amnezia-client/client/android/src/org/amnezia/vpn/PairingQrScanOverlayView.kt

package org.amnezia.vpn

import android.content.Context
import android.graphics.Canvas
import android.graphics.Paint
import android.graphics.Path
import android.graphics.RectF
import android.util.AttributeSet
import android.view.MotionEvent
import android.view.View
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import kotlin.math.max

class PairingQrScanOverlayView @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {

    init {
        isClickable = false
        isFocusable = false
    }

    @Suppress("ClickableViewAccessibility")
    override fun onTouchEvent(event: MotionEvent): Boolean = false

    private val dimPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
        color = 0x8C000000.toInt()
        style = Paint.Style.FILL
    }

    private val bracketPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
        color = 0xFFE8E8EC.toInt()
        style = Paint.Style.STROKE
        strokeCap = Paint.Cap.ROUND
        strokeJoin = Paint.Join.ROUND
    }

    private var hole = RectF()

    private val bracketPaths = arrayOfNulls<Path>(4)

    private val dimPath = Path()

    private var pairingHeaderBottomPx = 0f

    fun setPairingHeaderBottomPx(px: Float) {
        if (pairingHeaderBottomPx == px) {
            return
        }
        pairingHeaderBottomPx = px
        recomputePairingHole()
        invalidate()
    }

    private fun recomputePairingHole() {
        val w = width
        val h = height
        if (w <= 0 || h <= 0) {
            return
        }
        val topInset = ViewCompat.getRootWindowInsets(this)
            ?.getInsets(WindowInsetsCompat.Type.statusBars())?.top?.toFloat() ?: 0f
        val d = resources.displayMetrics.density
        hole = PairingQrScanGeometry.pairingIosStyleHoleRectF(w, h, pairingHeaderBottomPx, topInset, d)
        rebuildBracketPaths()
    }

    private fun rebuildBracketPaths() {
        val s = hole.width()
        if (s <= 0f) {
            bracketPaths.fill(null)
            return
        }
        val x0 = hole.left
        val y0 = hole.top
        val t = bracketPaint.strokeWidth
        val d = resources.displayMetrics.density
        val l = max(28f * d, s * 0.13f)
        val r = PairingQrScanGeometry.pairingIosStyleHoleCornerRadiusPx(s, d)
        for (i in 0..3) {
            bracketPaths[i] = PairingQrScanBracketPaths.bracketStrokePath(i, x0, y0, s, r, l, t)
        }
    }

    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
        super.onSizeChanged(w, h, oldw, oldh)
        bracketPaint.strokeWidth = max(3f, 5f * resources.displayMetrics.density)
        recomputePairingHole()
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        val w = width.toFloat()
        val h = height.toFloat()
        val side = hole.width()
        if (side > 0f) {
            val d = resources.displayMetrics.density
            val rx = PairingQrScanGeometry.pairingIosStyleHoleCornerRadiusPx(side, d)
            dimPath.rewind()
            dimPath.fillType = Path.FillType.EVEN_ODD
            dimPath.addRect(0f, 0f, w, h, Path.Direction.CW)
            dimPath.addRoundRect(hole, rx, rx, Path.Direction.CW)
            canvas.drawPath(dimPath, dimPaint)
        } else {
            canvas.drawRect(0f, 0f, w, h, dimPaint)
        }

        for (i in 0..3) {
            bracketPaths[i]?.let { canvas.drawPath(it, bracketPaint) }
        }
    }
}