using System;
using System.Collections.Generic;
using System.IO;
using Mirror;
using UnityEngine;

/// <summary>
/// Server-only match recorder. Samples poses every FixedUpdate; flushes JSON to disk on stop.
/// Admin playback must interpolate by time (Hermite using velocity) — never snap one FixedUpdate sample per render frame.
/// </summary>
public class ReplayRecorder : MonoBehaviour
{
    public static ReplayRecorder Instance { get; private set; }

    public static bool IsRecording => Instance != null && Instance._recording && !Instance._flushed;

    bool _recording;
    bool _flushed;
    int _matchId;
    bool _isPractice;
    float _startFixedTime;
    float _duration;

    readonly List<ReplayEntity> _entities = new List<ReplayEntity>();
    readonly List<Rigidbody2D> _bodies = new List<Rigidbody2D>();
    readonly Dictionary<int, int> _instanceIdToEntityId = new Dictionary<int, int>();
    readonly List<ReplayFrame> _frames = new List<ReplayFrame>();
    readonly List<ReplayEvent> _events = new List<ReplayEvent>();

    /// <returns>True if recording started (or already recording this session).</returns>
    public static bool StartRecording(int matchId, GameManager gm)
    {
        if (!NetworkServer.active || gm == null)
            return false;

        if (Instance == null)
        {
            var go = new GameObject("ReplayRecorder");
            DontDestroyOnLoad(go);
            Instance = go.AddComponent<ReplayRecorder>();
        }

        Instance.Begin(matchId, gm);
        return true;
    }

    public static void StopAndFlush()
    {
        if (Instance != null)
            Instance.Flush();
    }

    public static void RecordHit(string kind, float vol, Component source)
    {
        if (!IsRecording)
            return;
        Instance.AddHit(kind, vol, source);
    }

    public static void RecordGoal(Team concedingTeam, int redScore, int blueScore, bool kickoff)
    {
        if (!IsRecording)
            return;
        Instance.AddEvent(new ReplayEvent
        {
            t = Instance.CurrentT(),
            type = "goal",
            kind = "",
            vol = 0f,
            id = -1,
            team = concedingTeam.ToString(),
            redScore = redScore,
            blueScore = blueScore,
            kickoff = kickoff
        });
    }

    public static void RecordReset(bool kickoff)
    {
        if (!IsRecording)
            return;
        Instance.AddEvent(new ReplayEvent
        {
            t = Instance.CurrentT(),
            type = "reset",
            kind = "",
            vol = 0f,
            id = -1,
            team = "",
            redScore = 0,
            blueScore = 0,
            kickoff = kickoff
        });
    }

    public static bool TryGetEntityId(Component source, out int entityId)
    {
        entityId = -1;
        if (Instance == null || source == null)
            return false;
        return Instance._instanceIdToEntityId.TryGetValue(source.gameObject.GetInstanceID(), out entityId);
    }

    void Begin(int matchId, GameManager gm)
    {
        if (_recording && !_flushed)
            Flush();

        // Practice / tutorial host uses DedicatedMatchId 0 — mint a unique id so files don't overwrite.
        _isPractice = matchId <= 0 || GameTutorialManager.tutorialModeEnabled;
        if (matchId <= 0)
            matchId = GeneratePracticeMatchId();

        _matchId = matchId;
        _recording = true;
        _flushed = false;
        _startFixedTime = Time.fixedTime;
        _duration = 0f;
        _entities.Clear();
        _bodies.Clear();
        _instanceIdToEntityId.Clear();
        _frames.Clear();
        _events.Clear();

        // Keep log + replay siblings: Logs/{matchId}.txt and Logs/{matchId}.json
        if (_isPractice)
            Logger.SetFileName(_matchId.ToString());

        BuildEntities(gm);
        string mode = _isPractice ? "practice" : "match";
        Logger.Log($"ReplayRecorder started ({mode}) id {_matchId} with {_entities.Count} entities");
    }

