using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace MazeGen
{
    /// <summary>
    /// Owns the whole fight lifecycle: declaration, the join window, sneak attempts, resolution,
    /// and pushing the results back into the maze.
    ///
    /// Lifecycle of a fight:
    ///  1. An agent decides (or is forced) to fight -> <see cref="DeclareFight"/>. Every agent
    ///     already standing in that room is dragged in too; they were there when it kicked off.
    ///  2. A join window (default 5s, <see cref="JoinWindowSeconds"/>) counts down on
    ///     SimulationClock time. During it, agents walking into the room can join (better odds)
    ///     or attempt to sneak past - a failed sneak forces them in. Agents elsewhere in the maze
    ///     cannot join.
    ///  3. When the window expires the fight resolves via <see cref="CombatResolver"/>, either
    ///     log-only or replayed on the arena grid.
    ///  4. Results are applied to the real character sheets, so the room afterwards differs only
    ///     by who is dead and how hurt the survivors are.
    ///
    /// Committed agents are marked <see cref="MazeAgent.IsEngaged"/>, which parks their brain -
    /// they can't wander off mid-muster.
    /// </summary>
    [DisallowMultipleComponent]
    public class CombatDirector : MonoBehaviour
    {
        /// <summary>Outcome of an agent arriving in a room where a fight is already mustering.</summary>
        public enum ArrivalDecision
        {
            NoFight,
            Joined,
            SneakedPast,
            SneakFailedAndJoined
        }

        private const string ArenaHoldKey = "watching a fight";
        private const int MaxLogLines = 600;
        private const int MaxRecentFights = 12;

        [Header("Join window")]
        [Tooltip("Seconds between a fight being declared and it actually starting. Other agents can arrive and pile in (or try to sneak past) during this window.")]
        [SerializeField, Min(0f)] private float joinWindowSeconds = 5f;

        [Header("Observation")]
        [Tooltip("Freeze the whole simulation the moment a fight is declared, so you can zoom in and decide whether to watch it. The join window is frozen too - resume to let agents converge.")]
        [SerializeField] private bool pauseOnFightDeclared = true;
        [Tooltip("How a fight resolves when its join window runs out on its own: Simulate = log only, Watch = play it out on the arena grid.")]
        [SerializeField] private CombatViewMode timeoutResolution = CombatViewMode.Simulate;

        [Header("Resolution")]
        [Tooltip("Rounds after which an unresolved fight is called a stalemate and both sides disengage.")]
        [SerializeField, Min(1)] private int maxRounds = 40;

        [Header("Sneaking")]
        [Tooltip("Baseline chance an agent slips past a fight/monsters without being pulled in.")]
        [SerializeField, Range(0f, 1f)] private float sneakBaseChance = 0.55f;
        [Tooltip("How much each point of speed advantage over the monsters' average adds to the sneak chance.")]
        [SerializeField] private float sneakSpeedWeight = 0.02f;
        [Tooltip("Sneak chance penalty per hostile in the room beyond the first - more eyes, harder to slip by.")]
        [SerializeField] private float sneakPenaltyPerMonster = 0.08f;

        private readonly List<PendingFight> _active = new List<PendingFight>();
        private readonly List<PendingFight> _recent = new List<PendingFight>();
        private readonly List<MazeAgentController> _agents = new List<MazeAgentController>();
        private readonly Dictionary<MazeAgent, Color> _agentColors = new Dictionary<MazeAgent, Color>();
        private readonly List<string> _log = new List<string>();

        private BattleArenaView _arena;
        private int _nextFightId = 1;

        public float JoinWindowSeconds => joinWindowSeconds;
        public IReadOnlyList<PendingFight> ActiveFights => _active;
        public IReadOnlyList<PendingFight> RecentFights => _recent;
        public IReadOnlyList<string> CombatLog => _log;

