// SPDX-FileCopyrightText: 2021 Claudio Cambra <claudio.cambra@gmail.com>
// SPDX-FileCopyrightText: 2023 Carl Schwan <carl@carlschwan.eu>
// SPDX-License-Identifier: LGPL-2.1-or-later

import QtQuick
import QtQuick.Controls as QQC2
import QtQuick.Layouts
import org.kde.kirigami as Kirigami
import org.kde.kirigamiaddons.dateandtime
import org.kde.kirigamiaddons.components as Components
import org.kde.kirigamiaddons.delegates as Delegates

QQC2.Control {
    id: root

    signal datePicked(date pickedDate)

    property date selectedDate: new Date() // Decides calendar span
    readonly property int year: selectedDate.getFullYear()
    readonly property int month: selectedDate.getMonth()
    readonly property int day: selectedDate.getDate()
    property bool showDays: true
    property bool showControlHeader: true

    /**
     * This property holds the minimum date (inclusive) that the user can select.
     *
     * By default, no limit is applied to the date selection.
     */
    property date minimumDate

    /**
     * This property holds the maximum date (inclusive) that the user can select.
     *
     * By default, no limit is applied to the date selection.
     */
    property date maximumDate

    topPadding: Kirigami.Units.largeSpacing
    rightPadding: Kirigami.Units.largeSpacing
    bottomPadding: Kirigami.Units.largeSpacing
    leftPadding: Kirigami.Units.largeSpacing

    onActiveFocusChanged: if (activeFocus) {
        dateSegmentedButton.forceActiveFocus();
    }

    property bool _completed: false
    property bool _runSetDate: false

    onSelectedDateChanged: if (selectedDate !== null && _completed) {
        setToDate(selectedDate)
    }

    Component.onCompleted: {
        _completed = true;
        if (selectedDate) {
            setToDate(selectedDate);
        }
    }
    onShowDaysChanged: if (!showDays) pickerView.currentIndex = 1;

    function setToDate(date) {
        if (_runSetDate) {
            return;
        }
        _runSetDate = true;

        if (root.minimumDate.valueOf() && date.valueOf() < minimumDate.valueOf()) {
            date = minimumDate;
        }

        if (root.maximumDate.valueOf() && date.valueOf() > maximumDate.valueOf()) {
            date = maximumDate;
        }

        const yearDiff = date.getFullYear() - yearPathView.currentItem.startDate.getFullYear();
        // For the decadeDiff we add one to the input date year so that we use e.g. 2021, making the pathview move to the grid that contains the 2020 decade
        // instead of staying within the 2010 decade, which contains a 2020 cell at the very end
        const decadeDiff = Math.floor((date.getFullYear() + 1 - decadePathView.currentItem.startDate.getFullYear()) / 12); // 12 years in one decade grid

        let newYearIndex = yearPathView.currentIndex + yearDiff;
        let newDecadeIndex = decadePathView.currentIndex + decadeDiff;

        let firstYearItemDate = yearPathView.model.data(yearPathView.model.index(1,0), InfiniteCalendarViewModel.StartDateRole);
        let lastYearItemDate = yearPathView.model.data(yearPathView.model.index(yearPathView.model.rowCount() - 2,0), InfiniteCalendarViewModel.StartDateRole);
        let firstDecadeItemDate = decadePathView.model.data(decadePathView.model.index(1,0), InfiniteCalendarViewModel.StartDateRole);
        let lastDecadeItemDate = decadePathView.model.data(decadePathView.model.index(decadePathView.model.rowCount() - 1,0), InfiniteCalendarViewModel.StartDateRole);

        if(showDays) { // Set to correct index, including creating new dates in model if needed, for the month view
            const monthDiff = date.getMonth() - monthPathView.currentItem.firstDayOfMonth.getMonth() + (12 * (date.getFullYear() - monthPathView.currentItem.firstDayOfMonth.getFullYear()));
            let newMonthIndex = monthPathView.currentIndex + monthDiff;
            let firstMonthItemDate = monthPathView.model.data(monthPathView.model.index(1,0), InfiniteCalendarViewModel.FirstDayOfMonthRole);
            let lastMonthItemDate = monthPathView.model.data(monthPathView.model.index(monthPathView.model.rowCount() - 1,0), InfiniteCalendarViewModel.FirstDayOfMonthRole);

