// Chatter — UI only. The white "page" plus the top control bar. Ink is drawn
// directly into the framebuffer by the C++ InkEngine, not by the scene graph,
// so there is no canvas item here. Keep the scene STATIC (only the buttons ever
// repaint, on tap) so it never recomposites over the direct-drawn ink.

import QtQuick
import QtQuick.Window

Window {
    id: root
    width: Screen.width
    height: Screen.height
    visible: true
    color: "white"

    // Finger gestures (the stylus is handled in C++ and is NOT delivered here):
    //   1 finger  = erase wipe (a tap erases nothing — only movement does)
    //   2 fingers = vertical scroll (content follows the fingers)
    // The gesture type is latched until all fingers lift, so a 2-finger scroll
    // never turns into an erase when one finger is raised. Buttons (z:10) are above.
    MultiPointTouchArea {
        id: touch
        anchors.fill: parent
        z: 0
        minimumTouchPoints: 1
        maximumTouchPoints: 2
        touchPoints: [
            TouchPoint { id: tpA },
            TouchPoint { id: tpB }
        ]
        property int mode: 0      // 0 idle, 1 erase, 2 scroll
        property real lastPanY: 0

        function activeCount() { return (tpA.pressed ? 1 : 0) + (tpB.pressed ? 1 : 0); }
        function soloPoint() { return tpA.pressed ? tpA : tpB; }

        function handle() {
            var n = activeCount();
            if (n >= 2) {
                var cy = (tpA.y + tpB.y) / 2;
                if (mode !== 2) {
                    if (mode === 1) ink.eraseEnd();
                    mode = 2;
                    lastPanY = cy;
                } else {
                    ink.panBy(cy - lastPanY);
                    lastPanY = cy;
                }
            } else if (n === 1) {
                if (mode === 0) { mode = 1; ink.eraseStart(soloPoint().x, soloPoint().y); }
                else if (mode === 1) { ink.eraseMove(soloPoint().x, soloPoint().y); }
                // mode === 2 (one finger left after a scroll): stay idle until all up
            } else {
                if (mode === 1) ink.eraseEnd();
                else if (mode === 2) ink.panEnd(); // full refresh to clear scroll ghosts
                mode = 0;
            }
        }
        onPressed: handle()
        onUpdated: handle()
        onReleased: handle()
    }

    // Buttons keep a FIXED appearance in the Qt scene (rendered once); their
    // pressed/normal feedback and actions are handled by the ink engine
    // (ink.flashButton / ink.activateButton) so both finger AND stylus work and
    // updates are instant single-pass (no scene flashing).
    component TopButton: Rectangle {
        id: btn
        height: 90
        // Size to the label so horizontal padding ≈ vertical padding.
        width: label.implicitWidth + (height - label.implicitHeight)
        color: "white"
        border.color: "black"
        border.width: 3
        radius: 8
        z: 10
        property alias text: label.text
        Text { id: label; anchors.centerIn: parent; anchors.verticalCenterOffset: -2; font.pixelSize: 38 }
        // Register geometry once laid out (ink-exclusion, clear-redraw, stylus hit-test).
        Component.onCompleted: Qt.callLater(function() {
            ink.registerButton(btn.x, btn.y, btn.width, btn.height, btn.text);
        })
        MouseArea {
            anchors.fill: parent
            onPressed: ink.flashButton(btn.x, btn.y, btn.width, btn.height, btn.text, true)
            onClicked: ink.activateButton(btn.text)
        }
    }

    TopButton {
        id: backBtn
        text: "Back"
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.margins: 24
    }

    TopButton {
        id: clearBtn
        text: "Clear"
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.margins: 24
    }
}