/**
 *
 * A timed sequence of keyframes for a specific property.
 *
 *
 * @author Ben Houston / http://clara.io/
 * @author David Sarno / http://lighthaus.us/
 * @author tschw
 */

THREE.KeyframeTrack = function ( name, times, values, interpolation ) {

	if( name === undefined ) throw new Error( "track name is undefined" );

	if( times === undefined || times.length === 0 ) {

		throw new Error( "no keyframes in track named " + name );

	}

	this.name = name;

	this.times = THREE.AnimationUtils.convertArray( times, this.TimeBufferType );
	this.values = THREE.AnimationUtils.convertArray( values, this.ValueBufferType );

	this.setInterpolation( interpolation || this.DefaultInterpolation );

	this.validate();
	this.optimize();

};

THREE.KeyframeTrack.prototype = {

	constructor: THREE.KeyframeTrack,

	TimeBufferType: Float32Array,
	ValueBufferType: Float32Array,

	DefaultInterpolation: THREE.InterpolateLinear,

	InterpolantFactoryMethodDiscrete: function( result ) {

		return new THREE.DiscreteInterpolant(
				this.times, this.values, this.getValueSize(), result );

	},

	InterpolantFactoryMethodLinear: function( result ) {

		return new THREE.LinearInterpolant(
				this.times, this.values, this.getValueSize(), result );

	},

	InterpolantFactoryMethodSmooth: function( result ) {

		return new THREE.CubicInterpolant(
				this.times, this.values, this.getValueSize(), result );

	},

	setInterpolation: function( interpolation ) {

		var factoryMethod = undefined;

		switch ( interpolation ) {

			case THREE.InterpolateDiscrete:

				factoryMethod = this.InterpolantFactoryMethodDiscrete;

				break;

			case THREE.InterpolateLinear:

				factoryMethod = this.InterpolantFactoryMethodLinear;

				break;

			case THREE.InterpolateSmooth:

				factoryMethod = this.InterpolantFactoryMethodSmooth;

				break;

		}

		if ( factoryMethod === undefined ) {

			var message = "unsupported interpolation for " +
					this.ValueTypeName + " keyframe track named " + this.name;

			if ( this.createInterpolant === undefined ) {

				// fall back to default, unless the default itself is messed up
				if ( interpolation !== this.DefaultInterpolation ) {

					this.setInterpolation( this.DefaultInterpolation );

				} else {

					throw new Error( message ); // fatal, in this case

				}

			}

			console.warn( message );
			return;

		}

		this.createInterpolant = factoryMethod;

	},

	getInterpolation: function() {

		switch ( this.createInterpolant ) {

			case this.InterpolantFactoryMethodDiscrete:

				return THREE.InterpolateDiscrete;

			case this.InterpolantFactoryMethodLinear:

				return THREE.InterpolateLinear;

			case this.InterpolantFactoryMethodSmooth:

				return THREE.InterpolateSmooth;

		}

	},

	getValueSize: function() {

		return this.values.length / this.times.length;

	},

	// move all keyframes either forwards or backwards in time
	shift: function( timeOffset ) {

		if( timeOffset !== 0.0 ) {

			var times = this.times;

			for( var i = 0, n = times.length; i !== n; ++ i ) {

				times[ i ] += timeOffset;

			}

		}

		return this;

	},

	// scale all keyframe times by a factor (useful for frame <-> seconds conversions)
	scale: function( timeScale ) {

		if( timeScale !== 1.0 ) {

			var times = this.times;

			for( var i = 0, n = times.length; i !== n; ++ i ) {

				times[ i ] *= timeScale;

			}

		}

		return this;

	},

	// removes keyframes before and after animation without changing any values within the range [startTime, endTime].
	// IMPORTANT: We do not shift around keys to the start of the track time, because for interpolated keys this will change their values
	trim: function( startTime, endTime ) {

		var times = this.times;
		var nKeys = times.length;

		var firstKeysToRemove = 0;
		for ( var i = 1; i !== nKeys; ++ i ) {

			if ( times[i] <= startTime ) ++ firstKeysToRemove;

		}

		var lastKeysToRemove = 0;
		for ( var i = nKeys - 2; i !== 0; -- i ) {

			if ( times[i] >= endTime ) ++ lastKeysToRemove;
			else break;

		}

		// remove last keys first because it doesn't affect the position of the first keys (the otherway around doesn't work as easily)
		if( ( firstKeysToRemove + lastKeysToRemove ) !== 0 ) {

			var from = firstKeysToRemove;
			var to = nKeys - lastKeysToRemove - firstKeysToRemove;

			var stride = this.getValueSize();

			this.times = THREE.AnimationUtils.arraySlice( times, from, to );

			var values = this.values;
			this.values = THREE.AnimationUtils.arraySlice( values, from * stride, to * stride );

		}

		return this;

	},

	// ensure we do not get a GarbageInGarbageOut situation, make sure tracks are at least minimally viable
	validate: function() {

		var valid = true;

		var valueSize = this.getValueSize();
		if ( valueSize - Math.floor( valueSize ) !== 0 ) {

			console.error( "invalid value size in track", this );
			valid = false;