            while(firstMonthItemDate >= date) {
                monthPathView.model.addDates(false)
                firstMonthItemDate = monthPathView.model.data(monthPathView.model.index(1,0), InfiniteCalendarViewModel.FirstDayOfMonthRole);
                newMonthIndex = 0;
            }
            if(firstMonthItemDate < date && newMonthIndex === 0) {
                newMonthIndex = date.getMonth() - firstMonthItemDate.getMonth() + (12 * (date.getFullYear() - firstMonthItemDate.getFullYear())) + 1;
            }

            while(lastMonthItemDate <= date) {
                monthPathView.model.addDates(true)
                lastMonthItemDate = monthPathView.model.data(monthPathView.model.index(monthPathView.model.rowCount() - 1,0), InfiniteCalendarViewModel.FirstDayOfMonthRole);
            }

            monthPathView.currentIndex = newMonthIndex;
        }

        // Set to index and create dates if needed for year view
        while(firstYearItemDate >= date) {
            yearPathView.model.addDates(false)
            firstYearItemDate = yearPathView.model.data(yearPathView.model.index(1,0), InfiniteCalendarViewModel.StartDateRole);
            newYearIndex = 0;
        }
        if(firstYearItemDate < date && newYearIndex === 0) {
            newYearIndex = date.getFullYear() - firstYearItemDate.getFullYear() + 1;
        }

        while(lastYearItemDate <= date) {
            yearPathView.model.addDates(true)
            lastYearItemDate = yearPathView.model.data(yearPathView.model.index(yearPathView.model.rowCount() - 1,0), InfiniteCalendarViewModel.StartDateRole);
        }

        // Set to index and create dates if needed for decade view
        while(firstDecadeItemDate >= date) {
            decadePathView.model.addDates(false)
            firstDecadeItemDate = decadePathView.model.data(decadePathView.model.index(1,0), InfiniteCalendarViewModel.StartDateRole);
            newDecadeIndex = 0;
        }
        if(firstDecadeItemDate < date && newDecadeIndex === 0) {
            newDecadeIndex = date.getFullYear() - firstDecadeItemDate.getFullYear() + 1;
        }

        while(lastDecadeItemDate.getFullYear() <= date.getFullYear()) {
            decadePathView.model.addDates(true)
            lastDecadeItemDate = decadePathView.model.data(decadePathView.model.index(decadePathView.model.rowCount() - 1,0), InfiniteCalendarViewModel.StartDateRole);
        }

        yearPathView.currentIndex = newYearIndex;
        decadePathView.currentIndex = newDecadeIndex;

        _runSetDate = false;
    }

    function goToday() {
        selectedDate = new Date()
    }

    function prevMonth() {
        const newDate = new Date(selectedDate.getFullYear(), selectedDate.getMonth() - 1, selectedDate.getDate());
        if (root.minimumDate.valueOf() && newDate.valueOf() < minimumDate.valueOf()) {
            if (selectedDate == minimumDate) {
                return;
            }
            selectedDate = minimumDate;
        } else {
            selectedDate = newDate;
        }
    }

    function nextMonth() {
        const newDate = new Date(selectedDate.getFullYear(), selectedDate.getMonth() + 1, selectedDate.getDate());
        if (root.maximumDate.valueOf() && newDate.valueOf() > maximumDate.valueOf()) {
            if (selectedDate == maximumDate) {
                return;
            }
            selectedDate = maximumDate;
            return;
        } else {
            selectedDate = newDate;
        }
    }

