var ANode = require('./a-node');
var COMPONENTS = require('./component').components;
var registerElement = require('./a-register-element').registerElement;
var THREE = require('../lib/three');
var utils = require('../utils/');

var AEntity;
var debug = utils.debug('core:a-entity:debug');
var warn = utils.debug('core:a-entity:warn');

var MULTIPLE_COMPONENT_DELIMITER = '__';
var OBJECT3D_COMPONENTS = ['position', 'rotation', 'scale', 'visible'];
var ONCE = {once: true};

/**
 * Entity is a container object that components are plugged into to comprise everything in
 * the scene. In A-Frame, they inherently have position, rotation, and scale.
 *
 * To be able to take components, the scene element inherits from the entity definition.
 *
 * @member {object} components - entity's currently initialized components.
 * @member {object} object3D - three.js object.
 * @member {array} states
 * @member {boolean} isPlaying - false if dynamic behavior of the entity is paused.
 */
var proto = Object.create(ANode.prototype, {
  createdCallback: {
    value: function () {
      this.components = {};
      // To avoid double initializations and infinite loops.
      this.initializingComponents = {};
      this.componentsToUpdate = {};
      this.isEntity = true;
      this.isPlaying = false;
      this.object3D = new THREE.Group();
      this.object3D.el = this;
      this.object3DMap = {};
      this.parentEl = null;
      this.rotationObj = {};
      this.states = [];
    }
  },

  /**
   * Handle changes coming from the browser DOM inspector.
   */
  attributeChangedCallback: {
    value: function (attr, oldVal, newVal) {
      var component = this.components[attr];
      // If the empty string is passed by the component initialization
      // logic we ignore the component update.
      if (component && component.justInitialized && newVal === '') {
        delete component.justInitialized;
        return;
      }
      // When a component is removed after calling el.removeAttribute('material')
      if (!component && newVal === null) { return; }
      this.setEntityAttribute(attr, oldVal, newVal);
    }
  },

  /**
   * Add to parent, load, play.
   */
  attachedCallback: {
    value: function () {
      var assetsEl;  // Asset management system element.
      var sceneEl = this.sceneEl;
      var self = this;  // Component.

      this.addToParent();

      // Don't .load() scene on attachedCallback.
      if (this.isScene) { return; }

      // Gracefully not error when outside of <a-scene> (e.g., tests).
      if (!sceneEl) {
        this.load();
        return;
      }

      // Wait for asset management system to finish before loading.
      assetsEl = sceneEl.querySelector('a-assets');
      if (assetsEl && !assetsEl.hasLoaded) {
        assetsEl.addEventListener('loaded', function () { self.load(); });
        return;
      }
      this.load();
    }
  },

  /**
   * Tell parent to remove this element's object3D from its object3D.
   * Do not call on scene element because that will cause a call to document.body.remove().
   */
  detachedCallback: {
    value: function () {
      var componentName;

      if (!this.parentEl) { return; }

      // Remove components.
      for (componentName in this.components) {
        this.removeComponent(componentName, false);
      }

      if (this.isScene) { return; }

      this.removeFromParent();
      ANode.prototype.detachedCallback.call(this);

      // Remove cyclic reference.
      this.object3D.el = null;
    }
  },

  getObject3D: {
    value: function (type) {
      return this.object3DMap[type];
    }
  },

  /**
   * Set a THREE.Object3D into the map.
   *
   * @param {string} type - Developer-set name of the type of object, will be unique per type.
   * @param {object} obj - A THREE.Object3D.
   */
  setObject3D: {
    value: function (type, obj) {
      var oldObj;
      var self = this;

      if (!(obj instanceof THREE.Object3D)) {
        throw new Error(
          '`Entity.setObject3D` was called with an object that was not an instance of ' +
          'THREE.Object3D.'
        );
      }

      // Remove existing object of the type.
      oldObj = this.getObject3D(type);
      if (oldObj) { this.object3D.remove(oldObj); }

      // Set references to A-Frame entity.
      obj.el = this;
      if (obj.children.length) {
        obj.traverse(function bindEl (child) {
          child.el = self;
        });
      }

      // Add.
      this.object3D.add(obj);
      this.object3DMap[type] = obj;
      this.emit('object3dset', {object: obj, type: type});
    }
  },

