import { AnimationAction } from './AnimationAction.js';
import { EventDispatcher } from '../core/EventDispatcher.js';
import { LinearInterpolant } from '../math/interpolants/LinearInterpolant.js';
import { PropertyBinding } from './PropertyBinding.js';
import { PropertyMixer } from './PropertyMixer.js';
import { AnimationClip } from './AnimationClip.js';
import { NormalAnimationBlendMode } from '../constants.js';

class AnimationMixer extends EventDispatcher {
	constructor(root) {
		super();

		this._root = root;
		this._initMemoryManager();
		this._accuIndex = 0;
		this.time = 0;
		this.timeScale = 1.0;
	}

	_bindAction(action, prototypeAction) {
		const root = action._localRoot || this._root,
			tracks = action._clip.tracks,
			nTracks = tracks.length,
			bindings = action._propertyBindings,
			interpolants = action._interpolants,
			rootUuid = root.uuid,
			bindingsByRoot = this._bindingsByRootAndName;

		let bindingsByName = bindingsByRoot[rootUuid];

		if (bindingsByName === undefined) {
			bindingsByName = {};
			bindingsByRoot[rootUuid] = bindingsByName;
		}

		for (let i = 0; i !== nTracks; ++i) {
			const track = tracks[i],
				trackName = track.name;

			let binding = bindingsByName[trackName];

			if (binding !== undefined) {
				++binding.referenceCount;
				bindings[i] = binding;
			} else {
				binding = bindings[i];

				if (binding !== undefined) {
					// existing binding, make sure the cache knows

					if (binding._cacheIndex === null) {
						++binding.referenceCount;
						this._addInactiveBinding(binding, rootUuid, trackName);
					}

					continue;
				}

				const path = prototypeAction && prototypeAction._propertyBindings[i].binding.parsedPath;

				binding = new PropertyMixer(PropertyBinding.create(root, trackName, path), track.ValueTypeName, track.getValueSize());

				++binding.referenceCount;
				this._addInactiveBinding(binding, rootUuid, trackName);

				bindings[i] = binding;
			}

			interpolants[i].resultBuffer = binding.buffer;
		}
	}

	_activateAction(action) {
		if (!this._isActiveAction(action)) {
			if (action._cacheIndex === null) {
				// this action has been forgotten by the cache, but the user
				// appears to be still using it -> rebind

				const rootUuid = (action._localRoot || this._root).uuid,
					clipUuid = action._clip.uuid,
					actionsForClip = this._actionsByClip[clipUuid];

				this._bindAction(action, actionsForClip && actionsForClip.knownActions[0]);

				this._addInactiveAction(action, clipUuid, rootUuid);
			}

			const bindings = action._propertyBindings;

			// increment reference counts / sort out state
			for (let i = 0, n = bindings.length; i !== n; ++i) {
				const binding = bindings[i];

				if (binding.useCount++ === 0) {
					this._lendBinding(binding);
					binding.saveOriginalState();
				}
			}

			this._lendAction(action);
		}
	}

	_deactivateAction(action) {
		if (this._isActiveAction(action)) {
			const bindings = action._propertyBindings;

			// decrement reference counts / sort out state
			for (let i = 0, n = bindings.length; i !== n; ++i) {
				const binding = bindings[i];

				if (--binding.useCount === 0) {
					binding.restoreOriginalState();
					this._takeBackBinding(binding);
				}
			}

			this._takeBackAction(action);
		}
	}

	// Memory manager

	_initMemoryManager() {
		this._actions = []; // 'nActiveActions' followed by inactive ones
		this._nActiveActions = 0;

		this._actionsByClip = {};
		// inside:
		// {
		// 	knownActions: Array< AnimationAction > - used as prototypes
		// 	actionByRoot: AnimationAction - lookup
		// }

		this._bindings = []; // 'nActiveBindings' followed by inactive ones
		this._nActiveBindings = 0;

		this._bindingsByRootAndName = {}; // inside: Map< name, PropertyMixer >

		this._controlInterpolants = []; // same game as above
		this._nActiveControlInterpolants = 0;

		const scope = this;

		this.stats = {
			actions: {
				get total() {
					return scope._actions.length;
				},
				get inUse() {
					return scope._nActiveActions;
				},
			},
			bindings: {
				get total() {
					return scope._bindings.length;
				},
				get inUse() {
					return scope._nActiveBindings;
				},
			},
			controlInterpolants: {
				get total() {
					return scope._controlInterpolants.length;
				},
				get inUse() {
					return scope._nActiveControlInterpolants;
				},
			},
		};
	}

