import Node from './Node';
import Light from './Light';
import Camera from './Camera';
import BoundingBox from './math/BoundingBox';
import util from './core/util';
import mat4 from './glmatrix/mat4';
import LRUCache from './core/LRU';
import Matrix4 from './math/Matrix4';

var IDENTITY = mat4.create();
var WORLDVIEW = mat4.create();

var programKeyCache = {};

function getProgramKey(lightNumbers) {
    var defineStr = [];
    var lightTypes = Object.keys(lightNumbers);
    lightTypes.sort();
    for (var i = 0; i < lightTypes.length; i++) {
        var lightType = lightTypes[i];
        defineStr.push(lightType + ' ' + lightNumbers[lightType]);
    }
    var key = defineStr.join('\n');

    if (programKeyCache[key]) {
        return programKeyCache[key];
    }

    var id = util.genGUID();
    programKeyCache[key] = id;
    return id;
}

function RenderList() {

    this.opaque = [];
    this.transparent = [];

    this._opaqueCount = 0;
    this._transparentCount = 0;
}

RenderList.prototype.startCount = function () {
    this._opaqueCount = 0;
    this._transparentCount = 0;
};

RenderList.prototype.add = function (object, isTransparent) {
    if (isTransparent) {
        this.transparent[this._transparentCount++] = object;
    }
    else {
        this.opaque[this._opaqueCount++] = object;
    }
};

RenderList.prototype.endCount = function () {
    this.transparent.length = this._transparentCount;
    this.opaque.length = this._opaqueCount;
};

/**
 * @typedef {Object} clay.Scene.RenderList
 * @property {Array.<clay.Renderable>} opaque
 * @property {Array.<clay.Renderable>} transparent
 */

/**
 * @constructor clay.Scene
 * @extends clay.Node
 */
var Scene = Node.extend(function () {
    return /** @lends clay.Scene# */ {
        /**
         * Global material of scene
         * @type {clay.Material}
         */
        material: null,

        lights: [],

        /**
         * Scene bounding box in view space.
         * Used when camera needs to adujst the near and far plane automatically
         * so that the view frustum contains the visible objects as tightly as possible.
         * Notice:
         *  It is updated after rendering (in the step of frustum culling passingly). So may be not so accurate, but saves a lot of calculation
         *
         * @type {clay.BoundingBox}
         */
        viewBoundingBoxLastFrame: new BoundingBox(),

        // Uniforms for shadow map.
        shadowUniforms: {},

        _cameraList: [],

        // Properties to save the light information in the scene
        // Will be set in the render function
        _lightUniforms: {},

        _previousLightNumber: {},

        _lightNumber: {
            // groupId: {
                // POINT_LIGHT: 0,
                // DIRECTIONAL_LIGHT: 0,
                // SPOT_LIGHT: 0,
                // AMBIENT_LIGHT: 0,
                // AMBIENT_SH_LIGHT: 0
            // }
        },

        _lightProgramKeys: {},

        _nodeRepository: {},

        _renderLists: new LRUCache(20)

    };
}, function () {
    this._scene = this;
},
/** @lends clay.Scene.prototype. */
{

    // Add node to scene
    addToScene: function (node) {
        if (node instanceof Camera) {
            if (this._cameraList.length > 0) {
                console.warn('Found multiple camera in one scene. Use the fist one.');
            }
            this._cameraList.push(node);
        }
        else if (node instanceof Light) {
            this.lights.push(node);
        }
        if (node.name) {
            this._nodeRepository[node.name] = node;
        }
    },

    // Remove node from scene
    removeFromScene: function (node) {
        var idx;
        if (node instanceof Camera) {
            idx = this._cameraList.indexOf(node);
            if (idx >= 0) {
                this._cameraList.splice(idx, 1);
            }
        }
        else if (node instanceof Light) {
            idx = this.lights.indexOf(node);
            if (idx >= 0) {
                this.lights.splice(idx, 1);
            }
        }
        if (node.name) {
            delete this._nodeRepository[node.name];
        }
    },

    /**
     * Get node by name
     * @param  {string} name
     * @return {Node}
     * @DEPRECATED
     */
    getNode: function (name) {
        return this._nodeRepository[name];
    },

    /**
     * Set main camera of the scene.
     * @param {claygl.Camera} camera
     */
    setMainCamera: function (camera) {
        var idx = this._cameraList.indexOf(camera);
        if (idx >= 0) {
            this._cameraList.splice(idx, 1);
        }
        this._cameraList.unshift(camera);
    },
    /**
     * Get main camera of the scene.
     */
    getMainCamera: function () {
        return this._cameraList[0];
    },

    getLights: function () {
        return this.lights;
    },

    updateLights: function () {
        var lights = this.lights;
        this._previousLightNumber = this._lightNumber;

        var lightNumber = {};
        for (var i = 0; i < lights.length; i++) {
            var light = lights[i];
            if (light.invisible) {
                continue;
            }
            var group = light.group;
            if (!lightNumber[group]) {
                lightNumber[group] = {};
            }
            // User can use any type of light
            lightNumber[group][light.type] = lightNumber[group][light.type] || 0;
            lightNumber[group][light.type]++;
        }
        this._lightNumber = lightNumber;