		}

		var times = this.times,
			values = this.values,

			nKeys = times.length;

		if( nKeys === 0 ) {

			console.error( "track is empty", this );
			valid = false;

		}

		var prevTime = null;

		for( var i = 0; i !== nKeys; i ++ ) {

			var currTime = times[ i ];

			if ( typeof currTime === 'number' && isNaN( currTime ) ) {

				console.error( "time is not a valid number", this, i, currTime );
				valid = false;
				break;

			}

			if( prevTime !== null && prevTime > currTime ) {

				console.error( "out of order keys", this, i, currTime, prevTime );
				valid = false;
				break;

			}

			prevTime = currTime;

		}

		if ( values !== undefined ) {

			if ( THREE.AnimationUtils.isTypedArray( values ) ) {

				for ( var i = 0, n = values.length; i !== n; ++ i ) {

					var value = values[ i ];

					if ( isNaN( value ) ) {

						console.error( "value is not a valid number", this, i, value );
						valid = false;
						break;

					}

				}

			}

		}

		return valid;

	},

	// removes equivalent sequential keys as common in morph target sequences
	// (0,0,0,0,1,1,1,0,0,0,0,0,0,0) --> (0,0,1,1,0,0)
	optimize: function() {

		var times = this.times,
			values = this.values,
			stride = this.getValueSize(),

			writeIndex = 1;

		for( var i = 1, n = times.length - 1; i <= n; ++ i ) {

			var keep = false;

			var time = times[ i ];
			var timeNext = times[ i + 1 ];

			// remove adjacent keyframes scheduled at the same time

			if ( time !== timeNext && ( i !== 1 || time !== time[ 0 ] ) ) {

				// remove unnecessary keyframes same as their neighbors
				var offset = i * stride,
					offsetP = offset - stride,
					offsetN = offset + stride;

				for ( var j = 0; j !== stride; ++ j ) {

					var value = values[ offset + j ];

					if ( value !== values[ offsetP + j ] ||
							value !== values[ offsetN + j ] ) {

						keep = true;
						break;

					}

				}

			}

			// in-place compaction

			if ( keep ) {

				if ( i !== writeIndex ) {

					times[ writeIndex ] = times[ i ];

					var readOffset = i * stride,
						writeOffset = writeIndex * stride;

					for ( var j = 0; j !== stride; ++ j ) {

						values[ writeOffset + j ] = values[ readOffset + j ];

					}


				}

				++ writeIndex;

			}

		}

		if ( writeIndex !== times.length ) {

			this.times = THREE.AnimationUtils.arraySlice( times, 0, writeIndex );
			this.values = THREE.AnimationUtils.arraySlice( values, 0, writeIndex * stride );

		}

		return this;

	}

};

// Static methods:

Object.assign( THREE.KeyframeTrack, {

	// Serialization (in static context, because of constructor invocation
	// and automatic invocation of .toJSON):

	parse: function( json ) {

		if( json.type === undefined ) {

			throw new Error( "track type undefined, can not parse" );

		}

		var trackType = THREE.KeyframeTrack._getTrackTypeForValueTypeName( json.type );

		if ( json.times === undefined ) {

			console.warn( "legacy JSON format detected, converting" );

			var times = [], values = [];

			THREE.AnimationUtils.flattenJSON( json.keys, times, values, 'value' );

			json.times = times;
			json.values = values;

		}

		// derived classes can define a static parse method
		if ( trackType.parse !== undefined ) {

			return trackType.parse( json );

		} else {

			// by default, we asssume a constructor compatible with the base
			return new trackType(
					json.name, json.times, json.values, json.interpolation );

		}

	},

	toJSON: function( track ) {

		var trackType = track.constructor;

		var json;

		// derived classes can define a static toJSON method
		if ( trackType.toJSON !== undefined ) {

			json = trackType.toJSON( track );

		} else {

			// by default, we assume the data can be serialized as-is
			json = {

				'name': track.name,
				'times': THREE.AnimationUtils.convertArray( track.times, Array ),
				'values': THREE.AnimationUtils.convertArray( track.values, Array )

			};

			var interpolation = track.getInterpolation();

			if ( interpolation !== track.DefaultInterpolation ) {

				json.interpolation = interpolation;

			}

		}

		json.type = track.ValueTypeName; // mandatory

		return json;

	},

	_getTrackTypeForValueTypeName: function( typeName ) {

		switch( typeName.toLowerCase() ) {

			case "scalar":
			case "double":
			case "float":
			case "number":
			case "integer":

				return THREE.NumberKeyframeTrack;

			case "vector":
			case "vector2":
			case "vector3":
			case "vector4":

				return THREE.VectorKeyframeTrack;

			case "color":

				return THREE.ColorKeyframeTrack;

			case "quaternion":

				return THREE.QuaternionKeyframeTrack;

			case "bool":
			case "boolean":

				return THREE.BooleanKeyframeTrack;

			case "string":

				return THREE.StringKeyframeTrack;

		};

		throw new Error( "Unsupported typeName: " + typeName );

	}

} );