	// Memory management for AnimationAction objects

	_isActiveAction(action) {
		const index = action._cacheIndex;
		return index !== null && index < this._nActiveActions;
	}

	_addInactiveAction(action, clipUuid, rootUuid) {
		const actions = this._actions,
			actionsByClip = this._actionsByClip;

		let actionsForClip = actionsByClip[clipUuid];

		if (actionsForClip === undefined) {
			actionsForClip = {
				knownActions: [action],
				actionByRoot: {},
			};

			action._byClipCacheIndex = 0;

			actionsByClip[clipUuid] = actionsForClip;
		} else {
			const knownActions = actionsForClip.knownActions;

			action._byClipCacheIndex = knownActions.length;
			knownActions.push(action);
		}

		action._cacheIndex = actions.length;
		actions.push(action);

		actionsForClip.actionByRoot[rootUuid] = action;
	}

	_removeInactiveAction(action) {
		const actions = this._actions,
			lastInactiveAction = actions[actions.length - 1],
			cacheIndex = action._cacheIndex;

		lastInactiveAction._cacheIndex = cacheIndex;
		actions[cacheIndex] = lastInactiveAction;
		actions.pop();

		action._cacheIndex = null;

		const clipUuid = action._clip.uuid,
			actionsByClip = this._actionsByClip,
			actionsForClip = actionsByClip[clipUuid],
			knownActionsForClip = actionsForClip.knownActions,
			lastKnownAction = knownActionsForClip[knownActionsForClip.length - 1],
			byClipCacheIndex = action._byClipCacheIndex;

		lastKnownAction._byClipCacheIndex = byClipCacheIndex;
		knownActionsForClip[byClipCacheIndex] = lastKnownAction;
		knownActionsForClip.pop();

		action._byClipCacheIndex = null;

		const actionByRoot = actionsForClip.actionByRoot,
			rootUuid = (action._localRoot || this._root).uuid;

		delete actionByRoot[rootUuid];

		if (knownActionsForClip.length === 0) {
			delete actionsByClip[clipUuid];
		}

		this._removeInactiveBindingsForAction(action);
	}

	_removeInactiveBindingsForAction(action) {
		const bindings = action._propertyBindings;

		for (let i = 0, n = bindings.length; i !== n; ++i) {
			const binding = bindings[i];

			if (--binding.referenceCount === 0) {
				this._removeInactiveBinding(binding);
			}
		}
	}

	_lendAction(action) {
		// [ active actions |  inactive actions  ]
		// [  active actions >| inactive actions ]
		//                 s        a
		//                  <-swap->
		//                 a        s

		const actions = this._actions,
			prevIndex = action._cacheIndex,
			lastActiveIndex = this._nActiveActions++,
			firstInactiveAction = actions[lastActiveIndex];

		action._cacheIndex = lastActiveIndex;
		actions[lastActiveIndex] = action;

		firstInactiveAction._cacheIndex = prevIndex;
		actions[prevIndex] = firstInactiveAction;
	}

	_takeBackAction(action) {
		// [  active actions  | inactive actions ]
		// [ active actions |< inactive actions  ]
		//        a        s
		//         <-swap->
		//        s        a

		const actions = this._actions,
			prevIndex = action._cacheIndex,
			firstInactiveIndex = --this._nActiveActions,
			lastActiveAction = actions[firstInactiveIndex];

		action._cacheIndex = firstInactiveIndex;
		actions[firstInactiveIndex] = action;

		lastActiveAction._cacheIndex = prevIndex;
		actions[prevIndex] = lastActiveAction;
	}

