using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;

namespace JJServiceManager
{
    public enum LogLevel { Info, Success, Warning, Error, Notice }

    /// <summary>로그 한 줄</summary>
    public class LogLine : ObservableObject
    {
        private bool _isChecked;
        private double _fillerHeight;

        public int No { get; init; }
        public DateTime Time { get; init; }
        public string Text { get; init; } = "";
        public LogLevel Level { get; init; }
        public bool ShowTime { get; init; }
        public bool IsFiller { get; init; }

        public bool IsChecked { get => _isChecked; set => Set(ref _isChecked, value); }

        public double FillerHeight
        {
            get => _fillerHeight;
            set => Set(ref _fillerHeight, Math.Max(0, value));
        }

        public string NoText => IsFiller ? "" : No.ToString();
        public string Display => IsFiller ? "" : (ShowTime ? $"[{Time:HH:mm:ss}] {Text}" : Text);
        public Visibility FillerVisibility => IsFiller ? Visibility.Visible : Visibility.Collapsed;
        public Visibility LineVisibility => IsFiller ? Visibility.Collapsed : Visibility.Visible;

        public Brush Foreground => Level switch
        {
            LogLevel.Success => Brushes2.Running,
            LogLevel.Warning => Brushes2.Pending,
            LogLevel.Error => Brushes2.Stopped,
            LogLevel.Notice => LogPanel.NoticeBrush,
            _ => LogPanel.NormalBrush
        };

        /// <summary>복사할 때의 텍스트</summary>
        public string CopyText => ShowTime ? $"[{Time:yyyy-MM-dd HH:mm:ss}] {Text}" : Text;
    }

    /// <summary>앞쪽 여러 줄을 한 번에 지울 수 있는 컬렉션 (변경 알림 1회)</summary>
    public sealed class LogCollection : ObservableCollection<LogLine>
    {
        public void RemoveFirst(int count)
        {
            if (count <= 0) return;
            CheckReentrancy();
            var list = (List<LogLine>)Items;
            list.RemoveRange(0, Math.Min(count, list.Count));
            OnPropertyChanged(new System.ComponentModel.PropertyChangedEventArgs("Count"));
            OnPropertyChanged(new System.ComponentModel.PropertyChangedEventArgs("Item[]"));
            OnCollectionChanged(new System.Collections.Specialized.NotifyCollectionChangedEventArgs(
                System.Collections.Specialized.NotifyCollectionChangedAction.Reset));
        }
    }

    /// <summary>
    /// 번호 + 체크박스가 있는 로그 목록.
    /// - 화면클리어: 새 로그를 화면 맨 위부터 출력, 위로 스크롤하면 이전 로그가 보임, 번호는 이어짐
    /// - 로그 클리어: 화면의 로그를 모두 지우고 번호를 1번부터 다시 시작
    /// - 파일은 절대 지우지 않음
    /// </summary>
    public class LogPanel : ContentControl
    {
        public static readonly SolidColorBrush NormalBrush = Brushes2.Make("#212121");
        public static readonly SolidColorBrush NoticeBrush = Brushes2.Make("#1565C0");

        private const double LineHeight = 22;

        private readonly LogCollection _lines = new LogCollection();
        private readonly ListBox _list;
        private readonly TextBlock _info;
        private readonly DispatcherTimer _infoTimer;
        private ScrollViewer _scroll;
        private LogLine _filler;
        private int _fillerNewLines;
        private int _nextNo = 1;
        private bool _scrollPending;

        /// <summary>줄 앞에 시각 표시 여부 (작업 로그 = true, 파일 로그 = false)</summary>
        public bool ShowTimestamp { get; set; } = true;

        /// <summary>화면에 유지할 최대 줄 수 (오래된 줄부터 화면에서만 빠짐)</summary>
        public int MaxLines { get; set; } = 20000;

        public int Count => _lines.Count - (_filler != null ? 1 : 0);

        public LogPanel()
        {
            var root = XamlLoader.LoadElement("LogPanel.xaml");
            Content = root;

