Ranges, Progressions, and Coercion

fun main() {
    // Basic ranges
    val intRange = 1..10
    val charRange = 'a'..'z'
    val longRange = 1L..1_000_000L

    // Membership
    println("5 in 1..10: ${5 in intRange}")
    println("'m' in a..z: ${'m' in charRange}")
    println("15 in 1..10: ${15 in intRange}")

    // until (exclusive end)
    val exclusive = 0 until 10  // 0..9
    println("\n0 until 10: ${exclusive.toList()}")

    // downTo
    val countdown = 10 downTo 1
    println("10 downTo 1: ${countdown.toList()}")

    // Step
    val evens = 0..20 step 2
    println("Evens: ${evens.toList()}")

    val oddCountdown = 9 downTo 1 step 2
    println("Odd countdown: ${oddCountdown.toList()}")

    // Progression properties
    val prog = 1..10 step 3
    println("\nProgression: first=${prog.first}, last=${prog.last}, step=${prog.step}")

    // Range in when
    fun classify(score: Int): String = when (score) {
        in 90..100 -> "A"
        in 80 until 90 -> "B"
        in 70 until 80 -> "C"
        in 0 until 70 -> "F"
        else -> "Invalid"
    }
    println("\nScore 85: ${classify(85)}")
    println("Score 95: ${classify(95)}")

    // Coercion
    val value = 150
    println("\nCoerce 150 in 0..100: ${value.coerceIn(0..100)}")
    println("Coerce -5 at least 0: ${(-5).coerceAtLeast(0)}")
    println("Coerce 200 at most 100: ${200.coerceAtMost(100)}")

    // Custom range class
    data class Version(val major: Int, val minor: Int) : Comparable<Version> {
        override fun compareTo(other: Version) = when {
            major != other.major -> major - other.major
            else -> minor - other.minor
        }
        override fun toString() = "$major.$minor"
    }

    val supported = Version(2, 0)..Version(4, 0)
    val current = Version(3, 5)
    println("\n$current in $supported: ${current in supported}")

    // Range-based array slicing
    val arr = intArrayOf(10, 20, 30, 40, 50, 60, 70, 80)
    val slice = arr.slice(2..5)
    println("\nSlice [2..5]: $slice")

    // String range
    val alpha = "Hello World".slice(0..4)
    println("Slice: $alpha")

    // Iteration patterns
    println("\n--- Iterations ---")
    for (i in 1..5) print("$i "); println()
    for (i in 5 downTo 1) print("$i "); println()
    for (i in 0 until 10 step 3) print("$i "); println()
    for (c in 'A'..'F') print("$c "); println()

    // repeat
    repeat(3) { i -> print("repeat-$i ") }; println()

    // Functional with ranges
    val squares = (1..5).map { it * it }
    println("\nSquares: $squares")

    val sum = (1..100).sum()
    println("Sum 1..100: $sum")

    val filtered = (1..20).filter { it % 3 == 0 || it % 5 == 0 }
    println("FizzBuzz: $filtered")
}