import { Quaternion } from '../math/Quaternion.js';
import { AdditiveAnimationBlendMode } from '../constants.js';

const AnimationUtils = {
	// same as Array.prototype.slice, but also works on typed arrays
	arraySlice: function (array, from, to) {
		if (AnimationUtils.isTypedArray(array)) {
			// in ios9 array.subarray(from, undefined) will return empty array
			// but array.subarray(from) or array.subarray(from, len) is correct
			return new array.constructor(array.subarray(from, to !== undefined ? to : array.length));
		}

		return array.slice(from, to);
	},

	// converts an array to a specific type
	convertArray: function (array, type, forceClone) {
		if (
			!array || // let 'undefined' and 'null' pass
			(!forceClone && array.constructor === type)
		)
			return array;

		if (typeof type.BYTES_PER_ELEMENT === 'number') {
			return new type(array); // create typed array
		}

		return Array.prototype.slice.call(array); // create Array
	},

	isTypedArray: function (object) {
		return ArrayBuffer.isView(object) && !(object instanceof DataView);
	},

	// returns an array by which times and values can be sorted
	getKeyframeOrder: function (times) {
		function compareTime(i, j) {
			return times[i] - times[j];
		}

		const n = times.length;
		const result = new Array(n);
		for (let i = 0; i !== n; ++i) result[i] = i;

		result.sort(compareTime);

		return result;
	},

	// uses the array previously returned by 'getKeyframeOrder' to sort data
	sortedArray: function (values, stride, order) {
		const nValues = values.length;
		const result = new values.constructor(nValues);

		for (let i = 0, dstOffset = 0; dstOffset !== nValues; ++i) {
			const srcOffset = order[i] * stride;

			for (let j = 0; j !== stride; ++j) {
				result[dstOffset++] = values[srcOffset + j];
			}
		}

		return result;
	},

	// function for parsing AOS keyframe formats
	flattenJSON: function (jsonKeys, times, values, valuePropertyName) {
		let i = 1,
			key = jsonKeys[0];

		while (key !== undefined && key[valuePropertyName] === undefined) {
			key = jsonKeys[i++];
		}

		if (key === undefined) return; // no data

		let value = key[valuePropertyName];
		if (value === undefined) return; // no data

		if (Array.isArray(value)) {
			do {
				value = key[valuePropertyName];

				if (value !== undefined) {
					times.push(key.time);
					values.push.apply(values, value); // push all elements
				}

				key = jsonKeys[i++];
			} while (key !== undefined);
		} else if (value.toArray !== undefined) {
			// ...assume THREE.Math-ish

			do {
				value = key[valuePropertyName];

				if (value !== undefined) {
					times.push(key.time);
					value.toArray(values, values.length);
				}

				key = jsonKeys[i++];
			} while (key !== undefined);
		} else {
			// otherwise push as-is

			do {
				value = key[valuePropertyName];

				if (value !== undefined) {
					times.push(key.time);
					values.push(value);
				}

				key = jsonKeys[i++];
			} while (key !== undefined);
		}
	},

	subclip: function (sourceClip, name, startFrame, endFrame, fps = 30) {
		const clip = sourceClip.clone();

		clip.name = name;

		const tracks = [];

		for (let i = 0; i < clip.tracks.length; ++i) {
			const track = clip.tracks[i];
			const valueSize = track.getValueSize();

			const times = [];
			const values = [];

			for (let j = 0; j < track.times.length; ++j) {
				const frame = track.times[j] * fps;

				if (frame < startFrame || frame >= endFrame) continue;

				times.push(track.times[j]);

				for (let k = 0; k < valueSize; ++k) {
					values.push(track.values[j * valueSize + k]);
				}
			}

			if (times.length === 0) continue;

			track.times = AnimationUtils.convertArray(times, track.times.constructor);
			track.values = AnimationUtils.convertArray(values, track.values.constructor);

			tracks.push(track);
		}

		clip.tracks = tracks;

