherwise true or false.
 */
VTPMarkerProvider.prototype.getTileDataAvailable = function (x, y, level) {
    if (!this._ready) {
        return undefined;
    }

    if (level > this._maximumLevel - 1 || level < this._minimumLevel - 1) {
        return false; // 不在层级范围内
    }

    var result = undefined;
    result = this._tilingScheme.tileXYToRectangle(x, y, level, result);
    if (Cesium.Rectangle.intersection(this._rectangle, result) == undefined) {
        return false; // 不在地理范围内
    }

    return true;
};

// 根据层号、行号和列号构建请求地址
function buildUrl(provider, x, y, level) {
    var url = provider._tileUrlTemplate.replace('{z}', level).replace('{x}', x).replace('{y}', y);

    var proxy = provider._proxy;
    if (isatCesium.defined(proxy)) {
        url = proxy.getURL(url);
    }

    return url;
}

// 根据tile的层号、行号和列号计算地标块索引范围
function calcMinMaxRowCol(provider, x, y, level, minXY, maxXY) {
    var tileRect = provider._tilingScheme.tileXYToRectangle(x, y, level);
    var tileSize = tileRect.width;

    var sample = 18;
    var sampleGap = tileSize / sample;

    var val = tileRect.west;
    while (val < tileRect.east) {
        adjustMinMaxRowCol(val, tileRect.south, tileSize, minXY, maxXY);
        adjustMinMaxRowCol(val, tileRect.north, tileSize, minXY, maxXY);
        val += sampleGap;
    }
    val = tileRect.south;
    while (val < tileRect.north) {
        adjustMinMaxRowCol(tileRect.west, val, tileSize, minXY, maxXY);
        adjustMinMaxRowCol(tileRect.east, val, tileSize, minXY, maxXY);
        val += sampleGap;
    }
}

// 根据经纬度及瓦片范围调整地标块索引范围
function adjustMinMaxRowCol(lon, lat, tileSize, minXY, maxXY) {
    var result = getRowCol(lon, lat, tileSize);
    var x = Math.floor(result.x);
    var y = Math.floor(result.y);
    if (x >= 0) {
        if (minXY.x < 0 || x < minXY.x) {
            minXY.x = x;
        }
        if (maxXY.x < 0 || x > maxXY.x) {
            maxXY.x = x;
        }
    }
    if (y >= 0) {
        if (minXY.y < 0 || y < minXY.y) {
            minXY.y = y;
        }
        if (maxXY.y < 0 || y > maxXY.y) {
            maxXY.y = y;
        }
    }
}

// 根据经纬度及瓦片范围计算对应的地标块索引
function getRowCol(lon, lat, tileSize, result) {
    if (!isatCesium.defined(result)) {
        result = new isatCesium.Cartesian2();
    }

    result.x = (lon + Math.PI) / tileSize;
    var temp = Math.tan(Math.PI / 4.0 + lat / 2.0);
    if (temp > 0) {
        result.y = (Math.log(temp) + Math.PI) / tileSize;
    } else {
        result.y = -1;
    }

    return result;
}