// Micro-benchmarks (E.5) — recursive fib, string concat, array push.
// Prints lines: BENCH name iters total_us us_per_op
import Std::Io::{PrintLine, Print};
import Std::Time::{Time_NowUs};
import Std::String::{String_FromInt, String_Concat, String_Len};
import Std::Array::{Array, Array_New, Array_Push, Array_Len, Array_Get};

func Fib(n: int) -> int {
    if n <= 1 {
        return n;
    }
    return Fib(n - 1) + Fib(n - 2);
}

func Report(name: String, iters: int, usTotal: int64) {
    var perOpUs: int64 = 0;
    if iters > 0 {
        perOpUs = usTotal / (iters as int64);
    }
    Print("BENCH ");
    Print(name);
    Print(" iters=");
    Print(String_FromInt(iters as int64));
    Print(" total_us=");
    Print(String_FromInt(usTotal));
    Print(" us_per_op=");
    PrintLine(String_FromInt(perOpUs));
}

func BenchIntLoop() {
    let iters: int = 1000000;
    var acc: int = 0;
    var i: int = 0;
    let t0: int64 = Time_NowUs();
    while i < iters {
        acc = acc + i * 3 - 1;
        i = i + 1;
    }
    let t1: int64 = Time_NowUs();
    if acc == 0 && iters > 0 {
        PrintLine("unreachable");
    }
    Report("int_loop", iters, t1 - t0);
}

func BenchFib() {
    discard Fib(20);
    let n: int = 30;
    let t0: int64 = Time_NowUs();
    let r: int = Fib(n);
    let t1: int64 = Time_NowUs();
    if r < 0 {
        PrintLine("unreachable");
    }
    Report("fib30", 1, t1 - t0);
}

func BenchStringConcat() {
    let iters: int = 50000;
    var i: int = 0;
    let t0: int64 = Time_NowUs();
    var s: String = "";
    while i < iters {
        s = String_Concat(s, "x");
        if String_Len(s) > 256 {
            s = "x";
        }
        i = i + 1;
    }
    let t1: int64 = Time_NowUs();
    if String_Len(s) < 0 {
        PrintLine("unreachable");
    }
    Report("string_concat", iters, t1 - t0);
}

func BenchArrayPush() {
    let iters: int = 100000;
    var arr: Array<int> = Array_New<int>(16);
    var i: int = 0;
    let t0: int64 = Time_NowUs();
    while i < iters {
        Array_Push<int>(&arr, i);
        i = i + 1;
    }
    let t1: int64 = Time_NowUs();
    let n: uint = Array_Len<int>(&arr);
    if n as int != iters {
        Print("array len mismatch: ");
        PrintLine(String_FromInt(n as int64));
    }
    discard Array_Get<int>(&arr, (iters - 1) as uint);
    Report("array_push", iters, t1 - t0);
}

func Main() -> int {
    PrintLine("=== Bux micro-benchmarks (E.5) ===");
    BenchIntLoop();
    BenchFib();
    BenchStringConcat();
    BenchArrayPush();
    PrintLine("=== done ===");
    return 0;
}