        /// <summary>True while an arena playback is on screen; the maze HUD hides itself then.</summary>
        public bool IsWatching { get; private set; }

        public bool PauseOnFightDeclared
        {
            get => pauseOnFightDeclared;
            set => pauseOnFightDeclared = value;
        }

        public CombatViewMode TimeoutResolution
        {
            get => timeoutResolution;
            set => timeoutResolution = value;
        }

        public event Action<PendingFight> FightDeclared;
        public event Action<PendingFight> FightResolved;

        private void Awake()
        {
            EnsureArena();
        }

        /// <summary>
        /// Resolved lazily (and added if missing) because this component may itself have been
        /// added at runtime by MazeSceneBuilder, after its own Awake would have run.
        /// </summary>
        private BattleArenaView EnsureArena()
        {
            if (_arena == null)
                _arena = GetComponent<BattleArenaView>() ?? gameObject.AddComponent<BattleArenaView>();
            return _arena;
        }

        /// <summary>Agents must register so the director can find who else is standing in a room.</summary>
        public void RegisterAgent(MazeAgentController controller, Color color)
        {
            if (controller == null || _agents.Contains(controller)) return;
            _agents.Add(controller);
            if (controller.Agent != null)
                _agentColors[controller.Agent] = color;
        }

        private void Update()
        {
            if (IsWatching) return;

            float dt = SimulationClock.DeltaTime;

            // Backwards: resolving/cancelling removes from this list.
            for (int i = _active.Count - 1; i >= 0; i--)
            {
                PendingFight fight = _active[i];
                if (fight.State != FightState.Mustering) continue;

                DropUnavailableParticipants(fight);

                if (fight.Agents.Count == 0)
                {
                    Cancel(fight, "every committed agent died or left before it started");
                    continue;
                }
                if (!fight.Encounter.HasLivingMonsters)
                {
                    Cancel(fight, "the monsters were already dead");
                    continue;
                }

                if (dt <= 0f) continue; // paused - the join window is frozen too

                fight.JoinTimeRemaining -= dt;
                if (fight.JoinTimeRemaining <= 0f)
                    BeginResolution(fight, fight.PreferredResolution ?? timeoutResolution);
            }
        }

        // ---------------------------------------------------------------- declaring & joining

        /// <summary>
        /// An agent commits to fighting whatever is in <paramref name="room"/>. If a fight is
        /// already mustering there this just joins it instead of starting a second one.
        /// Returns null if there's nothing to fight.
        /// </summary>
        public PendingFight DeclareFight(Room room, MazeAgent declarer, string trigger)
        {
            if (room?.Encounter == null || !room.Encounter.HasLivingMonsters) return null;
            if (declarer == null || declarer.IsDead) return null;

            PendingFight existing = FindMusteringFight(room);
            if (existing != null)
            {
                if (!existing.Contains(declarer))
                    Commit(existing, declarer, trigger);
                return existing;
            }

            var fight = new PendingFight(_nextFightId++, room, room.Encounter)
            {
                JoinTimeRemaining = joinWindowSeconds,
                Trigger = trigger
            };
            _active.Add(fight);

            Commit(fight, declarer, trigger);

            // Anyone else already in this room is in it whether they like it or not.
            foreach (var controller in _agents)
            {
                MazeAgent other = controller.Agent;
                if (other == null || other == declarer) continue;
                if (!IsAvailable(other) || other.CurrentRoom != room) continue;
                Commit(fight, other, "was already in the room when the fight broke out");
            }

            Log($"{fight.Describe()} - declared by {declarer.CharacterSheet.Name} ({trigger}). Starts in {joinWindowSeconds:0.0}s.", echoToConsole: false);

            if (pauseOnFightDeclared)
                SimulationClock.PushHold(HoldKeyFor(fight));

            FightDeclared?.Invoke(fight);
            return fight;
        }

        /// <summary>
        /// Called by an agent's brain when it finds itself in a room where a fight is mustering.
        /// <paramref name="wantsToSneak"/> is the agent's own call; a failed sneak drags it in.
        /// </summary>
        public ArrivalDecision ResolveArrival(MazeAgent agent, bool wantsToSneak)
        {
            if (agent == null || agent.CurrentRoom == null) return ArrivalDecision.NoFight;

