/**
* Re-creating the format function -- at least sort of.
* And doing it is a pure-functional way
* But I do cheat and use the format funtion.
* Also gratuitously using an enum
*  
* @author gtowell
* Created: August 2021
* Modified: Nov 2021
 */

enum class Formats {
    s,
    d,
    f
}

fun main() {
    println(sprintf2("%s%d%f", "this", 1, 2.3))
    println(sprintf2("%s%d", "this", 42, "that"))
}


fun sprintf2(fmt:String, vararg qq:Any) : String {
    fun isp(fmmt:List<String>, vargs:List<Any>):String {
        if (vargs.size==0) { return "" }
        if (fmmt.size == 0) { return ""}
        val q = vargs.first()
        when (fmmt.first()) {
            // this really just checks the type of each arg against the 
            // format string, then it calls format.  With more work, I could 
            // get rid of the use if format entirely.
            Formats.s.name -> if (q is String) { 
                    return "%s %s".format(q, isp(fmmt.drop(1), vargs.drop(1))) 
                } else { 
                    println("type mismatch ${fmmt.first()} $q"); return isp(fmmt.drop(1), vargs.drop(1)) 
                }
            Formats.d.name -> if (q is Int) { 
                    return "%d %s".format(q, isp(fmmt.drop(1), vargs.drop(1))) 
                } else { 
                    println("type mismatch ${fmmt.first()} $q"); return isp(fmmt.drop(1), vargs.drop(1))
                }
            Formats.f.name -> if (q is Double) { 
                    return "%f %s".format(q, isp(fmmt.drop(1), vargs.drop(1))) 
                } else { 
                    println("type mismatch ${fmmt.first()} $q"); return isp(fmmt.drop(1), vargs.drop(1))
                }
            else -> { println("unknown format ${fmmt.first()}"); return isp(fmmt.drop(1), vargs.drop(1)) }
        }
    }
    return isp(fmt.split("%").drop(1), qq.toList())
}