using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using log4net;
using System.Management;

namespace Agent.Services
{
    class DriveService
    {
        private static readonly ILog log = LogManager.GetLogger(typeof(DriveService));

        private readonly HashService _hashService = new HashService();

        private const int ByteScale = 1024;

        /// <summary>
        /// 드라이브 통계 정보
        /// </summary>
        public List<DriveStat> GetStat()
        {
            try
            {
                return DriveInfo.GetDrives()
                    .Where(drive => drive.DriveType == DriveType.Fixed)
                    .Select(drive => new DriveStat()
                    {
                        Name = drive.Name,
                        TotalSize = FormatBytes(drive.TotalSize),
                        FreeSize = FormatBytes(drive.AvailableFreeSpace),
                        UsedSize = FormatBytes(drive.TotalSize - drive.AvailableFreeSpace),
                        Label = drive.VolumeLabel
                    })
                    .ToList();
            }
            catch (Exception e)
            {
                log.Error(e);

                return null;
            }
        }

        /// <summary>
        /// 전체 드라이브 통계 정보
        /// </summary>
        public DriveStat GetTotalStat()
        {
            var driveStat = new DriveStat()
            {
                Label = "Total",
                TotalSize = "Load Fail",
                FreeSize = "Load Fail",
                UsedSize = "Load Fail"
            };

            try
            {
                var drives = DriveInfo.GetDrives()
                       .Where(drive => drive.DriveType == DriveType.Fixed);
                if (0 == drives.Count())
                {
                    log.Warn("드라이브 없음");

                    return driveStat;
                }

                var totalSize = drives.Sum(drive => drive.TotalSize);
                var freeSize = drives.Sum(drive => drive.AvailableFreeSpace);
                var usedSize = totalSize - freeSize;

                driveStat.TotalSize = FormatBytes(totalSize);
                driveStat.FreeSize = FormatBytes(freeSize);
                driveStat.UsedSize = FormatBytes(usedSize);

                return driveStat;
            }
            catch (Exception e)
            {
                log.Error(e);

                return driveStat;
            }
        }

        /// <summary>
        /// Bytes -> 읽기 편한 용량
        /// </summary>
        public string FormatBytes(long bytes)
        {
            string[] orders = new string[] { "GB", "MB", "KB", "Bytes" };
            long max = (long)Math.Pow(ByteScale, orders.Length - 1);

            foreach (string order in orders)
            {
                if (bytes > max)
                {
                    return string.Format("{0:##.##} {1}", decimal.Divide(bytes, max), order);
                }

                max /= ByteScale;
            }

            return "0 Bytes";
        }

        /// <summary>
        /// 디스크 시리얼
        /// </summary>
        public string GetKey()
        {
            //try
            //{
            //    return _hashService.ToSHA256(Environment.MachineName);
            //}
            //catch (Exception e)
            //{
            //    log.Error(e);
            //    return _hashService.ToSHA256(Environment.MachineName);
            //}
            try
            {
                ManagementObjectSearcher search = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive");
                var management = search.Get().OfType<ManagementObject>().FirstOrDefault();

                if (null == management)
                {
                    log.Warn($"드라이브 없음. NetBIOS로 대체({Environment.MachineName})");

                    return _hashService.ToSHA256(Environment.MachineName);
                }

                var serial = string.Empty;
                foreach (var property in management.Properties)
                {
                    if ("SerialNumber".Equals(property.Name))
                    {
                        serial = property.Value as string;
                        break;
                    }
                }

                if (null == serial || string.Empty == serial)
                {
                    log.Warn($"드라이브 시리얼넘버 없음. NetBIOS로 대체({Environment.MachineName})");

                    return _hashService.ToSHA256(Environment.MachineName);
                }

                return _hashService.ToSHA256(management["SerialNumber"].ToString().Trim());
            }
            catch (Exception e)
            {
                log.Error(e);

                return _hashService.ToSHA256(Environment.MachineName);
            }
        }
    }

    public partial class DriveStat
    {
        /// <summary>
        /// 드라이브 이름(EX. C:\, D:\)
        /// </summary>
        public string Name { get; set; }
        /// <summary>
        /// 전체 공간
        /// </summary>
        public string TotalSize { get; set; }
        /// <summary>
        /// 사용가능한 공간
        /// </summary>
        public string FreeSize { get; set; }
        /// <summary>
        /// 사용중인 공간
        /// </summary>
        public string UsedSize { get; set; }
        /// <summary>
        /// 별명
        /// </summary>
        public string Label { get; set; }
    }
}