const std = @import("std");
const Io = std.Io;

var configured_io: ?Io = null;

pub fn init(io: Io) void {
    configured_io = io;
}

fn currentIo() Io {
    return configured_io orelse std.Options.debug_io;
}

pub fn nowNanos() i96 {
    return Io.Timestamp.now(currentIo(), .real).nanoseconds;
}

/// nanoseconds on the suspend-excluding monotonic clock; for durations only
pub fn monotonicNs() u64 {
    return @intCast(@max(0, Io.Timestamp.now(currentIo(), .awake).nanoseconds));
}

pub fn nowMs() i64 {
    return @intCast(@divTrunc(nowNanos(), std.time.ns_per_ms));
}

pub fn nowSeconds() i64 {
    return @intCast(@divTrunc(nowNanos(), std.time.ns_per_s));
}

test "clock runs without init and is monotone-ish across calls" {
    const a = nowSeconds();
    const b = nowMs();
    try std.testing.expect(a > 1_700_000_000);
    try std.testing.expect(@divTrunc(b, 1000) >= a);
}