// Copyright © SixtyFPS GmbH <info@slint-ui.com>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-commercial


import { md } from "md.slint";

// Allows to select a value from a range of values.
export Slider := Rectangle {
    property<float> maximum: 100;
    property<float> minimum: 0;
    property<float> value;
    property<bool> has-focus <=> fs.has-focus;
    property<bool> enabled <=> touch.enabled;
    callback changed(float);

    height: 20px;
    
    accessible-role: slider;
    accessible-value: value;
    accessible-value-minimum: minimum;
    accessible-value-maximum: maximum;
    accessible-value-step: (maximum - minimum) / 100;

    container := Rectangle {
        background: md.sys.color.surface-variant;
        opacity: 0.38;
        y: (parent.height - height) / 2;
        width: 100%;
        height: 4px;
        border-radius: 2px;
    }

    track := Rectangle {
        background: md.sys.color.primary;
        x: container.x;
        y: (parent.height - height) / 2;
        width: handle.x + (handle.width / 2);
        height: container.height;
        border-radius: container.border-radius;
    }

    state-layer := Rectangle {
        opacity: 0;
        background: md.sys.color.primary;
        x: handle.x - (width - handle.width) / 2;
        y: (parent.height - height) / 2;
        width: 40px;
        height: 40px;
        border-radius: max(width, height) / 2;
        animate opacity { duration: 250ms; easing: ease; }
    }

    handle := Rectangle {
        background: md.sys.color.primary;
        x: (parent.width - handle.width) * (value - minimum) / (maximum - minimum);
        y: (parent.height - height) / 2;
        width: root.height;
        height: root.height;
        border-radius: max(width, height) / 2;
        drop-shadow-color: md.sys.color.shadow;
        drop-shadow-blur: md.sys.elevation.level1;
        drop-shadow-offset-y: 1px;

        animate drop-shadow-blur { duration: 250ms; easing: ease; }
    }

    touch := TouchArea {
        property <float> pressed-value;
        property <bool> handle-hover: has-hover && mouse-x >= handle.x && mouse-x <= handle.x + handle.width 
            && mouse-y >= handle.y && mouse-y <= handle.y + handle.height;
        pointer-event(event) => {
            if (event.button == PointerEventButton.left && event.kind == PointerEventKind.down) {
                pressed-value = root.value;
            }
        }
        moved => {
            if (enabled && pressed) {
                value = max(root.minimum, min(root.maximum,
                    pressed-value + (touch.mouse-x - touch.pressed-x) * (maximum - minimum) / (root.width - handle.width)));
                root.changed(value);
            }
        }
    }

    fs := FocusScope {
        width: 0px;

        key-pressed(event) => {
            if (enabled && event.text == Keys.RightArrow) {
                value = Math.min(value + 1, maximum);
                accept
            } else if (enabled && event.text == Keys.LeftArrow) {
                value = Math.max(value - 1, minimum);
                accept
            } else {
                reject
            }
        }
    }

    states [
        disabled when !enabled : {
            handle.background: md.sys.color.on-surface;
            handle.drop-shadow-blur: md.sys.elevation.level0;
            track.background: md.sys.color.on-surface;
            container.background: md.sys.color.on-surface;
            root.opacity: 0.38;
        }
        pressed when (touch.pressed && touch.handle-hover) || fs.has-focus : {
            state-layer.opacity: 0.12;
            handle.drop-shadow-blur: md.sys.elevation.level0;
        }
        hover when touch.handle-hover : {
            state-layer.background: md.sys.color.on-surface;
            state-layer.opacity: 0.08;    
        }
    ]
}