using System.Collections.Generic;
using NeoModLoader.services;
using UnityEngine;

namespace IdleSpectator;

/// <summary>
/// Session gravestone stacks keyed by world tile. Drawn via QuantumSprites; click opens Lore.
/// </summary>
public static class GraveMarkers
{
    public const int PerStackSoftCap = 40;
    public const string QuantumAssetId = "idle_spectator_gravestones";
    /// <summary>World skull size - small tile marker, still hover/clickable.</summary>
    public const float SkullBaseScale = 0.055f;

    public sealed class GraveEntry
    {
        public long UnitId;
        public string DisplayName = "";
        public string MannerLabel = "";
        public float ExpireAt;
        public bool Favorite;
        public float CreatedAt;
    }

    public sealed class GraveStack
    {
        public int TileX;
        public int TileY;
        public Vector3 WorldPos;
        public readonly List<GraveEntry> Entries = new List<GraveEntry>();
        public float LastActivityAt;
        public bool HasFavorite;
        /// <summary>Kept via Lore Keep button - skips TTL; gold skull.</summary>
        public bool Permanent;

        public long Key => PackKey(TileX, TileY);
    }

    private static readonly Dictionary<long, GraveStack> Stacks = new Dictionary<long, GraveStack>();
    private static readonly List<long> EvictScratch = new List<long>(64);
    private static Sprite _skullSprite;
    private static bool _assetRegistered;
    private static Color _tempTint = new Color(0.85f, 0.88f, 0.92f, 0.95f);
    private static Color _permTint = new Color(0.92f, 0.78f, 0.42f, 0.98f);

    public static int StackCount
    {
        get
        {
            lock (Stacks)
            {
                return Stacks.Count;
            }
        }
    }

    public static void Clear()
    {
        lock (Stacks)
        {
            Stacks.Clear();
        }

    }

    public static void Update()
    {
        if (!ModSettings.Enabled || !ModSettings.GravestonesEnabled)
        {
            if (StackCount > 0)
            {
                Clear();
            }

            return;
        }

        EnsureQuantumAsset();
        Prune();
        GraveHover.Update();
        // Stack size is in the Lore title (Grave · N); no world count badges.
        GraveCountBadges.Hide();
    }

    public static void AddDeath(Actor victim)
    {
        if (!ModSettings.Enabled || !ModSettings.GravestonesEnabled || victim == null)
        {
            return;
        }

        if (ModSettings.GravestoneMaxStacks <= 0)
        {
            return;
        }

        long unitId = 0;
        string name = "Nameless";
        bool favorite = false;
        Vector3 pos = Vector3.zero;
        int tileX = 0;
        int tileY = 0;
        try
        {
            unitId = victim.getID();
            name = victim.getName();
            if (string.IsNullOrEmpty(name))
            {
                name = "Nameless";
            }

            favorite = victim.isFavorite();
            if (victim.current_tile != null)
            {
                tileX = victim.current_tile.x;
                tileY = victim.current_tile.y;
                pos = victim.current_tile.posV3;
            }
            else
            {
                pos = victim.current_position;
                tileX = Mathf.FloorToInt(pos.x);
                tileY = Mathf.FloorToInt(pos.y);
            }
        }
        catch
        {
            return;
        }

        if (unitId == 0)
        {
            return;
        }

        string mannerLabel = Chronicle.FormatGraveDeathSubtitle(unitId);
        AddEntry(tileX, tileY, pos, unitId, name, mannerLabel, favorite);
    }

    /// <summary>Harness / orphan path: place a grave entry at an explicit tile.</summary>
    public static bool ForceAdd(
        long unitId,
        string displayName,
        int tileX,
        int tileY,
        Vector3 worldPos,
        string mannerLabel = "",
        bool favorite = false)
    {
        if (unitId == 0 || ModSettings.GravestoneMaxStacks <= 0)
        {
            return false;
        }

        if (worldPos.sqrMagnitude < 0.0001f)
        {
            worldPos = new Vector3(tileX + 0.5f, tileY + 0.5f, 0f);
        }