            PendingFight fight = FindMusteringFight(agent.CurrentRoom);
            if (fight == null) return ArrivalDecision.NoFight;
            if (fight.Contains(agent)) return ArrivalDecision.Joined;

            if (!wantsToSneak)
            {
                Commit(fight, agent, "arrived and joined the fight");
                Log($"{agent.CharacterSheet.Name} joins fight #{fight.Id} - now {fight.Agents.Count} agent(s) vs {fight.Encounter.AliveMonsterCount} monster(s).", echoToConsole: false);
                return ArrivalDecision.Joined;
            }

            float odds = SneakChance(agent, fight.Encounter);
            if (UnityEngine.Random.value < odds)
            {
                agent.Thoughts.Add(ThoughtKind.Sneak, $"Slipped past the fight in room {fight.Room.Id} ({odds:P0} odds) - not my problem.");
                Log($"{agent.CharacterSheet.Name} sneaks past fight #{fight.Id} ({odds:P0} odds).", echoToConsole: false);
                return ArrivalDecision.SneakedPast;
            }

            Commit(fight, agent, $"was spotted sneaking past ({odds:P0} odds) and forced in");
            Log($"{agent.CharacterSheet.Name} is spotted sneaking past fight #{fight.Id} ({odds:P0} odds) and is forced into it.", echoToConsole: false);
            return ArrivalDecision.SneakFailedAndJoined;
        }

        /// <summary>
        /// Sneak attempt against monsters in a room where no fight has been declared yet (an
        /// agent that walked in, didn't like the odds, and wants to leave quietly). A failure
        /// leaves it to the caller to declare the fight it just got caught in.
        /// </summary>
        public bool TrySneakOut(MazeAgent agent, out float odds)
        {
            odds = 0f;
            MonsterEncounter encounter = agent?.CurrentRoom?.Encounter;
            if (encounter == null || !encounter.HasLivingMonsters) return true;

            odds = SneakChance(agent, encounter);
            return UnityEngine.Random.value < odds;
        }

        /// <summary>
        /// Faster than the monsters and few of them = good odds. Clamped so sneaking is never a
        /// certainty either way.
        /// </summary>
        public float SneakChance(MazeAgent agent, MonsterEncounter encounter)
        {
            if (encounter == null || !encounter.HasLivingMonsters) return 1f;

            float totalSpeed = 0f;
            int alive = 0;
            foreach (var monster in encounter.Monsters)
            {
                if (monster.IsDefeated) continue;
                totalSpeed += monster.CharacterSheet.GetEffectiveSpeed();
                alive++;
            }
            if (alive == 0) return 1f;

            float averageSpeed = totalSpeed / alive;
            float chance = sneakBaseChance
                + sneakSpeedWeight * (agent.CharacterSheet.GetEffectiveSpeed() - averageSpeed)
                - sneakPenaltyPerMonster * (alive - 1);

            return Mathf.Clamp(chance, 0.05f, 0.95f);
        }

        public PendingFight FindMusteringFight(Room room)
        {
            if (room == null) return null;
            foreach (var fight in _active)
                if (fight.State == FightState.Mustering && fight.Room.Id == room.Id)
                    return fight;
            return null;
        }

        private void Commit(PendingFight fight, MazeAgent agent, string reason)
        {
            if (fight.Contains(agent)) return;

            fight.Agents.Add(agent);
            agent.IsEngaged = true;
            agent.Thoughts.Add(ThoughtKind.Fight,
                $"In fight #{fight.Id} (room {fight.Room.Id}) - {reason}. {fight.Agents.Count} of us vs {fight.Encounter.AliveMonsterCount} hostile(s), starting in {Mathf.Max(0f, fight.JoinTimeRemaining):0.0}s.");
        }

        /// <summary>Drops committed agents that died (elsewhere) or finished before the fight began.</summary>
        private void DropUnavailableParticipants(PendingFight fight)
        {
            for (int i = fight.Agents.Count - 1; i >= 0; i--)
            {
                MazeAgent agent = fight.Agents[i];
                if (agent == null || agent.IsDead || agent.IsFinished)
                {
                    if (agent != null) agent.IsEngaged = false;
                    fight.Agents.RemoveAt(i);
                }
            }
        }

