/*
 * Copyright (C) 2017 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import QtQuick 2.15
import Lomiri.Components 1.3
import GSettings 1.0
import WindowManager 1.0
import "MathUtils.js" as MathUtils
import "../../Components"

Item {
    id: root
    implicitWidth: listView.contentWidth
    readonly property int minimumWidth: {
        var count = Math.min(3, listView.count);
        return listView.itemWidth * count + listView.spacing * (count - 1)
    }

    property QtObject screen: null
    property alias workspaceModel: listView.model
    property var background // TODO: should be stored in the workspace data
    property int selectedIndex: -1
    property bool readOnly: true
    property var activeWorkspace: null
    property Item availableDesktopArea

    signal commitScreenSetup();
    signal closeSpread();
    signal clicked(var workspace);

    DropArea {
        anchors.fill: root

        keys: ['workspace']

        onEntered: {
            var index = listView.getDropIndex(drag);
            drag.source.workspace.assign(workspaceModel, index)
            drag.source.inDropArea = true;
        }

        onPositionChanged: {
            var index = listView.getDropIndex(drag);
            if (listView.dropItemIndex == index) return;
            listView.model.move(listView.dropItemIndex, index, 1);
            listView.dropItemIndex = index;
        }

        onExited: {
            drag.source.workspace.unassign()
            listView.dropItemIndex = -1;
            listView.hoveredWorkspaceIndex = -1;
            drag.source.inDropArea = false;
        }

        onDropped: {
            drop.accept(Qt.MoveAction);
            listView.dropItemIndex = -1;
            drag.source.inDropArea = false;
        }
    }
    DropArea {
        anchors.fill: parent
        keys: ["application"]

        onPositionChanged: {
            listView.progressiveScroll(drag.x)
            listView.updateDropProperties(drag)
        }
        onExited: {
            listView.hoveredWorkspaceIndex = -1
        }
        onDropped: {
            var surface = drag.source.surface;
            drag.source.surface = null;
            var workspace = listView.model.get(listView.hoveredWorkspaceIndex);
            WorkspaceManager.moveSurfaceToWorkspace(surface, workspace);
            drop.accept(Qt.MoveAction)
            if (listView.hoveredHalf == "right") {
                root.closeSpread();
                workspace.activate();
            }
            surface.activate();
            listView.hoveredWorkspaceIndex = -1
        }
    }

    onSelectedIndexChanged: {
        listView.positionViewAtIndex(selectedIndex, ListView.Center);
    }

    Item {
        // We need to clip the listview as it has left/right margins and it would
        // overlap with items next to it and eat mouse input. However, we can't
        // just clip at the actual bounds as the delegates have the close button
        // on hover which reaches a bit outside, so lets some margins for the clipping
        anchors.fill: parent
        anchors.margins: -units.gu(2)
        clip: true


        ListView {
            id: listView
            anchors {
                fill: parent
                topMargin: -parent.anchors.margins
                bottomMargin: -parent.anchors.margins
                leftMargin: -itemWidth - parent.anchors.margins
                rightMargin: -itemWidth - parent.anchors.margins
            }
            boundsBehavior: Flickable.StopAtBounds

            Behavior on contentX {
                SmoothedAnimation { duration: 200 }
            }

            property var clickedWorkspace: null

            orientation: ListView.Horizontal
            spacing: units.gu(1)
            leftMargin: itemWidth
            rightMargin: itemWidth

            // FIXME: Screen orientation changed event does not trigger properly
            // so we rely on height getting changed when rotating hence updating the value as needed
            readonly property bool screenIsLandscape: screen.orientation == Qt.LandscapeOrientation
                                                            || screen.orientation == Qt.InvertedLandscapeOrientation ? height > 0
                                                                                                                     : height < 0

            // Get the screen size based on screen's current orientation
            readonly property var screenSize: screen.availableModes[screen.currentModeIndex].size
            readonly property real screenWidth: screenIsLandscape ? screenSize.width >= screenSize.height ? screenSize.width : screenSize.height
                                                                           : screenSize.width >= screenSize.height ? screenSize.height : screenSize.width
            readonly property real screenHeight: screenIsLandscape ? screenSize.width >= screenSize.height ? screenSize.height : screenSize.width
                                                                            : screenSize.width >= screenSize.height ? screenSize.width : screenSize.height

            readonly property real screenSpaceHeight: root.availableDesktopArea.height
            readonly property real screenSpaceWidth: root.availableDesktopArea.width
            readonly property real launcherWidth: screenWidth - screenSpaceWidth
            property real itemWidth: height * screenSpaceWidth / screenSpaceHeight
            property int foldingAreaWidth: itemWidth / 2
            property int maxAngle: 40

            property real realContentX: contentX - originX + leftMargin
            property int dropItemIndex: -1
            property int hoveredWorkspaceIndex: -1
            property string hoveredHalf: ""   // left or right

