gasm-host 0.6.0

//! Keyboard layouts: the same text format as the web player (`gasm-host.js`
//! `parseKeymap`). A line per binding: `<pad 1-4> <button> <key code>...`, where key
//! codes are W3C `KeyboardEvent.code` names (winit's `KeyCode` uses the same names).
//! Keyboard bindings for pad N >= 2 apply while fewer than N gamepads are connected.

use winit::keyboard::KeyCode;

pub use crate::keys::KEY_CODES;

pub const DEFAULT_KEYMAP: &str = include_str!("default-keymap.txt");
pub const BUTTONS: [&str; 12] = ["a", "b", "x", "y", "l", "r", "select", "start", "up", "down", "left", "right"];

/// (key, zero-based pad, button bit)
pub type Keymap = Vec<(KeyCode, usize, u32)>;

pub fn parse(text: &str) -> Result<Keymap, String> {
    let mut map = Vec::new();
    let mut errors = Vec::new();
    for (i, raw) in text.lines().enumerate() {
        let line = raw.split('#').next().unwrap_or("").trim();
        if line.is_empty() {
            continue;
        }
        let mut parts = line.split_whitespace();
        let (pad, button) = (parts.next(), parts.next());
        let keys: Vec<&str> = parts.collect();
        let pad = pad.and_then(|p| p.parse::<usize>().ok()).filter(|p| (1..=4).contains(p));
        let bit = button.and_then(|b| BUTTONS.iter().position(|n| n.eq_ignore_ascii_case(b)));
        let (Some(pad), Some(bit), false) = (pad, bit, keys.is_empty()) else {
            errors.push(format!("line {}: expected \"<pad 1-4> <button> <key>...\", got {line:?}", i + 1));
            continue;
        };
        for k in keys {
            match key_from_code(normalize(k)) {
                Some(KeyCode::Escape) => errors.push(format!("line {}: Escape is reserved (quit)", i + 1)),
                Some(code) => map.push((code, pad - 1, 1u32 << bit)),
                None => errors.push(format!("line {}: unknown key code {k:?}", i + 1)),
            }
        }
    }
    if errors.is_empty() { Ok(map) } else { Err(errors.join("\n")) }
}

/// Pads from held keys; keyboard pad N (zero-based n >= 1) only while `gamepads <= n`.
pub fn pads(map: &Keymap, held: &std::collections::HashSet<KeyCode>, gamepads: usize) -> [u32; 4] {
    let mut pads = [0u32; 4];
    for (key, pad, bit) in map {
        if held.contains(key) && (*pad == 0 || gamepads <= *pad) {
            pads[*pad] |= bit;
        }
    }
    pads
}

macro_rules! codes {
    ($($name:ident),* $(,)?) => {
        /// W3C KeyboardEvent.code name -> winit KeyCode.
        pub fn key_from_code(s: &str) -> Option<KeyCode> {
            match s { $(stringify!($name) => Some(KeyCode::$name),)* _ => None }
        }
    };
}

codes!(
    KeyA, KeyB, KeyC, KeyD, KeyE, KeyF, KeyG, KeyH, KeyI, KeyJ, KeyK, KeyL, KeyM,
    KeyN, KeyO, KeyP, KeyQ, KeyR, KeyS, KeyT, KeyU, KeyV, KeyW, KeyX, KeyY, KeyZ,
    Digit0, Digit1, Digit2, Digit3, Digit4, Digit5, Digit6, Digit7, Digit8, Digit9,
    ArrowUp, ArrowDown, ArrowLeft, ArrowRight,
    Numpad0, Numpad1, Numpad2, Numpad3, Numpad4, Numpad5, Numpad6, Numpad7, Numpad8, Numpad9,
    NumpadAdd, NumpadSubtract, NumpadMultiply, NumpadDivide, NumpadDecimal, NumpadEnter, NumpadEqual, NumpadComma,
    F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12,
    Space, Enter, Tab, Backspace, Escape, CapsLock,
    ShiftLeft, ShiftRight, ControlLeft, ControlRight, AltLeft, AltRight, SuperLeft, SuperRight,
    Comma, Period, Slash, Semicolon, Quote, BracketLeft, BracketRight, Backslash, Minus, Equal, Backquote, IntlBackslash,
    Insert, Delete, Home, End, PageUp, PageDown,
    F13, F14, F15, F16, F17, F18, F19, F20, F21, F22, F23, F24,
    PrintScreen, ScrollLock, Pause, NumLock, ContextMenu, IntlRo, IntlYen,
);

/// GASM_KEY_* code of a winit key (0 if it has none).
pub fn gasm_key(code: KeyCode) -> u16 {
    use std::sync::OnceLock;
    static MAP: OnceLock<Vec<(KeyCode, u16)>> = OnceLock::new();
    MAP.get_or_init(|| {
        KEY_CODES.iter().enumerate().skip(1).filter_map(|(i, n)| key_from_code(normalize(n)).map(|k| (k, i as u16))).collect()
    })
    .iter()
    .find(|(k, _)| *k == code)
    .map_or(0, |(_, i)| *i)
}

/// Browser names for keys whose winit name differs.
pub fn normalize(s: &str) -> &str {
    match s { "MetaLeft" | "OSLeft" => "SuperLeft", "MetaRight" | "OSRight" => "SuperRight", other => other }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::collections::HashSet;

    #[test]
    fn default_keymap_parses_and_two_players_share_a_keyboard() {
        let map = parse(DEFAULT_KEYMAP).unwrap();
        let held: HashSet<_> = [KeyCode::KeyX, KeyCode::KeyL, KeyCode::ControlRight].into();
        let p = pads(&map, &held, 0);
        assert_eq!(p[0], 1 << 0); // X = A on pad 1
        assert_eq!(p[1], (1 << 11) | (1 << 7)); // L = right, RCtrl = start on pad 2
        assert_eq!(pads(&map, &held, 2)[1], 0); // two gamepads: keyboard player 2 off
        assert!(parse("1 jump KeyX").is_err());
        assert!(parse("5 a KeyX").is_err());
        assert!(parse("1 a Escape").is_err());
    }
}