        // ---------------------------------------------------------------- observer controls

        /// <summary>Let a paused fight's join window continue counting down.</summary>
        public void ResumeMuster(PendingFight fight)
        {
            if (fight == null) return;
            SimulationClock.PopHold(HoldKeyFor(fight));
        }

        public void ResumeAllMusters()
        {
            foreach (var fight in _active)
                SimulationClock.PopHold(HoldKeyFor(fight));
        }

        /// <summary>
        /// Sets the observer's preference for how this fight resolves once its join window runs
        /// out. This is a preference only, NOT a trigger - the join window always has to elapse
        /// on its own first (so other agents keep getting their full chance to pile in or sneak
        /// past), even if the simulation is currently paused waiting on the observer.
        /// </summary>
        public void PreferSimulate(PendingFight fight) => SetPreferredResolution(fight, CombatViewMode.Simulate);

        /// <summary>See <see cref="PreferSimulate"/> - same, but plays out on the arena grid.</summary>
        public void PreferWatch(PendingFight fight) => SetPreferredResolution(fight, CombatViewMode.Watch);

        private void SetPreferredResolution(PendingFight fight, CombatViewMode mode)
        {
            if (fight == null || fight.State != FightState.Mustering) return;
            if (fight.PreferredResolution == mode) return;

            fight.PreferredResolution = mode;
            Log($"Fight #{fight.Id} in room {fight.Room.Id} will be {(mode == CombatViewMode.Watch ? "watched" : "logged only")} when its join window ends.", echoToConsole: false);
        }

        // ---------------------------------------------------------------- resolution

        private void BeginResolution(PendingFight fight, CombatViewMode mode)
        {
            if (fight == null || fight.State != FightState.Mustering) return;

            SimulationClock.PopHold(HoldKeyFor(fight));
            DropUnavailableParticipants(fight);

            if (fight.Agents.Count == 0)
            {
                Cancel(fight, "no agents left to fight");
                return;
            }
            if (!fight.Encounter.HasLivingMonsters)
            {
                Cancel(fight, "no monsters left to fight");
                return;
            }

            fight.State = FightState.Resolving;
            fight.ResolvedAs = mode;

            List<Combatant> combatants = BuildCombatants(fight);
            fight.Result = CombatResolver.Resolve(combatants, maxRounds);

            BattleArenaView arena = mode == CombatViewMode.Watch ? EnsureArena() : null;
            if (arena != null)
            {
                IsWatching = true;
                SimulationClock.PushHold(ArenaHoldKey);
                StartCoroutine(WatchRoutine(arena, fight, combatants));
            }
            else
            {
                ApplyResult(fight, combatants);
            }
        }

        private IEnumerator WatchRoutine(BattleArenaView arena, PendingFight fight, List<Combatant> combatants)
        {
            // Playback is pure animation over an already-decided event list, so however long the
            // observer takes (or if they skip), the outcome below is unchanged.
            yield return arena.Play(fight, combatants);

            SimulationClock.PopHold(ArenaHoldKey);
            IsWatching = false;
            ApplyResult(fight, combatants);
        }

        /// <summary>
        /// Pushes the decided outcome back into maze state: dead agents die, survivors are
        /// released to keep exploring, everyone involved gets the blow-by-blow in their thought
        /// log. Monster/agent health was already mutated in place by the resolver.
        /// </summary>
        private void ApplyResult(PendingFight fight, List<Combatant> combatants)
        {
            BattleResult result = fight.Result;

            foreach (var e in result.Events)
                RecordEvent(result, e);

            foreach (var combatant in combatants)
            {
                if (!combatant.IsAgent) continue;

