/*
    SPDX-FileCopyrightText: 2012-2013 Eike Hein <hein@kde.org>
    SPDX-FileCopyrightText: 2021 Fushan Wen <qydwhotmail@gmail.com>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

import QtQuick 2.15
// Deliberately imported after QtQuick to avoid missing restoreMode property in Binding. Fix in Qt 6.
import QtQml 2.15
import QtQml.Models 2.15
import QtQuick.Window 2.15

import org.kde.plasma.core 2.0 as PlasmaCore
import org.kde.plasma.components 3.0 as PlasmaComponents3
import org.kde.draganddrop 2.0

import "code/layout.js" as LayoutManager

PlasmaCore.Dialog {
    id: groupDialog
    visible: false

    type: PlasmaCore.Dialog.PopupMenu
    flags: Qt.WindowStaysOnTopHint
    hideOnWindowDeactivate: true
    location: plasmoid.location

    readonly property int preferredWidth: Screen.width / (3 * Screen.devicePixelRatio)
    readonly property int preferredHeight: Screen.height / (2 * Screen.devicePixelRatio)
    readonly property int contentWidth: mainItem.width // No padding here to avoid text elide.

    property alias overflowing: scrollView.overflowing
    property var _oldAppletStatus: PlasmaCore.Types.UnknownStatus

    property var activeTask: null

    function findActiveTaskIndex() {
        if (!activeTask) {
            return;
        }
        for (let i = 0; i < groupListView.count; i++) {
            if (tasksModel.makeModelIndex(visualParent.itemIndex, i) === activeTask) {
                groupListView.positionViewAtIndex(i, ListView.Contain); // Prevent visual glitches
                groupListView.currentIndex = i;
                return;
            }
        }
    }


    mainItem: MouseHandler {
        id: mouseHandler
        // HACK: 1 is to prevent "trying to show an empty dialog" warning.
        width: Math.min(groupDialog.preferredWidth, Math.max(groupListView.maxWidth, groupDialog.visualParent ? groupDialog.visualParent.width : 0, 1))
        height: Math.max(Math.min(groupDialog.preferredHeight, groupListView.maxHeight), 1)

        target: groupListView
        handleWheelEvents: !scrollView.overflowing
        isGroupDialog: true

        PlasmaComponents3.ScrollView {
            id: scrollView
            anchors.fill: parent
            readonly property bool overflowing: leftPadding > 0 || rightPadding > 0 // Scrollbar is visible

            PlasmaComponents3.ScrollBar.horizontal.policy: PlasmaComponents3.ScrollBar.AlwaysOff

            ListView {
                id: groupListView

                readonly property int maxWidth: groupFilter.maxTextWidth
                                                + LayoutManager.horizontalMargins()
                                                + PlasmaCore.Units.iconSizes.medium
                                                + 2 * (LayoutManager.labelMargin + LayoutManager.iconMargin)
                                                + scrollView.leftPadding + scrollView.rightPadding
                // Use groupFilter.count because sometimes count is not updated in time (BUG 446105)
                readonly property int maxHeight: groupFilter.count * (LayoutManager.verticalMargins() + Math.max(theme.mSize(theme.defaultFont).height, PlasmaCore.Units.iconSizes.medium))

                model: DelegateModel {
                    id: groupFilter

                    readonly property TextMetrics textMetrics: TextMetrics {}
                    property int maxTextWidth: 0

                    model: groupDialog.visualParent ? tasksModel : null
                    Binding on rootIndex { // Use Binding to re-evaluate rootIndex only when visible is true
                        // TasksModel::makeModelIndex() returns QModelIndex()
                        // when row argument is less than 0 or more than count
                        value: tasksModel.makeModelIndex(
                            groupDialog.visualParent ? groupDialog.visualParent.itemIndex : -1
                        )
                        when: groupDialog.visualParent && groupDialog.visible // implicitly using visible as a way to trigger re-evaluation
                        restoreMode: Binding.RestoreNone // Store rootIndex to avoid sudden changes in height
                    }
                    delegate: Task {
                        visible: true
                        inPopup: true

                        ListView.onRemove: Qt.callLater(groupFilter.updateMaxTextWidth)
                        Connections {
                            enabled: index < 20 // 20 is based on performance considerations.

                            function onLabelTextChanged() { // ListView.onAdd included
                                Qt.callLater(groupFilter.updateMaxTextWidth);
                            }
                        }
                    }

                    function updateMaxTextWidth() {
                        let tempMaxTextWidth = 0;
                        // 20 is based on performance considerations.
                        for (let i = 0; i < Math.min(count, 20); i++) {
                            textMetrics.text = items.get(i).model.display;
                            if (textMetrics.boundingRect.width > tempMaxTextWidth) {
                                tempMaxTextWidth = textMetrics.boundingRect.width;
                            }
                        }
                        maxTextWidth = tempMaxTextWidth;
                    }
                }

                reuseItems: false

                onCountChanged: if (count > 0) backend.cancelHighlightWindows()
            }
        }
    }

    onVisibleChanged: {
        if (visible && visualParent) {
            _oldAppletStatus = plasmoid.status;
            plasmoid.status = PlasmaCore.Types.RequiresAttentionStatus;

            groupDialog.requestActivate();
            groupListView.forceActiveFocus(); // Active focus on ListView so keyboard navigation can work.
            Qt.callLater(findActiveTaskIndex);
        } else {
            plasmoid.status = _oldAppletStatus;
        }
    }

    onVisualParentChanged: activeTask = null
}