            function getDropIndex(drag) {
                var coords = mapToItem(listView.contentItem, drag.x, drag.y)
                var index = Math.floor((drag.x + listView.realContentX) / (listView.itemWidth + listView.spacing));
                if (index < 0) index = 0;
                var upperLimit = dropItemIndex == -1 ? listView.count : listView.count - 1
                if (index > upperLimit) index = upperLimit;
                return index;
            }

            function updateDropProperties(drag) {
                var coords = mapToItem(listView.contentItem, drag.x, drag.y)
                var index = Math.floor(drag.x + listView.realContentX) / (listView.itemWidth + listView.spacing);
                if (index < 0) {
                    listView.hoveredWorkspaceIndex = -1;
                    listView.hoveredHalf = "";
                    return;
                }

                var upperLimit = dropItemIndex == -1 ? listView.count : listView.count - 1
                if (index > upperLimit) index = upperLimit;
                listView.hoveredWorkspaceIndex = index;
                var pixelsInTile = (drag.x + listView.realContentX) % (listView.itemWidth + listView.spacing);
                listView.hoveredHalf = (pixelsInTile / listView.itemWidth) < .5 ? "left" : "right";
            }

            function progressiveScroll(mouseX) {
                var progress = Math.max(0, Math.min(1, (mouseX - listView.itemWidth) / (width - listView.leftMargin * 2 - listView.itemWidth * 2)))
                listView.contentX = listView.originX + (listView.contentWidth - listView.width + listView.leftMargin + listView.rightMargin) * progress - listView.leftMargin
            }

            displaced: Transition { LomiriNumberAnimation { properties: "x" } }

            delegate: Item {
                id: workspaceDelegate
                objectName: "delegate" + index
                height: parent.height
                width: listView.itemWidth
                Behavior on width { LomiriNumberAnimation {} }
                visible: listView.dropItemIndex !== index

                property int itemX: -listView.realContentX + index * (listView.itemWidth + listView.spacing)
                property int distanceFromLeft: itemX //- listView.leftMargin
                property int distanceFromRight: listView.width - listView.leftMargin - listView.rightMargin - itemX - listView.itemWidth

                property int itemAngle: {
                    if (index == 0) {
                        if (distanceFromLeft < 0) {
                            var progress = (distanceFromLeft + listView.foldingAreaWidth) / listView.foldingAreaWidth
                            return MathUtils.linearAnimation(1, -1, 0, listView.maxAngle, Math.max(-1, Math.min(1, progress)));
                        }
                        return 0
                    }
                    if (index == listView.count - 1) {
                        if (distanceFromRight < 0) {
                            var progress = (distanceFromRight + listView.foldingAreaWidth) / listView.foldingAreaWidth
                            return MathUtils.linearAnimation(1, -1, 0, -listView.maxAngle, Math.max(-1, Math.min(1, progress)));
                        }
                        return 0
                    }

                    if (distanceFromLeft < listView.foldingAreaWidth) {
                        // itemX : 10gu = p : 100
                        var progress = distanceFromLeft / listView.foldingAreaWidth
                        return MathUtils.linearAnimation(1, -1, 0, listView.maxAngle, Math.max(-1, Math.min(1, progress)));
                    }
                    if (distanceFromRight < listView.foldingAreaWidth) {
                        var progress = distanceFromRight / listView.foldingAreaWidth
                        return MathUtils.linearAnimation(1, -1, 0, -listView.maxAngle, Math.max(-1, Math.min(1, progress)));
                    }
                    return 0
                }

                property int itemOffset: {
                    if (index == 0) {
                        if (distanceFromLeft < 0) {
                            return -distanceFromLeft
                        }
                        return 0
                    }
                    if (index == listView.count - 1) {
                        if (distanceFromRight < 0) {
                            return distanceFromRight
                        }
                        return 0
                    }

                    if (itemX < -listView.foldingAreaWidth) {
                        return -itemX
                    }
                    if (distanceFromLeft < listView.foldingAreaWidth) {
                        return (listView.foldingAreaWidth - distanceFromLeft) / 2
                    }

                    if (distanceFromRight < -listView.foldingAreaWidth) {
                        return distanceFromRight
                    }

                    if (distanceFromRight < listView.foldingAreaWidth) {
                        return -(listView.foldingAreaWidth - distanceFromRight) / 2
                    }

                    return 0
                }

                z: itemOffset < 0 ? itemOffset : -itemOffset
                transform: [
                    Rotation {
                        angle: itemAngle
                        axis { x: 0; y: 1; z: 0 }
                        origin { x: itemAngle < 0 ? listView.itemWidth : 0; y: height / 2 }
                    },
                    Translate {
                        x: itemOffset
                    }
                ]

                WorkspacePreview {
                    id: workspacePreview
                    height: listView.height
                    width: listView.itemWidth - settings.launcherWidth
                    anchors.horizontalCenter: parent.horizontalCenter
                    screen: root.screen
                    background: root.background
                    screenHeight: listView.screenSpaceHeight
                    launcherWidth: listView.launcherWidth
                    containsDragLeft: listView.hoveredWorkspaceIndex == index && listView.hoveredHalf == "left"
                    containsDragRight: listView.hoveredWorkspaceIndex == index && listView.hoveredHalf == "right"
                    isActive: workspace.isSameAs(root.activeWorkspace)
                    isSelected: index === root.selectedIndex
                    workspace: model.workspace
                }
                MouseArea {
                    anchors.fill: parent
                    onClicked: {
                        root.clicked(model.workspace)
                    }
                    onDoubleClicked: {
                        model.workspace.activate();
                        root.closeSpread();
                    }
                }