            _list = root.Find<ListBox>("lstLog");
            _info = root.Find<TextBlock>("txtInfo");
            _list.ItemsSource = _lines;

            root.Find<Button>("btnSelectAll").Click += (s, e) => SetAllChecked(true);
            root.Find<Button>("btnSelectNone").Click += (s, e) => SetAllChecked(false);
            root.Find<Button>("btnClearScreen").Click += (s, e) => ClearScreen();
            root.Find<Button>("btnCopy").Click += (s, e) => CopyChecked();
            root.Find<Button>("btnClearLog").Click += (s, e) => ClearLog();

            _list.Loaded += (s, e) => _scroll ??= FindChild<ScrollViewer>(_list);
            _list.SizeChanged += (s, e) => AdjustFiller();
            _list.PreviewKeyDown += OnListKeyDown;
            // 화면클리어용 빈 공간은 선택되지 않게 함
            _list.SelectionChanged += (s, e) =>
            {
                if (_filler != null && e.AddedItems.Contains(_filler)) _list.SelectedItems.Remove(_filler);
            };

            _infoTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(4) };
            _infoTimer.Tick += (s, e) => { _info.Text = ""; _infoTimer.Stop(); };
        }

        // ───────────────────────── 추가 ─────────────────────────

        public void Add(string text, LogLevel level = LogLevel.Info)
            => AddMany(new[] { text }, level);

        public void AddMany(IEnumerable<string> texts, LogLevel level = LogLevel.Info)
        {
            var list = texts as IList<string> ?? texts.ToList();
            if (list.Count == 0) return;

            if (!Dispatcher.CheckAccess())
            {
                Dispatcher.BeginInvoke(new Action(() => AddMany(list, level)));
                return;
            }

            bool atBottom = IsAtBottom();
            var now = DateTime.Now;

            foreach (var t in list)
            {
                var line = new LogLine
                {
                    No = _nextNo++,
                    Time = now,
                    Text = t ?? "",
                    Level = level,
                    ShowTime = ShowTimestamp
                };

                if (_filler != null)
                {
                    _lines.Insert(_lines.Count - 1, line);
                    _fillerNewLines++;
                    _filler.FillerHeight -= LineHeight;
                    if (_filler.FillerHeight <= 0)
                    {
                        _lines.Remove(_filler);
                        _filler = null;
                    }
                }
                else
                {
                    _lines.Add(line);
                }
            }

            // 최대 줄 수를 여유분 이상 넘으면 화면에서만 오래된 줄을 한 번에 제거
            int slack = Math.Max(500, MaxLines / 10);
            if (Count > MaxLines + slack)
            {
                int remove = Count - MaxLines;
                if (_filler != null) remove = Math.Min(remove, _lines.Count - 1);
                _lines.RemoveFirst(remove);
                atBottom = true;
            }

            if (atBottom) ScrollToEndDeferred();
        }

        // ───────────────────────── 버튼 동작 ─────────────────────────

        /// <summary>화면클리어: 이전 로그는 위쪽에 그대로 두고, 새 로그가 화면 맨 위부터 보이도록 함</summary>
        public void ClearScreen()
        {
            if (_filler != null)
            {
                _lines.Remove(_filler);
                _filler = null;
            }
            if (_lines.Count == 0) return;
            double vh = ViewportHeight();
            if (vh <= 0) return; // 화면이 보이지 않는 상태

            _filler = new LogLine { IsFiller = true, FillerHeight = vh };
            _fillerNewLines = 0;
            _lines.Add(_filler);
            ScrollToEndDeferred();
            ShowInfo("화면을 비웠습니다. 위로 스크롤하면 이전 로그를 볼 수 있습니다.");
        }

