Kotliin version of https://github.com/mariamrf/flat-color-generator

FlatColorGenerator.kt

import java.lang.IllegalArgumentException
import kotlin.math.floor
import kotlin.math.roundToInt

/**
 * Pass a hue value/degree between 0 and 360 or pass nothing and generate a random value. Returns a random flat color as hex string.
 */
fun flatColor(deg: Float? = null): String {
    val h = if (deg == null) {
        val phi = 0.618033988749895
        val hue = (floor(Math.random() * (360 - 0 + 1) + 0)) / 360
        ((hue + (hue / phi)) % 360).toFloat()
    } else {
        deg / 360f
    }

    var v = floor(Math.random() * (100 - 20 + 1) + 20)
    val s = (v - 10) / 100f
    v /= 100f

    val i = floor(h * 6.0)
    val f = h * 6 - i
    val p = v * (1 - s)
    val q = v * (1 - f * s)
    val t = v * (1 - (1 - f) * s)

    val (rr, gr, br) = when (i % 6) {
        0.0 -> Triple(v, t, p)
        1.0 -> Triple(q, v, p)
        2.0 -> Triple(p, v, t)
        3.0 -> Triple(p, q, v)
        4.0 -> Triple(t, p, v)
        5.0 -> Triple(v, q, p)
        else -> throw IllegalArgumentException()
    }

    val r = (rr * 255).roundToInt()
    val g = (gr * 255).roundToInt()
    val b = (br * 255).roundToInt()

    return "#" + ((1 shl 24) + (r shl 16) + (g shl 8) + b).toString(16).slice(IntRange(1, 6))
}