    /// <summary>Negative unix timestamp so practice ids never collide with positive matchmaker ids.</summary>
    static int GeneratePracticeMatchId()
    {
        long unix = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
        if (unix > int.MaxValue)
            unix %= int.MaxValue;
        int id = -(int)unix;
        return id == 0 ? -1 : id;
    }

    void BuildEntities(GameManager gm)
    {
        if (gm.ball != null)
        {
            RegisterEntity(gm.ball.gameObject, gm.ball, "ball", "");
        }

        var sorted = new List<Puck>(gm.pucks);
        sorted.Sort((a, b) =>
        {
            int teamCmp = a.team.CompareTo(b.team);
            if (teamCmp != 0)
                return teamCmp;
            int xCmp = a.transform.position.x.CompareTo(b.transform.position.x);
            if (xCmp != 0)
                return xCmp;
            return a.transform.position.y.CompareTo(b.transform.position.y);
        });

        foreach (Puck puck in sorted)
        {
            if (puck == null || puck.rb == null)
                continue;
            RegisterEntity(puck.gameObject, puck.rb, "puck", puck.team.ToString());
        }
    }

    void RegisterEntity(GameObject go, Rigidbody2D rb, string type, string team)
    {
        int id = _entities.Count;
        _entities.Add(new ReplayEntity { id = id, type = type, team = team ?? "" });
        _bodies.Add(rb);
        _instanceIdToEntityId[go.GetInstanceID()] = id;
    }

    float CurrentT() => Time.fixedTime - _startFixedTime;

    void FixedUpdate()
    {
        if (!_recording || _flushed || !NetworkServer.active)
            return;

        int n = _bodies.Count;
        if (n == 0)
            return;

        var frame = new ReplayFrame
        {
            t = CurrentT(),
            x = new float[n],
            y = new float[n],
            vx = new float[n],
            vy = new float[n]
        };

        for (int i = 0; i < n; i++)
        {
            Rigidbody2D rb = _bodies[i];
            if (rb == null)
                continue;
            Vector2 pos = rb.position;
            Vector2 vel = rb.linearVelocity;
            frame.x[i] = pos.x;
            frame.y[i] = pos.y;
            frame.vx[i] = vel.x;
            frame.vy[i] = vel.y;
        }

        _duration = frame.t;
        _frames.Add(frame);
    }

    void AddHit(string kind, float vol, Component source)
    {
        int entityId = -1;
        if (source != null)
            _instanceIdToEntityId.TryGetValue(source.gameObject.GetInstanceID(), out entityId);

        AddEvent(new ReplayEvent
        {
            t = CurrentT(),
            type = "hit",
            kind = kind ?? "",
            vol = vol,
            id = entityId,
            team = "",
            redScore = 0,
            blueScore = 0,
            kickoff = false
        });
    }

    void AddEvent(ReplayEvent ev)
    {
        _events.Add(ev);
    }

    void Flush()
    {
        if (!_recording || _flushed)
            return;

        _flushed = true;
        _recording = false;
        _duration = Mathf.Max(_duration, CurrentT());

        var file = new ReplayFile
        {
            version = 1,
            matchId = _matchId,
            isPractice = _isPractice,
            fixedDeltaTime = Time.fixedDeltaTime,
            duration = _duration,
            entities = _entities.ToArray(),
            frames = _frames.ToArray(),
            events = _events.ToArray()
        };

        try
        {
            string path = ResolveReplayFilePath();
            string json = JsonUtility.ToJson(file);
            File.WriteAllText(path, json);
            Logger.Log($"ReplayRecorder wrote {path} ({_frames.Count} frames, {_events.Count} events, duration {_duration:F2}s)");
        }
        catch (Exception e)
        {
            Logger.Log("ReplayRecorder flush failed: " + e.Message);
        }
    }

    /// <summary>
    /// Same directory and basename as the match log, extension <c>.json</c>
    /// (e.g. <c>Logs/228.txt</c> → <c>Logs/228.json</c>).
    /// </summary>
    string ResolveReplayFilePath()
    {
        string expectedName = _matchId.ToString();
        string logPath = Logger.instance != null ? Logger.instance.LogFilePath : null;
        if (!string.IsNullOrEmpty(logPath))
        {
            string logBase = Path.GetFileNameWithoutExtension(logPath);
            if (logBase == expectedName)
                return Path.ChangeExtension(logPath, ".json");
        }

        return Path.Combine(Logger.GetLogsDirectory(), expectedName + ".json");
    }

    void OnDestroy()
    {
        if (Instance == this)
        {
            Flush();
            Instance = null;
        }
    }
}