        /// <summary>로그 클리어: 화면의 로그를 모두 지우고 번호를 1번부터</summary>
        public void ClearLog()
        {
            _lines.Clear();
            _filler = null;
            _fillerNewLines = 0;
            _nextNo = 1;
            ShowInfo("화면의 로그를 지웠습니다. 번호는 1번부터 시작합니다.");
        }

        public void SetAllChecked(bool value)
        {
            foreach (var l in _lines)
                if (!l.IsFiller) l.IsChecked = value;
        }

        public void CopyChecked()
        {
            var picked = _lines.Where(l => !l.IsFiller && l.IsChecked).ToList();
            if (picked.Count == 0)
            {
                ShowInfo("복사할 줄을 체크하세요.");
                return;
            }
            CopyLines(picked);
        }

        private void CopyLines(IList<LogLine> lines)
        {
            var sb = new StringBuilder();
            foreach (var l in lines) sb.AppendLine(l.CopyText);

            for (int retry = 0; retry < 5; retry++)
            {
                try
                {
                    Clipboard.SetText(sb.ToString());
                    ShowInfo($"{lines.Count}줄을 복사했습니다.");
                    return;
                }
                catch
                {
                    System.Threading.Thread.Sleep(60);
                }
            }
            ShowInfo("클립보드를 사용할 수 없습니다. 잠시 후 다시 시도하세요.");
        }

        private void OnListKeyDown(object sender, KeyEventArgs e)
        {
            // Ctrl+C: 마우스로 선택(파란 표시)한 줄 복사, 없으면 체크한 줄 복사
            if (e.Key == Key.C && (Keyboard.Modifiers & ModifierKeys.Control) != 0)
            {
                var picked = new HashSet<LogLine>(_list.SelectedItems.Cast<LogLine>());
                var sel = _lines.Where(l => !l.IsFiller && picked.Contains(l)).ToList();
                if (sel.Count > 0) CopyLines(sel); else CopyChecked();
                e.Handled = true;
            }
            // Space: 선택한 줄의 체크 토글
            else if (e.Key == Key.Space)
            {
                var sel = _list.SelectedItems.Cast<LogLine>().Where(l => !l.IsFiller).ToList();
                if (sel.Count > 0)
                {
                    bool v = !sel.All(l => l.IsChecked);
                    foreach (var l in sel) l.IsChecked = v;
                    e.Handled = true;
                }
            }
        }

        // ───────────────────────── 스크롤 ─────────────────────────

        private double ViewportHeight()
        {
            _scroll ??= FindChild<ScrollViewer>(_list);
            if (_scroll != null && _scroll.ViewportHeight > 0) return _scroll.ViewportHeight;
            return Math.Max(0, _list.ActualHeight - 4);
        }

        private void AdjustFiller()
        {
            if (_filler == null) return;
            _filler.FillerHeight = ViewportHeight() - _fillerNewLines * LineHeight;
            if (_filler.FillerHeight <= 0)
            {
                _lines.Remove(_filler);
                _filler = null;
            }
            ScrollToEndDeferred();
        }

        private bool IsAtBottom()
        {
            _scroll ??= FindChild<ScrollViewer>(_list);
            if (_scroll == null) return true;
            return _scroll.VerticalOffset >= _scroll.ScrollableHeight - 2;
        }

        private void ScrollToEndDeferred()
        {
            if (_scrollPending) return;
            _scrollPending = true;
            Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =>
            {
                _scrollPending = false;
                _scroll ??= FindChild<ScrollViewer>(_list);
                _scroll?.ScrollToBottom();
            }));
        }

        private void ShowInfo(string msg)
        {
            _info.Text = msg;
            _infoTimer.Stop();
            _infoTimer.Start();
        }

        private static T FindChild<T>(DependencyObject parent) where T : DependencyObject
        {
            if (parent == null) return null;
            int n = VisualTreeHelper.GetChildrenCount(parent);
            for (int i = 0; i < n; i++)
            {
                var c = VisualTreeHelper.GetChild(parent, i);
                if (c is T t) return t;
                var r = FindChild<T>(c);
                if (r != null) return r;
            }
            return null;
        }
    }
}