    function prevYear() {
        const newDate = new Date(selectedDate.getFullYear() - 1, selectedDate.getMonth(), selectedDate.getDate())
        if (root.minimumDate.valueOf() && newDate.valueOf() < minimumDate.valueOf()) {
            if (selectedDate == minimumDate) {
                return;
            }
            selectedDate = minimumDate;
        } else {
            selectedDate = newDate;
        }
    }

    function nextYear() {
        const newDate = new Date(selectedDate.getFullYear() + 1, selectedDate.getMonth(), selectedDate.getDate());
        if (root.maximumDate && newDate.valueOf() > maximumDate.valueOf()) {
            if (selectedDate == maximumDate) {
                return;
            }
            selectedDate = maximumDate;
        } else {
            selectedDate = newDate;
        }
    }

    function prevDecade() {
        const newDate = new Date(selectedDate.getFullYear() - 10, selectedDate.getMonth(), selectedDate.getDate());
        if (root.minimumDate.valueOf() && newDate.valueOf() < minimumDate.valueOf()) {
            if (selectedDate == minimumDate) {
                return;
            }
            selectedDate = minimumDate;
        } else {
            selectedDate = newDate;
        }
    }

    function nextDecade() {
        const newDate = new Date(selectedDate.getFullYear() + 10, selectedDate.getMonth(), selectedDate.getDate())
        if (root.maximumDate && newDate.valueOf() > maximumDate.valueOf()) {
            if (selectedDate == maximumDate) {
                return;
            }
            selectedDate = maximumDate;
        } else {
            selectedDate = newDate;
        }
    }

    contentItem: ColumnLayout {
        id: pickerLayout

        RowLayout {
            id: headingRow
            Layout.fillWidth: true
            Layout.bottomMargin: Kirigami.Units.smallSpacing

            Components.SegmentedButton {
                id: dateSegmentedButton

                actions: [
                    Kirigami.Action {
                        id: dayAction
                        text: root.selectedDate.getDate()
                        onTriggered: pickerView.currentIndex = 0 // dayGrid is first item in pickerView
                        checked: pickerView.currentIndex === 0
                    },
                    Kirigami.Action {
                        id: monthAction
                        text: root.selectedDate.toLocaleDateString(Qt.locale(), "MMMM")
                        onTriggered: pickerView.currentIndex = 1
                        checked: pickerView.currentIndex === 1
                    },
                    Kirigami.Action {
                        id: yearsViewCheck
                        text: root.selectedDate.getFullYear()
                        onTriggered: pickerView.currentIndex = 2
                        checked: pickerView.currentIndex === 2
                    }
                ]
            }

            Instantiator {
                model:dateSegmentedButton.children
                Item {
                    required property Item modelData
                    parent: modelData
                    anchors.fill: parent
                    Accessible.ignored: !modelData.action
                    Accessible.role: Accessible.Dial
                    Accessible.focusable: true
                    Accessible.focused: parent.activeFocus
                    Accessible.name: {
                        if (modelData.action === dayAction) {
                            return i18nd("kirigami-addons6", "Day")
                        }
                        if (modelData.action === monthAction) {
                            return i18nd("kirigami-addons6", "Month")
                        }
                        if (modelData.action === yearsViewCheck) {
                            return i18nd("kirigami-addons6", "Year")
                        }
                        return ""
                    }
                    property int maximumValue: {
                        if (modelData.action === dayAction) {
                            if (maximumDate.valueOf() &&  root.year === maximumDate.getYear() && root.month === maximumDate.getMonth()) {
                                return maximumDate.getDate()
                            }
                            return 31
                        }
                        if (modelData.action === monthAction) {
                             if (maximumDate.valueOf() && root.year === maximumDate.getYear() ) {
                                return maximumDate.month() + 1
                            }
                            return 12
                        }
                        if (modelData.action === yearsViewCheck) {
                            if (maximumDate.valueOf()) {
                                return maximumDate.getYear()
                            }
                            return 9999
                        }
                        return 0
                    }
                    property int minimumValue: {
                        if (modelData.action === dayAction) {
                            if (minimumDate.valueOf() && root.year === minimumDate.getYear() && root.month === minimumDate.getMonth()) {
                                return minimumDate.getDate()
                            }
                            return 1
                        }
                        if (modelData.action === monthAction) {
                             if (minimumDate.valueOf() && root.year === minimumDate.getYear() ) {
                                return minimumDate.month() + 1
                            }
                            return 1
                        }
                        if (modelData.action === yearsViewCheck) {
                            if (minimumDate.valueOf()) {
                                return minimumDate.getYear()
                            }
                            return -9999
                        }
                        return 0
                    }
                    property int stepSize: 1
                    property int value: {
                        if (modelData.action === dayAction) {
                            return root.day
                        }
                        if (modelData.action === monthAction) {
                            return root.month + 1
                        }
                        if (modelData.action === yearsViewCheck) {
                            return root.year
                        }
                        return 0
                    }
                    onValueChanged: {
                        if (modelData.action === dayAction) {
                            selectedDate.setDate(value)
                        }
                        if (modelData.action === monthAction) {
                            selectedDate.setMonth(value - 1)
                        }
                        if (modelData.action === yearsViewCheck) {
                            selectedDate.setFullYear(value)
                        }
                    }
                }
                onObjectAdded: (index, object) => {
                    object.modelData.Accessible.ignored = true
                }
            }

