/*
    SPDX-FileCopyrightText: 2013-2015 Eike Hein <hein@kde.org>

    SPDX-License-Identifier: GPL-2.0-or-later
*/
pragma ComponentBehavior: Bound

import QtQuick
import QtQuick.Layouts

import org.kde.kirigami as Kirigami
import org.kde.ksvg as KSvg
import org.kde.plasma.components as PlasmaComponents3
import org.kde.plasma.core as PlasmaCore
import org.kde.plasma.extras as PlasmaExtras
import org.kde.plasma.plasmoid
import org.kde.plasma.private.kicker as Kicker

PlasmaComponents3.ScrollView {
    id: root

    required property Kicker.KAStatsFavoritesModel globalFavorites
    required property Kicker.SimpleFavoritesModel systemFavorites
    required property Kicker.RootModel rootModel
    required property Kicker.RunnerModel runnerModel

    signal interactionConcluded

    focus: true

    Layout.minimumWidth: Math.min(Math.max(mainRow.Layout.minimumWidth, mainRow.implicitWidth), Screen.width - Kirigami.Units.largeSpacing * 4)
    Layout.maximumWidth: Layout.minimumWidth

    contentWidth: mainRow.implicitWidth

    Layout.minimumHeight: Math.min(Math.max(sideBar.implicitHeight, rootList.implicitHeight + rootList.Layout.bottomMargin), Math.round(Screen.height * 0.8))
    Layout.maximumHeight: Layout.minimumHeight

    function ensureVisible(item: Item) : void {
        const actualItemX = item.x
        const viewXPosition = (item.width <= contentItem.width)
            ? Math.round(actualItemX + item.width / 2 - contentItem.width / 2)
            : actualItemX
        const flickable = contentItem as Flickable
        if (actualItemX < flickable.contentX) {
            flickable.contentX = Math.max(0, viewXPosition)
        } else if ((actualItemX + item.width) > (flickable.contentX + flickable.width)) {
            flickable.contentX = Math.min(flickable.contentWidth - flickable.width, viewXPosition)
        }
        flickable.returnToBounds()
    }

    function focusRunnerColumn(column, focusTopElement = true) : void {
        if (runnerColumns.visibleChildren.length <= column + 1) { // visibleChildren includes repeater
            return
        }
        const targetList = runnerColumns.visibleChildren[column]
        targetList.currentIndex = focusTopElement ? 0 : (targetList.count - 1)
        targetList.giveFocus(Qt.TabFocusReason)
        root.ensureVisible(targetList)
    }

    function focusRootList(focusTopElement = true) : void {
        rootList.currentIndex = focusTopElement ? 0 : (rootList.model.count - 1)
        rootList.forceActiveFocus(Qt.TabFocusReason)
    }

    function focusSideBar() : void {
        sideBar.forceActiveFocus(Qt.TabFocusReason)
        root.ensureVisible(sideBar)
    }


    function reset() {
        rootList.currentIndex = -1;
        hoverBlock.reset();

        searchField.text = "";
        searchField.focus = true;
    }

    RowLayout {
        id: mainRow

        anchors.fill: parent

        spacing: 0

        Layout.minimumWidth: sideBar.implicitWidth + sideBar.Layout.rightMargin + searchField.defaultWidth
        LayoutMirroring.enabled: ((Plasmoid.location === PlasmaCore.Types.RightEdge)
            || (Application.layoutDirection === Qt.RightToLeft && Plasmoid.location !== PlasmaCore.Types.LeftEdge))

        KSvg.FrameSvgItem {
            id: sideBar

            property bool onTopPanel: Plasmoid.location === PlasmaCore.Types.TopEdge

            visible: (root.globalFavorites.count + root.systemFavorites.count) > 0

            Layout.fillHeight: true
            Layout.rightMargin: Kirigami.Units.smallSpacing

            implicitWidth: Math.max(favoriteApps.implicitWidth, favoriteSystemActions.implicitWidth) + margins.left + margins.right + sideBarScrollView.actualScrollBarWidth
            implicitHeight: sideBarLayout.implicitHeight + margins.top + margins.bottom

            imagePath: "widgets/frame"
            prefix: "plain"

            function handleLeftRightArrow(event: KeyEvent) : void {
                let backArrowKey = (event.key === Qt.Key_Left && !mainRow.LayoutMirroring.enabled) ||
                    (event.key === Qt.Key_Right && mainRow.LayoutMirroring.enabled)
                let forwardArrowKey = (event.key === Qt.Key_Right && !mainRow.LayoutMirroring.enabled) ||
                    (event.key === Qt.Key_Left && mainRow.LayoutMirroring.enabled)
                if (backArrowKey & runnerColumns.visibleChildren.length > 1) {
                    root.focusRunnerColumn(runnerColumns.visibleChildren.length - 2, true)
                } else if (forwardArrowKey) {
                    if (runnerColumns.visibleChildren.length > 1) {
                        root.focusRunnerColumn(0, true)
                    } else if (rootList.visible) {
                        root.focusRootList(true)
                    } else {
                        searchField.forceActiveFocus(Qt.TabFocusReason)
                    }
                } else {
                    event.accepted = false
                }
            }