  /**
   * Remove object from scene and entity object3D map.
   */
  removeObject3D: {
    value: function (type) {
      var obj = this.getObject3D(type);
      if (!obj) {
        warn('Tried to remove `Object3D` of type:', type, 'which was not defined.');
        return;
      }
      this.object3D.remove(obj);
      delete this.object3DMap[type];
      this.emit('object3dremove', {type: type});
    }
  },

  /**
   * Gets or creates an object3D of a given type.
   *
   * @param {string} type - Type of the object3D.
   * @param {string} Constructor - Constructor to use to create the object3D if needed.
   * @returns {object}
   */
  getOrCreateObject3D: {
    value: function (type, Constructor) {
      var object3D = this.getObject3D(type);
      if (!object3D && Constructor) {
        object3D = new Constructor();
        this.setObject3D(type, object3D);
      }
      warn('`getOrCreateObject3D` has been deprecated. Use `setObject3D()` ' +
           'and `object3dset` event instead.');
      return object3D;
    }
  },

  /**
   * Add child entity.
   *
   * @param {Element} el - Child entity.
   */
  add: {
    value: function (el) {
      if (!el.object3D) {
        throw new Error("Trying to add an element that doesn't have an `object3D`");
      }
      this.object3D.add(el.object3D);
      this.emit('child-attached', {el: el});
    }
  },

  /**
   * Tell parentNode to add this entity to itself.
   */
  addToParent: {
    value: function () {
      var parentNode = this.parentEl = this.parentNode;

      // `!parentNode` check primarily for unit tests.
      if (!parentNode || !parentNode.add || this.attachedToParent) { return; }

      parentNode.add(this);
      this.attachedToParent = true;  // To prevent multiple attachments to same parent.
    }
  },

  /**
   * Tell parentNode to remove this entity from itself.
   */
  removeFromParent: {
    value: function () {
      var parentEl = this.parentEl;
      this.parentEl.remove(this);
      this.attachedToParent = false;
      this.parentEl = null;
      parentEl.emit('child-detached', {el: this});
    }
  },

  load: {
    value: function () {
      var self = this;

      if (this.hasLoaded || !this.parentEl) { return; }

      ANode.prototype.load.call(this, function entityLoadCallback () {
        // Check if entity was detached while it was waiting to load.
        if (!self.parentEl) { return; }

        self.updateComponents();
        if (self.isScene || self.parentEl.isPlaying) { self.play(); }
      });
    },
    writable: window.debug
  },

  /**
   * Remove child entity.
   *
   * @param {Element} el - Child entity.
   */
  remove: {
    value: function (el) {
      if (el) {
        this.object3D.remove(el.object3D);
      } else {
        this.parentNode.removeChild(this);
      }
    }
  },

  /**
   * @returns {array} Direct children that are entities.
   */
  getChildEntities: {
    value: function () {
      var children = this.children;
      var childEntities = [];

      for (var i = 0; i < children.length; i++) {
        var child = children[i];
        if (child instanceof AEntity) {
          childEntities.push(child);
        }
      }

      return childEntities;
    }
  },

  /**
   * Initialize component.
   *
   * @param {string} attrName - Attribute name asociated to the component.
   * @param {object} data - Component data
   * @param {boolean} isDependency - True if the component is a dependency.
   */
  initComponent: {
    value: function (attrName, data, isDependency) {
      var component;
      var componentId;
      var componentInfo;
      var componentName;
      var isComponentDefined;

      componentInfo = utils.split(attrName, MULTIPLE_COMPONENT_DELIMITER);
      componentName = componentInfo[0];
      componentId = componentInfo.length > 2
        ? componentInfo.slice(1).join('__')
        : componentInfo[1];

      // Not a registered component.
      if (!COMPONENTS[componentName]) { return; }

      // Component is not a dependency and is undefined.
      // If a component is a dependency, then it is okay to have no data.
      isComponentDefined = checkComponentDefined(this, attrName) ||
                           data !== undefined;
      if (!isComponentDefined && !isDependency) { return; }

      // Component already initialized.
      if (attrName in this.components) { return; }

      // Initialize dependencies first
      this.initComponentDependencies(componentName);

