using System;
using System.Collections.Generic;
using Windows.System;

namespace ClipForge
{
    /// <summary>Converts between hotkey modifier/vk and display strings.</summary>
    public static class HotkeyHelper
    {
        public const uint MOD_ALT = 0x0001;
        public const uint MOD_CONTROL = 0x0002;
        public const uint MOD_SHIFT = 0x0004;
        public const uint MOD_WIN = 0x0008;
        public const uint MOD_NOREPEAT = 0x4000;

        // Built in static ctor with TryAdd so duplicate VirtualKey enum values (e.g. Kana/Hangul = 0x15) don't throw.
        private static readonly Dictionary<VirtualKey, string> KeyNames = new();

        static HotkeyHelper()
        {
            TryAdd(VirtualKey.LeftButton, "LMB");
            TryAdd(VirtualKey.RightButton, "RMB");
            TryAdd(VirtualKey.Cancel, "Cancel");
            TryAdd(VirtualKey.Back, "Backspace");
            TryAdd(VirtualKey.Tab, "Tab");
            TryAdd(VirtualKey.Clear, "Clear");
            TryAdd(VirtualKey.Enter, "Enter");
            TryAdd(VirtualKey.Shift, "Shift");
            TryAdd(VirtualKey.Control, "Ctrl");
            TryAdd(VirtualKey.Menu, "Alt");
            TryAdd(VirtualKey.Pause, "Pause");
            TryAdd(VirtualKey.CapitalLock, "Caps Lock");
            TryAdd(VirtualKey.Kana, "Kana");
            TryAdd(VirtualKey.Hangul, "Hangul"); // same value as Kana on some SDKs; TryAdd skips duplicate
            TryAdd(VirtualKey.Junja, "Junja");
            TryAdd(VirtualKey.Final, "Final");
            TryAdd(VirtualKey.Hanja, "Hanja");
            TryAdd(VirtualKey.Kanji, "Kanji");
            TryAdd(VirtualKey.Escape, "Escape");
            TryAdd(VirtualKey.Convert, "Convert");
            TryAdd(VirtualKey.NonConvert, "NonConvert");
            TryAdd(VirtualKey.Accept, "Accept");
            TryAdd(VirtualKey.ModeChange, "ModeChange");
            TryAdd(VirtualKey.Space, "Space");
            TryAdd(VirtualKey.PageUp, "PgUp");
            TryAdd(VirtualKey.PageDown, "PgDn");
            TryAdd(VirtualKey.End, "End");
            TryAdd(VirtualKey.Home, "Home");
            TryAdd(VirtualKey.Left, "Left");
            TryAdd(VirtualKey.Up, "Up");
            TryAdd(VirtualKey.Right, "Right");
            TryAdd(VirtualKey.Down, "Down");
            TryAdd(VirtualKey.Select, "Select");
            TryAdd(VirtualKey.Print, "Print");
            TryAdd(VirtualKey.Execute, "Execute");
            TryAdd(VirtualKey.Snapshot, "Print Screen");
            TryAdd(VirtualKey.Insert, "Insert");
            TryAdd(VirtualKey.Delete, "Delete");
            TryAdd(VirtualKey.Help, "Help");
            TryAdd(VirtualKey.Number0, "0");
            TryAdd(VirtualKey.Number1, "1");
            TryAdd(VirtualKey.Number2, "2");
            TryAdd(VirtualKey.Number3, "3");
            TryAdd(VirtualKey.Number4, "4");
            TryAdd(VirtualKey.Number5, "5");
            TryAdd(VirtualKey.Number6, "6");
            TryAdd(VirtualKey.Number7, "7");
            TryAdd(VirtualKey.Number8, "8");
            TryAdd(VirtualKey.Number9, "9");
            TryAdd(VirtualKey.A, "A");
            TryAdd(VirtualKey.B, "B");
            TryAdd(VirtualKey.C, "C");
            TryAdd(VirtualKey.D, "D");
            TryAdd(VirtualKey.E, "E");
            TryAdd(VirtualKey.F, "F");
            TryAdd(VirtualKey.G, "G");
            TryAdd(VirtualKey.H, "H");
            TryAdd(VirtualKey.I, "I");
            TryAdd(VirtualKey.J, "J");
            TryAdd(VirtualKey.K, "K");
            TryAdd(VirtualKey.L, "L");
            TryAdd(VirtualKey.M, "M");
            TryAdd(VirtualKey.N, "N");
            TryAdd(VirtualKey.O, "O");
            TryAdd(VirtualKey.P, "P");
            TryAdd(VirtualKey.Q, "Q");
            TryAdd(VirtualKey.R, "R");
            TryAdd(VirtualKey.S, "S");
            TryAdd(VirtualKey.T, "T");
            TryAdd(VirtualKey.U, "U");
            TryAdd(VirtualKey.V, "V");
            TryAdd(VirtualKey.W, "W");
            TryAdd(VirtualKey.X, "X");
            TryAdd(VirtualKey.Y, "Y");
            TryAdd(VirtualKey.Z, "Z");
            TryAdd(VirtualKey.LeftWindows, "Win");
            TryAdd(VirtualKey.RightWindows, "Win");
            TryAdd(VirtualKey.Application, "App");
            TryAdd(VirtualKey.Sleep, "Sleep");
            TryAdd(VirtualKey.NumberPad0, "Num 0");
            TryAdd(VirtualKey.NumberPad1, "Num 1");
            TryAdd(VirtualKey.NumberPad2, "Num 2");
            TryAdd(VirtualKey.NumberPad3, "Num 3");
            TryAdd(VirtualKey.NumberPad4, "Num 4");
            TryAdd(VirtualKey.NumberPad5, "Num 5");
            TryAdd(VirtualKey.NumberPad6, "Num 6");
            TryAdd(VirtualKey.NumberPad7, "Num 7");
            TryAdd(VirtualKey.NumberPad8, "Num 8");
            TryAdd(VirtualKey.NumberPad9, "Num 9");
            TryAdd(VirtualKey.Multiply, "Num *");
            TryAdd(VirtualKey.Add, "Num +");
            TryAdd(VirtualKey.Separator, "Num ,");
            TryAdd(VirtualKey.Subtract, "Num -");
            TryAdd(VirtualKey.Decimal, "Num .");
            TryAdd(VirtualKey.Divide, "Num /");
            TryAdd(VirtualKey.F1, "F1");
            TryAdd(VirtualKey.F2, "F2");
            TryAdd(VirtualKey.F3, "F3");
            TryAdd(VirtualKey.F4, "F4");
            TryAdd(VirtualKey.F5, "F5");
            TryAdd(VirtualKey.F6, "F6");
            TryAdd(VirtualKey.F7, "F7");
            TryAdd(VirtualKey.F8, "F8");
            TryAdd(VirtualKey.F9, "F9");
            TryAdd(VirtualKey.F10, "F10");
            TryAdd(VirtualKey.F11, "F11");
            TryAdd(VirtualKey.F12, "F12");
            TryAdd(VirtualKey.F13, "F13");
            TryAdd(VirtualKey.F14, "F14");
            TryAdd(VirtualKey.F15, "F15");
            TryAdd(VirtualKey.F16, "F16");
            TryAdd(VirtualKey.F17, "F17");
            TryAdd(VirtualKey.F18, "F18");
            TryAdd(VirtualKey.F19, "F19");
            TryAdd(VirtualKey.F20, "F20");
            TryAdd(VirtualKey.F21, "F21");
            TryAdd(VirtualKey.F22, "F22");
            TryAdd(VirtualKey.F23, "F23");
            TryAdd(VirtualKey.F24, "F24");
            TryAdd(VirtualKey.NumberKeyLock, "NumLock");
            TryAdd(VirtualKey.Scroll, "Scroll Lock");
            TryAdd(VirtualKey.LeftShift, "Shift");
            TryAdd(VirtualKey.RightShift, "Shift");
            TryAdd(VirtualKey.LeftControl, "Ctrl");
            TryAdd(VirtualKey.RightControl, "Ctrl");
            TryAdd(VirtualKey.LeftMenu, "Alt");
            TryAdd(VirtualKey.RightMenu, "Alt");
        }

