using FATrace.WPLApp.Core;
using Prism.Commands;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Threading;

namespace FATrace.WPLApp.ViewModels
{
    public class LogViewModel : NavigationViewModel
    {
        private readonly DispatcherTimer _timer;

        public LogViewModel()
        {
            Levels = new ObservableCollection<string>(new[] { "ALL", "DEBUG", "INFO", "WARN", "ERROR", "FATAL" });
            _selectedDate = DateTime.Today;
            _levelFilter = Levels.First();
            _maxLines = 2000;

            RefreshCommand = new DelegateCommand(async () => await LoadAsync(), () => !IsBusy).ObservesProperty(() => IsBusy);
            OpenFolderCommand = new DelegateCommand(OpenFolder);

            _timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(2) };
            _timer.Tick += async (_, __) =>
            {
                if (AutoRefresh && !IsBusy)
                    await LoadAsync();
            };
            _timer.Start();

            // 初始加载当日日志
            _ = LoadAsync();
        }

        public ObservableCollection<string> Levels { get; }

        private ObservableCollection<LogEntry> _items = new();
        public ObservableCollection<LogEntry> Items { get => _items; set { _items = value; RaisePropertyChanged(); } }

        private DateTime? _selectedDate;
        public DateTime? SelectedDate { get => _selectedDate; set { _selectedDate = value; RaisePropertyChanged(); _ = LoadAsync(); } }

        private string _levelFilter;
        public string LevelFilter { get => _levelFilter; set { _levelFilter = value; RaisePropertyChanged(); _ = LoadAsync(); } }

        private string _keyword;
        public string Keyword { get => _keyword; set { _keyword = value; RaisePropertyChanged(); _ = LoadAsync(); } }

        private bool _autoRefresh;
        public bool AutoRefresh { get => _autoRefresh; set { _autoRefresh = value; RaisePropertyChanged(); } }

        private int _maxLines;
        public int MaxLines { get => _maxLines; set { _maxLines = value; RaisePropertyChanged(); } }

        private bool _isBusy;
        public bool IsBusy { get => _isBusy; set { _isBusy = value; RaisePropertyChanged(); } }

        public DelegateCommand RefreshCommand { get; }
        public DelegateCommand OpenFolderCommand { get; }

        private string GetLogDirectory()
        {
            return Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "logs");
        }

        private string GetLogFilePath(DateTime? date)
        {
            var dir = GetLogDirectory();
            var dt = date ?? DateTime.Today;
            var file = dt.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture) + ".log";
            return Path.Combine(dir, file);
        }

        private static bool PassLevel(string levelFilter, string level)
        {
            if (string.Equals(levelFilter, "ALL", StringComparison.OrdinalIgnoreCase)) return true;
            return string.Equals(level, levelFilter, StringComparison.OrdinalIgnoreCase);
        }

        private async Task LoadAsync()
        {
            if (IsBusy) return;
            IsBusy = true;
            try
            {
                var path = GetLogFilePath(SelectedDate);
                var list = await Task.Run(() => ReadLogFile(path, MaxLines));

                var filtered = list.Where(x => PassLevel(LevelFilter, x.Level)
                                            && (string.IsNullOrWhiteSpace(Keyword) || (x.Message?.IndexOf(Keyword, StringComparison.OrdinalIgnoreCase) >= 0)
                                                                                    || (x.Logger?.IndexOf(Keyword, StringComparison.OrdinalIgnoreCase) >= 0)));

                Items = new ObservableCollection<LogEntry>(filtered);
            }
            catch
            {
                Items = new ObservableCollection<LogEntry>();
            }
            finally
            {
                IsBusy = false;
            }
        }

        private static IReadOnlyList<LogEntry> ReadLogFile(string path, int maxLines)
        {
            var result = new LinkedList<LogEntry>();
            if (!File.Exists(path)) return result.ToList();

            using var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            using var sr = new StreamReader(fs, Encoding.UTF8);

            string? line;
            while ((line = sr.ReadLine()) != null)
            {
                var entry = ParseLine(line);
                result.AddLast(entry);
                if (result.Count > maxLines) result.RemoveFirst();
            }
            return result.ToList();
        }

        private static LogEntry ParseLine(string line)
        {
            // layout: longdate|LEVEL|logger|threadid|message[|exception]
            var parts = line.Split('|');
            var entry = new LogEntry();
            if (parts.Length >= 4)
            {
                entry.Time = parts[0];
                entry.Level = parts[1];
                entry.Logger = parts[2];
                entry.ThreadId = parts[3];
                if (parts.Length >= 5)
                {
                    entry.Message = string.Join("|", parts.Skip(4));
                }
            }
            else
            {
                entry.Message = line;
            }
            return entry;
        }

        private void OpenFolder()
        {
            var dir = GetLogDirectory();
            Directory.CreateDirectory(dir);
            try
            {
                Process.Start(new ProcessStartInfo
                {
                    FileName = dir,
                    UseShellExecute = true
                });
            }
            catch { }
        }
    }

    public class LogEntry
    {
        public string Time { get; set; }
        public string Level { get; set; }
        public string Logger { get; set; }
        public string ThreadId { get; set; }
        public string Message { get; set; }
    }
}