        AddEntry(
            tileX,
            tileY,
            worldPos,
            unitId,
            string.IsNullOrEmpty(displayName) ? "Nameless" : displayName,
            mannerLabel ?? "",
            favorite);
        return true;
    }

    public static int EntryCountAt(int tileX, int tileY)
    {
        long key = PackKey(tileX, tileY);
        lock (Stacks)
        {
            return Stacks.TryGetValue(key, out GraveStack stack) ? stack.Entries.Count : 0;
        }
    }

    public static bool TryGetStack(int tileX, int tileY, out GraveStack stack)
    {
        long key = PackKey(tileX, tileY);
        lock (Stacks)
        {
            if (Stacks.TryGetValue(key, out stack))
            {
                return true;
            }
        }

        stack = null;
        return false;
    }

    public static bool TryGetStackAtWorld(Vector3 worldPos, out GraveStack stack)
    {
        int tileX = Mathf.FloorToInt(worldPos.x);
        int tileY = Mathf.FloorToInt(worldPos.y);
        return TryGetStack(tileX, tileY, out stack);
    }

    public static GraveStack FindNearestStack(Vector2 worldPos, float maxDist)
    {
        float maxSq = maxDist * maxDist;
        GraveStack best = null;
        float bestSq = maxSq;
        lock (Stacks)
        {
            foreach (GraveStack stack in Stacks.Values)
            {
                float dx = stack.WorldPos.x - worldPos.x;
                float dy = stack.WorldPos.y - worldPos.y;
                float sq = dx * dx + dy * dy;
                if (sq <= bestSq)
                {
                    bestSq = sq;
                    best = stack;
                }
            }
        }

        return best;
    }

    /// <summary>Newest matching grave entry by display name (any stack).</summary>
    public static bool TryFindEntryByName(string nameNeedle, out GraveEntry entry, out GraveStack stack)
    {
        entry = null;
        stack = null;
        if (string.IsNullOrEmpty(nameNeedle))
        {
            return false;
        }

        lock (Stacks)
        {
            foreach (GraveStack s in Stacks.Values)
            {
                for (int i = s.Entries.Count - 1; i >= 0; i--)
                {
                    GraveEntry e = s.Entries[i];
                    if (e.DisplayName != null
                        && e.DisplayName.IndexOf(nameNeedle, System.StringComparison.OrdinalIgnoreCase) >= 0)
                    {
                        entry = e;
                        stack = s;
                        return true;
                    }
                }
            }
        }

        return false;
    }

    public static void CopyStacks(List<GraveStack> into)
    {
        into.Clear();
        lock (Stacks)
        {
            foreach (GraveStack stack in Stacks.Values)
            {
                into.Add(stack);
            }
        }
    }

    public static void SnapshotEntries(GraveStack stack, List<GraveEntry> into)
    {
        into.Clear();
        if (stack == null)
        {
            return;
        }

        lock (Stacks)
        {
            for (int i = 0; i < stack.Entries.Count; i++)
            {
                into.Add(stack.Entries[i]);
            }
        }
    }

    public static Color TempTint => _tempTint;

    public static Color PermTint => _permTint;

    public static bool TrySetStackPermanent(int tileX, int tileY, bool permanent)
    {
        long key = PackKey(tileX, tileY);
        float now = Time.unscaledTime;
        float ttl = ModSettings.GravestoneTtlSeconds;
        lock (Stacks)
        {
            if (!Stacks.TryGetValue(key, out GraveStack stack))
            {
                return false;
            }

            stack.Permanent = permanent;
            stack.LastActivityAt = now;
            for (int i = 0; i < stack.Entries.Count; i++)
            {
                stack.Entries[i].ExpireAt = permanent
                    ? float.PositiveInfinity
                    : now + ttl;
            }

            return true;
        }
    }

    public static bool IsStackPermanent(int tileX, int tileY)
    {
        long key = PackKey(tileX, tileY);
        lock (Stacks)
        {
            return Stacks.TryGetValue(key, out GraveStack stack) && stack.Permanent;
        }
    }

    /// <summary>Remove one tile stack (Delete in Lore). Returns false if missing.</summary>
    public static bool TryRemoveStack(int tileX, int tileY)
    {
        long key = PackKey(tileX, tileY);
        lock (Stacks)
        {
            return Stacks.Remove(key);
        }
    }

    public static Sprite SkullSprite
    {
        get
        {
            if (_skullSprite == null)
            {
                _skullSprite = SpriteTextureLoader.getSprite("ui/Icons/iconSkulls")
                    ?? SpriteTextureLoader.getSprite("ui/Icons/iconDead")
                    ?? SpriteTextureLoader.getSprite("ui/icons/iconSkulls");
            }

