/*
Copyright (C) 2020 Devin Lin <espidev@gmail.com>

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; either version 2 of the License, or
(at your option) any later version.

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 2.12
import QtQuick.Controls 2.1
import QtQuick.Layouts 1.1
import QtGraphicalEffects 1.12
import org.kde.plasma.components 2.0 as PlasmaComponents
import org.kde.plasma.core 2.0 as PlasmaCore
import org.kde.plasma.workspace.keyboardlayout 1.0
import org.kde.kirigami 2.12 as Kirigami

Rectangle {
    id: keypadRoot
    
    // 0 - keypad is not shown, 1 - keypad is shown
    property double swipeProgress
    
    // slightly translucent background, for key contrast
    color: Kirigami.ColorUtils.adjustColor(PlasmaCore.Theme.backgroundColor, {"alpha": 0.9*255})
    property string pinLabel: qsTr("Enter PIN")
    
    // for displaying temporary number in pin dot display
    property string lastKeyPressValue: "0"
    property int indexWithNumber: -2 
    
    // if waiting for result of auth
    property bool waitingForAuth: false
    
    // colour calculations
    property color buttonColor: Qt.lighter(PlasmaCore.Theme.backgroundColor, 1.3)
    property color buttonPressedColor: Qt.darker(PlasmaCore.Theme.backgroundColor, 1.08)
    property color buttonTextColor: PlasmaCore.Theme.textColor
    property color dropShadowColor: Qt.darker(PlasmaCore.Theme.backgroundColor, 1.2)
    property color headerBackgroundColor: Qt.lighter(PlasmaCore.Theme.backgroundColor, 1.3)
    property color headerTextColor: Kirigami.ColorUtils.adjustColor(PlasmaCore.Theme.textColor, {"alpha": 0.75*255})
    property color headerTextInactiveColor: Kirigami.ColorUtils.adjustColor(PlasmaCore.Theme.textColor, {"alpha": 0.4*255})
    
    opacity: Math.sin((Math.PI / 2) * swipeProgress + 1.5 * Math.PI) + 1
    
    // keypad functions
    function reset() {
        waitingForAuth = false;
        root.password = "";
        keypadRoot.pinLabel = qsTr("Enter PIN");
    }
    
    function backspace() {
        if (!keypadRoot.waitingForAuth) {
            keypadRoot.lastKeyPressValue = "0";
            keypadRoot.indexWithNumber = -2;
            root.password = root.password.substr(0, root.password.length - 1);
        }
    }

    function clear() {
        if (!keypadRoot.waitingForAuth) {
            keypadRoot.lastKeyPressValue = "0";
            keypadRoot.indexWithNumber = -2;
            root.password = "";
        }
    }
    
    function enter() {
        if (root.password !== "") { // prevent typing lock when password is empty
            keypadRoot.waitingForAuth = true;
        }
        
        // don't try to unlock if there is a timeout (unlock once unlocked)
        if (!authenticator.graceLocked) {
            authenticator.tryUnlock(root.password);
        }
    }
    
    function keyPress(data) {
        if (!keypadRoot.waitingForAuth) {
            if (keypadRoot.pinLabel !== qsTr("Enter PIN")) {
                keypadRoot.pinLabel = qsTr("Enter PIN");
            }
            keypadRoot.lastKeyPressValue = data;
            keypadRoot.indexWithNumber = root.password.length;
            root.password += data
            
            // trigger turning letter into dot later
            letterTimer.restart();
        }
    }
    
    Connections {
        target: authenticator
        function onSucceeded() {
            pinLabel = qsTr("Logging in...");
            keypadRoot.waitingForAuth = false;
        }
        function onFailed() {
            root.password = "";
            pinLabel = qsTr("Wrong PIN");
            keypadRoot.waitingForAuth = false;
        }
        function onGraceLockedChanged() {
            // try authenticating if it was waiting for grace lock to stop and it has stopped
            if (!authenticator.graceLocked && keypadRoot.waitingForAuth) {
                authenticator.tryUnlock(root.password);
            }
        }
    }
    
    // listen for keyboard events
    Keys.onPressed: {
        if (event.modifiers === Qt.NoModifier) {
            if (event.key === Qt.Key_Backspace) {
                keypadRoot.backspace();
            } else if (event.key === Qt.Key_Return) {
                keypadRoot.enter();
            } else if (event.text != "") {
                keypadRoot.keyPress(event.text);
            }
        }
    }
    
    // trigger turning letter into dot after 500 milliseconds
    Timer {
        id: letterTimer
        interval: 500
        running: false
        repeat: false
        onTriggered: {
            keypadRoot.lastKeyPressValue = 0;
            keypadRoot.indexWithNumber = -2;
        }
    }
    
    // rectangle "bar" on the top of the keypad
    Rectangle {
        id: topTextDisplay
        anchors.top: parent.top
        anchors.left: parent.left
        anchors.right: parent.right
        color: keypadRoot.headerBackgroundColor
        implicitHeight: units.gridUnit * 2.5
        opacity: (Math.sin(2*((Math.PI / 2) * keypadRoot.swipeProgress + 1.5 * Math.PI)) + 1)
    }
    