      // If component name has an id we check component type multiplic
      if (componentId && !COMPONENTS[componentName].multiple) {
        throw new Error('Trying to initialize multiple ' +
                        'components of type `' + componentName +
                        '`. There can only be one component of this type per entity.');
      }
      component = new COMPONENTS[componentName].Component(this, data, componentId);
      if (this.isPlaying) { component.play(); }

      // Components are reflected in the DOM as attributes but the state is not shown
      // hence we set the attribute to empty string.
      // The flag justInitialized is for attributeChangedCallback to not overwrite
      // the component with the empty string.
      if (!this.hasAttribute(attrName)) {
        component.justInitialized = true;
        window.HTMLElement.prototype.setAttribute.call(this, attrName, '');
      }

      debug('Component initialized: %s', attrName);
    },
    writable: window.debug
  },

  /**
   * Initialize dependencies of a component.
   *
   * @param {string} name - Root component name.
   */
  initComponentDependencies: {
    value: function (name) {
      var self = this;
      var component = COMPONENTS[name];
      var dependencies;
      var i;

      // Not a component.
      if (!component) { return; }

      // No dependencies.
      dependencies = COMPONENTS[name].dependencies;

      if (!dependencies) { return; }

      // Initialize dependencies.
      for (i = 0; i < dependencies.length; i++) {
        // Call getAttribute to initialize the data from the DOM.
        self.initComponent(
          dependencies[i],
          window.HTMLElement.prototype.getAttribute.call(self, dependencies[i]) || undefined,
          true
        );
      }
    }
  },

  removeComponent: {
    value: function (name, destroy) {
      var component;

      component = this.components[name];
      if (!component) { return; }

      // Wait for component to initialize.
      if (!component.initialized) {
        this.addEventListener('componentinitialized', function tryRemoveLater (evt) {
          if (evt.detail.name !== name) { return; }
          this.removeComponent(name, destroy);
          this.removeEventListener('componentinitialized', tryRemoveLater);
        });
        return;
      }

      component.pause();
      component.remove();

      // Keep component attached to entity in case of just full entity detach.
      if (destroy) {
        component.destroy();
        delete this.components[name];
      }

      this.emit('componentremoved', component.evtDetail, false);
    },
    writable: window.debug
  },

  /**
   * Initialize or update all components.
   * Build data using initial components, defined attributes, mixins, and defaults.
   * Update default components before the rest.
   *
   * @member {function} getExtraComponents - Can be implemented to include component data
   *   from other sources (e.g., implemented by primitives).
   */
  updateComponents: {
    value: function () {
      var data;
      var extraComponents;
      var i;
      var name;
      var componentsToUpdate = this.componentsToUpdate;

      if (!this.hasLoaded) { return; }

      // Gather mixin-defined components.
      for (i = 0; i < this.mixinEls.length; i++) {
        for (name in this.mixinEls[i].componentCache) {
          if (isComponent(name)) { componentsToUpdate[name] = true; }
        }
      }

      // Gather from extra initial component data if defined (e.g., primitives).
      if (this.getExtraComponents) {
        extraComponents = this.getExtraComponents();
        for (name in extraComponents) {
          if (isComponent(name)) { componentsToUpdate[name] = true; }
        }
      }

      // Gather entity-defined components.
      for (i = 0; i < this.attributes.length; ++i) {
        name = this.attributes[i].name;
        if (OBJECT3D_COMPONENTS.indexOf(name) !== -1) { continue; }
        if (isComponent(name)) { componentsToUpdate[name] = true; }
      }

      // object3D components first (position, rotation, scale, visible).
      for (i = 0; i < OBJECT3D_COMPONENTS.length; i++) {
        name = OBJECT3D_COMPONENTS[i];
        if (!this.hasAttribute(name)) { continue; }
        this.updateComponent(name, this.getDOMAttribute(name));
      }

      // Initialize or update rest of components.
      for (name in componentsToUpdate) {
        data = mergeComponentData(this.getDOMAttribute(name),
                                  extraComponents && extraComponents[name]);
        this.updateComponent(name, data);
        delete componentsToUpdate[name];
      }
    },
    writable: window.debug
  },

