using System;
using System.Collections;
using System.Linq;
using LibMMD.Model;
using UnityEngine;

namespace LibMMD.Unity3D
{
    internal sealed class MmdMaterialController
    {
        internal IEnumerator LoadAsync(MmdModel model, MaterialLoader loader,
            MmdUnityConfig config, MmdModelResourceCache.Entry cacheEntry,
            UnityEngine.Material[] currentMaterials, Action<UnityEngine.Material[]> completed)
        {
            if (cacheEntry != null && cacheEntry.Materials != null)
            {
                var materials = cacheEntry.Materials;
                if (materials.Length != model.Parts.Length)
                {
                    materials = new UnityEngine.Material[model.Parts.Length];
                    cacheEntry.Materials = materials;
                }
                for (var i = 0; i < materials.Length; i++)
                {
                    if (materials[i] == null)
                    {
                        var index = i;
                        var materialLoader = loader.LoadMaterialAsync(model.Parts[i].Material, config,
                            value => materials[index] = value);
                        while (materialLoader.MoveNext()) yield return materialLoader.Current;
                    }
                    else
                        loader.RefreshMaterialConfig(model.Parts[i].Material, config, materials[i]);
                    yield return null;
                }
                ReorderRender(materials);
                completed(materials);
                yield break;
            }

            Release(currentMaterials, cacheEntry);
            var loaded = new UnityEngine.Material[model.Parts.Length];
            for (var i = 0; i < loaded.Length; i++)
            {
                var index = i;
                var materialLoader = loader.LoadMaterialAsync(model.Parts[i].Material, config,
                    value => loaded[index] = value);
                while (materialLoader.MoveNext()) yield return materialLoader.Current;
                yield return null;
            }
            ReorderRender(loaded);
            if (cacheEntry != null) cacheEntry.Materials = loaded;
            completed(loaded);
        }

        internal void Refresh(MmdModel model, MaterialLoader loader,
            UnityEngine.Material[] materials, MmdUnityConfig config)
        {
            if (model == null) return;
            if (materials.Length != model.Parts.Length)
                throw new ArgumentException("UpdateMaterialsConfig: material count should be equal to model part count");
            for (var i = 0; i < model.Parts.Length; i++)
                loader.RefreshMaterialConfig(model.Parts[i].Material, config, materials[i]);
        }

        internal void Release(UnityEngine.Material[] materials, MmdModelResourceCache.Entry cacheEntry)
        {
            if (materials == null || cacheEntry != null) return;
            foreach (var material in materials) UnityEngine.Object.Destroy(material);
        }

        private static void ReorderRender(UnityEngine.Material[] materials)
        {
            if (materials == null || materials.Length == 0) return;
            var order = materials.Where(material => material != null).OrderBy(material => material.renderQueue);
            var lastQueue = int.MinValue;
            foreach (var material in order)
            {
                if (lastQueue >= material.renderQueue) material.renderQueue = ++lastQueue;
                else lastQueue = material.renderQueue;
            }
        }
    }
}