/*
 * Copyright 2022 Devin Lin <devin@kde.org>
 * SPDX-License-Identifier: LGPL-2.0-or-later
 */

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

import org.kde.kirigami as Kirigami

import "private" as Private

/**
 * @brief A single card that follows a form style.
 *
 * This is the entrypoint component for FormCard.
 *
 * A FormCard consists of a container that can be used to create your
 * own Settings pages. It has a different color than the background.
 *
 * Each FormCard can contain one or more Form delegates in its ::contentItem.
 * To add more than one Form delegate to a FormCard, use a
 * QtQuick.Layouts.ColumnLayout to group them.
 *
 * Multiple FormCards can be grouped with a QtQuick.Layouts.ColumnLayout to
 * represent different Settings sections.
 *
 * Each section is expected to contain a FormCardHeader as the first
 * delegate, which serves the role of a section title.
 *
 * The height of the FormCard matches the implicit height of the
 * ::contentItem and does not need to be set, while the width is expected
 * to be given by the parent, for example, via a Layout.fillWidth.
 *
 * @since KirigamiAddons 0.11.0
 *
 * @inherit QtQuick.Item
 */
Item {
    id: root

    /**
     * @brief The delegates inside the Form card.
     *
     * This is where you should add new Form delegates.
     */
    default property alias delegates: internalColumn.data

    /**
     * @brief The maximum width of the card.
     *
     * This can be set to a specific value to force its delegates to wrap
     * instead of using the entire width of the parent.
     *
     * default: `Kirigami.Units.gridUnit * 30`
     *
     * @see cardWidthRestricted
     */
    property real maximumWidth: Kirigami.Units.gridUnit * 30

    /**
     * @brief The padding used around the content edges.
     *
     * default: `0`
     */
    property real padding: 0
    property real verticalPadding: padding
    property real horizontalPadding: padding
    property real topPadding: verticalPadding
    property real bottomPadding: verticalPadding
    property real leftPadding: horizontalPadding
    property real rightPadding: horizontalPadding

    /**
     * Whether the card's width is being restricted.
     */
    readonly property bool cardWidthRestricted: root.width > root.maximumWidth

    Kirigami.Theme.colorSet: Kirigami.Theme.View
    Kirigami.Theme.inherit: false

    Layout.fillWidth: true

    implicitHeight: topPadding + bottomPadding + internalColumn.implicitHeight + rectangle.borderWidth * 2

    Kirigami.ShadowedRectangle {
        id: rectangle

        readonly property real borderWidth: 1
        readonly property bool isDarkColor: {
            const temp = Qt.darker(Kirigami.Theme.backgroundColor, 1);
            return temp.a > 0 && getDarkness(Kirigami.Theme.backgroundColor) >= 0.4;
        }

        // only have card radius if it isn't filling the entire width
        radius: root.cardWidthRestricted ? Kirigami.Units.cornerRadius : 0
        color: Kirigami.Theme.backgroundColor

        function getDarkness(background: color): real {
            // Thanks to Gojir4 from the Qt forum
            // https://forum.qt.io/topic/106362/best-way-to-set-text-color-for-maximum-contrast-on-background-color/
            var temp = Qt.darker(background, 1);
            var a = 1 - ( 0.299 * temp.r + 0.587 * temp.g + 0.114 * temp.b);
            return a;
        }

        anchors {
            top: parent.top
            bottom: parent.bottom
            left: parent.left
            right: parent.right

            leftMargin: root.cardWidthRestricted ? Math.round((root.width - root.maximumWidth) / 2) : -1
            rightMargin: root.cardWidthRestricted ? Math.round((root.width - root.maximumWidth) / 2) : -1
        }

        border {
            color: isDarkColor ? Qt.darker(Kirigami.Theme.backgroundColor, 1.2) : Kirigami.ColorUtils.linearInterpolation(Kirigami.Theme.backgroundColor, Kirigami.Theme.textColor, 0.15)
            width: borderWidth
        }

        shadow {
            size: isDarkColor ? Kirigami.Units.smallSpacing : Kirigami.Units.largeSpacing
            color: Qt.alpha(Kirigami.Theme.textColor, 0.10)
        }

        ColumnLayout {
            id: internalColumn

            // used in FormDelegateBackground to determine whether to round corners of the background
            readonly property bool _roundCorners: root.cardWidthRestricted

            spacing: 0

            // add 1 to margins to account for the border (so content doesn't overlap it)
            anchors {
                fill: parent
                leftMargin: root.leftPadding + rectangle.borderWidth
                rightMargin: root.rightPadding + rectangle.borderWidth
                topMargin: root.topPadding + rectangle.borderWidth
                bottomMargin: root.bottomPadding + rectangle.borderWidth
            }
        }
    }
}