            Item {
                Layout.fillWidth: true
            }

            Components.SegmentedButton {
                actions: [
                    Kirigami.Action {
                        id: goPreviousAction
                        icon.name: 'go-previous-view'
                        text: i18ndc("kirigami-addons6", "@action:button", "Go Previous")
                        displayHint: Kirigami.DisplayHint.IconOnly
                        onTriggered: {
                            if (pickerView.currentIndex === 1) { // monthGrid index
                                prevYear();
                            } else if (pickerView.currentIndex === 2) { // yearGrid index
                                prevDecade();
                            } else { // dayGrid index
                                prevMonth();
                            }
                        }
                    },
                    Kirigami.Action {
                        text: i18ndc("kirigami-addons6", "@action:button", "Jump to today")
                        displayHint: Kirigami.DisplayHint.IconOnly
                        icon.name: 'go-jump-today'
                        onTriggered: goToday()
                    },
                    Kirigami.Action {
                        id: goNextAction
                        text: i18ndc("kirigami-addons6", "@action:button", "Go Next")
                        icon.name: 'go-next-view'
                        displayHint: Kirigami.DisplayHint.IconOnly
                        onTriggered: {
                            if (pickerView.currentIndex === 1) { // monthGrid index
                                nextYear();
                            } else if (pickerView.currentIndex === 2) { // yearGrid index
                                nextDecade();
                            } else { // dayGrid index
                                nextMonth();
                            }
                        }
                    }
                ]
            }
        }

        QQC2.SwipeView {
            id: pickerView

            clip: true
            interactive: false
            padding: 0

            Layout.fillWidth: true
            Layout.fillHeight: true

            DatePathView {
                id: monthPathView

                mainView: pickerView
                enabled: QQC2.SwipeView.isCurrentItem

                model: InfiniteCalendarViewModel {
                    scale: InfiniteCalendarViewModel.MonthScale
                    currentDate: root.selectedDate
                    minimumDate: root.minimumDate
                    maximumDate: root.maximumDate
                    datesToAdd: 10
                }


                delegate: Loader {
                    id: monthViewLoader
                    property date firstDayOfMonth: model.firstDay
                    property bool isNextOrCurrentItem: index >= monthPathView.currentIndex -1 && index <= monthPathView.currentIndex + 1

                    active: isNextOrCurrentItem && root.showDays

                    sourceComponent: GridLayout {
                        id: dayGrid
                        columns: 7
                        rows: 7
                        width: monthPathView.width
                        height: monthPathView.height
                        Layout.topMargin: Kirigami.Units.smallSpacing

