using BanTur.Core.Entity;
using BanTur.Core.Rss;
using BanTur.Core.Utility;
using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace BanTur.Core
{
    public static class BanTurProgram
    {
        public static readonly string EnvVarDbPath = "BanTurDbPath";

        internal const string CmdDaemon = "daemon";
        internal const string CmdFetch = "fetch";
        internal const string CmdHandleNew = "handlenew";

        internal const string CmdComplete = "complete";

        private static void PrintLine(string line)
        {
            Console.WriteLine($"{DateTime.Now:yyyy-MM-dd HH:mm:ss.ff} {line}");
        }

        // Fetch
        //    Fetch all feed source, add news
        // HandleNew
        //    Get All New Entry,Generate notice executable AND start download
        // Complete <id>
        //    Call by download complete executable, Update entry state and Send email, delete notice executable
        private static void Main(string[] args)
        {
            switch (args.FirstOrDefault()?.ToLower())
            {
                case CmdDaemon:
                    if (args.Length < 2 || !int.TryParse(args[1], out var intervalMin)) throw new ArgumentException("Missing interval(Min)");
                    Daemon(intervalMin);
                    break;

                case CmdFetch:
                default:
                    Fetch();
                    break;

                case CmdHandleNew:
                    HandleNew();
                    Console.WriteLine("Wait 5 Second, for sending email (if available)...");
                    Thread.Sleep(5000);
                    break;

                case CmdComplete:
                    if (args.Length < 2 || !int.TryParse(args[1], out var id)) throw new ArgumentException("Missing id");
                    if (args.Length < 3) throw new ArgumentException("Missing FilePath");

                    Complete(id, args[2]);
                    break;
            }
        }

        private static void Daemon(int intervalMin)
        {
            PrintLine($"Run Bangumi Turret as Daemon, Interval {intervalMin} min. To exit Press Enter");

            var intervalSeconds = intervalMin * 60;
            var isRunning = true;

            void Loop()
            {
                // ReSharper disable once AccessToModifiedClosure
                while (isRunning)
                {
                    Fetch();
                    for (int i = 0; i < intervalSeconds; i++)
                    {
                        // ReSharper disable once AccessToModifiedClosure
                        if (false == isRunning) break;

                        Console.Write($"Sleeping... {i}/{intervalSeconds}");
                        Thread.Sleep(1000);

                        //clear line and reset cursor
                        var left = Console.CursorLeft;
                        Console.CursorLeft = 0;
                        Console.Write("".PadLeft(left));
                        Console.CursorLeft = 0;
                    }
                }
            }

            var task = Task.Run(Loop);

            Console.ReadLine();
            isRunning = false;

            Console.WriteLine("Stopping...");
            task.Wait();
            Console.WriteLine("Bye.");
        }

        private static void Fetch()
        {
            //Call by scheduler
            var sources = DbAccess.GetFeedSources();
            if (sources.Length == 0)
            {
                PrintLine("[Fetch] Nothing to do, Please add source entry into database");
                return;
            }

            PrintLine($"Start Fetch...");
            var totalNewItemCount = 0;
            foreach (var feed in sources)
            {
                try
                {
                    var xml = HttpAccess.Get(feed.Url);
                    var items = RssParser.Parse(xml);

                    var newItemCount = 0;
                    foreach (var item in items)
                    {
                        if (DbAccess.CheckExist(item)) continue;
                        item.Status = item.PubDate > feed.CreationTime
                            ? BangumiEntryStatus.New
                            : BangumiEntryStatus.Skipped;
                        DbAccess.AddEntry(item);
                        ++newItemCount;
                    }

                    totalNewItemCount += newItemCount;

                    PrintLine(newItemCount > 0
                        ? $"「{feed.Name}」New {newItemCount} item."
                        : $"「{feed.Name}」Checked.");
                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }
            PrintLine($"Finish Fetch...");


            if (totalNewItemCount > 0) HandleNew();
        }

        private static void HandleNew()
        {
            //Call by scheduler
            PrintLine("[HandleNew] Loading new entries...");
            var entries = DbAccess.GetNewEntries();

            if (entries.Length == 0)
            {
                PrintLine("[HandleNew] Nothing to do.");
                return;
            }

            PrintLine($"[HandleNew] Get {entries.Length} items to handle");

            foreach (var item in entries)
            {
                PrintLine($"[HandleNew] Starting download 「{item.Title}」");

                //Prep executable for complete notice
                var onBtDownloadComplete = Aria2Helper.CreateNoticeFile(item.Id);
                var logFilePath = Aria2Helper.GetLogFilePath(item.Id);
                //start download with notice executable
                Aria2Helper.StartBitTorrentDownload(item.Magnet, DbAccess.Config.DownloadDirectory, onBtDownloadComplete, logFilePath);
                //set status to downloading
                DbAccess.UpdateStatus(item.Id, BangumiEntryStatus.Downloading);
                //send email tell download started
                if (DbAccess.Config.EnableMail) new MailSender().SendMailAndForget($"Download Start #{item.Id}", $"Id: {item.Id}{Environment.NewLine}Title: {item.Title}");
            }

            PrintLine("[HandleNew] Finished");
        }

        private static void Complete(int id, string filePath)
        {
            //Call by download completed notice executable
            var ce = DbAccess.GetEntry(id);
            if (ce == null) throw new EntryNotFoundException();
            //Update entry state and Send email
            if (DbAccess.UpdateStatus(id, BangumiEntryStatus.DownloadComplete, filePath))
            {
                if (DbAccess.Config.EnableMail) new MailSender().SendMail($"Download Completed #{id}", $"Id: {id}{Environment.NewLine}Title: {ce.Title}{Environment.NewLine}Saved to {filePath}");
                //delete notice executable
                Aria2Helper.DeleteNoticeFile(id);
            }
        }

        private class EntryNotFoundException : Exception { }
    }
}