using System;
using System.IO;

namespace AibisDream.Kit
{
    internal class FileLogger
    {
        private StreamWriter _fileWriter;

        private readonly string _filename;
        private readonly string _filePath;
        private readonly int _saveDays;

        private static string CurrentDay => DateTime.Now.ToString("yyyyMMdd");
        private string _currentLogDay;
        private string _preSavePath;

        /// <summary>
        /// 开始打印
        /// </summary>
        public FileLogger(string filename, string filePath, int saveDays)
        {
            _filename = filename;
            _filePath = filePath.TrimEnd('/') + "/";
            _saveDays = saveDays;
            StartNewFile();
            DeleteOldFile();
            _currentLogDay = CurrentDay;
            Write("*********************************************************\nSystem Start at " +
                       DateTime.Now.ToString("HH:mm:ss") +
                       "\n*********************************************************\n");
        }

        /// <summary>
        /// 新建文件
        /// </summary>
        private void StartNewFile()
        {
            if (_fileWriter != null)
            {
                _fileWriter.Close();
                _fileWriter.Dispose();
            }

            _fileWriter = null;

            if (!Directory.Exists(_filePath))
            {
                Directory.CreateDirectory(_filePath);
            }

            _fileWriter = File.AppendText(_filePath + string.Format(_filename, DateTime.Now));
        }

        public void Write(string content)
        {
            System.Globalization.CultureInfo.CurrentCulture.ClearCachedData();
            if (_currentLogDay != CurrentDay)
            {
                StartNewFile();
                DeleteOldFile();
                _currentLogDay = CurrentDay;
            }

            if (_fileWriter is { BaseStream: { CanWrite: true } })
                _fileWriter.WriteLine(content);
        }

        void DeleteOldFile()
        {
            var fileList = Directory.GetFiles(_filePath);
            if (fileList.Length > _saveDays)
            {
                _preSavePath = _filePath + string.Format(this._filename, DateTime.Now.AddDays(-_saveDays + 1));
                foreach (var t in fileList)
                {
                    if (string.CompareOrdinal(_preSavePath, t) == 1)
                    {
                        File.Delete(t);
                    }
                }
            }
        }

        public void OnDestroy()
        {
            if (_fileWriter == null)
                return;

            Write("*********************************************************\nSystem Shutdown at " +
                       DateTime.Now.ToString("HH:mm:ss") +
                       "\n*********************************************************\n");

            _fileWriter.Flush();
            _fileWriter.Close();
            _fileWriter = null;
        }
    }
}