using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using XIVChatCommon;

namespace XIVChat_Desktop {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : INotifyPropertyChanged {
        #region commands

        private void AlwaysTrue_CanExecute(object sender, CanExecuteRoutedEventArgs e) {
            e.CanExecute = true;
        }

        public static readonly RoutedUICommand EditTab = new RoutedUICommand(
            "EditTab",
            "EditTab",
            typeof(MainWindow)
        );

        private void EditTab_OnExecuted(object sender, ExecutedRoutedEventArgs e) {
            if (!(e.Parameter is Tab tab)) {
                return;
            }

            new ManageTab(this, tab).Show();
        }

        public static readonly RoutedUICommand DeleteTab = new RoutedUICommand(
            "DeleteTab",
            "DeleteTab",
            typeof(MainWindow)
        );

        private void DeleteTab_OnExecuted(object sender, ExecutedRoutedEventArgs e) {
            if (!(e.Parameter is Tab tab)) {
                return;
            }

            this.App.Config.Tabs.Remove(tab);
            this.App.Config.Save();
        }

        public static readonly RoutedUICommand AddTab = new RoutedUICommand(
            "AddTab",
            "AddTab",
            typeof(MainWindow)
        );

        private void AddTab_OnExecuted(object sender, ExecutedRoutedEventArgs e) {
            new ManageTab(this, null).Show();
        }

        public static readonly RoutedUICommand ManageTabs = new RoutedUICommand(
            "ManageTabs",
            "ManageTabs",
            typeof(MainWindow)
        );

        private void ManageTabs_OnExecuted(object sender, ExecutedRoutedEventArgs e) {
            new ManageTabs(this).Show();
        }

        #endregion

        public App App => (App)Application.Current;

        public List<ServerMessage> Messages { get; } = new List<ServerMessage>();
        public ObservableCollection<Player> FriendList { get; } = new ObservableCollection<Player>();

        private int historyIndex = -1;

        private int HistoryIndex {
            get => this.historyIndex;
            set {
                var idx = Math.Min(this.History.Count - 1, Math.Max(-1, value));
                this.historyIndex = idx;
            }
        }

        private int ReverseHistoryIndex => this.HistoryIndex == -1 ? -1 : Math.Max(-1, this.History.Count - this.HistoryIndex - 1);

        private string? HistoryBuffer { get; set; }

        private List<string> History { get; } = new List<string>();

        public string InputPlaceholder => this.App.Connection?.Available == true ? "Send a message..." : "Chat is currently unavailable";

        public MainWindow() {
            this.InitializeComponent();
            this.DataContext = this;
        }

        private T? FindElementByName<T>(DependencyObject element, string sChildName) where T : FrameworkElement {
            T? childElement = null;
            var nChildCount = VisualTreeHelper.GetChildrenCount(element);
            for (int i = 0; i < nChildCount; i++) {
                if (!(VisualTreeHelper.GetChild(element, i) is FrameworkElement child)) {
                    continue;
                }

                if (child is T t && child.Name.Equals(sChildName)) {
                    childElement = t;
                    break;
                }

                childElement = this.FindElementByName<T>(child, sChildName);

                if (childElement != null) {
                    break;
                }
            }

            return childElement;
        }

        public void ClearAllMessages() {
            this.Messages.Clear();
            foreach (var tab in this.App.Config.Tabs) {
                tab.ClearMessages();
            }
        }

        public void AddSystemMessage(string content) {
            var message = new ServerMessage(
                DateTime.UtcNow,
                0,
                new byte[0],
                Encoding.UTF8.GetBytes(content),
                new List<Chunk> {
                    new TextChunk(content) {
                        Foreground = 0xb38cffff,
                    },
                }
            );
            this.AddMessage(message);
        }

        private int lastSequence = -1;
        private int insertAt;

        public void AddReversedChunk(ServerMessage[] messages, int sequence) {
            if (sequence != this.lastSequence) {
                this.lastSequence = sequence;
                this.insertAt = this.Messages.Count;
            }

            // detect if scroller is at the bottom
            var scroller = this.FindElementByName<ScrollViewer>(this.Tabs, "scroller");
            var wasAtBottom = Math.Abs(scroller!.VerticalOffset - scroller.ScrollableHeight) < .0001;