                        property var modelLoader: Loader {
                            asynchronous: true
                            sourceComponent: MonthModel {
                                year: firstDay.getFullYear()
                                month: firstDay.getMonth() + 1 // From pathview model
                            }
                        }

                        QQC2.ButtonGroup {
                            buttons: dayGrid.children
                        }

                        Repeater {
                            model: dayGrid.modelLoader.item?.weekDays
                            delegate: QQC2.Label {
                                Layout.fillWidth: true
                                Layout.fillHeight: true
                                horizontalAlignment: Text.AlignHCenter
                                rightPadding: Kirigami.Units.mediumSpacing
                                leftPadding: Kirigami.Units.mediumSpacing
                                opacity: 0.7
                                text: modelData
                                Accessible.ignored: true
                            }
                        }

                        Repeater {
                            id: dayRepeater

                            model: dayGrid.modelLoader.item

                            delegate: DatePickerDelegate {
                                id: dayDelegate

                                required property bool isToday
                                required property bool sameMonth
                                required property int dayNumber

                                repeater: dayRepeater
                                minimumDate: root.minimumDate
                                maximumDate: root.maximumDate
                                previousAction: goPreviousAction
                                nextAction: goNextAction

                                horizontalPadding: 0

                                Accessible.name: date.toLocaleDateString(locale, Locale.ShortFormat)
                                Accessible.ignored: !monthPathView.QQC2.SwipeView.isCurrentItem || !monthViewLoader.PathView.isCurrentItem

                                background {
                                    visible: sameMonth
                                }

                                highlighted: isToday
                                checkable: true
                                checked: date.getDate() === selectedDate.getDate() &&
                                    date.getMonth() === selectedDate.getMonth() &&
                                    date.getFullYear() === selectedDate.getFullYear()
                                opacity: sameMonth && inScope ? 1 : 0.6
                                text: dayNumber
                                onClicked: {
                                    selectedDate = date;
                                    datePicked(date);
                                }
                            }
                        }
                    }
                }

                onCurrentIndexChanged: {
                    if (pickerView.currentIndex === 0) {
                        root.selectedDate = new Date(currentItem.firstDayOfMonth.getFullYear(), currentItem.firstDayOfMonth.getMonth(), root.selectedDate.getDate());
                    }

                    if (currentIndex >= count - 2) {
                        model.addDates(true);
                    } else if (currentIndex <= 1) {
                        model.addDates(false);
                        startIndex += model.datesToAdd;
                    }
                }
            }

            DatePathView {
                id: yearPathView

                mainView: pickerView

                model: InfiniteCalendarViewModel {
                    scale: InfiniteCalendarViewModel.YearScale
                    currentDate: root.selectedDate
                }

                delegate: Loader {
                    id: yearViewLoader

                    required property int index
                    required property date startDate

                    property bool isNextOrCurrentItem: index >= yearPathView.currentIndex -1 && index <= yearPathView.currentIndex + 1

                    width: parent.width
                    height: parent.height

                    active: isNextOrCurrentItem

                    sourceComponent: GridLayout {
                        id: yearGrid
                        columns: 3
                        rows: 4

                        QQC2.ButtonGroup {
                            buttons: yearGrid.children
                        }

                        Repeater {
                            id: monthRepeater

                            model: yearGrid.columns * yearGrid.rows

                            delegate: DatePickerDelegate {
                                id: monthDelegate

                                date: new Date(yearViewLoader.startDate.getFullYear(), index)

                                minimumDate: root.minimumDate.valueOf() ? new Date(root.minimumDate).setDate(0) : new Date("invalid")
                                maximumDate: root.maximumDate.valueOf() ? new Date(root.maximumDate.getFullYear(), root.maximumDate.getMonth() + 1, 0) : new Date("invalid")
                                repeater: monthRepeater
                                previousAction: goPreviousAction
                                nextAction: goNextAction

                                Accessible.ignored: !yearPathView.QQC2.SwipeView.isCurrentItem || !yearViewLoader.PathView.isCurrentItem
                                Accessible.name: date.toLocaleDateString(Qt.locale(), "MMMM yyyy")

