using System.IO;
using System.Linq;
using System.Text;
using Luneraria.UI;
using UnityEditor;
using UnityEngine;
using UnityEngine.TextCore.LowLevel;
using UnityEngine.TextCore.Text;
using UnityEngine.UIElements;

namespace Luneraria.EditorTools
{
    /// <summary>
    /// Builds Settings/LuneUi.asset (U3): static SDF font atlases from the variable fonts of the
    /// reference (assets/fonts, OFL). Unity's text engine has no weight axis; FreeType loads the
    /// named instances through the face index (named instance &lt;&lt; 16): Cantarell Regular (3) and
    /// Bold (4), Cinzel Bold (2). The atlases hold every character the HUD texts use, so the player
    /// never needs the font files.
    /// Unity -batchmode -projectPath . -executeMethod Luneraria.EditorTools.LuneUiAssetsBuilder.Build -logFile -
    /// </summary>
    public static class LuneUiAssetsBuilder
    {
        public const string AssetPath = "Assets/Luneraria/Settings/LuneUi.asset";
        const string Fonts = "Assets/Luneraria/UI/Fonts/";

        public static void Build()
        {
            var assets = AssetDatabase.LoadAssetAtPath<LuneUiAssets>(AssetPath);
            if (assets == null)
            {
                assets = ScriptableObject.CreateInstance<LuneUiAssets>();
                AssetDatabase.CreateAsset(assets, AssetPath);
            }
            assets.Text = Font("Cantarell-VF.otf", 3, "Cantarell-Regular");
            assets.TextBold = Font("Cantarell-VF.otf", 4, "Cantarell-Bold");
            assets.Display = Font("Cinzel-VF.ttf", 2, "Cinzel-Bold");
            assets.Theme = AssetDatabase.LoadAssetAtPath<ThemeStyleSheet>("Assets/Luneraria/UI/LuneRuntimeTheme.tss");
            EditorUtility.SetDirty(assets);
            AssetDatabase.SaveAssets();
            Debug.Log("LUNE_UI built " + AssetPath);
            if (Application.isBatchMode)
                EditorApplication.Exit(0);
        }

        /// <summary>Printable ASCII, Latin-1 and the punctuation and symbols of the HUD texts.</summary>
        public static string Characters()
        {
            var text = new StringBuilder();
            for (char c = (char)32; c < 127; c++)
                text.Append(c);
            for (char c = (char)160; c <= 255; c++)
                text.Append(c);
            text.Append("–—‘’‚“”„•…‰‹›€→←↑↓−×★≈≤≥∞·ŒœŠšŽžŸ");
            return new string(text.ToString().Distinct().ToArray());
        }

        static FontAsset Font(string file, int namedInstance, string name)
        {
            string path = Fonts + name + ".asset";
            if (AssetDatabase.LoadAssetAtPath<FontAsset>(path) != null)
                AssetDatabase.DeleteAsset(path);
            string source = Path.GetFullPath(Fonts + file);
            FontAsset font = FontAsset.CreateFontAsset(source, namedInstance << 16, 64, 8, GlyphRenderMode.SDFAA, 1024, 1024);
            if (font == null)
                throw new System.InvalidOperationException("Font asset failed: " + file + " instance " + namedInstance);
            font.name = name;
            AssetDatabase.CreateAsset(font, path);
            if (!font.TryAddCharacters(Characters(), out string missing))
                Debug.LogWarning("LUNE_UI " + name + " misses: " + missing);
            for (int index = 0; index < font.atlasTextures.Length; index++)
            {
                Texture2D atlas = font.atlasTextures[index];
                if (atlas == null)
                    continue;
                atlas.name = name + " Atlas " + index;
                AssetDatabase.AddObjectToAsset(atlas, font);
            }
            font.material.name = name + " Material";
            AssetDatabase.AddObjectToAsset(font.material, font);
            font.atlasPopulationMode = AtlasPopulationMode.Static;
            // A static atlas needs no source at runtime: keep no machine path and never clear it in builds.
            var serialized = new SerializedObject(font);
            serialized.FindProperty("m_SourceFontFilePath").stringValue = Fonts + file;
            serialized.FindProperty("m_ClearDynamicDataOnBuild").boolValue = false;
            serialized.ApplyModifiedPropertiesWithoutUndo();
            EditorUtility.SetDirty(font);
            AssetDatabase.SaveAssets();
            Debug.Log(string.Format("LUNE_UI font {0}: {1} / {2}, {3} glyphs, {4} atlas(es)", name, font.faceInfo.familyName, font.faceInfo.styleName, font.glyphTable.Count, font.atlasTextures.Length));
            return font;
        }
    }
}