/*
SPDX-FileCopyrightText: 2020-2021 Devin Lin <espidev@gmail.com>

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

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
import org.kde.plasma.workspace.keyboardlayout 1.0 as Keyboards

Rectangle {
    id: root
    implicitHeight: units.gridUnit * 2.5
    
    // toggle between pin and password mode
    property bool isPinMode: true
    
    property string password
    
    // for displaying temporary number in pin dot display
    property int previewCharIndex
    
    property string pinLabel
    property bool keypadOpen
    
    // if waiting for result of auth
    property bool waitingForAuth: false
    
    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})
    
    signal changePassword();
    
    // keypad functions
    function reset() {
        waitingForAuth = false;
        root.password = "";
        changePassword();
        root.pinLabel = qsTr("Enter PIN");
    }
    
    function backspace() {
        if (!root.waitingForAuth) {
            root.previewCharIndex = -2;
            root.password = root.password.substr(0, root.password.length - 1);
            changePassword();
        }
    }

    function clear() {
        if (!root.waitingForAuth) {
            root.previewCharIndex = -2;
            root.password = "";
            changePassword();
        }
    }
    
    function enter() {
        if (root.password !== "") { // prevent typing lock when password is empty
            root.waitingForAuth = true;
        }
        
        // don't try to unlock if there is a timeout (unlock once unlocked)
        if (!authenticator.graceLocked) {
            authenticator.tryUnlock(root.password);
        }
        if (keypadOpen && !isPinMode) {
            // make sure keyboard doesn't close
            openKeyboardTimer.restart();
        }
    }
    
    function keyPress(data) {
        if (!root.waitingForAuth) {
            if (root.pinLabel !== qsTr("Enter PIN")) {
                root.pinLabel = qsTr("Enter PIN");
            }
            root.previewCharIndex = root.password.length;
            root.password += data
            changePassword();
            
            // trigger turning letter into dot later
            letterTimer.restart();
        }
    }
    
    // HACK: we have to open the virtual keyboard after a certain amount of time or else it will close anyway
    Timer {
        id: openKeyboardTimer
        interval: 10
        running: false
        repeat: false
        onTriggered: Keyboards.KWinVirtualKeyboard.active = true
    }
    
    // trigger turning letter into dot after 500 milliseconds
    Timer {
        id: letterTimer
        interval: 500
        running: false
        repeat: false
        onTriggered: {
            root.previewCharIndex = -2;
        }
    }
    
    // we need to use a listmodel to avoid all delegates from reloading
    ListModel {
        id: dotDisplayModel
    }
    onPasswordChanged: {
        while (password.length < dotDisplayModel.count) {
            dotDisplayModel.remove(dotDisplayModel.count - 1);
        }
        while (password.length > dotDisplayModel.count) {
            dotDisplayModel.append({"char": password.charAt(dotDisplayModel.count)});
        }
    }
    
    // hidden textfield so that the virtual keyboard shows up
    TextField {
        id: textField
        visible: false
        focus: keypadOpen && !isPinMode
        z: 1
        
        onFocusChanged: {
            if (focus) {
                Keyboards.KWinVirtualKeyboard.active = true;
            }
        }
        
        property bool externalEdit: false
        property string prevText: ""
        
        Connections {
            target: root
            function onChangePassword() {
                if (textField.text != root.password) {
                    textField.externalEdit = true;
                    textField.text = root.password;
                }
            }
        }
        onEditingFinished: {
            if (textField.focus) {
                root.enter();
            }
        }
        onTextChanged: {
            if (!externalEdit) {
                if (prevText.length > text.length) { // backspace
                    for (let i = 0; i < (prevText.length - text.length); i++) {
                        root.backspace();
                    }
                } else if (text.length > 0) { // key enter
                    root.keyPress(text.charAt(text.length - 1));
                }
                prevText = text;
            }
            externalEdit = false;
        }
    }
    
    MouseArea {
        anchors.fill: parent
        onClicked: {
            // clicking on rectangle opens keyboard if not already open
            if (!isPinMode) {
                Keyboards.KWinVirtualKeyboard.active = true;
            }
        }
        
        // toggle between showing keypad and not
        ToolButton {
            anchors.right: parent.right
            anchors.top: parent.top
            anchors.bottom: parent.bottom
            anchors.margins: units.smallSpacing
            implicitWidth: height
            icon.name: "input-keyboard-virtual-symbolic"
            onClicked: {
                root.isPinMode = !root.isPinMode;
                if (!root.isPinMode) {
                    Keyboards.KWinVirtualKeyboard.active = true;
                }
            }
        }
        
        // label ("wrong pin", "enter pin")
        Label {
            opacity: password.length === 0 ? 1 : 0
            anchors.centerIn: parent
            text: root.pinLabel
            font.pointSize: 12
            color: root.headerTextColor 
            
            Behavior on opacity {
                NumberAnimation { duration: 200 }
            }
        }
        
        // pin dot display
        ColumnLayout {
            anchors.fill: parent
            
            ListView {
                id: dotDisplay
                property int dotWidth: Math.round(units.gridUnit * 0.35)
                
                Layout.alignment: Qt.AlignHCenter | Qt.AlignVCenter
                Layout.bottomMargin: Math.round(dotWidth / 2)
                orientation: ListView.Horizontal
                implicitWidth: count * dotWidth + spacing * (count - 1)
                spacing: 8
                model: dotDisplayModel
                
                Behavior on implicitWidth {
                    NumberAnimation { duration: 50 }
                }
                
                delegate: Item {
                    implicitWidth: dotDisplay.dotWidth
                    implicitHeight: dotDisplay.dotWidth
                    property bool showChar: index === root.previewCharIndex
                    
                    Component.onCompleted: {
                        if (showChar) {
                            charAnimation.to = 1;
                            charAnimation.duration = 75;
                            charAnimation.restart();
                        } else {
                            dotAnimation.to = 1;
                            dotAnimation.restart();
                        }
                    }
                    
                    onShowCharChanged: {
                        if (!showChar) {
                            charAnimation.to = 0;
                            charAnimation.duration = 50;
                            charAnimation.restart();
                            dotAnimation.to = 1;
                            dotAnimation.start();
                        }
                    }
                    
                    Rectangle { // dot
                        id: dot
                        scale: 0
                        anchors.fill: parent
                        radius: width
                        color: root.waitingForAuth ? root.headerTextInactiveColor : root.headerTextColor // dim when waiting for auth
                        
                        PropertyAnimation {
                            id: dotAnimation
                            target: dot;
                            property: "scale";
                            duration: 50
                        }
                    }
                    
                    Label { // number/letter
                        id: charLabel
                        scale: 0
                        anchors.centerIn: parent
                        color: root.waitingForAuth ? root.headerTextInactiveColor : root.headerTextColor // dim when waiting for auth
                        text: model.char
                        font.pointSize: 12
                        
                        PropertyAnimation {
                            id: charAnimation
                            target: charLabel;
                            property: "scale";
                        }
                    }
                }
            }
        }
    }
}