            activeFocusOnTab: true
            onActiveFocusChanged: if (activeFocus) {
                let target = (onTopPanel && favoriteSystemActions.model.count) ? favoriteSystemActions : favoriteApps
                target.forceActiveFocus(Qt.TabFocusReason)
            }
            KeyNavigation.right: rootList

            PlasmaComponents3.ScrollView {
                id: sideBarScrollView

                anchors.top: parent.top
                anchors.horizontalCenter: parent.horizontalCenter
                height: parent.height

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

                readonly property int actualScrollBarWidth: scrollBarVisible ? sideBarScrollView.PlasmaComponents3.ScrollBar.vertical.width : 0
                property bool scrollBarVisible
                Binding on scrollBarVisible {
                    value: sideBarScrollView.contentHeight > Screen.width - Kirigami.Units.largeSpacing * 4
                    delayed: true // this needs to be delayed or it can get stuck in a resize loop
                }

                function ensureVisible(item: Item) {
                    let flickable = (contentItem as Flickable)
                    let actualItemY = flickable.mapFromItem(item, 0, 0).y
                    let viewYPosition = (item.height <= contentItem.height)
                        ? Math.round(actualItemY + item.height / 2 - contentItem.height / 2)
                        : actualItemY
                    if (actualItemY < flickable.contentY) {
                        flickable.contentY = Math.max(0, viewYPosition)
                    } else if ((actualItemY + item.height) > (flickable.contentY + flickable.height)) {
                        flickable.contentY = Math.min(flickable.contentHeight - flickable.height, viewYPosition)
                    }
                    flickable.returnToBounds()
                }

                ColumnLayout {
                    id: sideBarLayout
                    height: Math.max(implicitHeight, parent.height)
                    width: parent.width

                    Accessible.role: Accessible.List
                    Accessible.name: i18nc("@title:group accessible name for favorite group in sidebar", "Favorites")

                    Keys.onLeftPressed: event => sideBar.handleLeftRightArrow(event)
                    Keys.onRightPressed: event => sideBar.handleLeftRightArrow(event)

                    LayoutItemProxy {
                        target: sideBar.onTopPanel ? favoriteSystemActions : favoriteApps
                        Layout.topMargin: sideBar.margins.top
                    }
                    KSvg.SvgItem {
                        id: sidebarSeparator

                        Layout.fillWidth: true
                        Layout.leftMargin: Kirigami.Units.smallSpacing
                        Layout.rightMargin: Layout.leftMargin
                        Layout.alignment: Qt.AlignHCenter

                        visible: (favoriteApps.model && favoriteApps.model.count
                            && favoriteSystemActions.model && favoriteSystemActions.model.count)

                        imagePath: "widgets/line"
                        elementId: "horizontal-line"
                    }
                    LayoutItemProxy {
                        target: sideBar.onTopPanel ? favoriteApps : favoriteSystemActions
                        Layout.topMargin: sideBar.margins.bottom
                    }

                    SideBarSection {
                        id: favoriteApps

                        Layout.fillHeight: true
                        Layout.alignment: Qt.AlignHCenter

                        KeyNavigation.up: favoriteSystemActions.bottomSideBarItem
                        KeyNavigation.down: favoriteSystemActions

                        model: root.globalFavorites
                        onItemFocused: item => sideBarScrollView.ensureVisible(item)
                        onInteractionConcluded: root.interactionConcluded()

                        Binding {
                            target: root.globalFavorites
                            property: "iconSize"
                            value: Kirigami.Units.iconSizes.medium
                            restoreMode: Binding.RestoreBinding
                        }
                    }

                    SideBarSection {
                        id: favoriteSystemActions

                        Layout.alignment: Qt.AlignHCenter

                        model: root.systemFavorites
                        onItemFocused: item => sideBarScrollView.ensureVisible(item)
                        onInteractionConcluded: root.interactionConcluded()
                        KeyNavigation.up: favoriteApps.bottomSideBarItem
                        KeyNavigation.down: favoriteApps
                    }
                }
            }
        }

