using UnityEditor;
using UnityEngine;

namespace Game.WorldGen
{
    public class WorldGenWindow : EditorWindow
    {
        const string LastSettingsKey = "WorldGen.LastSettingsPath";

        WorldGenSettings _settings;
        Editor _settingsEditor;
        Vector2 _scroll;

        [MenuItem("Tools/World Generator")]
        public static void Open()
        {
            var w = GetWindow<WorldGenWindow>("World Generator");
            w.minSize = new Vector2(360f, 480f);
            w.Show();
        }

        void OnEnable()
        {
            string path = EditorPrefs.GetString(LastSettingsKey, "");
            if (!string.IsNullOrEmpty(path))
                _settings = AssetDatabase.LoadAssetAtPath<WorldGenSettings>(path);
        }

        void OnDisable()
        {
            if (_settingsEditor != null) DestroyImmediate(_settingsEditor);
        }

        void OnGUI()
        {
            EditorGUILayout.Space(4);
            EditorGUILayout.LabelField("World Generator", EditorStyles.boldLabel);
            EditorGUILayout.HelpBox(
                "Bakes a grid of stitched Unity Terrain tiles from a settings asset. " +
                "Noise is sampled in world space, so tiles are seamless. " +
                "Re-baking clears the previous world first.",
                MessageType.Info);

            EditorGUI.BeginChangeCheck();
            _settings = (WorldGenSettings)EditorGUILayout.ObjectField(
                "Settings", _settings, typeof(WorldGenSettings), false);
            if (EditorGUI.EndChangeCheck())
            {
                EditorPrefs.SetString(LastSettingsKey,
                    _settings != null ? AssetDatabase.GetAssetPath(_settings) : "");
                if (_settingsEditor != null) { DestroyImmediate(_settingsEditor); _settingsEditor = null; }
            }

            if (_settings == null)
            {
                EditorGUILayout.Space(6);
                if (GUILayout.Button("Create new settings asset…", GUILayout.Height(28)))
                    CreateSettingsAsset();
                EditorGUILayout.HelpBox("Assign or create a WorldGenSettings asset to begin.", MessageType.Warning);
                return;
            }

            DrawSummary();

            EditorGUILayout.Space(6);
            using (var sv = new EditorGUILayout.ScrollViewScope(_scroll))
            {
                _scroll = sv.scrollPosition;
                if (_settingsEditor == null) _settingsEditor = Editor.CreateEditor(_settings);
                _settingsEditor.OnInspectorGUI();
            }

            EditorGUILayout.Space(8);
            DrawActions();
        }

        void DrawSummary()
        {
            float tileSize = _settings.worldSizeMeters / Mathf.Max(1, _settings.tilesPerSide);
            int n = _settings.tilesPerSide;
            float metersPerTexel = tileSize / Mathf.Max(1, _settings.heightmapResolution - 1);

            EditorGUILayout.Space(4);
            EditorGUILayout.LabelField(
                $"{n}×{n} = {n * n} tiles · {tileSize:0} m/tile · {metersPerTexel:0.00} m/texel",
                EditorStyles.miniBoldLabel);

            if (!WorldGenSettings.IsPowerOfTwoPlusOne(_settings.heightmapResolution))
                EditorGUILayout.HelpBox(
                    "Heightmap resolution must be 2^n + 1 (513, 1025, 2049, 4097).",
                    MessageType.Error);
        }

        void DrawActions()
        {
            using (new EditorGUILayout.HorizontalScope())
            {
                GUI.backgroundColor = new Color(0.6f, 0.9f, 0.6f);
                if (GUILayout.Button("Generate World", GUILayout.Height(34)))
                {
                    if (EditorUtility.DisplayDialog(
                            "Generate World",
                            $"This clears any existing '{_settings.worldRootName}' and regenerates " +
                            $"{_settings.tilesPerSide * _settings.tilesPerSide} terrain tiles. Continue?",
                            "Generate", "Cancel"))
                    {
                        WorldGenerator.Generate(_settings);
                    }
                }
                GUI.backgroundColor = Color.white;

                if (GUILayout.Button("Clear", GUILayout.Height(34), GUILayout.Width(80)))
                {
                    if (EditorUtility.DisplayDialog("Clear World",
                            $"Delete '{_settings.worldRootName}' and its generated TerrainData assets?",
                            "Clear", "Cancel"))
                    {
                        WorldGenerator.ClearWorld(_settings);
                    }
                }
            }

