using System.Collections.Generic;
using System.Linq;
using UnityEditor;
using UnityEngine;

namespace Luneraria.EditorTools
{
    /// <summary>
    /// Import rules for every FBX of the Blender pipeline under Assets/Luneraria/Art (U2A).
    /// Metres stay metres, Blender's Z-up axes are converted by baking (no root rotation),
    /// normals come from the file, tangents are computed with MikkTSpace (as in Blender), rigs are
    /// generic with the Blender bone names, and clips get their Blender action names, loop flags
    /// and contact events.
    /// </summary>
    public sealed class LuneModelPostprocessor : AssetPostprocessor
    {
        public const string ArtRoot = "Assets/Luneraria/Art/";
        /// <summary>Raised on the figure at the hit frame of attack and ability clips.</summary>
        public const string ContactEvent = "OnLuneContact";

        public override uint GetVersion() { return 5; }

        void OnPreprocessModel()
        {
            if (!assetPath.StartsWith(ArtRoot) || !assetPath.EndsWith(".fbx"))
                return;
            ExportReport report = ExportReport.ForModel(assetPath);
            var importer = (ModelImporter)assetImporter;
            importer.globalScale = 1f;
            importer.useFileScale = true;
            importer.bakeAxisConversion = true;
            importer.importCameras = false;
            importer.importLights = false;
            importer.importVisibility = false;
            importer.importBlendShapes = false;
            importer.importNormals = ModelImporterNormals.Import;
            importer.importTangents = ModelImporterTangents.CalculateMikk;
            importer.meshCompression = ModelImporterMeshCompression.Off;
            importer.isReadable = true;
            importer.materialImportMode = ModelImporterMaterialImportMode.ImportViaMaterialDescription;
            importer.materialLocation = ModelImporterMaterialLocation.InPrefab;
            bool skinned = report != null && report.Skinned;
            importer.animationType = skinned ? ModelImporterAnimationType.Generic : ModelImporterAnimationType.None;
            importer.avatarSetup = skinned ? ModelImporterAvatarSetup.CreateFromThisModel : ModelImporterAvatarSetup.NoAvatar;
            importer.importAnimation = skinned;
            importer.optimizeGameObjects = false;
            importer.animationCompression = ModelImporterAnimationCompression.Off;
            importer.resampleCurves = false;
        }

        /// <summary>
        /// U5.5: a figure with a lane copy (meshes &lt;body&gt;_LOD0/_LOD1, Unity builds the LODGroup
        /// from the names) switches to it below the screen height the generator names; the lane
        /// copy is never culled, so a figure never vanishes at map zoom.
        /// </summary>
        void OnPostprocessModel(GameObject root)
        {
            if (!assetPath.StartsWith(ArtRoot) || !assetPath.EndsWith(".fbx"))
                return;
            LODGroup group = root.GetComponentInChildren<LODGroup>();
            ExportReport report = ExportReport.ForModel(assetPath);
            var lod = report?.Data["generator"]?["lod"];
            if (group == null || lod == null)
                return;
            LOD[] lods = group.GetLODs();
            if (lods.Length != 2)
                return;
            lods[0].screenRelativeTransitionHeight = (float)lod["lod0_screen"];
            lods[1].screenRelativeTransitionHeight = 0f;
            group.SetLODs(lods);
        }

        void OnPreprocessAnimation()
        {
            if (!assetPath.StartsWith(ArtRoot) || !assetPath.EndsWith(".fbx"))
                return;
            ExportReport report = ExportReport.ForModel(assetPath);
            if (report == null || !report.Skinned)
                return;
            var importer = (ModelImporter)assetImporter;
            var blender = report.Clips.ToDictionary(c => (string)c["name"], c => c);
            var clips = new List<ModelImporterClipAnimation>();
            foreach (ModelImporterClipAnimation clip in importer.defaultClipAnimations)
            {
                // Blender names takes "<armature>|<action>"; Unity keeps the action name.
                string name = clip.takeName.Contains("|") ? clip.takeName.Substring(clip.takeName.LastIndexOf('|') + 1) : clip.takeName;
                clip.name = name;
                if (blender.TryGetValue(name, out var facts))
                {
                    clip.loopTime = (bool)facts["loop"];
                    double contact = (double)facts["contact_seconds"];
                    double seconds = (double)facts["seconds"];
                    if (contact > 0.0 && seconds > 0.0)
                        clip.events = new[] { new AnimationEvent { functionName = ContactEvent, time = (float)(contact / seconds) } };
                }
                clips.Add(clip);
            }
            importer.clipAnimations = clips.ToArray();
        }
    }
}