time.echo

; std/time — wall clock and sleep.
; Privileged std may `/ runtime` and call `runtime.*` (docs/stdlib.md).
;
; Public API:
;   now_ms — milliseconds since Unix epoch (UTC), i64
;   sleep_ms — sleep at least `ms` milliseconds (no-op if ms ≤ 0)
;
; Suite: xo test std/time.echo (XO_TEST).

/ runtime
/ std/test
/ std/str

$ now_ms = () {
    ^ runtime.now_ms()
}

$ sleep_ms = (ms) {
    runtime.sleep_ms(ms)
    ^
}

; Monotonic milliseconds since process start (not wall clock).
$ mono_ms = () {
    ^ runtime.now_mono_ms()
}

; Format wall-ms with a strftime-like pattern (chrono; e.g. "%Y-%m-%d").
$ format = (ms, fmt) {
    ^ runtime.time_format(ms, fmt)
}

; Parse text with pattern → result ms since epoch, or ! "parse failed".
$ parse = (s, fmt) {
    $ r = runtime.time_parse(s, fmt)
    ? r.ok == 0 {
        ! "parse failed"
    }
    ^ r.val
}

; --- suite ---

test.it("now_ms_nonneg", () {
    $ t = now_ms()
    test.true(t >= 0)
    ; Epoch is far in the past; after 2020-01-01 ≈ 1.5e12 ms.
    test.true(t > 1500000000000)
})

test.it("sleep_ms_zero", () {
    sleep_ms(0)
    sleep_ms(-1)
    test.eq(1, 1)
})

test.it("sleep_ms_advances", () {
    $ a = now_ms()
    sleep_ms(30)
    $ b = now_ms()
    ; Allow small clock noise; should not go backwards by much and usually advances.
    test.true(b >= a)
    test.true(b - a >= 20)
})

test.it("mono_ms_nonneg", () {
    test.true(mono_ms() >= 0)
})

test.it("format_parse_day", () {
    $ ms = 1700000000000
    $ s = format(ms, "%Y-%m-%d")
    test.true(str.starts_with(s, "2023"))
    | parse(s, "%Y-%m-%d") {
        $ t {
            test.true(t > 0)
        }
        ! e {
            test.fail(e)
        }
    }
})

\ now_ms, sleep_ms, mono_ms, format, parse