                                horizontalPadding: padding * 2
                                rightPadding: undefined
                                leftPadding: undefined
                                highlighted: date.getMonth() === new Date().getMonth() &&
                                    date.getFullYear() === new Date().getFullYear()
                                checkable: true
                                checked: date.getMonth() === selectedDate.getMonth() &&
                                    date.getFullYear() === selectedDate.getFullYear()
                                text: Qt.locale().standaloneMonthName(date.getMonth())
                                onClicked: {
                                    selectedDate = new Date(date);
                                    root.datePicked(date);
                                    if(root.showDays) pickerView.currentIndex = 0;
                                }
                            }
                        }
                    }
                }

                onCurrentIndexChanged: {
                    if (pickerView.currentIndex === 1) {
                        root.selectedDate = new Date(currentItem.startDate.getFullYear(), root.selectedDate.getMonth(), root.selectedDate.getDate());
                    }

                    if (currentIndex >= count - 2) {
                        model.addDates(true);
                    } else if (currentIndex <= 1) {
                        model.addDates(false);
                        startIndex += model.datesToAdd;
                    }
                }

            }

            DatePathView {
                id: decadePathView

                mainView: pickerView

                model: InfiniteCalendarViewModel {
                    scale: InfiniteCalendarViewModel.DecadeScale
                    currentDate: root.selectedDate
                }

                delegate: Loader {
                    id: decadeViewLoader

                    required property int index
                    required property date startDate

                    property bool isNextOrCurrentItem: index >= decadePathView.currentIndex -1 && index <= decadePathView.currentIndex + 1

                    width: parent.width
                    height: parent.height

                    active: isNextOrCurrentItem

                    sourceComponent: GridLayout {
                        id: decadeGrid

                        columns: 3
                        rows: 4

                        QQC2.ButtonGroup {
                            buttons: decadeGrid.children
                        }

                        Repeater {
                            id: decadeRepeater

                            model: decadeGrid.columns * decadeGrid.rows

                            delegate: DatePickerDelegate {
                                id: yearDelegate

                                readonly property bool sameDecade: Math.floor(date.getFullYear() / 10) == Math.floor(year / 10)

                                Accessible.ignored: !decadePathView.QQC2.SwipeView.isCurrentItem || !decadeViewLoader.PathView.isCurrentItem

                                date: new Date(startDate.getFullYear() + index, 0)
                                minimumDate: root.minimumDate.valueOf() ? new Date(root.minimumDate.getFullYear(), 0, 0) : new Date("invalid")
                                maximumDate: root.maximumDate.valueOf() ? new Date(root.maximumDate.getFullYear(), 12, 0) : new Date("invalid")
                                repeater: decadeRepeater
                                previousAction: goPreviousAction
                                nextAction: goNextAction

                                highlighted: date.getFullYear() === new Date().getFullYear()

                                horizontalPadding: padding * 2
                                rightPadding: undefined
                                leftPadding: undefined
                                checkable: true
                                checked: date.getFullYear() === selectedDate.getFullYear()
                                opacity: sameDecade ? 1 : 0.7
                                text: date.getFullYear()
                                onClicked: {
                                    selectedDate = new Date(date);
                                    root.datePicked(date);
                                    pickerView.currentIndex = 1;
                                }
                            }
                        }
                    }
                }

                onCurrentIndexChanged: {
                    if (pickerView.currentIndex === 2) {
                        // getFullYear + 1 because the startDate is e.g. 2019, but we want the 2020 decade to be selected
                        root.selectedDate = new Date(currentItem.startDate.getFullYear() + 1, root.selectedDate.getMonth(), root.selectedDate.getDate());
                    }

                    if (currentIndex >= count - 2) {
                        model.addDates(true);
                    } else if (currentIndex <= 1) {
                        model.addDates(false);
                        startIndex += model.datesToAdd;
                    }
                }

            }
        }
    }
}