/**
* @author herzig / http://github.com/herzig
*
* Description: reads BVH files and outputs a single THREE.Skeleton and an THREE.AnimationClip
*
* Currently only supports bvh files containing a single root.
*
*/

THREE.BVHLoader = function( manager ) {

	this.animateBonePositions = true;
	this.animateBoneRotations = true;

	this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager;

}

THREE.BVHLoader.prototype.load = function( url, onLoad, onProgress, onError ) {

	var scope = this;

	var loader = new THREE.XHRLoader( scope.manager );
	loader.setResponseType( 'arraybuffer' );
	loader.load( url, function( buffer ) {

		onLoad( scope.parse( buffer ) );

	}, onProgress, onError );

}


THREE.BVHLoader.prototype.parse = function( buffer ) {

	// convert buffer to ASCII string
	var text = "";
	var raw = new Uint8Array( buffer );
	for ( var i = 0; i < raw.length; ++ i ) {

		text += String.fromCharCode( raw[ i ] );

	}

	var lines = text.split( /[\r\n]+/g );

	var bones = this._readBvh( lines );

	var threeBones = [];
	this._toTHREEBone( bones[ 0 ], threeBones );

	var threeClip = this._toTHREEAnimation( bones );

	return {
		skeleton: new THREE.Skeleton( threeBones ),
		clip: threeClip
	};


}

/*
	reads a string array (lines) from a BVH file
	and outputs a skeleton structure including motion data

	returns thee root node:
	{ name: "", channels: [], children: [] }
*/
THREE.BVHLoader.prototype._readBvh = function( lines ) {

	// read model structure
	if ( this._nextLine( lines ) !== "HIERARCHY" ) {

		throw "HIERARCHY expected";

	}

	var list = []; // collects flat array of all bones
	var root = this._readNode( lines, this._nextLine( lines ), list );

	// read motion data
	if ( this._nextLine( lines ) != "MOTION" ) {

		throw "MOTION  expected";

	}

	// number of frames
	var tokens = this._nextLine( lines ).split( /[\s]+/ );
	var numFrames = parseInt( tokens[ 1 ] );
	if ( isNaN( numFrames ) ) {

		throw "Failed to read number of frames.";

	}

	// frame time
	tokens = this._nextLine( lines ).split( /[\s]+/ );
	var frameTime = parseFloat( tokens[ 2 ] );
	if ( isNaN( frameTime ) ) {

		throw "Failed to read frame time.";

	}

	// read frame data line by line
	for ( var i = 0; i < numFrames; ++ i ) {

		tokens = this._nextLine( lines ).split( /[\s]+/ );

		this._readFrameData( tokens, i * frameTime, root, list );

	}

	return list;

}

/*
	Recursively reads data from a single frame into the bone hierarchy.
	The passed bone hierarchy has to be structured in the same order as the BVH file.
	keyframe data is stored in bone.frames.

	- data: splitted string array (frame values), values are shift()ed so
	this should be empty after parsing the whole hierarchy.
	- frameTime: playback time for this keyframe.
	- bone: the bone to read frame data from.
*/
THREE.BVHLoader.prototype._readFrameData = function( data, frameTime, bone ) {

	// end sites have no motion data
	if ( bone.type === "ENDSITE" ) {

		return;

	}

	// add keyframe
	var keyframe = {
		time: frameTime,
		position: { x: 0, y: 0, z: 0 },
		rotation: new THREE.Quaternion(),
	};

	bone.frames.push( keyframe );

	var vx = new THREE.Vector3( 1, 0, 0 );
	var vy = new THREE.Vector3( 0, 1, 0 );
	var vz = new THREE.Vector3( 0, 0, 1 );

	// parse values for each channel in node
	for ( var i = 0; i < bone.channels.length; ++ i ) {

		switch ( bone.channels[ i ] ) {

		case "Xposition":
			keyframe.position.x = parseFloat( data.shift().trim() );
			break;
		case "Yposition":
			keyframe.position.y = parseFloat( data.shift().trim() );
			break;
		case "Zposition":
			keyframe.position.z = parseFloat( data.shift().trim() );
			break;
		case "Xrotation":
			var quat = new THREE.Quaternion();
			quat.setFromAxisAngle( vx, parseFloat( data.shift().trim() ) * Math.PI / 180 );

			keyframe.rotation.multiply( quat );
			break;
		case "Yrotation":
			var quat = new THREE.Quaternion();
			quat.setFromAxisAngle( vy, parseFloat( data.shift().trim() ) * Math.PI / 180 );

			keyframe.rotation.multiply( quat );
			break;
		case "Zrotation":
			var quat = new THREE.Quaternion();
			quat.setFromAxisAngle( vz, parseFloat( data.shift().trim() ) * Math.PI / 180 );

			keyframe.rotation.multiply( quat );
			break;
		default:
			throw "invalid channel type";
			break;