                MazeAgent agent = combatant.Agent;
                agent.IsEngaged = false;

                if (!combatant.IsAlive)
                {
                    agent.Thoughts.Add(ThoughtKind.Goal, $"Killed in fight #{fight.Id}, room {fight.Room.Id}.");
                    agent.Die();
                    continue;
                }

                agent.Thoughts.Add(ThoughtKind.Outcome,
                    $"Fight #{fight.Id} over: {result.Summary} I'm on {combatant.Sheet.Stats.CurrentHealth:0.#}/{combatant.MaxHealth:0.#} hp.");

                // A stalemate would otherwise have the agent immediately re-declare the same
                // fight forever, so remember not to pick this one again.
                if (result.Outcome == BattleOutcome.Stalemate)
                {
                    agent.NoteFledFrom(fight.Room.Id);
                    agent.Thoughts.Add(ThoughtKind.Avoid, $"Couldn't finish them off in room {fight.Room.Id} - disengaging and not trying that again.");
                }
            }

            fight.State = FightState.Resolved;
            _active.Remove(fight);
            Remember(fight);

            Log($"Fight #{fight.Id} ({(fight.ResolvedAs == CombatViewMode.Watch ? "watched" : "simulated")}) in room {fight.Room.Id}: {result.Summary}", echoToConsole: false);
            FightResolved?.Invoke(fight);
        }

        private void Cancel(PendingFight fight, string why)
        {
            SimulationClock.PopHold(HoldKeyFor(fight));
            foreach (var agent in fight.Agents)
                if (agent != null) agent.IsEngaged = false;

            fight.State = FightState.Cancelled;
            _active.Remove(fight);
            Remember(fight);

            Log($"Fight #{fight.Id} in room {fight.Room.Id} called off - {why}.", echoToConsole: false);
            FightResolved?.Invoke(fight);
        }

        private List<Combatant> BuildCombatants(PendingFight fight)
        {
            var combatants = new List<Combatant>();
            int id = 0;

            foreach (var agent in fight.Agents)
            {
                Color color = _agentColors.TryGetValue(agent, out var c) ? c : Color.white;
                combatants.Add(Combatant.ForAgent(id++, agent, color));
            }

            foreach (var monster in fight.Encounter.Monsters)
            {
                if (monster.IsDefeated) continue; // already dead from an earlier fight in this room
                combatants.Add(Combatant.ForMonster(id++, monster));
            }

            return combatants;
        }

        /// <summary>Mirrors one combat event into the global log and the thought logs of the agents it involved.</summary>
        private void RecordEvent(BattleResult result, CombatEvent e)
        {
            // Blow-by-blow lines stay in the in-memory log/HUD only. A long fight between big
            // groups emits hundreds of events, and echoing every one to Debug.Log would drown
            // the Console and cost real frame time.
            Log(e.Text, echoToConsole: false);

            if (e.Kind == CombatEventKind.RoundStart) return;

            AddCombatThought(result, e.ActorId, e.Text);
            if (e.TargetId != e.ActorId)
                AddCombatThought(result, e.TargetId, e.Text);
        }

        private void AddCombatThought(BattleResult result, int combatantId, string text)
        {
            if (combatantId < 0 || result.Combatants == null || combatantId >= result.Combatants.Count) return;

            Combatant combatant = result.Combatants[combatantId];
            if (combatant.IsAgent)
                combatant.Agent.Thoughts.Add(ThoughtKind.Combat, text);
        }

        private void Remember(PendingFight fight)
        {
            _recent.Insert(0, fight);
            if (_recent.Count > MaxRecentFights)
                _recent.RemoveAt(_recent.Count - 1);
        }

        private void Log(string line, bool echoToConsole = true)
        {
            _log.Add(line);
            if (_log.Count > MaxLogLines)
                _log.RemoveAt(0);
            if (echoToConsole)
                Debug.Log($"[Combat] {line}");
        }

        private static bool IsAvailable(MazeAgent agent)
            => agent != null && !agent.IsDead && !agent.IsFinished && !agent.IsEngaged;

        private static string HoldKeyFor(PendingFight fight) => $"fight #{fight.Id} in room {fight.Room.Id}";
    }
}