using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using UnityEditor;
using UnityEngine;
using UnityEngine.TextCore;
using TMPro;

public static class SpriteAssetGenerator
{
    [MenuItem("Tools/Generate Prize Sprite Assets")]
    public static void Generate()
    {
        string sourceDir = "Assets/Resources/Sprites/UI/Labels";
        string destDir = "Assets/Resources/Sprite Assets";

        if (!Directory.Exists(destDir))
        {
            Directory.CreateDirectory(destDir);
            AssetDatabase.Refresh();
        }

        if (!Directory.Exists(sourceDir))
        {
            Debug.LogError($"[SpriteAssetGenerator] Source directory not found: {sourceDir}");
            return;
        }

        string[] pngFiles = Directory.GetFiles(sourceDir, "*.png");
        if (pngFiles.Length == 0)
        {
            Debug.LogWarning($"[SpriteAssetGenerator] No PNG files found in {sourceDir}");
            return;
        }

        foreach (string pngPath in pngFiles)
        {
            try
            {
                string fileNameWithoutExtension = Path.GetFileNameWithoutExtension(pngPath);
                string assetPath = $"{destDir}/{fileNameWithoutExtension}.asset";

                Texture2D sourceTex = AssetDatabase.LoadAssetAtPath<Texture2D>(pngPath);
                if (sourceTex == null)
                {
                    Debug.LogWarning($"[SpriteAssetGenerator] Failed to load Texture2D at: {pngPath}");
                    continue;
                }

                // Create new Sprite Asset
                TMP_SpriteAsset spriteAsset = ScriptableObject.CreateInstance<TMP_SpriteAsset>();
                spriteAsset.name = fileNameWithoutExtension;
                spriteAsset.spriteInfoList = new List<TMP_Sprite>();

                // Set version to 1.1.0 to avoid UpgradeSpriteAsset trigger in Awake/UpdateLookupTables
                var versionField = typeof(TMP_Asset).GetField("m_Version", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
                if (versionField != null)
                {
                    versionField.SetValue(spriteAsset, "1.1.0");
                }

                spriteAsset.hashCode = TMP_TextUtilities.GetSimpleHashCode(fileNameWithoutExtension);
                spriteAsset.spriteSheet = sourceTex;

                // Populate tables
                List<TMP_SpriteGlyph> spriteGlyphTable = new List<TMP_SpriteGlyph>();
                List<TMP_SpriteCharacter> spriteCharacterTable = new List<TMP_SpriteCharacter>();

                // Get all sprites contained in this texture file
                Sprite[] sprites = AssetDatabase.LoadAllAssetsAtPath(pngPath)
                    .Select(x => x as Sprite)
                    .Where(x => x != null)
                    .OrderByDescending(x => x.rect.y)
                    .ThenBy(x => x.rect.x)
                    .ToArray();

                if (sprites.Length == 0)
                {
                    Debug.LogWarning($"[SpriteAssetGenerator] No sprites sliced inside texture {pngPath}. Make sure it is sliced as Sprite (Multiple) or Sprite (Single).");
                    continue;
                }

                // Configure FaceInfo to scale the sprites properly
                float baseHeight = sprites[0].rect.height;
                FaceInfo faceInfo = spriteAsset.faceInfo;
                faceInfo.pointSize = (int)baseHeight;
                faceInfo.scale = 1.0f;
                faceInfo.ascentLine = baseHeight;
                faceInfo.capLine = baseHeight * 0.7f;
                faceInfo.baseline = 0;
                faceInfo.descentLine = 0;
                spriteAsset.faceInfo = faceInfo;

                for (int i = 0; i < sprites.Length; i++)
                {
                    Sprite sprite = sprites[i];

                    TMP_SpriteGlyph spriteGlyph = new TMP_SpriteGlyph();
                    spriteGlyph.index = (uint)i;
                    
                    float spriteHeight = sprite.rect.height;
                    // Center the sprite vertically around the cap-height (70% of font size)
                    float bearingY = spriteHeight * 0.85f;
                    float bearingX = 0f;

                    spriteGlyph.metrics = new GlyphMetrics(sprite.rect.width, sprite.rect.height, bearingX, bearingY, sprite.rect.width);
                    spriteGlyph.glyphRect = new GlyphRect(sprite.rect);
                    spriteGlyph.scale = 1.0f;
                    spriteGlyph.sprite = sprite;

                    spriteGlyphTable.Add(spriteGlyph);

                    TMP_SpriteCharacter spriteCharacter = new TMP_SpriteCharacter(0xFFFE, spriteGlyph);
                    spriteCharacter.name = sprite.name;
                    spriteCharacter.scale = 1.0f;

                    spriteCharacterTable.Add(spriteCharacter);
                }

                spriteAsset.spriteCharacterTable.Clear();
                spriteAsset.spriteCharacterTable.AddRange(spriteCharacterTable);

                spriteAsset.spriteGlyphTable.Clear();
                spriteAsset.spriteGlyphTable.AddRange(spriteGlyphTable);

                // Add default material
                Shader shader = Shader.Find("TextMeshPro/Sprite");
                if (shader == null)
                {
                    shader = Shader.Find("UI/Default");
                }
                
                if (shader == null)
                {
                    Debug.LogError("[SpriteAssetGenerator] Shader not found!");
                    continue;
                }

                Material material = new Material(shader);
                material.SetTexture(ShaderUtilities.ID_MainTex, sourceTex);
                material.name = fileNameWithoutExtension + " Material";

                AssetDatabase.CreateAsset(spriteAsset, assetPath);
                AssetDatabase.AddObjectToAsset(material, spriteAsset);

                spriteAsset.material = material;
                spriteAsset.UpdateLookupTables();

                EditorUtility.SetDirty(spriteAsset);
                Debug.Log($"[SpriteAssetGenerator] Created Sprite Asset at: {assetPath} with {sprites.Length} sprites.");
            }
            catch (System.Exception ex)
            {
                Debug.LogException(ex);
            }
        }

        AssetDatabase.SaveAssets();
        AssetDatabase.Refresh();
    }
}