//! Input device configuration, as declared in config.zig.
//!
//! Like action.zig this module depends on nothing but the standard library, so
//! that config.zig can import it without a cycle back into the window manager.
//! `src/InputManager.zig` is what puts these values onto river's protocol
//! objects.
//!
//! Every device setting is optional, and null means "leave it alone" — libinput
//! picks per-device defaults that are usually right, so a rule should say only
//! what it wants changed.

const std = @import("std");

/// The kind of device, mirroring `river_input_device_v1.type`.
///
/// Note that a touchpad reports `pointer`, not `touch`: libinput models it as a
/// pointer that happens to support tapping. `touch` is a touchscreen.
pub const Type = enum { keyboard, pointer, touch, tablet };

/// xkb rule names — the RMLVO that `setxkbmap` and every other Wayland
/// compositor take. att_wm compiles these into a keymap and hands it to every
/// keyboard river reports.
///
/// A null field is left to xkbcommon, which reads the `XKB_DEFAULT_*`
/// environment variables and otherwise falls back to a plain `us` layout. So
/// the default of all-null is exactly what you get without this protocol at all.
pub const Keymap = struct {
    /// Rules file, e.g. "evdev". Rarely worth setting.
    rules: ?[]const u8 = null,
    model: ?[]const u8 = null,
    /// One layout, or several separated by commas: "us,se".
    layout: ?[]const u8 = null,
    /// Variants, positionally matching `layout`: "dvorak," is dvorak for the
    /// first layout and the default variant for the second.
    variant: ?[]const u8 = null,
    /// Comma separated, e.g. "grp:alt_shift_toggle,caps:escape". With more than
    /// one layout configured, a `grp:` option is how you switch between them —
    /// xkb does the switching itself, so att_wm needs no binding for it.
    options: ?[]const u8 = null,

    /// True when nothing is set, in which case there is no point compiling a
    /// keymap: river's own default is already what we would produce.
    pub fn isDefault(self: Keymap) bool {
        inline for (std.meta.fields(Keymap)) |field| {
            if (@field(self, field.name) != null) return false;
        }
        return true;
    }
};

/// Key repeat as applied by the compositor to the focused client.
///
/// This is not the same thing as `config.binding_repeat_delay` and
/// `config.binding_repeat_interval`, which govern how fast att_wm re-runs a held-down
/// *binding*: river reports binding press and release and leaves repeating to
/// us. These two are what every other application sees.
/// The defaults are river's own, so a config that says nothing about repeat
/// leaves keyboards exactly as they would have been.
pub const Repeat = struct {
    /// Repeats per second. Zero disables key repeat entirely.
    rate: i32 = 40,
    /// Milliseconds a key must be held before repeating starts.
    delay: i32 = 400,
};

pub const ButtonMap = enum {
    /// One finger left, two right, three middle. libinput's default.
    lrm,
    /// One finger left, two middle, three right.
    lmr,
};

pub const DragLock = enum {
    disabled,
    /// Lifting the finger keeps the drag alive for a short timeout.
    timeout,
    /// Lifting the finger keeps the drag alive until the next tap.
    sticky,
};

pub const ThreeFingerDrag = enum { disabled, three_finger, four_finger };

pub const ClickMethod = enum {
    none,
    /// Bottom of the touchpad split into left/middle/right zones.
    button_areas,
    /// Number of fingers on the pad decides the button.
    clickfinger,
};

pub const AccelProfile = enum {
    /// No acceleration: movement maps to pointer travel one to one.
    none,
    /// Constant factor, no acceleration.
    flat,
    /// Speed-dependent acceleration. libinput's default for most devices.
    adaptive,
};

pub const ScrollMethod = enum {
    none,
    two_finger,
    edge,
    /// Moving the device while `scroll_button` is held scrolls.
    on_button_down,
};

pub const SendEvents = enum {
    enabled,
    disabled,
    /// Useful for a laptop touchpad that should go quiet when a mouse is
    /// plugged in.
    disabled_on_external_mouse,
};

/// Matched against the name and type of every input device river reports.
///
/// att_wm logs one line per device at startup — name and type — which is where
/// the names come from; there is no `list-inputs` to run because the protocol
/// only shows devices to the window manager itself.
pub const Rule = struct {
    /// Device name to match. `*` matches any run of characters, so
    /// `"*Touchpad*"` catches the usual "ELAN0501:00 04F3:3060 Touchpad"
    /// without you having to write it out. Null matches every device.
    name: ?[]const u8 = null,
    /// Restrict the rule to one kind of device. Null matches every kind.
    type: ?Type = null,

    // ─── Keyboards ───

    /// Per-device override of `config.repeat`.
    repeat: ?Repeat = null,

    // ─── Pointers, touchpads, touchscreens ───

    /// Confine a touchscreen or tablet to one output, named as river names it —
    /// "eDP-1", the same name the IPC `outputs` list uses.
    ///
    /// Two reasons to want this. On multiple monitors an unmapped touchscreen
    /// spans the whole output layout, so touching the left of the panel lands on
    /// the wrong screen. And it is what makes touch survive **display
    /// rotation**: a mapped device has the output's transform applied to its
    /// coordinates on every event, so rotating with `wlr-randr` or rot8 rotates
    /// touch along with it, with no rotation hook and no calibration matrix.
    ///
    /// Do not combine with an external calibration matrix for rotation — the two
    /// transforms compose, and the result is rotated twice.
    ///
    /// Ignored for keyboards, which have no coordinates to map.
    map_to_output: ?[]const u8 = null,