            return _skullSprite;
        }
    }

    public static long PackKey(int tileX, int tileY)
    {
        return ((long)tileX << 32) ^ (uint)tileY;
    }

    private static void AddEntry(
        int tileX,
        int tileY,
        Vector3 worldPos,
        long unitId,
        string displayName,
        string mannerLabel,
        bool favorite)
    {
        float now = Time.unscaledTime;
        float ttl = ModSettings.GravestoneTtlSeconds;
        long key = PackKey(tileX, tileY);

        lock (Stacks)
        {
            if (!Stacks.TryGetValue(key, out GraveStack stack))
            {
                stack = new GraveStack
                {
                    TileX = tileX,
                    TileY = tileY,
                    WorldPos = worldPos.sqrMagnitude > 0.0001f
                        ? worldPos
                        : new Vector3(tileX + 0.5f, tileY + 0.5f, 0f),
                    LastActivityAt = now
                };
                Stacks[key] = stack;
            }
            else if (worldPos.sqrMagnitude > 0.0001f)
            {
                stack.WorldPos = worldPos;
            }

            float expireAt = stack.Permanent ? float.PositiveInfinity : now + ttl;

            // Refresh existing entry for same unit if re-added.
            for (int i = 0; i < stack.Entries.Count; i++)
            {
                if (stack.Entries[i].UnitId == unitId)
                {
                    stack.Entries.RemoveAt(i);
                    break;
                }
            }

            stack.Entries.Add(new GraveEntry
            {
                UnitId = unitId,
                DisplayName = displayName,
                MannerLabel = mannerLabel ?? "",
                ExpireAt = expireAt,
                Favorite = favorite,
                CreatedAt = now
            });
            stack.LastActivityAt = now;
            while (stack.Entries.Count > PerStackSoftCap)
            {
                stack.Entries.RemoveAt(0);
            }

            RefreshFavoriteFlag(stack);
            EnforceStackCapUnlocked();
        }
    }

    private static void Prune()
    {
        float now = Time.unscaledTime;
        lock (Stacks)
        {
            EvictScratch.Clear();
            foreach (KeyValuePair<long, GraveStack> kv in Stacks)
            {
                GraveStack stack = kv.Value;
                if (!stack.Permanent)
                {
                    for (int i = stack.Entries.Count - 1; i >= 0; i--)
                    {
                        if (stack.Entries[i].ExpireAt <= now)
                        {
                            stack.Entries.RemoveAt(i);
                        }
                    }
                }

                if (stack.Entries.Count == 0)
                {
                    EvictScratch.Add(kv.Key);
                }
                else
                {
                    RefreshFavoriteFlag(stack);
                }
            }

            for (int i = 0; i < EvictScratch.Count; i++)
            {
                Stacks.Remove(EvictScratch[i]);
            }

            EnforceStackCapUnlocked();
        }
    }

    private static void EnforceStackCapUnlocked()
    {
        int max = ModSettings.GravestoneMaxStacks;
        if (max <= 0)
        {
            Stacks.Clear();
            return;
        }

        while (Stacks.Count > max)
        {
            long victimKey = 0;
            float oldest = float.PositiveInfinity;
            bool foundNonFav = false;
            foreach (KeyValuePair<long, GraveStack> kv in Stacks)
            {
                if (kv.Value.HasFavorite || kv.Value.Permanent)
                {
                    continue;
                }

                if (kv.Value.LastActivityAt < oldest)
                {
                    oldest = kv.Value.LastActivityAt;
                    victimKey = kv.Key;
                    foundNonFav = true;
                }
            }

            if (!foundNonFav)
            {
                oldest = float.PositiveInfinity;
                foreach (KeyValuePair<long, GraveStack> kv in Stacks)
                {
                    if (kv.Value.LastActivityAt < oldest)
                    {
                        oldest = kv.Value.LastActivityAt;
                        victimKey = kv.Key;
                    }
                }
            }

            if (victimKey == 0 && Stacks.Count > 0)
            {
                foreach (long k in Stacks.Keys)
                {
                    victimKey = k;
                    break;
                }
            }

            if (victimKey == 0)
            {
                break;
            }

            Stacks.Remove(victimKey);
        }
    }

    private static void RefreshFavoriteFlag(GraveStack stack)
    {
        bool fav = false;
        for (int i = 0; i < stack.Entries.Count; i++)
        {
            if (stack.Entries[i].Favorite)
            {
                fav = true;
                break;
            }
        }

        stack.HasFavorite = fav;
    }

    private static void EnsureQuantumAsset()
    {
        if (_assetRegistered)
        {
            EnsureGroupSystem();
            return;
        }

        try
        {
            if (AssetManager.quantum_sprites == null)
            {
                return;
            }

