// Copyright 2022 Garrett D'Amore
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE or https://www.boost.org/LICENSE_1_0.txt)

module dcell.key;

import std.string;
import std.algorithm;

/**
 * Key represents a single, unmodified key stroke.  Modifier keys are
 * not considered as Keys.
 */
enum Key
{
    none = 0,

    // control keys are assigned their ASCII values
    // these definitions should not be used by apps, but instead
    // by using key rune, the character, and a modifier.
    // TODO: consider just removing these.
    ctrlSpace = 0,
    ctrlA,
    ctrlB,
    ctrlC,
    ctrlD,
    ctrlE,
    ctrlF,
    ctrlG,
    ctrlH,
    ctrlI,
    ctrlJ,
    ctrlK,
    ctrlL,
    ctrlM,
    ctrlN,
    ctrlO,
    ctrlP,
    ctrlQ,
    ctrlR,
    ctrlS,
    ctrlT,
    ctrlU,
    ctrlV,
    ctrlW,
    ctrlX,
    ctrlY,
    ctrlZ,
    ctrlLeftSq, // Escape
    ctrlBackslash,
    ctrlRightSq,
    ctrlCarat,
    ctrlUnderscore,

    rune = 256, // start of defined keys, numbered high to avoid conflicts
    up,
    down,
    right,
    left,
    upLeft,
    upRight,
    downLeft,
    downRight,
    center,
    pgUp,
    pgDn,
    home,
    end,
    insert,
    del2, // secondary delete button, apart from DEL
    help,
    exit,
    clear,
    cancel,
    print,
    pause,
    backtab,
    f1,
    f2,
    f3,
    f4,
    f5,
    f6,
    f7,
    f8,
    f9,
    f10,
    f11,
    f12,
    f13,
    f14,
    f15,
    f16,
    f17,
    f18,
    f19,
    f20,
    f21,
    f22,
    f23,
    f24,
    f25,
    f26,
    f27,
    f28,
    f29,
    f30,
    f31,
    f32,
    f33,
    f34,
    f35,
    f36,
    f37,
    f38,
    f39,
    f40,
    f41,
    f42,
    f43,
    f44,
    f45,
    f46,
    f47,
    f48,
    f49,
    f50,
    f51,
    f52,
    f53,
    f54,
    f55,
    f56,
    f57,
    f58,
    f59,
    f60,
    f61,
    f62,
    f63,
    f64,

    // convenience aliases
    backspace = ctrlH,
    tab = ctrlI,
    esc = ctrlLeftSq,
    enter = ctrlM,
    del = 0x7F, // Note del2 has a different value
}

