using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.IO;
using UnityEngine.Events;
using Unity.VisualScripting;

namespace Moloch
{
    public class NarrationManager : MonoBehaviour
    {
        // Singleton Implementation //
        private static NarrationManager _instance;
        public static NarrationManager Instance
        {
            get 
            { 
                if( _instance == null)
                {
                    _instance = FindAnyObjectByType<NarrationManager>();
                    if( _instance != null)
                    {
                        _instance = new GameObject().AddComponent<NarrationManager>();
                    }
                }
                return _instance;
            }
        }

        // Variables //
        private List<string> m_scriptSlices = new List<string>();

        public TextAsset m_Filename;

        private string m_UnprocessedFile;

        private int m_ScriptIndex;

        private float m_SubtitileWaitTime = 8;

        // Unity Events //
        public delegate void onUpdateSubtitileDelegate(string subtitle, float waitTime);
        public static onUpdateSubtitileDelegate m_UpdateSubtitile;

        private void Awake()
        {
            if (_instance != null)
                Destroy(this);
            DontDestroyOnLoad(this);
        }

        // Read in a text file, split into sentences, and add to list.
        void Start()
        {
            if (m_Filename != null)
            {
                m_UnprocessedFile = m_Filename.text;
                ParseSentences();
                m_ScriptIndex = 0;
                StartCoroutine(WaitToStart());
            }
            else
            {
                Debug.Log($"No filename given for script.");
            }
        }

        IEnumerator WaitToStart() 
        {
            yield return new WaitForSecondsRealtime(5f);
            updateSubtitle();
        }

        // Coroutine for subtitles, when to start the next one after a delay
        IEnumerator SubtitleWait()
        {
            m_SubtitileWaitTime = Random.Range(15f, 45f);
            yield return new WaitForSeconds(m_SubtitileWaitTime);
            updateSubtitle();
        }

        private void CalculateVariableWaitTime(string sentence)
        {
            var temp = Mathf.Ceil(sentence.Length / 5);
            if (temp <= 0)
            {
                m_SubtitileWaitTime = 1;
            }
            else
            {
                m_SubtitileWaitTime = temp;
            }
        }

        // Increments to next index in list, and updates UI.
        void updateSubtitle() 
        {
            m_ScriptIndex++;
            if(m_ScriptIndex == m_scriptSlices.Count)
                m_ScriptIndex = 0;
            CalculateVariableWaitTime(m_scriptSlices[m_ScriptIndex]);
            DisplayText(m_scriptSlices[m_ScriptIndex]);
            StartCoroutine(SubtitleWait());
        }

        // Invokes a Unity Event which updates UI.
        private void DisplayText(string slice) 
        {
            m_UpdateSubtitile?.Invoke(slice, m_SubtitileWaitTime);
        }

        // Parse sentences by newlines
        private void ParseSentences()
        {
            m_scriptSlices.AddRange(
                    m_UnprocessedFile.Split("\n"[0]));
            Debug.Log($"Parsing of text done, line count: {m_scriptSlices.Count}");
        }
    }

}