            // add messages to main list
            this.Messages.InsertRange(this.insertAt, messages);
            // add message to each tab if the filter allows for it
            foreach (var tab in this.App.Config.Tabs) {
                tab.AddReversedChunk(messages, sequence, this.App.Config);
            }

            var diff = this.Messages.Count - this.App.Config.LocalBacklogMessages;
            if (diff > 0) {
                this.Messages.RemoveRange(0, (int)diff);
            }

            // scroll to the bottom if previously at the bottom
            if (wasAtBottom) {
                scroller.ScrollToBottom();
            }
        }

        public void AddMessage(ServerMessage message) {
            // detect if scroller is at the bottom
            var scroller = this.FindElementByName<ScrollViewer>(this.Tabs, "scroller");
            var wasAtBottom = Math.Abs(scroller!.VerticalOffset - scroller.ScrollableHeight) < .0001;

            // add message to main list
            this.Messages.Add(message);
            // add message to each tab if the filter allows for it
            foreach (var tab in this.App.Config.Tabs) {
                tab.AddMessage(message, this.App.Config);
            }

            var diff = this.Messages.Count - this.App.Config.LocalBacklogMessages;
            if (diff > 0) {
                this.Messages.RemoveRange(0, (int)diff);
            }

            // scroll to the bottom if previously at the bottom
            if (wasAtBottom) {
                scroller.ScrollToBottom();
            }
        }

        private void Connect_Click(object sender, RoutedEventArgs e) {
            new ConnectDialog(this).ShowDialog();
        }

        private void Disconnect_Click(object sender, RoutedEventArgs e) {
            this.App.Disconnect();
        }

        private void Input_Submit(object sender, KeyEventArgs e) {
            if (!(sender is TextBox textBox)) {
                return;
            }

            switch (e.Key) {
                case Key.Return:
                    this.Submit(textBox);
                    break;
                case Key.Up:
                    this.ArrowNavigate(textBox, true);
                    break;
                case Key.Down:
                    this.ArrowNavigate(textBox, false);
                    break;
            }
        }

        private void Submit(TextBox textBox) {
            var conn = this.App.Connection;
            if (conn == null) {
                return;
            }

            conn.SendMessage(textBox.Text);
            this.History.Add(textBox.Text);
            while (this.History.Count > 100) {
                this.History.RemoveAt(0);
            }

            textBox.Text = "";
        }

        private void ArrowNavigate(TextBox textBox, bool up) {
            var caretLine = textBox.GetLineIndexFromCharacterIndex(textBox.CaretIndex);
            var inFirstLine = caretLine == 0;
            var inLastLine = caretLine == textBox.LineCount - 1;

            if (this.HistoryIndex == -1) {
                this.HistoryBuffer = textBox.Text;
            }

            if (up && inFirstLine) {
                // go up in history
                this.HistoryIndex += 1;
                textBox.Text = this.History[this.ReverseHistoryIndex];
            } else if (!up && inLastLine) {
                // go down in history
                this.HistoryIndex -= 1;

                if (this.HistoryIndex == -1) {
                    textBox.Text = this.HistoryBuffer;
                    this.HistoryBuffer = null;
                } else {
                    textBox.Text = this.History[this.ReverseHistoryIndex];
                }
            }
        }

        private void Configuration_Click(object sender, RoutedEventArgs e) {
            new ConfigWindow(this, this.App.Config).Show();
        }

        private void Tabs_Loaded(object sender, RoutedEventArgs e) {
            this.Tabs.SelectedIndex = 0;
        }

        public TextBox? GetCurrentInputBox() {
            return this.FindElementByName<TextBox>(this.Tabs, "InputBox");
        }

        private void Tabs_SelectionChanged(object sender, SelectionChangedEventArgs e) {
            var scroller = this.FindElementByName<ScrollViewer>(this.Tabs, "scroller");
            scroller?.ScrollToBottom();
        }

        private void Scan_Click(object sender, RoutedEventArgs e) {
            new ServerScan(this).Show();
        }

        public event PropertyChangedEventHandler? PropertyChanged;

        internal void OnPropertyChanged([CallerMemberName] string? propertyName = null) {
            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        private void Export_Click(object sender, RoutedEventArgs e) {
            new Export(this).Show();
        }

        private void Licence_Click(object sender, RoutedEventArgs e) {
            new LicenceWindow(this, false).Show();
        }

        private void Exit_Click(object sender, RoutedEventArgs e) {
            this.Close();
            this.App.Shutdown();
        }

        private void FriendList_Click(object sender, RoutedEventArgs e) {
            new FriendList(this).Show();
        }
    }
}