    DropShadow {
        anchors.fill: topTextDisplay
        source: topTextDisplay
        cached: true
        horizontalOffset: 0
        verticalOffset: 1
        radius: 4
        samples: 6
        color: keypadRoot.dropShadowColor
        opacity: (Math.sin(2*((Math.PI / 2) * keypadRoot.swipeProgress + 1.5 * Math.PI)) + 1)
    }
    
    // pin dot display
    Item {
        anchors.verticalCenter: topTextDisplay.verticalCenter
        anchors.horizontalCenter: topTextDisplay.horizontalCenter
        
        // label ("wrong pin", "enter pin")
        Label {
            visible: root.password.length === 0
            anchors.centerIn: parent
            text: keypadRoot.pinLabel
            font.pointSize: 12
            color: keypadRoot.headerTextColor 
        }
        
        // dot display and letter
        RowLayout {
            id: dotDisplay
            anchors.centerIn: parent
            height: units.gridUnit * 1.5 // maintain height when letter is shown
            spacing: 6
            
            Repeater {
                model: root.password.length
                delegate: Rectangle { // dot
                    visible: index !== indexWithNumber // hide dot if number is shown
                    Layout.preferredWidth: units.gridUnit * 0.35
                    Layout.preferredHeight: Layout.preferredWidth
                    Layout.alignment: Qt.AlignVCenter
                    radius: width
                    color: keypadRoot.waitingForAuth ? keypadRoot.headerTextInactiveColor : keypadRoot.headerTextColor // dim when waiting for auth
                }
            }
            Label { // number/letter
                visible: root.password.length-1 === indexWithNumber // hide label if no label needed
                Layout.alignment: Qt.AlignHCenter
                color: keypadRoot.waitingForAuth ? keypadRoot.headerTextInactiveColor : keypadRoot.headerTextColor // dim when waiting for auth
                text: lastKeyPressValue
                font.pointSize: 12
            }
        }
    }
    
    // actual number keys
    ColumnLayout {
        anchors {
            left: parent.left
            right: parent.right
            top: topTextDisplay.bottom
            bottom: parent.bottom
            topMargin: units.gridUnit
            bottomMargin: units.gridUnit
        }
        spacing: units.gridUnit

        GridLayout {
            property string thePw
            Layout.alignment: Qt.AlignHCenter | Qt.AlignVCenter
            Layout.leftMargin: units.gridUnit * 0.5
            Layout.rightMargin: units.gridUnit * 0.5
            Layout.maximumWidth: units.gridUnit * 22
            Layout.maximumHeight: units.gridUnit * 12.5
            columns: 4

            // numpad keys
            Repeater {
                model: ["1", "2", "3", "R", "4", "5", "6", "0", "7", "8", "9", "E"]

                delegate: Item {
                    Layout.fillWidth: true
                    Layout.fillHeight: true

                    Rectangle {
                        id: keyRect
                        anchors.centerIn: parent
                        width: parent.width
                        height: parent.height
                        radius: 5
                        color: keypadRoot.buttonColor
                        
                        visible: modelData.length > 0
                        opacity: (Math.sin(2*((Math.PI / 2) * keypadRoot.swipeProgress + 1.5 * Math.PI)) + 1)

                        AbstractButton {
                            anchors.fill: parent
                            onPressedChanged: {
                                if (pressed) {
                                    parent.color = keypadRoot.buttonPressedColor;
                                } else {
                                    parent.color = keypadRoot.buttonColor;
                                }
                            }

                            onClicked: {
                                if (modelData === "R") {
                                    keypadRoot.backspace();
                                } else if (modelData === "E") {
                                    keypadRoot.enter();
                                } else {
                                    keypadRoot.keyPress(modelData);
                                }
                            }
                            onPressAndHold: {
                                if (modelData === "R") {
                                    clear();
                                }
                            }
                        }
                    }

                    DropShadow {
                        anchors.fill: keyRect
                        source: keyRect
                        cached: true
                        horizontalOffset: 0
                        verticalOffset: 1
                        radius: 4
                        samples: 6
                        color: keypadRoot.dropShadowColor
                        opacity: (Math.sin(2*((Math.PI / 2) * keypadRoot.swipeProgress + 1.5 * Math.PI)) + 1)
                    }

                    PlasmaComponents.Label {
                        visible: modelData !== "R" && modelData !== "E"
                        text: modelData
                        anchors.centerIn: parent
                        font.pointSize: 18
                        color: keypadRoot.buttonTextColor
                    }

                    PlasmaCore.IconItem {
                        visible: modelData === "R"
                        anchors.centerIn: parent
                        source: "edit-clear"
                    }

                    PlasmaCore.IconItem {
                        visible: modelData === "E"
                        anchors.centerIn: parent
                        source: "go-next"
                    }
                }
            }
        }
    }
}