        for (var groupId in lightNumber) {
            this._lightProgramKeys[groupId] = getProgramKey(lightNumber[groupId]);
        }

        this._updateLightUniforms();
    },

    /**
     * Clone a node and it's children, including mesh, camera, light, etc.
     * Unlike using `Node#clone`. It will clone skeleton and remap the joints. Material will also be cloned.
     *
     * @param {clay.Node} node
     * @return {clay.Node}
     */
    cloneNode: function (node) {
        var newNode = node.clone();
        var clonedNodesMap = {};
        function buildNodesMap(sNode, tNode) {
            clonedNodesMap[sNode.__uid__] = tNode;

            for (var i = 0; i < sNode._children.length; i++) {
                var sChild = sNode._children[i];
                var tChild = tNode._children[i];
                buildNodesMap(sChild, tChild);
            }
        }
        buildNodesMap(node, newNode);

        newNode.traverse(function (newChild) {
            if (newChild.skeleton) {
                newChild.skeleton = newChild.skeleton.clone(clonedNodesMap);
            }
            if (newChild.material) {
                newChild.material = newChild.material.clone();
            }
        });

        return newNode;
    },

    /**
     * Traverse the scene and add the renderable object to the render list.
     * It needs camera for the frustum culling.
     *
     * @param {clay.Camera} camera
     * @param {boolean} updateSceneBoundingBox
     * @return {clay.Scene.RenderList}
     */
    updateRenderList: function (camera, updateSceneBoundingBox) {
        var id = camera.__uid__;
        var renderList = this._renderLists.get(id);
        if (!renderList) {
            renderList = new RenderList();
            this._renderLists.put(id, renderList);
        }
        renderList.startCount();

        if (updateSceneBoundingBox) {
            this.viewBoundingBoxLastFrame.min.set(Infinity, Infinity, Infinity);
            this.viewBoundingBoxLastFrame.max.set(-Infinity, -Infinity, -Infinity);
        }

        var sceneMaterialTransparent = this.material && this.material.transparent || false;
        this._doUpdateRenderList(this, camera, sceneMaterialTransparent, renderList, updateSceneBoundingBox);

        renderList.endCount();

        return renderList;
    },

    /**
     * Get render list. Used after {@link clay.Scene#updateRenderList}
     * @param {clay.Camera} camera
     * @return {clay.Scene.RenderList}
     */
    getRenderList: function (camera) {
        return this._renderLists.get(camera.__uid__);
    },

    _doUpdateRenderList: function (parent, camera, sceneMaterialTransparent, renderList, updateSceneBoundingBox) {
        if (parent.invisible) {
            return;
        }
        // TODO Optimize
        for (var i = 0; i < parent._children.length; i++) {
            var child = parent._children[i];

            if (child.isRenderable()) {
                // Frustum culling
                var worldM = child.isSkinnedMesh() ? IDENTITY : child.worldTransform.array;
                var geometry = child.geometry;

                mat4.multiplyAffine(WORLDVIEW, camera.viewMatrix.array, worldM);
                if (updateSceneBoundingBox && !geometry.boundingBox || !this.isFrustumCulled(child, camera, WORLDVIEW)) {
                    renderList.add(child, child.material.transparent || sceneMaterialTransparent);
                }
            }
            if (child._children.length > 0) {
                this._doUpdateRenderList(child, camera, sceneMaterialTransparent, renderList, updateSceneBoundingBox);
            }
        }
    },

    /**
     * If an scene object is culled by camera frustum
     *
     * Object can be a renderable or a light
     *
     * @param {clay.Node} object
     * @param {clay.Camera} camera
     * @param {Array.<number>} worldViewMat represented with array
     * @param {Array.<number>} projectionMat represented with array
     */
    isFrustumCulled: (function () {
        // Frustum culling
        // http://www.cse.chalmers.se/~uffe/vfc_bbox.pdf
        var cullingBoundingBox = new BoundingBox();
        var cullingMatrix = new Matrix4();
        return function(object, camera, worldViewMat) {
            // Bounding box can be a property of object(like light) or renderable.geometry
            // PENDING
            var geoBBox = object.boundingBox;
            if (!geoBBox) {
                if (object.skeleton && object.skeleton.boundingBox) {
                    geoBBox = object.skeleton.boundingBox;
                }
                else {
                    geoBBox = object.geometry.boundingBox;
                }
            }

            if (!geoBBox) {
                return false;
            }

            cullingMatrix.array = worldViewMat;
            cullingBoundingBox.transformFrom(geoBBox, cullingMatrix);

            // Passingly update the scene bounding box
            // FIXME exclude very large mesh like ground plane or terrain ?
            // FIXME Only rendererable which cast shadow ?

