// 物体状态
var EntityState = {
    FAILED: 0,
    UNLOADED: 1,
    RECEIVING: 2,
    RECEIVED: 3,
    TRANSFORMING: 4,
    TRANSFORMED: 5,
    READY: 6
};

/**
 * 物体瓦片，负责管理瓦片内物体的加载过程。
 * @param provider
 * @constructor
 */
function TileEntity(provider) {
    if (!Cesium.defined(provider)) {
        throw new DeveloperError('provider is required.');
    }

    this.provider = provider;

    this.state = EntityState.UNLOADED;

    this.buffers = [];
    this.dataList = [];
}

/**
 * Processes the load state machine for this instance.
 *
 */
TileEntity.prototype.processStateMachine = function (frameState, entityProvider, x, y, level, priorityFunction) {
    if (this.state === EntityState.UNLOADED) {
        requestEntityData(this, entityProvider, x, y, level, priorityFunction);
    }

    if (this.state === EntityState.RECEIVED) {
        transform(this, frameState, entityProvider, x, y, level);
    }

    if (this.state === EntityState.TRANSFORMED) {
        createResources(this, frameState.context, entityProvider, x, y, level);
    }

    if (this.state === EntityState.READY) {
        return true; // done loading
    }


    // 没有加载完成也应该使用父节点的，不能四个子节点都使用父节点显示那样就重复了；可以给节点增加计数，确保每个节点只显示一次。
    // 目前所有父节点都是可见，后期再完善。

    // Find some ancestor imagery we can use while this imagery is still loading.
    // var ancestor = this.parent;
    // var closestAncestorThatNeedsLoading;
    // while (defined(ancestor) && (ancestor.state !== ImageryState.READY || (!this.useWebMercatorT && !defined(ancestor.texture)))) {
    //     if (ancestor.state !== ImageryState.FAILED && ancestor.state !== ImageryState.INVALID) {
    //         // ancestor is still loading
    //         closestAncestorThatNeedsLoading = closestAncestorThatNeedsLoading || ancestor;
    //     }
    //     ancestor = ancestor.parent;
    // }
    //
    // if (this.readyImagery !== ancestor) {
    //     if (defined(this.readyImagery)) {
    //         this.readyImagery.releaseReference();
    //     }
    //
    //     this.readyImagery = ancestor;
    //
    //     if (defined(ancestor)) {
    //         ancestor.addReference();
    //         this.textureTranslationAndScale = imageryLayer._calculateTextureTranslationAndScale(tile, this);
    //     }
    // }

    if (this.state === EntityState.FAILED) {
        // The imagery tile is failed or invalid, so we'd like to use an ancestor instead.
        // if (defined(closestAncestorThatNeedsLoading)) {
        //     // Push the ancestor's load process along a bit.  This is necessary because some ancestor imagery
        //     // tiles may not be attached directly to a terrain tile.  Such tiles will never load if
        //     // we don't do it here.
        //     closestAncestorThatNeedsLoading.processStateMachine(frameState, !this.useWebMercatorT, tile._priorityFunction);
        //     return false; // not done loading
        // }
        // This imagery tile is failed or invalid, and we have the "best available" substitute.
        return true; // done loading
    }

    return false; // not done loading
}

function requestEntityData(tileEntity, entityProvider, x, y, level, priorityFunction) {
    function success(buffers) {
        if (!Cesium.defined(buffers)) {
            tileEntity.state = EntityState.UNLOADED;
            tileEntity.request = undefined;
            return;
        }

        tileEntity.buffers = buffers;
        tileEntity.state = EntityState.RECEIVED;
        tileEntity.request = undefined;
    }

    function failure() {
        if (tileEntity.request.state === RequestState.CANCELLED) {
            // Cancelled due to low priority - try again later.
            tileEntity.state = EntityState.UNLOADED;
            tileEntity.request = undefined;
            return;
        }

        // Initially assume failure.  handleError may retry, in which case the state will
        // change to RECEIVING or UNLOADED.
        tileEntity.state = EntityState.FAILED;
        tileEntity.request = undefined;

        var message = 'Failed to obtain entity tile X: ' + x + ' Y: ' + y + ' Level: ' + level + '.';
        entityProvider._requestError = Cesium.TileProviderError.handleError(
            entityProvider._requestError,
            entityProvider,
            entityProvider.errorEvent,
            message,
            x, y, level,
            doRequest);
    }

    function doRequest() {
        // Request the entity data from the entity provider.
        var request = new Cesium.Request({
            throttle: true,
            throttleByServer: true,
            type: Cesium.RequestType.TILES3D,
            priorityFunction: priorityFunction
        });
        tileEntity.request = request;
        var data = entityProvider.requestEntityData(x, y, level, request);

        // If the request method returns undefined (instead of a promise), the request
        // has been deferred.
        if (Cesium.defined(data)) {
            tileEntity.state = tileEntity.RECEIVING;
            Cesium.when(data, success, failure);
        } else {
            // Deferred - try again later.
            //tileEntity.state = EntityState.UNLOADED;
            tileEntity.request = undefined;

            tileEntity.state = EntityState.FAILED;
        }
    }

    doRequest();
}

function transform(tileEntity, frameState, provider, x, y, level) {
    if (!Cesium.defined(tileEntity.buffers)) {
        return null;
    }

    // 解析数据（也可以放在分支线程）
    for (var i = 0, len = tileEntity.buffers.length; i < len; ++i) {
        var stream = new MemStream(tileEntity.buffers[i]);
        var version = stream.readInt32();
        var count = stream.readInt32();
        for (var j = 0; j < count; ++j) {
            var lon = stream.readFloat();
            var lat = stream.readFloat();
            var h = stream.readFloat();
            var text = '';

            var textLen = stream.readUChar8();
            if (textLen > 0) {
                var strData = stream.readUChar8Array2(textLen);
                text = new TextDecoder("utf-8").decode(strData);
                text = text.replace(/\|/g, ''); // 替换掉所有的|字符
            }

            var useFont = provider.fontSize * 2 + "px " + provider.fontFamily;

            var entity = provider.viewer.entities.add({
                parent: provider.fatherGroup,
                position: Cesium.Cartesian3.fromDegrees(lon, lat, h),
                label: {
                    text: text,
                    font: useFont,
                    fillColor: Cesium.Color.WHITE,
                    outlineColor: Cesium.Color.BLACK,
                    outlineWidth: 6,
                    style: Cesium.LabelStyle.FILL_AND_OUTLINE,
                    scale: 0.5
                }
            });

            tileEntity.dataList.push(entity.id); // 保留id供移除时使用
        }
    }

    tileEntity.buffers.length = 0;

    tileEntity.state = EntityState.TRANSFORMING;

    // 如果是在其他线程做，完成后再改变状态
    // when(meshPromise, function(mesh) {
    //     tileTerrain.mesh = mesh;
    //     tileTerrain.state = TerrainState.TRANSFORMED;
    // }, function() {
    //     tileTerrain.state = TerrainState.FAILED;
    // });

    tileEntity.state = EntityState.TRANSFORMED;

}

function createResources(tileEntity, context) {

    // 使用现有的结构就不手动构建渲染单元了

    // tileTerrain.vertexArray = new VertexArray({
    //     context : context,
    //     attributes : attributes,
    //     indexBuffer : indexBuffer
    // });


    tileEntity.state = EntityState.READY;
}

TileEntity.prototype.freeResources = function () {
    for (var i = 0, len = this.dataList.length; i < len; ++i) {
        this.provider.viewer.entities.removeById(this.dataList[i]);
    }
    this.dataList.length = 0;

    this.buffers.length = 0;
};