package dodd

import kotlin.math.*

typealias Fn = (Double) -> Double

fun List<Double>.rangeMap(minOut: Double, maxOut: Double): List<Double> {
    val minIn = this.min()!!
    val maxIn = this.max()!!
    val deltaIn = maxIn - minIn
    val deltaOut = maxOut - minOut

    return this.map{ minOut + (it - minIn) * deltaOut / deltaIn }
}

const val width = 100
const val height = 12

const val a = 0.0
const val b = 4 * PI

val fn: Fn = ::sin

fun main() {
    val indices = Array(width) { it }.toList()

    val ys = indices.map{ a + (it + 0.5) * b / width }.map(fn).rangeMap(0.5, height - 0.5)

    val steps = mutableListOf(ys.first()).apply {
        addAll(ys)
        add(ys.last())
    }

    val ds = indices.map{ (steps[it + 2] - steps[it]) * if (it == 0 || it == width - 1) 1.0 else 0.5 }

    val grads = mapOf(-1.0 to '\\', -0.0 to '-', 0.0 to '-', 1.0 to '/')

    fun grad(d: Double) = grads.getOrDefault(round(d), '|')

    fun col(index: Int): Array<Char> {
        val arr = Array(height) { ' ' }
        arr[round(ys[index] - 0.5).roundToInt()] = grad(ds[index])
        return arr
    }

    val cols = indices.map(::col)

    val rows = (height - 1 downTo 0).map{ i -> Array(width) { j -> cols[j][i] }.toList() }

    for (row in rows) {
        for (ch in row) {
            print(ch)
        }
        println()
    }
}