using System.Collections.Generic;
using UnityEngine;

namespace OnDeviceAgent.Inference
{
    public sealed class SupertonicTtsRequest
    {
        public string Text;
        public string Language;
        public string VoiceStyle;
    }

    public static class SupertonicTtsModule
    {
        const int MaxQueuedRequests = 8;

        static readonly object s_Lock = new object();
        static readonly Queue<SupertonicTtsRequest> s_Requests = new Queue<SupertonicTtsRequest>();
        static SupertonicTtsPlayer s_Player;
        // There is a single player, so speaking is a simple on/off flag. (A counter could drift upward if
        // SetSpeaking(true) was ever called more often than SetSpeaking(false), leaving IsSpeaking stuck.)
        static bool s_Speaking;

        public static bool IsAvailable
        {
            get
            {
                lock (s_Lock)
                    return !ReferenceEquals(s_Player, null);
            }
        }

        public static bool IsSpeaking
        {
            get
            {
                lock (s_Lock)
                    return s_Speaking;
            }
        }

        public static void StopSpeaking()
        {
            SupertonicTtsPlayer player;
            lock (s_Lock)
            {
                s_Requests.Clear();
                player = s_Player;
            }
            if (!ReferenceEquals(player, null))
                player.StopPlayback();
        }

        internal static void SetSpeaking(bool speaking)
        {
            lock (s_Lock)
                s_Speaking = speaking;
        }

        public static bool TryPlay(string text, string language, string voiceStyle, out string message)
        {
            if (string.IsNullOrWhiteSpace(text))
            {
                message = "TTS text is empty.";
                return false;
            }

            lock (s_Lock)
            {
                if (ReferenceEquals(s_Player, null))
                {
                    message = "No Supertonic TTS player is registered in the active scene.";
                    return false;
                }

                if (s_Requests.Count >= MaxQueuedRequests)
                {
                    var preview = text.Length <= 50 ? text : text.Substring(0, 50) + "...";
                    Debug.LogWarning("[TTS] Queue full (" + MaxQueuedRequests + "); dropping: '" + preview + "'");
                    message = "The Supertonic TTS request queue is full.";
                    return false;
                }

                s_Requests.Enqueue(new SupertonicTtsRequest
                {
                    Text = text.Trim(),
                    Language = string.IsNullOrWhiteSpace(language) ? string.Empty : language.Trim(),
                    VoiceStyle = string.IsNullOrWhiteSpace(voiceStyle) ? string.Empty : voiceStyle.Trim()
                });
            }

            message = "Queued Supertonic TTS playback.";
            return true;
        }

        internal static void Register(SupertonicTtsPlayer player)
        {
            if (ReferenceEquals(player, null))
                return;

            lock (s_Lock)
                s_Player = player;
        }

        internal static void Unregister(SupertonicTtsPlayer player)
        {
            lock (s_Lock)
            {
                if (!ReferenceEquals(s_Player, player))
                    return;

                s_Player = null;
                s_Requests.Clear();
                s_Speaking = false;
            }
        }

        internal static bool TryDequeue(out SupertonicTtsRequest request)
        {
            lock (s_Lock)
            {
                if (s_Requests.Count == 0)
                {
                    request = null;
                    return false;
                }

                request = s_Requests.Dequeue();
                return true;
            }
        }
    }
}