            EditorGUILayout.Space(4);
            if (GUILayout.Button("Sync Layers to All Tiles", GUILayout.Height(24)))
                WorldGenerator.SyncLayers(_settings);
            EditorGUILayout.HelpBox(
                "Set up your textures on ONE tile (Terrain ▸ Paint ▸ Edit Terrain Layers), select it, " +
                "then click this to copy the same palette onto every tile so you can paint everywhere.",
                MessageType.None);

            EditorGUILayout.Space(2);
            float aTexel = (_settings.worldSizeMeters / Mathf.Max(1, _settings.tilesPerSide))
                           / Mathf.Max(16, _settings.alphamapResolution);
            if (GUILayout.Button($"Apply Splatmap Resolution to All Tiles  ({aTexel:0.00} m/texel)", GUILayout.Height(24)))
                WorldGenerator.ApplyAlphamapResolution(_settings);
            EditorGUILayout.HelpBox(
                "Blocky paint? Raise 'Alphamap Resolution' above, then click this. " +
                "1024 ≈ 1 m/texel (good balance). 2048 is sharper but uses a lot more VRAM across 36 tiles.",
                MessageType.None);

            EditorGUILayout.Space(2);
            if (GUILayout.Button("Apply Detail Resolution to All Tiles (grass painting)", GUILayout.Height(24)))
                WorldGenerator.ApplyDetailResolution(_settings);
            EditorGUILayout.HelpBox(
                "Can't paint grass/details (\"Detail patches allocated: 0\")? Click this. " +
                "It initialises the detail grid on every tile so the Paint Details tool works.",
                MessageType.None);

            EditorGUILayout.Space(6);
            EditorGUILayout.LabelField("Auto texturing by height", EditorStyles.boldLabel);
            float sea = _settings.seaLevel01 * _settings.maxHeightMeters;
            EditorGUILayout.LabelField($"Sea level ≈ {sea:0} m · Max height = {_settings.maxHeightMeters:0} m",
                EditorStyles.miniLabel);

            using (new EditorGUILayout.HorizontalScope())
            {
                if (GUILayout.Button("Add Height-Band Preset", GUILayout.Height(24)))
                    WorldGenerator.AddHeightBandPreset(_settings);

                using (new EditorGUI.DisabledScope(!_settings.autoTexture))
                {
                    if (GUILayout.Button("Apply Auto-Texture to All Tiles", GUILayout.Height(24)))
                    {
                        if (EditorUtility.DisplayDialog("Auto Texture",
                                "This repaints the splatmap on every tile from the height bands and " +
                                "overwrites any manual painting. Continue?", "Apply", "Cancel"))
                        {
                            WorldGenerator.ApplyAutoTexture(_settings);
                        }
                    }
                }
            }
            EditorGUILayout.HelpBox(
                "1) Add the preset (Sand/Grass/Rock/Snow). 2) Drop a Terrain Layer into each rule and " +
                "tune the meter ranges + fades. 3) Apply. 'Auto texture' must be checked.",
                MessageType.None);
        }

        void CreateSettingsAsset()
        {
            string path = EditorUtility.SaveFilePanelInProject(
                "Create World Gen Settings", "WorldGenSettings", "asset",
                "Choose where to save the settings asset.", "Assets");
            if (string.IsNullOrEmpty(path)) return;

            var asset = ScriptableObject.CreateInstance<WorldGenSettings>();
            AssetDatabase.CreateAsset(asset, path);
            AssetDatabase.SaveAssets();
            _settings = asset;
            EditorPrefs.SetString(LastSettingsKey, path);
            Selection.activeObject = asset;
        }
    }
}