    /// Multiplier on scroll distance: 0.5 scrolls half as far, 3.0 three times
    /// as far. Applied by river rather than libinput, so it works on any
    /// pointer.
    scroll_factor: ?f64 = null,

    /// Tap to click.
    tap: ?bool = null,
    /// Which button each finger count taps.
    tap_button_map: ?ButtonMap = null,
    /// Tap and then drag without a second tap.
    drag: ?bool = null,
    /// Whether lifting the finger mid-drag ends it.
    drag_lock: ?DragLock = null,
    /// Hold three (or four) fingers to drag.
    three_finger_drag: ?ThreeFingerDrag = null,

    /// What a physical click on a touchpad means.
    click_method: ?ClickMethod = null,
    /// Which button each finger count clicks, under `.clickfinger`.
    clickfinger_button_map: ?ButtonMap = null,
    /// Left and right buttons together act as middle click.
    middle_emulation: ?bool = null,
    /// Swap left and right buttons.
    left_handed: ?bool = null,

    /// Content follows the fingers rather than the viewport, as on a phone.
    natural_scroll: ?bool = null,
    scroll_method: ?ScrollMethod = null,
    /// Linux input event code — `input.btn.middle` and friends. Only meaningful
    /// with `scroll_method = .on_button_down`.
    scroll_button: ?u32 = null,
    /// Whether the scroll button must be held, or toggles.
    scroll_button_lock: ?bool = null,

    accel_profile: ?AccelProfile = null,
    /// Pointer speed in [-1, 1]; 0 is the device's default.
    accel_speed: ?f64 = null,

    /// Ignore the touchpad while the keyboard is being typed on.
    disable_while_typing: ?bool = null,
    /// Ignore the touchpad while the trackpoint is in use.
    disable_while_trackpointing: ?bool = null,

    /// Clockwise rotation in degrees, for a device mounted sideways.
    rotation: ?u32 = null,

    /// Whether the device sends events at all.
    send_events: ?SendEvents = null,

    /// Fields that select which devices a rule applies to rather than
    /// configuring them, and so are not merged by `merge`.
    const selectors = .{ "name", "type" };

    /// Fold `other` on top of `self`: every setting `other` states wins, every
    /// setting it leaves null keeps the value it had.
    ///
    /// Rules are applied in the order they are declared, so a broad rule can set
    /// a house style and a later, narrower one can dissent from it — the same
    /// last-one-wins that dwm's window rules have.
    pub fn merge(self: Rule, other: Rule) Rule {
        var out = self;
        inline for (std.meta.fields(Rule)) |field| {
            comptime var is_selector = false;
            inline for (selectors) |name| {
                if (comptime std.mem.eql(u8, field.name, name)) is_selector = true;
            }
            if (!is_selector) {
                if (@field(other, field.name)) |v| @field(out, field.name) = v;
            }
        }
        return out;
    }

    /// True if this rule should apply to a device with the given name and type.
    pub fn matchesDevice(self: Rule, device_name: []const u8, device_type: Type) bool {
        if (self.type) |t| {
            if (t != device_type) return false;
        }
        if (self.name) |pattern| {
            if (!matches(pattern, device_name)) return false;
        }
        return true;
    }
};

/// Glob match supporting `*` as "any run of characters, including none".
///
/// Deliberately no `?` or character classes: device names are long, noisy and
/// full of punctuation, and `*` on either end is all anyone needs to pin one
/// down. Iterative with a backtrack point rather than recursive, so a pattern
/// like `"*a*a*a*"` cannot blow the stack.
pub fn matches(pattern: []const u8, name: []const u8) bool {
    var p: usize = 0;
    var n: usize = 0;
    // Where to resume if the run we are in turns out not to match: the `*` that
    // let us in, and how far it had consumed.
    var star: ?usize = null;
    var star_n: usize = 0;

    while (n < name.len) {
        if (p < pattern.len and pattern[p] == '*') {
            star = p;
            p += 1;
            star_n = n;
        } else if (p < pattern.len and pattern[p] == name[n]) {
            p += 1;
            n += 1;
        } else if (star) |s| {
            // Let the last `*` swallow one more byte and try again.
            p = s + 1;
            star_n += 1;
            n = star_n;
        } else {
            return false;
        }
    }

    // Trailing `*`s can still match the empty remainder.
    while (p < pattern.len and pattern[p] == '*') p += 1;
    return p == pattern.len;
}

/// Linux input event codes for the buttons worth binding to scrolling. The same
/// values `action.btn` has; duplicated rather than imported so this module keeps
/// its single dependency on the standard library.
pub const btn = struct {
    pub const left: u32 = 0x110;
    pub const right: u32 = 0x111;
    pub const middle: u32 = 0x112;
};