  /**
   * Initialize, update, or remove a single component.
   *
   * When initializing, we set the component on `this.components`.
   *
   * @param {string} attr - Component name.
   * @param {object} attrValue - Value of the DOM attribute.
   * @param {boolean} clobber - If new attrValue completely replaces previous properties.
   */
  updateComponent: {
    value: function (attr, attrValue, clobber) {
      var component = this.components[attr];

      if (component) {
        // Remove component.
        if (attrValue === null && !checkComponentDefined(this, attr)) {
          this.removeComponent(attr, true);
          return;
        }
        // Component already initialized. Update component.
        component.updateProperties(attrValue, clobber);
        return;
      }

      // Component not yet initialized. Initialize component.
      this.initComponent(attr, attrValue, false);
    }
  },

  /**
   * If `attr` is a component name, detach the component from the entity.
   *
   * If `propertyName` is given, reset the component property value to its default.
   *
   * @param {string} attr - Attribute name, which could also be a component name.
   * @param {string} propertyName - Component prop name, if resetting an individual prop.
   */
  removeAttribute: {
    value: function (attr, propertyName) {
      var component = this.components[attr];

      // Remove component.
      if (component && propertyName === undefined) {
        this.removeComponent(attr, true);
      }

      // Reset component property value.
      if (component && propertyName !== undefined) {
        component.resetProperty(propertyName);
        return;
      }

      // Remove mixins.
      if (attr === 'mixin') {
        this.mixinUpdate('');
      }

      window.HTMLElement.prototype.removeAttribute.call(this, attr);
    }
  },

  /**
   * Start dynamic behavior associated with entity such as dynamic components and animations.
   * Tell all children entities to also play.
   */
  play: {
    value: function () {
      var entities;
      var i;
      var key;

      // Already playing.
      if (this.isPlaying || !this.hasLoaded) { return; }
      this.isPlaying = true;

      // Wake up all components.
      for (key in this.components) { this.components[key].play(); }

      // Tell all child entities to play.
      entities = this.getChildEntities();
      for (i = 0; i < entities.length; i++) { entities[i].play(); }

      this.emit('play');
    },
    writable: true
  },

  /**
   * Pause dynamic behavior associated with entity such as dynamic components and animations.
   * Tell all children entities to also pause.
   */
  pause: {
    value: function () {
      var entities;
      var i;
      var key;

      if (!this.isPlaying) { return; }
      this.isPlaying = false;

      // Sleep all components.
      for (key in this.components) { this.components[key].pause(); }

      // Tell all child entities to pause.
      entities = this.getChildEntities();
      for (i = 0; i < entities.length; i++) { entities[i].pause(); }

      this.emit('pause');
    },
    writable: true
  },

  /**
   * Deals with updates on entity-specific attributes (i.e., components and mixins).
   *
   * @param {string} attr
   * @param {string} oldVal
   * @param {string|object} newVal
   */
  setEntityAttribute: {
    value: function (attr, oldVal, newVal) {
      if (COMPONENTS[attr] || this.components[attr]) {
        this.updateComponent(attr, newVal);
        return;
      }
      if (attr === 'mixin') {
        // Ignore if `<a-node>` code is just updating computed mixin in the DOM.
        if (newVal === this.computedMixinStr) { return; }
        this.mixinUpdate(newVal, oldVal);
      }
    }
  },

  /**
   * When mixins updated, trigger init or optimized-update of relevant components.
   */
  mixinUpdate: {
    value: (function () {
      var componentsUpdated = [];

      return function (newMixins, oldMixins) {
        var component;
        var mixinEl;
        var mixinIds;
        var i;
        var self = this;

        if (!this.hasLoaded) {
          this.addEventListener('loaded', function () {
            self.mixinUpdate(newMixins, oldMixins);
          }, ONCE);
          return;
        }

        oldMixins = oldMixins || this.getAttribute('mixin');
        mixinIds = this.updateMixins(newMixins, oldMixins);

        // Loop over current mixins.
        componentsUpdated.length = 0;
        for (i = 0; i < this.mixinEls.length; i++) {
          for (component in this.mixinEls[i].componentCache) {
            if (componentsUpdated.indexOf(component) === -1) {
              if (this.components[component]) {
                // Update. Just rebuild data.
                this.components[component].handleMixinUpdate();
              } else {
                // Init. buildData will gather mixin values.
                this.initComponent(component, null);
              }
              componentsUpdated.push(component);
            }
          }
        }

