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

public class AudioManager : MonoBehaviour
{
    private const int MaxVirtualChannels = 1024;    // Should match MAX_CHANNELS in q_sound.h
    private const int MaxRealChannels = 128;        // Should match MAX_DYNAMIC_CHANNELS in q_sound.h
    
    private FMOD.System fmodSystem;
    public FMOD.System FmodSystem => fmodSystem;

    private static AudioManager instance;
    public static AudioManager Instance
    {
        get
        {
            if (instance == null)
            {
                instance = FindObjectOfType<AudioManager>();
                if (instance == null)
                {
                    var gameObject = new GameObject("FMOD Audio Manager");
                    instance = gameObject.AddComponent<AudioManager>();
                }
            }

            return instance;
        }
    }

    [SerializeField, Range(0, 1)]
    private float masterVolume = 1f;

    private float prevMasterVolume;

    private FMOD.ChannelGroup masterChannelGroup;
    
    void Awake()
    {
        // Ensure FMOD is initialized the moment Instance is accessed
        InitFmod();
    }

    void OnEnable()
    {
        // Ensure FMOD gets re-initialized after hot reload
        InitFmod();
    }

    void Update()
    {
        if (!fmodSystem.hasHandle() || !masterChannelGroup.hasHandle())
            return;

        if (!Mathf.Approximately(masterVolume, prevMasterVolume))
        {
            masterChannelGroup.setVolume(masterVolume);
            prevMasterVolume = masterVolume;
        }
        
        masterChannelGroup.getVolume(out masterVolume);
    }

    void OnDisable()
    {
        // Ensure FMOD gets closed before hot reload
        CloseFmod();
    }

    void OnDestroy()
    {
        CloseFmod();
        instance = null;
    }
    
    private void InitFmod()
    {
        if (fmodSystem.hasHandle())
            return;
        
        FMOD.RESULT result = FMOD.Factory.System_Create(out fmodSystem);
        CheckFmodResult(result, "FMOD.Factory.System_Create");

        result = fmodSystem.getVersion(out uint version);
        CheckFmodResult(result, "FMOD.System.getVersion");
        
        Debug.LogFormat("[FMOD] Initialized FMOD System version {0:X1}.{1:X2}.{2:X2}",
            (version >> 16) & 0xFF, (version >> 8) & 0xFF, version & 0xFF);

        result = fmodSystem.getNumDrivers(out int numDrivers);
        CheckFmodResult(result, "FMOD.System.getNumDrivers");

        result = fmodSystem.setOutput(numDrivers > 0 ? FMOD.OUTPUTTYPE.AUTODETECT : FMOD.OUTPUTTYPE.NOSOUND);
        CheckFmodResult(result, "FMOD.System.setOutput");

        result = fmodSystem.getOutput(out FMOD.OUTPUTTYPE output);
        CheckFmodResult(result, "FMOD.System.getOutput");
        
        Debug.Log($"[FMOD] Using output type: {output}");

        result = fmodSystem.setSoftwareChannels(MaxRealChannels);
        CheckFmodResult(result, "FMOD.System.setSoftwareChannels");

        result = fmodSystem.init(MaxVirtualChannels, FMOD.INITFLAGS.VOL0_BECOMES_VIRTUAL, IntPtr.Zero);
        CheckFmodResult(result, "FMOD.System.init");

        result = fmodSystem.getMasterChannelGroup(out masterChannelGroup);
        CheckFmodResult(result, "FMOD.System.getMasterChannelGroup");
        masterChannelGroup.setVolume(masterVolume);
        prevMasterVolume = masterVolume;
    }

    private void CheckFmodResult(FMOD.RESULT result, string cause)
    {
        if (result != FMOD.RESULT.OK)
        {
            CloseFmod();
            throw new Exception($"[FMOD] Initialization failed : {cause} : {result.ToString()} : {FMOD.Error.String(result)}");
        }
    }
    
    private void CloseFmod()
    {
        if (fmodSystem.hasHandle())
        {
            Debug.Log("[FMOD] Closing FMOD System");
            fmodSystem.close();
            fmodSystem.release();
            fmodSystem.clearHandle();
        }
    }
    
#if UNITY_EDITOR || DEVELOPMENT_BUILD
    void OnGUI()
    {
        var debug = new StringBuilder("FMOD System\n");
        
        FMOD.Memory.GetStats(out int currentAlloc, out int maxAlloc);
        debug.AppendFormat("MEMORY: cur = {0}MB, max = {1}MB\n", currentAlloc >> 20, maxAlloc >> 20);

        fmodSystem.getChannelsPlaying(out int channels, out int realChannels);
        debug.AppendFormat("CHANNELS: real = {0}, total = {1}\n", realChannels, channels);
        
        GUI.Box(new Rect(0, 300, 250, 60), debug.ToString());
    }
#endif
}