using UnityEngine;
using UnityEditor;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using FastScriptReload.Editor;
using System;
using System.Threading;

[InitializeOnLoad]
public class CustomFileWatcher : EditorWindow
{
    public class HashEntry
    {
        private Dictionary<string, string> _hashes = new Dictionary<string, string>();
        // Some metadata for the update function to use
        // WARN: Note this data isn't exactly synced up or anything. It just reads it in when the filewatcher is initialized.
        private string _searchPattern;
        private bool _includeSubdirectories;
        
        public Dictionary<string, string> Hashes => _hashes;
        public string SearchPattern => _searchPattern;
        public bool IncludeSubdirectories => _includeSubdirectories;

        public HashEntry(Dictionary<string, string> hashes, string searchPattern, bool includeSubdirectories)
        {
            _hashes = hashes;
            _searchPattern = searchPattern;
            _includeSubdirectories = includeSubdirectories;
        }
    }

    private static Dictionary<string, HashEntry> FileHashes;
    private static object StateLock = new object();

    private static object ListLock; // Shared lock object
    private static Thread LivewatcherThread;

    public static bool InitSignaled = false;
    private static readonly int WatcherThreadRunEveryNSeconds = 500; //TODO: expose in settings

    static CustomFileWatcher()
    {
        FileHashes = new Dictionary<string, HashEntry>();
        ListLock = new object();
        LivewatcherThread = null;
    }
    
    private static void UpdateFileWatcher()
    {
        if (FileHashes.Count > 0)
        {
            foreach (var kvp in FileHashes)
            {
                CheckForChanges(kvp.Key, kvp.Value.SearchPattern, kvp.Value.IncludeSubdirectories);
            }
        }
        else
        {
            Debug.LogError("File watcher has not been initialized yet. Please initialize first.");
        }
    }
    
    public static void TryEnableLivewatching()
    {
        if (LivewatcherThread != null)
        {
            Debug.LogWarning("Livewatcher is already running.");
            return;
        }

        // Run on a separate thread every 1 second
        LivewatcherThread = new Thread(() =>
        {
            var timer = new Timer((state) =>
            {
                // Go at it if we've initialized
                if (FileHashes.Count > 0)
                    UpdateFileWatcher();
            }, null, 0, WatcherThreadRunEveryNSeconds);
        });

        LivewatcherThread.Start();
    }
    
    public static void InitializeSingularFilewatcher(string directoryPath, string searchPattern, bool includeSubdirectories)
    {
#if ImmersiveVrTools_DebugEnabled
        Debug.Log("Initializing hashes for directory: " + directoryPath);
#endif

        var thread = new Thread(() =>
        {
            lock (StateLock)
            {
                var hashes = new Dictionary<string, string>();
                var files = Directory.GetFiles(directoryPath, searchPattern, includeSubdirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly);

                foreach (var filePath in files)
                {
                    var hash = GetFileHash(filePath);
                    hashes[filePath] = hash;
                }

                FileHashes[directoryPath] = new HashEntry(hashes, searchPattern, includeSubdirectories);
            }
        });
        thread.Start();
    }

    private static void CheckForChanges(string directoryPath, string searchPattern, bool includeSubdirectories)
    {
        // Not really sure if this nuclear locking is needed
        lock (StateLock)
        {
            var hashes = FileHashes[directoryPath].Hashes;

            // Time profiling: Start the stopwatch for Directory.GetFiles
#if ImmersiveVrTools_DebugEnabled

            System.Diagnostics.Stopwatch getFilesStopwatch = new System.Diagnostics.Stopwatch();
            getFilesStopwatch.Start();
#endif

            string[] files = Directory.GetFiles(directoryPath, searchPattern, includeSubdirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly);

#if ImmersiveVrTools_DebugEnabled

            // Time profiling: Stop the stopwatch for Directory.GetFiles and log the elapsed time
            getFilesStopwatch.Stop();
            Debug.Log("Directory.GetFiles elapsed time: " + getFilesStopwatch.ElapsedMilliseconds + " ms");
#endif

            // Check if files were created or modified
            // Time profiling: Start the stopwatch for file creation/modification
            var fileChangeStopwatch = new System.Diagnostics.Stopwatch();
            fileChangeStopwatch.Start();

            foreach (var file in files)
            {
                if (!hashes.ContainsKey(file))
                {
                    // New file
#if ImmersiveVrTools_DebugEnabled
                    Debug.Log("New file: " + file);
#endif
                    continue;
                }

                else if (hashes[file] != GetFileHash(file))
                {
                    // File changed
#if ImmersiveVrTools_DebugEnabled
                    Debug.Log("File changed: " + file);
#endif
                    RecordChange(file);
                }
            }

#if ImmersiveVrTools_DebugEnabled
            // Time profiling: Stop the stopwatch for file creation/modification and log the elapsed time
            fileChangeStopwatch.Stop();
            Debug.Log("File creation/modification elapsed time: " + fileChangeStopwatch.ElapsedMilliseconds + " ms");
#endif

            // Check if any files were deleted
            // Time profiling: Start the stopwatch for file deletion
            var fileDeletionStopwatch = new System.Diagnostics.Stopwatch();
            fileDeletionStopwatch.Start();

            foreach (var kvp in hashes)
            {
                if (!File.Exists(kvp.Key))
                {
#if ImmersiveVrTools_DebugEnabled
                    Debug.Log("File deleted: " + kvp.Key);
#endif
                }
            }

            // Time profiling: Stop the stopwatch for file deletion and log the elapsed time
#if ImmersiveVrTools_DebugEnabled
            fileDeletionStopwatch.Stop();
            Debug.Log("File deletion elapsed time: " + fileDeletionStopwatch.ElapsedMilliseconds + " ms");
#endif

            // Update hashes
            hashes.Clear();
            foreach (var file in files)
            {
                var hash = GetFileHash(file);
                hashes[file] = hash;
            }
        }
    }


    private static string GetFileHash(string filePath)
    {
        using (var md5 = MD5.Create())
        using (var stream = File.OpenRead(filePath))
        {
            var hashBytes = md5.ComputeHash(stream);
            var sb = new StringBuilder();
            for (var i = 0; i < hashBytes.Length; i++)
            {
                sb.Append(hashBytes[i].ToString("x2"));
            }
            return sb.ToString();
        }
    }

    private static void RecordChange(string path)
    {
        if (FastScriptReloadManager.Instance.ShouldIgnoreFileChange()) return;

        lock (ListLock)
        {
            FastScriptReloadManager.Instance.AddFileChangeToProcess(path);
        }
    }
}