		// find minimum .times value across all tracks in the trimmed clip

		let minStartTime = Infinity;

		for (let i = 0; i < clip.tracks.length; ++i) {
			if (minStartTime > clip.tracks[i].times[0]) {
				minStartTime = clip.tracks[i].times[0];
			}
		}

		// shift all tracks such that clip begins at t=0

		for (let i = 0; i < clip.tracks.length; ++i) {
			clip.tracks[i].shift(-1 * minStartTime);
		}

		clip.resetDuration();

		return clip;
	},

	makeClipAdditive: function (targetClip, referenceFrame = 0, referenceClip = targetClip, fps = 30) {
		if (fps <= 0) fps = 30;

		const numTracks = referenceClip.tracks.length;
		const referenceTime = referenceFrame / fps;

		// Make each track's values relative to the values at the reference frame
		for (let i = 0; i < numTracks; ++i) {
			const referenceTrack = referenceClip.tracks[i];
			const referenceTrackType = referenceTrack.ValueTypeName;

			// Skip this track if it's non-numeric
			if (referenceTrackType === 'bool' || referenceTrackType === 'string') continue;

			// Find the track in the target clip whose name and type matches the reference track
			const targetTrack = targetClip.tracks.find(function (track) {
				return track.name === referenceTrack.name && track.ValueTypeName === referenceTrackType;
			});

			if (targetTrack === undefined) continue;

			let referenceOffset = 0;
			const referenceValueSize = referenceTrack.getValueSize();

			if (referenceTrack.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline) {
				referenceOffset = referenceValueSize / 3;
			}

			let targetOffset = 0;
			const targetValueSize = targetTrack.getValueSize();

			if (targetTrack.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline) {
				targetOffset = targetValueSize / 3;
			}

			const lastIndex = referenceTrack.times.length - 1;
			let referenceValue;

			// Find the value to subtract out of the track
			if (referenceTime <= referenceTrack.times[0]) {
				// Reference frame is earlier than the first keyframe, so just use the first keyframe
				const startIndex = referenceOffset;
				const endIndex = referenceValueSize - referenceOffset;
				referenceValue = AnimationUtils.arraySlice(referenceTrack.values, startIndex, endIndex);
			} else if (referenceTime >= referenceTrack.times[lastIndex]) {
				// Reference frame is after the last keyframe, so just use the last keyframe
				const startIndex = lastIndex * referenceValueSize + referenceOffset;
				const endIndex = startIndex + referenceValueSize - referenceOffset;
				referenceValue = AnimationUtils.arraySlice(referenceTrack.values, startIndex, endIndex);
			} else {
				// Interpolate to the reference value
				const interpolant = referenceTrack.createInterpolant();
				const startIndex = referenceOffset;
				const endIndex = referenceValueSize - referenceOffset;
				interpolant.evaluate(referenceTime);
				referenceValue = AnimationUtils.arraySlice(interpolant.resultBuffer, startIndex, endIndex);
			}

			// Conjugate the quaternion
			if (referenceTrackType === 'quaternion') {
				const referenceQuat = new Quaternion().fromArray(referenceValue).normalize().conjugate();
				referenceQuat.toArray(referenceValue);
			}

			// Subtract the reference value from all of the track values

			const numTimes = targetTrack.times.length;
			for (let j = 0; j < numTimes; ++j) {
				const valueStart = j * targetValueSize + targetOffset;

				if (referenceTrackType === 'quaternion') {
					// Multiply the conjugate for quaternion track types
					Quaternion.multiplyQuaternionsFlat(targetTrack.values, valueStart, referenceValue, 0, targetTrack.values, valueStart);
				} else {
					const valueEnd = targetValueSize - targetOffset * 2;

					// Subtract each value for all other numeric track types
					for (let k = 0; k < valueEnd; ++k) {
						targetTrack.values[valueStart + k] -= referenceValue[k];
					}
				}
			}
		}

		targetClip.blendMode = AdditiveAnimationBlendMode;

		return targetClip;
	},
};

export { AnimationUtils };