	// Memory management for PropertyMixer objects

	_addInactiveBinding(binding, rootUuid, trackName) {
		const bindingsByRoot = this._bindingsByRootAndName,
			bindings = this._bindings;

		let bindingByName = bindingsByRoot[rootUuid];

		if (bindingByName === undefined) {
			bindingByName = {};
			bindingsByRoot[rootUuid] = bindingByName;
		}

		bindingByName[trackName] = binding;

		binding._cacheIndex = bindings.length;
		bindings.push(binding);
	}

	_removeInactiveBinding(binding) {
		const bindings = this._bindings,
			propBinding = binding.binding,
			rootUuid = propBinding.rootNode.uuid,
			trackName = propBinding.path,
			bindingsByRoot = this._bindingsByRootAndName,
			bindingByName = bindingsByRoot[rootUuid],
			lastInactiveBinding = bindings[bindings.length - 1],
			cacheIndex = binding._cacheIndex;

		lastInactiveBinding._cacheIndex = cacheIndex;
		bindings[cacheIndex] = lastInactiveBinding;
		bindings.pop();

		delete bindingByName[trackName];

		if (Object.keys(bindingByName).length === 0) {
			delete bindingsByRoot[rootUuid];
		}
	}

	_lendBinding(binding) {
		const bindings = this._bindings,
			prevIndex = binding._cacheIndex,
			lastActiveIndex = this._nActiveBindings++,
			firstInactiveBinding = bindings[lastActiveIndex];

		binding._cacheIndex = lastActiveIndex;
		bindings[lastActiveIndex] = binding;

		firstInactiveBinding._cacheIndex = prevIndex;
		bindings[prevIndex] = firstInactiveBinding;
	}

	_takeBackBinding(binding) {
		const bindings = this._bindings,
			prevIndex = binding._cacheIndex,
			firstInactiveIndex = --this._nActiveBindings,
			lastActiveBinding = bindings[firstInactiveIndex];

		binding._cacheIndex = firstInactiveIndex;
		bindings[firstInactiveIndex] = binding;

		lastActiveBinding._cacheIndex = prevIndex;
		bindings[prevIndex] = lastActiveBinding;
	}

	// Memory management of Interpolants for weight and time scale

	_lendControlInterpolant() {
		const interpolants = this._controlInterpolants,
			lastActiveIndex = this._nActiveControlInterpolants++;

		let interpolant = interpolants[lastActiveIndex];

		if (interpolant === undefined) {
			interpolant = new LinearInterpolant(new Float32Array(2), new Float32Array(2), 1, this._controlInterpolantsResultBuffer);

			interpolant.__cacheIndex = lastActiveIndex;
			interpolants[lastActiveIndex] = interpolant;
		}

		return interpolant;
	}

	_takeBackControlInterpolant(interpolant) {
		const interpolants = this._controlInterpolants,
			prevIndex = interpolant.__cacheIndex,
			firstInactiveIndex = --this._nActiveControlInterpolants,
			lastActiveInterpolant = interpolants[firstInactiveIndex];

		interpolant.__cacheIndex = firstInactiveIndex;
		interpolants[firstInactiveIndex] = interpolant;

		lastActiveInterpolant.__cacheIndex = prevIndex;
		interpolants[prevIndex] = lastActiveInterpolant;
	}

	// return an action for a clip optionally using a custom root target
	// object (this method allocates a lot of dynamic memory in case a
	// previously unknown clip/root combination is specified)
	clipAction(clip, optionalRoot, blendMode) {
		const root = optionalRoot || this._root,
			rootUuid = root.uuid;

		let clipObject = typeof clip === 'string' ? AnimationClip.findByName(root, clip) : clip;

		const clipUuid = clipObject !== null ? clipObject.uuid : clip;

		const actionsForClip = this._actionsByClip[clipUuid];
		let prototypeAction = null;

		if (blendMode === undefined) {
			if (clipObject !== null) {
				blendMode = clipObject.blendMode;
			} else {
				blendMode = NormalAnimationBlendMode;
			}
		}

		if (actionsForClip !== undefined) {
			const existingAction = actionsForClip.actionByRoot[rootUuid];

			if (existingAction !== undefined && existingAction.blendMode === blendMode) {
				return existingAction;
			}

			// we know the clip, so we don't have to parse all
			// the bindings again but can just copy
			prototypeAction = actionsForClip.knownActions[0];

			// also, take the clip from the prototype action
			if (clipObject === null) clipObject = prototypeAction._clip;
		}

		// clip must be known when specified via string
		if (clipObject === null) return null;

		// allocate all resources required to run it
		const newAction = new AnimationAction(this, clipObject, optionalRoot, blendMode);

		this._bindAction(newAction, prototypeAction);