            QuantumSpriteAsset existing = null;
            try
            {
                existing = AssetManager.quantum_sprites.get(QuantumAssetId);
            }
            catch
            {
                existing = null;
            }

            if (existing == null)
            {
                QuantumSpriteAsset asset = new QuantumSpriteAsset
                {
                    id = QuantumAssetId,
                    id_prefab = "p_gameSprite",
                    base_scale = SkullBaseScale,
                    render_gameplay = true,
                    render_map = true,
                    default_amount = 64,
                    create_object = (QuantumSpriteAsset _, QuantumSprite q) =>
                    {
                        Sprite sprite = SkullSprite;
                        if (sprite != null)
                        {
                            q.setSprite(sprite);
                        }

                        try
                        {
                            q.sprite_renderer.sortingLayerID = SortingLayer.NameToID("Objects");
                            q.sprite_renderer.sortingOrder = 2;
                        }
                        catch
                        {
                            // sorting optional
                        }
                    },
                    draw_call = DrawGraves
                };
                AssetManager.quantum_sprites.add(asset);
                LogService.LogInfo("[IdleSpectator] Registered gravestone QuantumSprite asset");
            }

            _assetRegistered = true;
            EnsureGroupSystem();
        }
        catch (System.Exception ex)
        {
            LogService.LogInfo($"[IdleSpectator] Gravestone QuantumSprite register failed: {ex.Message}");
        }
    }

    private static void EnsureGroupSystem()
    {
        try
        {
            QuantumSpriteAsset asset = AssetManager.quantum_sprites.get(QuantumAssetId);
            if (asset == null)
            {
                return;
            }

            if (asset.group_system != null)
            {
                return;
            }

            QuantumSpriteGroupSystem system = new GameObject("IdleSpectatorGravesQS")
                .AddComponent<QuantumSpriteGroupSystem>();
            system.create(asset);
            asset.group_system = system;
            asset.group_system.turn_off_renderer = asset.turn_off_renderer;
        }
        catch (System.Exception ex)
        {
            LogService.LogInfo($"[IdleSpectator] Gravestone group_system init failed: {ex.Message}");
        }
    }

    private static void DrawGraves(QuantumSpriteAsset asset)
    {
        if (!ModSettings.Enabled || !ModSettings.GravestonesEnabled || asset?.group_system == null)
        {
            return;
        }

        Sprite sprite = SkullSprite;
        if (sprite == null)
        {
            return;
        }

        // Keep tiny even if an older asset instance kept a larger base_scale.
        asset.base_scale = SkullBaseScale;
        long highlightKey = GraveHover.HighlightStackKey;
        float pulse = 0.55f + 0.45f * Mathf.Abs(Mathf.Sin(Time.unscaledTime * 9f));
        lock (Stacks)
        {
            foreach (GraveStack stack in Stacks.Values)
            {
                if (stack.Entries.Count == 0)
                {
                    continue;
                }

                QuantumSprite qs = asset.group_system.getNext();
                if (qs == null)
                {
                    continue;
                }

                Vector3 pos = stack.WorldPos;
                pos.y += 0.12f;
                float scale = SkullBaseScale;
                if (stack.Entries.Count > 1)
                {
                    scale *= Mathf.Min(1.25f, 1f + 0.02f * (stack.Entries.Count - 1));
                }

                Color baseTint = stack.Permanent ? _permTint : _tempTint;
                Color tint = baseTint;
                bool highlight = highlightKey != 0 && stack.Key == highlightKey;
                if (highlight)
                {
                    // Bright flicker so hover/selection is obvious on a tiny sprite.
                    Color flash = stack.Permanent
                        ? new Color(1f, 0.95f, 0.55f, 1f)
                        : new Color(1f, 1f, 1f, 1f);
                    tint = Color.Lerp(baseTint, flash, pulse);
                    scale *= 1.12f + 0.1f * pulse;
                }

                qs.set(ref pos, scale);
                qs.setSprite(sprite);
                qs.setColor(ref tint);
            }
        }
    }
}