Coverage Summary for Class: SurferAuthBackgroundKt (com.georgeci.moneysurfer.uikit.components)

 package com.georgeci.moneysurfer.uikit.components
 
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Brush
 import androidx.compose.ui.graphics.Path
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.georgeci.moneysurfer.uikit.tokens.AuthColors
 
 private val WaveBandHeight: Dp = 220.dp
 
 private const val DefaultCp1X: Float = 0.22f
 private const val DefaultCp1Y: Float = -30f
 private const val DefaultCp2X: Float = 0.42f
 private const val DefaultCp2Y: Float = 30f
 private const val DefaultMidX: Float = 0.63f
 private const val DefaultCp3X: Float = 0.78f
 private const val DefaultCp3Y: Float = -25f
 private const val DefaultCp4X: Float = 0.92f
 private const val DefaultCp4Y: Float = 15f
 
 private data class WaveCrest(
     val startY: Float,
     val midY: Float,
     val endY: Float,
     val cp1X: Float = DefaultCp1X,
     val cp1Y: Float = DefaultCp1Y,
     val cp2X: Float = DefaultCp2X,
     val cp2Y: Float = DefaultCp2Y,
     val midX: Float = DefaultMidX,
     val cp3X: Float = DefaultCp3X,
     val cp3Y: Float = DefaultCp3Y,
     val cp4X: Float = DefaultCp4X,
     val cp4Y: Float = DefaultCp4Y,
 )
 
 private val BackCrest = WaveCrest(startY = 0.40f, midY = 0.60f, endY = 0.50f)
 private val MidCrest = WaveCrest(startY = 0.60f, midY = 0.78f, endY = 0.65f)
 private const val BackCrestAlpha: Float = 0.55f
 private const val MidCrestAlpha: Float = 0.85f
 private const val FrontCrestStartY: Float = 0.82f
 private const val FrontCp1X: Float = 0.20f
 private const val FrontCp1Y: Float = 0.74f
 private const val FrontCp2X: Float = 0.45f
 private const val FrontCp2Y: Float = 0.93f
 private const val FrontMidX: Float = 0.66f
 private const val FrontMidY: Float = 0.84f
 private const val FrontCp3X: Float = 0.83f
 private const val FrontCp3Y: Float = 0.76f
 private const val FrontCp4X: Float = 0.95f
 private const val FrontCp4Y: Float = 0.88f
 private const val FrontEndY: Float = 0.82f
 private const val FrontGradientStartY: Float = 0.74f
 private const val FrontGradientAlpha: Float = 0.55f
 
 /** Which way the brand gradient runs behind a pre-auth screen. */
 enum class SurferAuthGradient {
     /** Top to bottom — the stacked phone / tablet-portrait layout the ramp was drawn for. */
     Vertical,
 
     /**
      * Top-left to bottom-right. On a short, wide window a vertical ramp is compressed into almost
      * no travel and reads as a flat fill; running it along the diagonal restores the tonal shift.
      */
     Diagonal,
 }
 
 /**
  * The green gradient + wave band behind every pre-auth screen (onboarding + sign-in). Draw it edge
  * to edge (outside of [com.georgeci.moneysurfer.uikit.modifier.surferSafeInsets]) so it tints the
  * status bar and the navigation bar / gesture ribbon as well.
  */
 @Composable
 fun SurferAuthBackground(
     modifier: Modifier = Modifier,
     gradient: SurferAuthGradient = SurferAuthGradient.Vertical,
 ) {
     val colors = listOf(AuthColors.GreenTop, AuthColors.GreenBottom)
     Box(
         modifier = modifier.background(
             when (gradient) {
                 SurferAuthGradient.Vertical -> Brush.verticalGradient(colors)
                 // Defaults run corner to corner, which is the diagonal we want.
                 SurferAuthGradient.Diagonal -> Brush.linearGradient(colors)
             },
         ),
     ) {
         WaveDecoration(
             modifier = Modifier
                 .align(Alignment.BottomCenter)
                 .fillMaxWidth()
                 .height(WaveBandHeight),
         )
     }
 }
 
 @Composable
 private fun WaveDecoration(modifier: Modifier = Modifier) {
     Canvas(modifier = modifier) {
         val w = size.width
         val h = size.height
 
         fun crestPath(crest: WaveCrest): Path {
             val startY = h * crest.startY
             val midY = h * crest.midY
             val endY = h * crest.endY
             return Path().apply {
                 moveTo(0f, startY)
                 cubicTo(
                     w * crest.cp1X,
                     startY + crest.cp1Y,
                     w * crest.cp2X,
                     midY + crest.cp2Y,
                     w * crest.midX,
                     midY,
                 )
                 cubicTo(
                     w * crest.cp3X,
                     midY + crest.cp3Y,
                     w * crest.cp4X,
                     endY + crest.cp4Y,
                     w,
                     endY,
                 )
                 lineTo(w, h)
                 lineTo(0f, h)
                 close()
             }
         }
 
         drawPath(
             path = crestPath(BackCrest),
             color = AuthColors.WaveBack,
             alpha = BackCrestAlpha,
         )
         drawPath(
             path = crestPath(MidCrest),
             color = AuthColors.WaveMid,
             alpha = MidCrestAlpha,
         )
         drawPath(
             path = Path().apply {
                 moveTo(0f, h * FrontCrestStartY)
                 cubicTo(
                     w * FrontCp1X,
                     h * FrontCp1Y,
                     w * FrontCp2X,
                     h * FrontCp2Y,
                     w * FrontMidX,
                     h * FrontMidY,
                 )
                 cubicTo(
                     w * FrontCp3X,
                     h * FrontCp3Y,
                     w * FrontCp4X,
                     h * FrontCp4Y,
                     w,
                     h * FrontEndY,
                 )
                 lineTo(w, h)
                 lineTo(0f, h)
                 close()
             },
             brush = Brush.verticalGradient(
                 colors = listOf(
                     AuthColors.WaveFront.copy(alpha = 0f),
                     AuthColors.WaveFront.copy(alpha = FrontGradientAlpha),
                 ),
                 startY = h * FrontGradientStartY,
                 endY = h,
             ),
         )
     }
 }