        ItemListView {
            id: rootList

            Layout.alignment: Qt.AlignTop
            Layout.bottomMargin: searchField.implicitHeight + Kirigami.Units.smallSpacing
            Layout.fillHeight: true
            Layout.fillWidth: true
            Layout.maximumHeight: implicitHeight


            visible: searchField.text === ""

            iconsEnabled: Plasmoid.configuration.showIconsRootLevel

            hoverEnabled: !hoverBlock.enabled

            mainSearchField: searchField

            model: root.rootModel

            LayoutMirroring.enabled: mainRow.LayoutMirroring.enabled

            showSeparators: true // keep even if sorted, the one between recents and categories works

            onInteractionConcluded: root.interactionConcluded()
            onKeyNavigationAtListEnd: {
                searchField.focus = true;
            }

            onNavigateLeftRequested: {
                if (!sideBar.visible) {
                    return
                }
                currentIndex = -1
                root.focusSideBar()
            }

            Component.onCompleted: {
                rootList.exited.connect(root.reset);
            }
        }

        RowLayout {
            id: runnerColumns

            readonly property bool searchResultsPresent: runnerColumns.visibleChildren[0] instanceof RunnerResultsList

            Layout.fillHeight: true

            visible: searchField.text !== "" && root.runnerModel.count > 0

            spacing: Kirigami.Units.smallSpacing

            LayoutMirroring.enabled: mainRow.LayoutMirroring.enabled

            Repeater {
                id: runnerColumnsRepeater

                model: root.runnerModel

                delegate: RunnerResultsList {
                    id: runnerMatches

                    Layout.fillHeight: true
                    Layout.fillWidth: true

                    visible: model.count > 0 || (model.querying && visible)

                    model: root.runnerModel.modelForRow(index)
                    mainSearchField: searchField

                    LayoutMirroring.enabled: runnerColumns.LayoutMirroring.enabled

                    function navigateToAdjacentColumn(forward = true) {
                        let currentColumnIndex = runnerColumns.visibleChildren.indexOf(runnerMatches)
                        let targetColumnIndex = currentColumnIndex + (forward ? 1 : -1)
                        if (currentColumnIndex < 0 || runnerColumns.visibleChildren.length <= 2) {
                            return
                        }
                        currentIndex = -1
                        if (targetColumnIndex >= 0 && targetColumnIndex < (runnerColumns.visibleChildren.length - 1)) {
                            root.focusRunnerColumn(targetColumnIndex)
                        } else if (sideBar.visible) {
                            root.focusSideBar()
                        } else {
                            root.focusRunnerColumn(forward ? 0 : runnerColumns.visibleChildren.length - 2)
                        }
                    }

                    onFocusChanged: {
                        if (!focus) {
                            currentIndex = -1;
                        }
                    }

                    onInteractionConcluded: root.interactionConcluded()
                    onNavigateLeftRequested: navigateToAdjacentColumn(false)
                    onNavigateRightRequested: navigateToAdjacentColumn(true)
                }
            }

        }
        PlasmaExtras.PlaceholderMessage {
            id: noMatchesPlaceholder

            property bool searchRunning: false
            property string lastQuery: "" // copy to avoid timing conflicts with visible binding

            Layout.minimumWidth: searchField.defaultWidth
            Layout.alignment: Qt.AlignHCenter | Qt.AlignVCenter

            visible: lastQuery !== "" && !runnerColumns.searchResultsPresent && (!searchRunning || visible)
            iconName: "edit-none"
            text: i18nc("@info:status", "No matches")

            Connections {
                target: root.runnerModel

                function onQueryFinished() {
                    noMatchesPlaceholder.searchRunning = false
                }
            }

            Connections {
                target: searchField

                function onTextChanged() {
                    noMatchesPlaceholder.searchRunning = searchField.text !== ""
                    noMatchesPlaceholder.lastQuery = searchField.text
                }
            }

            Binding {
                searchField.width: searchField.defaultWidth
                when: noMatchesPlaceholder.visible
            }
        }
    }

    PlasmaExtras.SearchField {
        id: searchField

        readonly property int spacing: sideBar.width ? sideBar.Layout.rightMargin : 0

        anchors.bottom: mainRow.bottom
        anchors.left: parent.left
        anchors.leftMargin: sideBar.visible ? sideBar.width + spacing : 0

        readonly property real defaultWidth: Kirigami.Units.gridUnit * 14

        width: runnerColumns.visible
            ? (runnerColumns.searchResultsPresent ? runnerColumns.visibleChildren[0].width : defaultWidth)
            : (rootList.visible ? rootList.width : defaultWidth)

        focus: !Kirigami.InputMethod.willShowOnActive

        onTextChanged: {
            root.runnerModel.query = text;
        }

        onFocusChanged: {
            if (focus) {
                // FIXME: Cleanup arbitration between rootList/runnerCols here and in Keys.
                if (rootList.visible) {
                    rootList.currentIndex = -1;
                }

                if (runnerColumns.visible) {
                    runnerColumnsRepeater.itemAt(0).currentIndex = -1;
                }
            }
        }

        states: [
            State {
                name: "right"
                when: (Plasmoid.location === PlasmaCore.Types.RightEdge && Application.layoutDirection === Qt.LeftToRight)
                    || (Plasmoid.location === PlasmaCore.Types.LeftEdge && Application.layoutDirection === Qt.RightToLeft)