            // FIXME boundingBox becomes much larger after transformd.
            if (object.castShadow) {
                this.viewBoundingBoxLastFrame.union(cullingBoundingBox);
            }
            // Ignore frustum culling if object is skinned mesh.
            if (object.frustumCulling)  {
                if (!cullingBoundingBox.intersectBoundingBox(camera.frustum.boundingBox)) {
                    return true;
                }

                cullingMatrix.array = camera.projectionMatrix.array;
                if (
                    cullingBoundingBox.max.array[2] > 0 &&
                    cullingBoundingBox.min.array[2] < 0
                ) {
                    // Clip in the near plane
                    cullingBoundingBox.max.array[2] = -1e-20;
                }

                cullingBoundingBox.applyProjection(cullingMatrix);

                var min = cullingBoundingBox.min.array;
                var max = cullingBoundingBox.max.array;

                if (
                    max[0] < -1 || min[0] > 1
                    || max[1] < -1 || min[1] > 1
                    || max[2] < -1 || min[2] > 1
                ) {
                    return true;
                }
            }

            return false;
        };
    })(),

    _updateLightUniforms: function () {
        var lights = this.lights;
        // Put the light cast shadow before the light not cast shadow
        lights.sort(lightSortFunc);

        var lightUniforms = this._lightUniforms;
        for (var group in lightUniforms) {
            for (var symbol in lightUniforms[group]) {
                lightUniforms[group][symbol].value.length = 0;
            }
        }
        for (var i = 0; i < lights.length; i++) {

            var light = lights[i];

            if (light.invisible) {
                continue;
            }

            var group = light.group;

            for (var symbol in light.uniformTemplates) {
                var uniformTpl = light.uniformTemplates[symbol];
                var value = uniformTpl.value(light);
                if (value == null) {
                    continue;
                }
                if (!lightUniforms[group]) {
                    lightUniforms[group] = {};
                }
                if (!lightUniforms[group][symbol]) {
                    lightUniforms[group][symbol] = {
                        type: '',
                        value: []
                    };
                }
                var lu = lightUniforms[group][symbol];
                lu.type = uniformTpl.type + 'v';
                switch (uniformTpl.type) {
                    case '1i':
                    case '1f':
                    case 't':
                        lu.value.push(value);
                        break;
                    case '2f':
                    case '3f':
                    case '4f':
                        for (var j = 0; j < value.length; j++) {
                            lu.value.push(value[j]);
                        }
                        break;
                    default:
                        console.error('Unkown light uniform type ' + uniformTpl.type);
                }
            }
        }
    },

    getLightGroups: function () {
        var lightGroups = [];
        for (var groupId in this._lightNumber) {
            lightGroups.push(groupId);
        }
        return lightGroups;
    },

    getNumberChangedLightGroups: function () {
        var lightGroups = [];
        for (var groupId in this._lightNumber) {
            if (this.isLightNumberChanged(groupId)) {
                lightGroups.push(groupId);
            }
        }
        return lightGroups;
    },

    // Determine if light group is different with since last frame
    // Used to determine whether to update shader and scene's uniforms in Renderer.render
    isLightNumberChanged: function (lightGroup) {
        var prevLightNumber = this._previousLightNumber;
        var currentLightNumber = this._lightNumber;
        // PENDING Performance
        for (var type in currentLightNumber[lightGroup]) {
            if (!prevLightNumber[lightGroup]) {
                return true;
            }
            if (currentLightNumber[lightGroup][type] !== prevLightNumber[lightGroup][type]) {
                return true;
            }
        }
        for (var type in prevLightNumber[lightGroup]) {
            if (!currentLightNumber[lightGroup]) {
                return true;
            }
            if (currentLightNumber[lightGroup][type] !== prevLightNumber[lightGroup][type]) {
                return true;
            }
        }
        return false;
    },

    getLightsNumbers: function (lightGroup) {
        return this._lightNumber[lightGroup];
    },

    getProgramKey: function (lightGroup) {
        return this._lightProgramKeys[lightGroup];
    },

    setLightUniforms: (function () {
        function setUniforms(uniforms, program, renderer) {
            for (var symbol in uniforms) {
                var lu = uniforms[symbol];
                if (lu.type === 'tv') {
                    if (!program.hasUniform(symbol)) {
                        continue;
                    }
                    var texSlots = [];
                    for (var i = 0; i < lu.value.length; i++) {
                        var texture = lu.value[i];
                        var slot = program.takeCurrentTextureSlot(renderer, texture);
                        texSlots.push(slot);
                    }
                    program.setUniform(renderer.gl, '1iv', symbol, texSlots);
                }
                else {
                    program.setUniform(renderer.gl, lu.type, symbol, lu.value);
                }
            }
        }

        return function (program, lightGroup, renderer) {
            setUniforms(this._lightUniforms[lightGroup], program, renderer);
            // Set shadows
            setUniforms(this.shadowUniforms, program, renderer);
        };
    })(),

    /**
     * Dispose self, clear all the scene objects
     * But resources of gl like texuture, shader will not be disposed.
     * Mostly you should use disposeScene method in Renderer to do dispose.
     */
    dispose: function () {
        this.material = null;
        this._opaqueList = [];
        this._transparentList = [];

        this.lights = [];

        this._lightUniforms = {};

        this._lightNumber = {};
        this._nodeRepository = {};
    }
});

function lightSortFunc(a, b) {
    if (b.castShadow && !a.castShadow) {
        return true;
    }
}

export default Scene;