        private static void TryAdd(VirtualKey key, string name)
        {
            KeyNames.TryAdd(key, name);
        }

        /// <summary>Format modifier flags + virtual key as display string (e.g. "Alt + PgUp").</summary>
        public static string ToDisplayString(uint modifiers, uint vk)
        {
            var parts = new List<string>();
            if ((modifiers & MOD_WIN) != 0) parts.Add("Win");
            if ((modifiers & MOD_CONTROL) != 0) parts.Add("Ctrl");
            if ((modifiers & MOD_ALT) != 0) parts.Add("Alt");
            if ((modifiers & MOD_SHIFT) != 0) parts.Add("Shift");
            var keyName = GetKeyName((VirtualKey)vk);
            if (!string.IsNullOrEmpty(keyName))
                parts.Add(keyName);
            return parts.Count > 0 ? string.Join(" + ", parts) : "None";
        }

        public static string GetKeyName(VirtualKey key)
        {
            return KeyNames.TryGetValue(key, out var name) ? name : key.ToString();
        }

        /// <summary>True if the key is typically used only as a modifier (don't use as sole key).</summary>
        public static bool IsModifierKey(VirtualKey key)
        {
            return key == VirtualKey.LeftWindows || key == VirtualKey.RightWindows
                || key == VirtualKey.Control || key == VirtualKey.LeftControl || key == VirtualKey.RightControl
                || key == VirtualKey.Menu || key == VirtualKey.LeftMenu || key == VirtualKey.RightMenu
                || key == VirtualKey.Shift || key == VirtualKey.LeftShift || key == VirtualKey.RightShift;
        }
    }
}