using System;
using LibMMD.Model;
using LibMMD.Motion;
using UnityEngine;

namespace LibMMD.Unity3D.Animation
{
    internal sealed class MmdMorphRenderer
    {
        private SkinnedMeshRenderer _mainRenderer;
        private SkinnedMeshRenderer[] _partRenderers;
        private int[] _mainBlendShapeIndexes;
        private int[][] _partBlendShapeIndexes;
        private float[] _weights;
        private float[] _appliedWeights;

        internal void Configure(MmdModel model, SkinnedMeshRenderer mainRenderer,
            SkinnedMeshRenderer[] partRenderers, int[] mainBlendShapeIndexes,
            int[][] partBlendShapeIndexes)
        {
            if (model == null) throw new ArgumentNullException(nameof(model));
            _mainRenderer = mainRenderer;
            _partRenderers = partRenderers;
            _mainBlendShapeIndexes = mainBlendShapeIndexes;
            _partBlendShapeIndexes = partBlendShapeIndexes;
            _weights = new float[model.Morphs.Length];
            _appliedWeights = new float[model.Morphs.Length];
        }

        internal void Update(MmdModel model, MotionPlayer motionPlayer, double poseTime)
        {
            if (motionPlayer == null || model == null || _weights == null) return;
            motionPlayer.CalculateMorphWeights(model, poseTime, _weights);
            ApplyWeights();
        }

        internal void Reset()
        {
            if (_weights == null) return;
            Array.Clear(_weights, 0, _weights.Length);
            ApplyWeights();
        }

        private void ApplyWeights()
        {
            if (_mainRenderer != null)
            {
                ApplyWeightsToRenderer(_mainRenderer, _mainBlendShapeIndexes);
            }
            else if (_partRenderers != null)
            {
                for (var i = 0; i < _partRenderers.Length; ++i)
                    ApplyWeightsToRenderer(_partRenderers[i], _partBlendShapeIndexes[i]);
            }
            Array.Copy(_weights, _appliedWeights, _weights.Length);
        }

        private void ApplyWeightsToRenderer(SkinnedMeshRenderer renderer, int[] morphToBlendShapeIndex)
        {
            for (var morphIndex = 0; morphIndex < morphToBlendShapeIndex.Length; ++morphIndex)
            {
                var blendShapeIndex = morphToBlendShapeIndex[morphIndex];
                if (blendShapeIndex < 0) continue;
                var weight = _weights[morphIndex];
                if (Mathf.Approximately(weight, _appliedWeights[morphIndex])) continue;
                renderer.SetBlendShapeWeight(blendShapeIndex, weight * 100f);
            }
        }
    }
}