                AnchorChanges {
                    target: searchField
                    anchors.top: undefined
                    anchors.bottom: mainRow.bottom
                    anchors.left: undefined
                    anchors.right: parent.right
                }

                PropertyChanges {
                    searchField.anchors.leftMargin: undefined
                    searchField.anchors.rightMargin: sideBar.visible ? sideBar.width + spacing : 0
                }
            }
        ]

        function handleUpDownArrow(event: KeyEvent) : void {
            if (rootList.visible) {
                root.focusRootList(event.key === Qt.Key_Down);
            } else if (runnerColumns.visible) {
                let index = runnerColumns.visibleChildren[0].currentIndex
                root.focusRunnerColumn(0, event.key === Qt.Key_Down)
                // First column, first entry is initially selected even when focus is on the search
                // field, as Return will activate it. Down should immediately go to the second entry.
                if (index === 0 && event.key === Qt.Key_Down) {
                    runnerColumns.visibleChildren[0].currentIndex = Math.min(index + 1, runnerColumns.visibleChildren[0].count - 1)
                }
            } else {
                event.accepted = false
            }
        }

        function handleLeftRightArrow(event: KeyEvent) : void {
            let backArrowKey = (event.key === Qt.Key_Left && !mainRow.LayoutMirroring.enabled) ||
                (event.key === Qt.Key_Right && mainRow.LayoutMirroring.enabled)
            let forwardArrowKey = (event.key === Qt.Key_Right && !mainRow.LayoutMirroring.enabled) ||
                (event.key === Qt.Key_Left && mainRow.LayoutMirroring.enabled)

            if (backArrowKey) {
                if (!sideBar.visible && !runnerColumns.visible) {
                    return;
                }
                if (runnerColumns.visibleChildren[0]?.length > 1) {
                    runnerColumns.visibleChildren[0].currentIndex = -1;
                }
                if (sideBar.visible) {
                    root.focusSideBar(true)
                } else {
                    root.focusRunnerColumn(runnerColumns.visibleChildren.length - 2, true)
                }
            } else if (forwardArrowKey && runnerColumns.visibleChildren.length > 2) {
                runnerColumns.visibleChildren[0].currentIndex = -1;
                root.focusRunnerColumn(1, true)
            } else {
                event.accepted = false
            }
        }

        function launchBestMatch() : void  {
            if (runnerColumns.visible) {
                for (let i = 0; i < root.runnerModel.count; ++i) {
                    if (root.runnerModel.modelForRow(i).count) {
                        root.runnerModel.modelForRow(i).trigger(0, "", null);
                        onInteractionConcluded: root.interactionConcluded()
                        break;
                    }
                }
            }
        }

        Keys.priority: Keys.AfterItem // arrow keys should move cursor first
        Keys.onUpPressed: event => handleUpDownArrow(event)
        Keys.onDownPressed: event => handleUpDownArrow(event)
        Keys.onLeftPressed: event => handleLeftRightArrow(event)
        Keys.onRightPressed: event => handleLeftRightArrow(event)
        Keys.onEnterPressed: launchBestMatch()
        Keys.onReturnPressed: launchBestMatch()
        Keys.onEscapePressed: root.interactionConcluded()

        function appendText(newText) {
            focus = true;
            text = text + newText;
        }
    }

    Component.onCompleted: {
        kicker.modelRefreshed.connect(() => {
            const searchTerm = searchField.text
            root.reset()
            runnerModel.clear() // runnerModel is on a timer, clearing and setting query is too fast to work
            searchField.text = searchTerm
        });
        kicker.reset.connect(reset)

        rootModel.refresh();
    }

    MouseArea {
        id: hoverBlock  // don't hover-activate until mouse is moved to not interfere with keyboard use
        anchors.fill: parent
        hoverEnabled: true
        propagateComposedEvents: true // clicking should still work if hovering is blocked

        property bool mouseMoved: false

        function reset() {
            mouseMoved = false
            enabled = true
        }

        onPositionChanged: if (!mouseMoved) {
            mouseMoved = true
        } else {
            enabled = false // this immediately triggers other hover events when bound to their hoverEnabled
        }

        onPressed: event => {
            enabled = false
            event.accepted = false
        }
    }
}