                MouseArea {
                    id: closeMouseArea
                    objectName: "closeMouseArea"
                    anchors { left: parent.left; top: parent.top; leftMargin: -height / 2; topMargin: -height / 2 }
                    hoverEnabled: true
                    height: units.gu(4)
                    width: height
                    visible: !root.readOnly && listView.count > 1

                    onClicked: {
                        model.workspace.unassign();
                        root.commitScreenSetup();
                    }
                    Image {
                        id: closeImage
                        source: "../graphics/window-close.svg"
                        anchors.fill: closeMouseArea
                        anchors.margins: units.gu(1)
                        sourceSize.width: width
                        sourceSize.height: height
                        readonly property var mousePos: hoverMouseArea.mapToItem(workspaceDelegate, hoverMouseArea.mouseX, hoverMouseArea.mouseY)
                        readonly property bool shown: (hoverMouseArea.containsMouse || parent.containsMouse)
                                                 && mousePos.y < workspaceDelegate.width / 4
                                                 && mousePos.y > -units.gu(2)
                                                 && mousePos.x > -units.gu(2)
                                                 && mousePos.x < workspaceDelegate.height / 4
                        opacity: shown ? 1 : 0
                        visible: opacity > 0
                        Behavior on opacity { LomiriNumberAnimation { duration: LomiriAnimation.SnapDuration } }

                    }
                }
            }

            MouseArea {
                id: hoverMouseArea
                anchors.fill: parent
                hoverEnabled: true
                propagateComposedEvents: true
                anchors.leftMargin: listView.leftMargin
                anchors.rightMargin: listView.rightMargin
                enabled: !root.readOnly

                property int draggedIndex: -1

                property int startX: 0
                property int startY: 0

                onMouseXChanged: {
                    if (!pressed || dragging) {
                        listView.progressiveScroll(mouseX)
                    }
                }
                onMouseYChanged: {
                    if (Math.abs(mouseY - startY) > units.gu(3)) {
                        drag.axis = Drag.XAndYAxis;
                    }
                }

                onReleased: {
                    var result = fakeDragItem.Drag.drop();
    //                if (result == Qt.IgnoreAction) {
    //                    WorkspaceManager.destroyWorkspace(fakeDragItem.workspace);
    //                }
                    root.commitScreenSetup();
                    drag.target = null;
                }

                property bool dragging: drag.active
                onDraggingChanged: {
                    if (drag.active) {
                        var ws = listView.model.get(draggedIndex);
                        if (ws) ws.unassign();
                    }
                }

                onPressed: {
                    startX = mouseX;
                    startY = mouseY;
                    if (listView.model.count < 2) return;

                    var coords = mapToItem(listView.contentItem, mouseX, mouseY)
                    draggedIndex = listView.indexAt(coords.x, coords.y)
                    var clickedItem = listView.itemAt(coords.x, coords.y)

                    var itemCoords = clickedItem.mapToItem(listView, -listView.leftMargin, 0);
                    fakeDragItem.x = itemCoords.x
                    fakeDragItem.y = itemCoords.y
                    fakeDragItem.workspace = listView.model.get(draggedIndex)

                    var mouseCoordsInItem = mapToItem(clickedItem, mouseX, mouseY);
                    fakeDragItem.Drag.hotSpot.x = mouseCoordsInItem.x
                    fakeDragItem.Drag.hotSpot.y = mouseCoordsInItem.y

                    drag.axis = Drag.YAxis;
                    drag.target = fakeDragItem;
                }

                WorkspacePreview {
                    id: fakeDragItem
                    height: listView.height
                    width: listView.itemWidth
                    screen: root.screen
                    background: root.background
                    screenHeight: listView.screenSpaceHeight
                    launcherWidth: listView.launcherWidth
                    visible: Drag.active

                    Drag.active: hoverMouseArea.drag.active
                    Drag.keys: ['workspace']

                    property bool inDropArea: false

                    Rectangle {
                        anchors.fill: parent
                        color: "#33000000"
                        opacity: parent.inDropArea ? 0 : 1
                        Behavior on opacity { LomiriNumberAnimation { } }
                        Rectangle {
                            anchors.centerIn: parent
                            width: units.gu(6)
                            height: units.gu(6)
                            radius: width / 2
                            color: "#aa000000"
                        }

                        Icon {
                            height: units.gu(3)
                            width: height
                            anchors.centerIn: parent
                            name: "edit-delete"
                            color: "white"
                        }
                    }

                    states: [
                        State {
                            when: fakeDragItem.Drag.active
                            ParentChange { target: fakeDragItem; parent: shell }
                        }
                    ]
                }
            }
        }
    }
}