// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.2 OR LicenseRef-Slint-commercial


import { MaterialPalette } from "styling.slint";

component ScrollBar inherits Rectangle {
    in-out property <bool> horizontal;
    in-out property <length> maximum;
    in-out property <length> page-size;
    // this is always negative and bigger than  -maximum
    in-out property <length> value;
    in-out property <bool> enabled <=> i-touch-area.enabled;

    states [
        disabled when !i-touch-area.enabled : {
            i-background.border-color: MaterialPalette.control-foreground;
            i-handle.opacity: 0.12;
        }
        hover when i-touch-area.has-hover : {
            i-state-layer.opacity: 0.08;
        }
        pressed when i-touch-area.has-hover : {
            i-state-layer.opacity: 0.12;
        }
    ]

    i-state-layer := Rectangle {
        width: 100%;
        height: 100%;
        background: MaterialPalette.accent-background;
        border-radius: 4px;
        opacity: 0;
        visible: i-handle.width > 0 && i-handle.height > 0;

        animate opacity { duration: 250ms; easing: ease; }
    }

    i-handle := Rectangle {
        x: !root.horizontal ? 0phx : (root.width - i-handle.width) * (-root.value / root.maximum);
        y: root.horizontal ? 0phx : (root.height - i-handle.height) * (-root.value / root.maximum);
        width: !root.horizontal ? parent.width : root.maximum <= 0phx ? 0phx : max(32px, parent.width * max(root.page-size / (root.maximum + root.page-size)));
        height: root.horizontal ? parent.height : root.maximum <= 0phx ? 0phx : max(32px, parent.height * (root.page-size / (root.maximum + root.page-size)));

        i-background := Rectangle {
            width: 100%;
            height: 100%;
            border-radius: 4px;
            border-color: MaterialPalette.border;
            border-width: 1px;
        }
    }

    i-touch-area := TouchArea {
        property <length> pressed-value;

        width: parent.width;
        height: parent.height;

        pointer-event(event) => {
            if (event.button == PointerEventButton.left && event.kind == PointerEventKind.down) {
                self.pressed-value = -root.value;
            }
        }

        moved => {
            if (self.enabled && self.pressed) {
                root.value = -max(0px, min(root.maximum, self.pressed-value + (
                    root.horizontal ? (i-touch-area.mouse-x - i-touch-area.pressed-x) * (root.maximum / (root.width - i-handle.width))
                               : (i-touch-area.mouse-y - i-touch-area.pressed-y) * (root.maximum / (root.height - i-handle.height))
                )));
            }
        }

        scroll-event(event) => {
            if (root.horizontal && event.delta-x != 0) {
                root.value = max(-root.maximum, min(0px, root.value + event.delta-x));
                return accept;
            } else if (!root.horizontal && event.delta-y != 0) {
                root.value = max(-root.maximum, min(0px, root.value + event.delta-y));
                return accept;
            }
            reject
        }
    }
}

// Scrollview contains a viewport that is bigger than the view and can be scrolled.
export component ScrollView {
    in property <bool> enabled: true;
    out property <length> visible-width <=> i-flickable.width;
    out property <length> visible-height <=> i-flickable.height;
    in-out property <bool> has-focus;
    in-out property <length> viewport-width <=> i-flickable.viewport-width;
    in-out property <length> viewport-height <=> i-flickable.viewport-height;
    in-out property <length> viewport-x <=> i-flickable.viewport-x;
    in-out property <length> viewport-y <=> i-flickable.viewport-y;

    min-height: 50px;
    min-width: 50px;
    horizontal-stretch: 1;
    vertical-stretch: 1;
    preferred-height: 100%;
    preferred-width: 100%;

    Rectangle {
        background: MaterialPalette.alternate-background;
    }

    i-flickable := Flickable {
        x:0;y:0;
        viewport-y <=> i-vertical-bar.value;
        viewport-x <=> i-horizontal-bar.value;
        width: parent.width - i-vertical-bar.width - 4px;
        height: parent.height - i-horizontal-bar.height - 4px;

        @children
    }

    i-vertical-bar := ScrollBar {
        width: 8px;
        x: i-flickable.width + i-flickable.x;
        y: i-flickable.y;
        height: i-flickable.height;
        horizontal: false;
        maximum: i-flickable.viewport-height - i-flickable.height;
        page-size: i-flickable.height;
        enabled: root.enabled;
    }

    i-horizontal-bar := ScrollBar {
        height: 8px;
        y: i-flickable.height + i-flickable.y;
        x: i-flickable.x;
        width: i-flickable.width;
        horizontal: true;
        maximum: i-flickable.viewport-width - i-flickable.width;
        page-size: i-flickable.width;
        enabled: root.enabled;
    }
}