        // Loop over old mixins to call for data rebuild.
        for (i = 0; i < mixinIds.oldMixinIds.length; i++) {
          mixinEl = document.getElementById(mixinIds.oldMixinIds[i]);
          if (!mixinEl) { continue; }
          for (component in mixinEl.componentCache) {
            if (componentsUpdated.indexOf(component) === -1) {
              if (this.components[component]) {
                if (this.getDOMAttribute(component)) {
                  // Update component if explicitly defined.
                  this.components[component].handleMixinUpdate();
                } else {
                  // Remove component if not explicitly defined.
                  this.removeComponent(component, true);
                }
              }
            }
          }
        }
      };
    })()
  },

  /**
   * setAttribute can:
   *
   * 1. Set a single property of a multi-property component.
   * 2. Set multiple properties of a multi-property component.
   * 3. Replace properties of a multi-property component.
   * 4. Set a value for a single-property component, mixin, or normal HTML attribute.
   *
   * @param {string} attrName - Component or attribute name.
   * @param {*} arg1 - Can be a value, property name, CSS-style property string, or
   *   object of properties.
   * @param {*|bool} arg2 - If arg1 is a property name, this should be a value. Otherwise,
   *   it is a boolean indicating whether to clobber previous values (defaults to false).
   */
  setAttribute: {
    value: (function () {
      var singlePropUpdate = {};

      return function (attrName, arg1, arg2) {
        var newAttrValue;
        var clobber;
        var componentName;
        var delimiterIndex;
        var isDebugMode;
        var key;

        delimiterIndex = attrName.indexOf(MULTIPLE_COMPONENT_DELIMITER);
        componentName = delimiterIndex > 0 ? attrName.substring(0, delimiterIndex) : attrName;

        // Not a component. Normal set attribute.
        if (!COMPONENTS[componentName]) {
          if (attrName === 'mixin') { this.mixinUpdate(arg1); }
          ANode.prototype.setAttribute.call(this, attrName, arg1);
          return;
        }

        // Initialize component first if not yet initialized.
        if (!this.components[attrName] && this.hasAttribute(attrName)) {
          this.updateComponent(
            attrName,
            window.HTMLElement.prototype.getAttribute.call(this, attrName));
        }

        // Determine new attributes from the arguments
        if (typeof arg2 !== 'undefined' &&
            typeof arg1 === 'string' &&
            arg1.length > 0 &&
            typeof utils.styleParser.parse(arg1) === 'string') {
          // Update a single property of a multi-property component
          for (key in singlePropUpdate) { delete singlePropUpdate[key]; }
          newAttrValue = singlePropUpdate;
          newAttrValue[arg1] = arg2;
          clobber = false;
        } else {
          // Update with a value, object, or CSS-style property string, with the possiblity
          // of clobbering previous values.
          newAttrValue = arg1;
          clobber = (arg2 === true);
        }

        // Update component
        this.updateComponent(attrName, newAttrValue, clobber);

        // In debug mode, write component data up to the DOM.
        isDebugMode = this.sceneEl && this.sceneEl.getAttribute('debug');
        if (isDebugMode) { this.components[attrName].flushToDOM(); }
      };
    })(),
    writable: window.debug
  },

  /**
   * Reflect component data in the DOM (as seen from the browser DOM Inspector).
   *
   * @param {bool} recursive - Also flushToDOM on the children.
   **/
  flushToDOM: {
    value: function (recursive) {
      var components = this.components;
      var child;
      var children = this.children;
      var i;
      var key;

      // Flush entity's components to DOM.
      for (key in components) {
        components[key].flushToDOM();
      }

      // Recurse.
      if (!recursive) { return; }
      for (i = 0; i < children.length; ++i) {
        child = children[i];
        if (!child.flushToDOM) { continue; }
        child.flushToDOM(recursive);
      }
    }
  },

  /**
   * If `attr` is a component, returns ALL component data including applied mixins and
   * defaults.
   *
   * If `attr` is not a component, fall back to HTML getAttribute.
   *
   * @param {string} attr
   * @returns {object|string} Object if component, else string.
   */
  getAttribute: {
    value: function (attr) {
      // If component, return component data.
      var component;
      if (attr === 'position') { return this.object3D.position; }
      if (attr === 'rotation') { return getRotation(this); }
      if (attr === 'scale') { return this.object3D.scale; }
      if (attr === 'visible') { return this.object3D.visible; }
      component = this.components[attr];
      if (component) { return component.data; }
      return window.HTMLElement.prototype.getAttribute.call(this, attr);
    },
    writable: window.debug
  },