		}

	}

	// parse child nodes
	for ( var i = 0; i < bone.children.length; ++ i ) {

		this._readFrameData( data, frameTime, bone.children[ i ] );

	}

}

/*
 Recursively parses the HIERACHY section of the BVH file

 - lines: all lines of the file. lines are consumed as we go along.
 - firstline: line containing the node type and name e.g. "JOINT hip"
 - list: collects a flat list of nodes

 returns: a BVH node including children
*/
THREE.BVHLoader.prototype._readNode = function( lines, firstline, list ) {

	var node = { name: "", type: "", frames: [] };
	list.push( node );

	// parse node type and name.
	var tokens = firstline.split( /[\s]+/ )

	if ( tokens[ 0 ].toUpperCase() === "END" && tokens[ 1 ].toUpperCase() === "SITE" ) {

		node.type = "ENDSITE";
		node.name = "ENDSITE"; // bvh end sites have no name

	}
	else {

		node.name = tokens[ 1 ];
		node.type = tokens[ 0 ].toUpperCase();

	}

	if ( this._nextLine( lines ) != "{" ) {

		throw "Expected opening { after type & name";

	}

	// parse OFFSET
	tokens = this._nextLine( lines ).split( /[\s]+/ );

	if ( tokens[ 0 ] !== "OFFSET" ) {

		throw "Expected OFFSET, but got: " + tokens[ 0 ];

	}
	if ( tokens.length != 4 ) {

		throw "OFFSET: Invalid number of values";

	}

	var offset = {
		x: parseFloat( tokens[ 1 ] ),
		y: parseFloat( tokens[ 2 ] ),
		z: parseFloat( tokens[ 3 ] )
	};

	if ( isNaN( offset.x ) || isNaN( offset.y ) || isNaN( offset.z ) ) {

		throw "OFFSET: Invalid values";

	}

	node.offset = offset;

	// parse CHANNELS definitions
	if ( node.type != "ENDSITE" ) {

		tokens = this._nextLine( lines ).split( /[\s]+/ );

		if ( tokens[ 0 ] != "CHANNELS" ) {

			throw "Expected CHANNELS definition";

		}

		var numChannels = parseInt( tokens[ 1 ] );
		node.channels = tokens.splice( 2, numChannels );
		node.children = [];

	}

	// read children
	while ( true ) {

		var line = this._nextLine( lines );

		if ( line === "}" ) {

			return node;

		} else {

			node.children.push( this._readNode( lines, line, list ) );

		}

	}

}

/*
	recursively converts the internal bvh node structure to a THREE.Bone hierarchy

	source: the bvh root node
	list: pass an empty array, collects a flat list of all converted THREE.Bones

	returns the root THREE.Bone
*/
THREE.BVHLoader.prototype._toTHREEBone = function( source, list ) {

	var bone = new THREE.Bone();
	list.push( bone );

	bone.position.add( source.offset );
	bone.name = source.name;

	if ( source.type != "ENDSITE" ) {

		for ( var i = 0; i < source.children.length; ++ i ) {

			bone.add( this._toTHREEBone( source.children[ i ], list ) );

		}

	}

	return bone;

}

/*
	builds a THREE.AnimationClip from the keyframe data saved in each bone.

	bone: bvh root node

	returns: a THREE.AnimationClip containing position and quaternion tracks
*/
THREE.BVHLoader.prototype._toTHREEAnimation = function( bones ) {

	var tracks = [];

	// create a position and quaternion animation track for each node
	for ( var i = 0; i < bones.length; ++ i ) {

		var bone = bones[ i ];

		if ( bone.type == "ENDSITE" )
			continue;

		// track data
		var times = [];
		var positions = [];
		var rotations = [];

		for ( var j = 0; j < bone.frames.length; ++ j ) {

			var frame = bone.frames[ j ];

			times.push( frame.time );

			// the animation system animates the position property,
			// so we have to add the joint offset to all values
			positions.push( frame.position.x + bone.offset.x );
			positions.push( frame.position.y + bone.offset.y );
			positions.push( frame.position.z + bone.offset.z );

			rotations.push( frame.rotation.x );
			rotations.push( frame.rotation.y );
			rotations.push( frame.rotation.z );
			rotations.push( frame.rotation.w );

		}

		if ( this.animateBonePositions ) {

			tracks.push( new THREE.VectorKeyframeTrack(
				".bones[" + bone.name + "].position", times, positions ) );

		}

		if ( this.animateBoneRotations ) {

			tracks.push( new THREE.QuaternionKeyframeTrack(
				".bones[" + bone.name + "].quaternion", times, rotations ) );

		}

	}

	var clip = new THREE.AnimationClip( "animation", - 1, tracks );

	return clip;

}

/*
	returns the next non-empty line in lines
*/
THREE.BVHLoader.prototype._nextLine = function( lines ) {

	var line;
	// skip empty lines
	while ( ( line = lines.shift().trim() ).length === 0 ) { }
	return line;

}