using Newtonsoft.Json.Linq;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using UnityEngine;
using UnityEngine.Networking;

public class ModelViewerDownloader
{
    public static string UrlBase = "";
    public static string SaveLocation = "/idbfs/ModelViewer/";

    public static ModelViewerDownloader Instance;
    public bool SyncRequired;

    public ModelViewerDownloader() : this(UrlBase, "/idbfs/ModelViewer/") { }

    public ModelViewerDownloader(string baseUrl, string saveLocation)
    {
        UrlBase = baseUrl;
        SaveLocation = saveLocation;
        ModelViewerMain.GetInstance().StartCoroutine(Loop());
    }

    public class DownloadTask
    {
        public string Name;
        public bool Redownload = false;
        public bool Finished = false;
        public bool Success = false;
        public int Priority = 0;
        public string ResultText;
        public byte[] ResultBytes;
        public System.Action OnDownloadSuccess;

        public DownloadTask(string name, int priority, bool redownload)
        {
            Name = name;
            Priority = priority;
            Redownload = redownload;
        }
    }

    private static List<DownloadTask> _downloadRunning = new List<DownloadTask>();
    private static List<DownloadTask> _downloadQueue = new List<DownloadTask>();

    public IEnumerator Loop()
    {
        float lastSync = 5;
        while (true)
        {
            if(_downloadQueue.Count > 0)
            {
                _downloadRunning.AddRange(_downloadQueue);
                _downloadRunning = _downloadRunning.OrderByDescending(d=>d.Priority).ToList();
                _downloadQueue.Clear();
            }
            if(_downloadRunning.Count > 0)
            {
                var fileToDownload = _downloadRunning[0];
                _downloadRunning.RemoveAt(0);
                yield return DownloadFile(fileToDownload);
                if(!_downloadRunning.Any() && !_downloadQueue.Any())
                {
                    SyncRequired = true;
                    lastSync = 0;
                }
            }
            if(SyncRequired)
            {
                lastSync += Time.deltaTime;
                if(lastSync >= 5)
                {
                    CommitChanges();
                }
            }
            yield return 0;
        }
    }

    public static IEnumerator WaitForDownload(string name, int priority = 0, bool redownload = false, System.Action<string[]> lines = null, System.Action<byte[]> bytes = null, System.Action<string> text = null, System.Action onDownloadSuccess = null)
    {
        var task = _downloadQueue.Concat(_downloadRunning).FirstOrDefault(t => t.Name == name);
            
        if(task == null)
        {
            task = new DownloadTask(name, priority, redownload);
            task.OnDownloadSuccess = onDownloadSuccess;
            _downloadQueue.Add(task);
        }

        while (!task.Finished)
        {
            yield return 0;
        }

        lines?.Invoke(task.ResultText.Split('\n').Select(s => s.Trim()).ToArray());
        bytes?.Invoke(task.ResultBytes);
        text?.Invoke(task.ResultText);
    }

    private IEnumerator DownloadFile(DownloadTask task)
    {
#if UNITY_WEBGL && !UNITY_EDITOR
        string fileSavePath = $"{SaveLocation}{task.Name}";
#else
        string fileSavePath = Application.persistentDataPath + " /" + task.Name;
#endif

        if (!task.Redownload && LoadFromIdbfs(fileSavePath, out var data))
        {
            //Debug.Log("Loaded from " + fileSavePath);
            task.Success = true;
            task.ResultText = Encoding.UTF8.GetString(data);
            task.ResultBytes = data;
            task.Finished = true;
            yield break;
        }

        string url = UrlBase + task.Name + (task.Redownload ? "?time=" + DateTime.Now.Ticks.ToString() : "");
        //var downloadPanel = KFKViewerUI.Instance.DownloadPanel;

        //Msg.Log(url);

        using (var www = UnityWebRequest.Get(url))
        {
            //downloadPanel.gameObject.SetActive(true);

            var operation = www.SendWebRequest();

            do
            {
                //downloadPanel.SetStatus(task.Name, www.downloadProgress);
                yield return null;
            }
            while (!operation.isDone);

            if (www.result != UnityWebRequest.Result.Success)
            {
                Error.Log(Color.red, www.error);
                task.Success = false;
                task.ResultText = "";
                task.ResultBytes = new byte[0];
            }
            else
            {
                SaveToIdbfs(fileSavePath, www.downloadHandler.data);
                task.OnDownloadSuccess?.Invoke();
                task.Success = true;
                task.ResultText = www.downloadHandler.text;
                task.ResultBytes = www.downloadHandler.data;
            }
        }

        //downloadPanel.SetStatus(task.Name, 0);
        //downloadPanel.gameObject.SetActive(false);

        task.Finished = true;
    }

    public static bool LoadFromIdbfs(string name, out byte[] data)
    {
        if(File.Exists(name))
        {
            data = File.ReadAllBytes(name);
            return true;
        }
        else
        {
            data = null;
            return false;
        }
    }

    public static void SaveToIdbfs(string path, byte[] data)
    {
        Directory.CreateDirectory(Path.GetDirectoryName(path));
        File.WriteAllBytes(path, data);
        //Debug.Log("Saved " + path);
    }

    private static void CommitChanges()
    {
        Instance.SyncRequired = false;
        Debug.Log("Database Updated");
#if UNITY_WEBGL && !UNITY_EDITOR
        SyncFiles();
#endif
    }

    [DllImport("__Internal")]
    private static extern void SyncFiles();
}