  /**
   * If `attr` is a component, returns JUST the component data defined on the entity.
   * Like a partial version of `getComputedAttribute` as returned component data
   * does not include applied mixins or defaults.
   *
   * If `attr` is not a component, fall back to HTML getAttribute.
   *
   * @param {string} attr
   * @returns {object|string} Object if component, else string.
   */
  getDOMAttribute: {
    value: function (attr) {
      // If cached value exists, return partial component data.
      var component = this.components[attr];
      if (component) { return component.attrValue; }
      return window.HTMLElement.prototype.getAttribute.call(this, attr);
    },
    writable: window.debug
  },

  addState: {
    value: function (state) {
      if (this.is(state)) { return; }
      this.states.push(state);
      this.emit('stateadded', state);
    }
  },

  removeState: {
    value: function (state) {
      var stateIndex = this.states.indexOf(state);
      if (stateIndex === -1) { return; }
      this.states.splice(stateIndex, 1);
      this.emit('stateremoved', state);
    }
  },

  /**
   * Checks if the element is in a given state. e.g. el.is('alive');
   * @type {string} state - Name of the state we want to check
   */
  is: {
    value: function (state) {
      return this.states.indexOf(state) !== -1;
    }
  },

  /**
   * Open Inspector to this entity.
   */
  inspect: {
    value: function () {
      this.sceneEl.components.inspector.openInspector(this);
    }
  },

  /**
   * Clean up memory and return memory to object pools.
   */
  destroy: {
    value: function () {
      var key;
      if (this.parentNode) {
        warn('Entity can only be destroyed if detached from scenegraph.');
        return;
      }
      for (key in this.components) {
        this.components[key].destroy();
      }
    }
  }
});

/**
 * Check if a component is *defined* for an entity, including defaults and mixins.
 * Does not check whether the component has been *initialized* for an entity.
 *
 * @param {string} el - Entity.
 * @param {string} name - Component name.
 * @returns {boolean}
 */
function checkComponentDefined (el, name) {
  // Check if element contains the component.
  if (el.components[name] && el.components[name].attrValue) { return true; }

  return isComponentMixedIn(name, el.mixinEls);
}

/**
 * Check if any mixins contains a component.
 *
 * @param {string} name - Component name.
 * @param {array} mixinEls - Array of <a-mixin>s.
 */
function isComponentMixedIn (name, mixinEls) {
  var i;
  var inMixin = false;
  for (i = 0; i < mixinEls.length; ++i) {
    inMixin = mixinEls[i].hasAttribute(name);
    if (inMixin) { break; }
  }
  return inMixin;
}

/**
 * Given entity defined value, merge in extra data if necessary.
 * Handle both single and multi-property components.
 *
 * @param {string} attrValue - Entity data.
 * @param extraData - Entity data from another source to merge in.
 */
function mergeComponentData (attrValue, extraData) {
  // Extra data not defined, just return attrValue.
  if (!extraData) { return attrValue; }

  // Merge multi-property data.
  if (extraData.constructor === Object) {
    return utils.extend(extraData, utils.styleParser.parse(attrValue || {}));
  }

  // Return data, precendence to the defined value.
  return attrValue || extraData;
}

function isComponent (componentName) {
  if (componentName.indexOf(MULTIPLE_COMPONENT_DELIMITER) !== -1) {
    componentName = utils.split(componentName, MULTIPLE_COMPONENT_DELIMITER)[0];
  }
  if (!COMPONENTS[componentName]) { return false; }
  return true;
}

function getRotation (entityEl) {
  var radToDeg = THREE.Math.radToDeg;
  var rotation = entityEl.object3D.rotation;
  var rotationObj = entityEl.rotationObj;
  rotationObj.x = radToDeg(rotation.x);
  rotationObj.y = radToDeg(rotation.y);
  rotationObj.z = radToDeg(rotation.z);
  return rotationObj;
}

AEntity = registerElement('a-entity', {prototype: proto});
module.exports = AEntity;