using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading.Tasks;

namespace Logging
{
    public class FileLogger
    {
        #region signleton

        private static Lazy<FileLogger>
            instance =
                new Lazy<FileLogger>
                    (() => new FileLogger());

        public static FileLogger Instance => instance.Value;

        public static void DestroyInstance()
        {
            if (instance.IsValueCreated)
            {
                instance.Value.Dispose();
                instance =
                    new Lazy<FileLogger>
                        (() => new FileLogger());
            }
        }

        #endregion

        private DateTime startTimestamp;
        private Dictionary<string, AsyncLogFileWriter> writers;
        private List<ILogable> logables;

        private FileLogger()
        {
            startTimestamp = DateTime.Now;
            writers = new Dictionary<string, AsyncLogFileWriter>();
            logables = new List<ILogable>();
        }

        public async Task RegisterLogable(ILogable l)
        {
            logables.Add(l);
            var writer = new AsyncLogFileWriter($"Assets/Logs/{startTimestamp:yyyy-MM-dd_HHmmss}/log_{l.Key}.tsv");
            await writer.WriteDataLine(l.HeaderNames);
            writers[l.Key] = writer;
        }

        private async Task UpdateLog(ILogable l)
        {
            if (!writers.ContainsKey(l.Key))
            {
                throw new KeyNotFoundException($"File Logger has no Logable with key {l.Key}");
            }

            await writers[l.Key].WriteDataLines(l.BufferLines);
            l.ClearBuffer();
        }

        public async Task UpdateRegisteredLogs()
        {
            foreach (var l in logables)
            {
                await UpdateLog(l);
            }
        }

        public void Dispose()
        {
            foreach (var w in writers.Values)
            {
                w.Dispose();
            }
            writers.Clear();
            logables.Clear();
        }
    }
}