		// and make the action known to the memory manager
		this._addInactiveAction(newAction, clipUuid, rootUuid);

		return newAction;
	}

	// get an existing action
	existingAction(clip, optionalRoot) {
		const root = optionalRoot || this._root,
			rootUuid = root.uuid,
			clipObject = typeof clip === 'string' ? AnimationClip.findByName(root, clip) : clip,
			clipUuid = clipObject ? clipObject.uuid : clip,
			actionsForClip = this._actionsByClip[clipUuid];

		if (actionsForClip !== undefined) {
			return actionsForClip.actionByRoot[rootUuid] || null;
		}

		return null;
	}

	// deactivates all previously scheduled actions
	stopAllAction() {
		const actions = this._actions,
			nActions = this._nActiveActions;

		for (let i = nActions - 1; i >= 0; --i) {
			actions[i].stop();
		}

		return this;
	}

	// advance the time and update apply the animation
	update(deltaTime) {
		deltaTime *= this.timeScale;

		const actions = this._actions,
			nActions = this._nActiveActions,
			time = (this.time += deltaTime),
			timeDirection = Math.sign(deltaTime),
			accuIndex = (this._accuIndex ^= 1);

		// run active actions

		for (let i = 0; i !== nActions; ++i) {
			const action = actions[i];

			action._update(time, deltaTime, timeDirection, accuIndex);
		}

		// update scene graph

		const bindings = this._bindings,
			nBindings = this._nActiveBindings;

		for (let i = 0; i !== nBindings; ++i) {
			bindings[i].apply(accuIndex);
		}

		return this;
	}

	// Allows you to seek to a specific time in an animation.
	setTime(timeInSeconds) {
		this.time = 0; // Zero out time attribute for AnimationMixer object;
		for (let i = 0; i < this._actions.length; i++) {
			this._actions[i].time = 0; // Zero out time attribute for all associated AnimationAction objects.
		}

		return this.update(timeInSeconds); // Update used to set exact time. Returns "this" AnimationMixer object.
	}

	// return this mixer's root target object
	getRoot() {
		return this._root;
	}

	// free all resources specific to a particular clip
	uncacheClip(clip) {
		const actions = this._actions,
			clipUuid = clip.uuid,
			actionsByClip = this._actionsByClip,
			actionsForClip = actionsByClip[clipUuid];

		if (actionsForClip !== undefined) {
			// note: just calling _removeInactiveAction would mess up the
			// iteration state and also require updating the state we can
			// just throw away

			const actionsToRemove = actionsForClip.knownActions;

			for (let i = 0, n = actionsToRemove.length; i !== n; ++i) {
				const action = actionsToRemove[i];

				this._deactivateAction(action);

				const cacheIndex = action._cacheIndex,
					lastInactiveAction = actions[actions.length - 1];

				action._cacheIndex = null;
				action._byClipCacheIndex = null;

				lastInactiveAction._cacheIndex = cacheIndex;
				actions[cacheIndex] = lastInactiveAction;
				actions.pop();

				this._removeInactiveBindingsForAction(action);
			}

			delete actionsByClip[clipUuid];
		}
	}

	// free all resources specific to a particular root target object
	uncacheRoot(root) {
		const rootUuid = root.uuid,
			actionsByClip = this._actionsByClip;

		for (const clipUuid in actionsByClip) {
			const actionByRoot = actionsByClip[clipUuid].actionByRoot,
				action = actionByRoot[rootUuid];

			if (action !== undefined) {
				this._deactivateAction(action);
				this._removeInactiveAction(action);
			}
		}

		const bindingsByRoot = this._bindingsByRootAndName,
			bindingByName = bindingsByRoot[rootUuid];

		if (bindingByName !== undefined) {
			for (const trackName in bindingByName) {
				const binding = bindingByName[trackName];
				binding.restoreOriginalState();
				this._removeInactiveBinding(binding);
			}
		}
	}

	// remove a targeted clip from the cache
	uncacheAction(clip, optionalRoot) {
		const action = this.existingAction(clip, optionalRoot);

		if (action !== null) {
			this._deactivateAction(action);
			this._removeInactiveAction(action);
		}
	}
}

AnimationMixer.prototype._controlInterpolantsResultBuffer = new Float32Array(1);

export { AnimationMixer };