static immutable dstring[Key] keyNames;
shared static this()
{
    keyNames[Key.enter] = "Enter";
    keyNames[Key.backspace] = "Backspace";
    keyNames[Key.tab] = "Tab";
    keyNames[Key.backtab] = "Backtab";
    keyNames[Key.esc] = "Esc";
    keyNames[Key.del2] = "Delete2";
    keyNames[Key.del] = "Delete";
    keyNames[Key.insert] = "Insert";
    keyNames[Key.up] = "Up";
    keyNames[Key.down] = "Down";
    keyNames[Key.left] = "Left";
    keyNames[Key.right] = "Right";
    keyNames[Key.home] = "Home";
    keyNames[Key.end] = "End";
    keyNames[Key.upLeft] = "UpLeft";
    keyNames[Key.upRight] = "UpRight";
    keyNames[Key.downLeft] = "DownLeft";
    keyNames[Key.downRight] = "DownRight";
    keyNames[Key.center] = "Center";
    keyNames[Key.pgDn] = "PgDn";
    keyNames[Key.pgUp] = "PgUp";
    keyNames[Key.clear] = "Clear";
    keyNames[Key.exit] = "Exit";
    keyNames[Key.cancel] = "Cancel";
    keyNames[Key.pause] = "Pause";
    keyNames[Key.print] = "Print";
    keyNames[Key.f1] = "F1";
    keyNames[Key.f2] = "F2";
    keyNames[Key.f3] = "F3";
    keyNames[Key.f4] = "F4";
    keyNames[Key.f5] = "F5";
    keyNames[Key.f6] = "F6";
    keyNames[Key.f7] = "F7";
    keyNames[Key.f8] = "F8";
    keyNames[Key.f9] = "F9";
    keyNames[Key.f10] = "F10";
    keyNames[Key.f11] = "F11";
    keyNames[Key.f12] = "F12";
    keyNames[Key.f13] = "F13";
    keyNames[Key.f14] = "F14";
    keyNames[Key.f15] = "F15";
    keyNames[Key.f16] = "F16";
    keyNames[Key.f17] = "F17";
    keyNames[Key.f18] = "F18";
    keyNames[Key.f19] = "F19";
    keyNames[Key.f20] = "F20";
    keyNames[Key.f21] = "F21";
    keyNames[Key.f22] = "F22";
    keyNames[Key.f23] = "F23";
    keyNames[Key.f24] = "F24";
    keyNames[Key.f25] = "F25";
    keyNames[Key.f26] = "F26";
    keyNames[Key.f27] = "F27";
    keyNames[Key.f28] = "F28";
    keyNames[Key.f29] = "F29";
    keyNames[Key.f30] = "F30";
    keyNames[Key.f31] = "F31";
    keyNames[Key.f32] = "F32";
    keyNames[Key.f33] = "F33";
    keyNames[Key.f34] = "F34";
    keyNames[Key.f35] = "F35";
    keyNames[Key.f36] = "F36";
    keyNames[Key.f37] = "F37";
    keyNames[Key.f38] = "F38";
    keyNames[Key.f39] = "F39";
    keyNames[Key.f40] = "F40";
    keyNames[Key.f41] = "F41";
    keyNames[Key.f42] = "F42";
    keyNames[Key.f43] = "F43";
    keyNames[Key.f44] = "F44";
    keyNames[Key.f45] = "F45";
    keyNames[Key.f46] = "F46";
    keyNames[Key.f47] = "F47";
    keyNames[Key.f48] = "F48";
    keyNames[Key.f49] = "F49";
    keyNames[Key.f50] = "F50";
    keyNames[Key.f51] = "F51";
    keyNames[Key.f52] = "F52";
    keyNames[Key.f53] = "F53";
    keyNames[Key.f54] = "F54";
    keyNames[Key.f55] = "F55";
    keyNames[Key.f56] = "F56";
    keyNames[Key.f57] = "F57";
    keyNames[Key.f58] = "F58";
    keyNames[Key.f59] = "F59";
    keyNames[Key.f60] = "F60";
    keyNames[Key.f61] = "F61";
    keyNames[Key.f62] = "F62";
    keyNames[Key.f63] = "F63";
    keyNames[Key.f64] = "F64";
    keyNames[Key.ctrlA] = "Ctrl-A";
    keyNames[Key.ctrlB] = "Ctrl-B";
    keyNames[Key.ctrlC] = "Ctrl-C";
    keyNames[Key.ctrlD] = "Ctrl-D";
    keyNames[Key.ctrlE] = "Ctrl-E";
    keyNames[Key.ctrlF] = "Ctrl-F";
    keyNames[Key.ctrlG] = "Ctrl-G";
    keyNames[Key.ctrlJ] = "Ctrl-J";
    keyNames[Key.ctrlK] = "Ctrl-K";
    keyNames[Key.ctrlL] = "Ctrl-L";
    keyNames[Key.ctrlN] = "Ctrl-N";
    keyNames[Key.ctrlO] = "Ctrl-O";
    keyNames[Key.ctrlP] = "Ctrl-P";
    keyNames[Key.ctrlQ] = "Ctrl-Q";
    keyNames[Key.ctrlR] = "Ctrl-R";
    keyNames[Key.ctrlS] = "Ctrl-S";
    keyNames[Key.ctrlT] = "Ctrl-T";
    keyNames[Key.ctrlU] = "Ctrl-U";
    keyNames[Key.ctrlV] = "Ctrl-V";
    keyNames[Key.ctrlW] = "Ctrl-W";
    keyNames[Key.ctrlX] = "Ctrl-X";
    keyNames[Key.ctrlY] = "Ctrl-Y";
    keyNames[Key.ctrlZ] = "Ctrl-Z";
    keyNames[Key.ctrlSpace] = "Ctrl-Space";
    keyNames[Key.ctrlUnderscore] = "Ctrl-_";
    keyNames[Key.ctrlRightSq] = "Ctrl-]";
    keyNames[Key.ctrlBackslash] = "Ctrl-\\";
    keyNames[Key.ctrlCarat] = "Ctrl-^";
}

/** 
 * Modifiers are special keys that when combined with other keys
 * change their meaning.
 */
enum Modifiers
{
    none = 0,
    shift = 1 << 0,
    ctrl = 1 << 1,
    alt = 1 << 2,
    meta = 1 << 3,
}

/**
 * This represents a single pressed key, possibly with modifiers.
 */
struct KeyEvent
{
    Key key; /// Key pressed.
    dchar ch; /// Set if key == rune.
    Modifiers mod; /// Any modifiers pressed together.

    dstring toString() const pure
    {
        dstring s = "";
        if (mod & Modifiers.meta)
        {
            s ~= "Meta-";
        }
        if (mod & Modifiers.alt)
        {
            s ~= "Alt-";
        }
        dstring kn = "";
        if (key in keyNames)
        {
            kn = keyNames[key];
        }
        else if (key == Key.rune)
        {
            kn = [ch];
        }
        else
        {

            kn = format("Key[%02X]"d, key);
        }
        if ((mod & Modifiers.ctrl) && !startsWith(kn, "Ctrl-"))
        {
            s ~= "Ctrl-";
        }

        return s ~ kn;
    }
}