using NeonSprawl.Server.Game.Combat;
using NeonSprawl.Server.Game.PositionState;

namespace NeonSprawl.Server.Game.Npc;

/// <summary>Maps <c>GET /game/world/npc-runtime-snapshot</c> (NEO-94).</summary>
public static class NpcRuntimeSnapshotWorldApi
{
    public static WebApplication MapNpcRuntimeSnapshotWorldApi(this WebApplication app)
    {
        app.MapGet(
            "/game/world/npc-runtime-snapshot",
            (
                TimeProvider clock,
                INpcRuntimeStateStore runtimeStore,
                IThreatStateStore threatStore,
                INpcBehaviorDefinitionRegistry behaviorRegistry,
                IAbilityDefinitionRegistry abilityRegistry,
                ICombatEntityHealthStore combatHealthStore,
                IPositionStateStore positionStore,
                IPlayerCombatHealthStore playerHealthStore) =>
            {
                var now = clock.GetUtcNow();
                NpcRuntimeOperations.AdvanceAll(
                    now,
                    runtimeStore,
                    threatStore,
                    behaviorRegistry,
                    abilityRegistry,
                    combatHealthStore,
                    positionStore,
                    playerHealthStore);
                return Results.Json(BuildSnapshot(now, runtimeStore, threatStore, behaviorRegistry));
            });

        return app;
    }

    internal static NpcRuntimeSnapshotResponse BuildSnapshot(
        DateTimeOffset nowUtc,
        INpcRuntimeStateStore runtimeStore,
        IThreatStateStore threatStore,
        INpcBehaviorDefinitionRegistry behaviorRegistry)
    {
        var ids = PrototypeNpcRegistry.GetInstanceIdsInOrder();
        var instances = new List<NpcInstanceRuntimeJson>(ids.Count);
        foreach (var npcInstanceId in ids)
        {
            if (!PrototypeNpcRegistry.TryGet(npcInstanceId, out var entry))
            {
                throw new InvalidOperationException(
                    $"Prototype NPC instance '{npcInstanceId}' is missing from {nameof(PrototypeNpcRegistry)}.");
            }

            if (!behaviorRegistry.TryGetDefinition(entry.BehaviorDefId, out var behavior))
            {
                throw new InvalidOperationException(
                    $"Behavior definition '{entry.BehaviorDefId}' for NPC '{npcInstanceId}' is missing from {nameof(INpcBehaviorDefinitionRegistry)}.");
            }

            if (!runtimeStore.TryGet(npcInstanceId, out var runtime))
            {
                throw new InvalidOperationException(
                    $"Prototype NPC runtime row '{npcInstanceId}' is registered but missing from {nameof(INpcRuntimeStateStore)}.");
            }

            string? aggroHolderPlayerId = null;
            if (threatStore.TryGet(npcInstanceId, out var threat))
            {
                aggroHolderPlayerId = threat.AggroHolderPlayerId;
            }

            ActiveTelegraphJson? activeTelegraph = null;
            if (runtime.BehaviorState == NpcBehaviorState.TelegraphWindup &&
                runtime.ActiveTelegraph is { } telegraph)
            {
                var elapsedSeconds = (nowUtc - telegraph.WindupStartedUtc).TotalSeconds;
                var remainingSeconds = Math.Max(0, behavior.TelegraphWindupSeconds - elapsedSeconds);
                activeTelegraph = new ActiveTelegraphJson
                {
                    TelegraphId = telegraph.TelegraphId,
                    NpcInstanceId = npcInstanceId,
                    WindupRemainingSeconds = remainingSeconds,
                    ArchetypeKind = behavior.ArchetypeKind,
                };
            }

            instances.Add(
                new NpcInstanceRuntimeJson
                {
                    NpcInstanceId = npcInstanceId,
                    BehaviorDefId = entry.BehaviorDefId,
                    State = NpcBehaviorStateWire.ToWireName(runtime.BehaviorState),
                    AggroHolderPlayerId = aggroHolderPlayerId,
                    ActiveTelegraph = activeTelegraph,
                });
        }

        return new NpcRuntimeSnapshotResponse
        {
            ServerTimeUtc = nowUtc,
            NpcInstances = instances,
        };
    }
}