@[has_globals]
module trace_calls

@[markused]
__global g_stack_base = &u8(unsafe { nil })
__global g_start_time = u64(0)

@[markused]
pub fn on_call(fname string) {
    mut volatile pfbase := &u8(unsafe { nil })
    volatile fbase := u8(0)
    ns := current_time() - g_start_time
    mut ssize := u64(0)
    mut tid := u32(0)
    unsafe {
        $if windows {
            tid = C.GetCurrentThreadId()
        } $else $if no_gettid ? {
            tid = u32(C.pthread_self())
        } $else $if linux && !musl ? {
            tid = C.gettid()
        } $else {
            tid = u32(C.pthread_self())
        }
        pfbase = &fbase
        ssize = u64(g_stack_base) - u64(pfbase)
    }
    $if x64 {
        C.fprintf(C.stderr, c'> trace %8d %8ld %8ld %s\n', tid, ns, ssize, fname.str)
    } $else {
        C.fprintf(C.stderr, c'> trace %8d %8lld %8lld %s\n', tid, ns, ssize, fname.str)
    }
    C.fflush(C.stderr)
}

@[inline]
fn current_time() u64 {
    unsafe {
        $if windows {
            tm := u64(0)
            C.QueryPerformanceCounter(&tm)
            return tm
        } $else {
            ts := C.timespec{}
            C.clock_gettime(C.CLOCK_MONOTONIC, &ts)
            return u64(ts.tv_sec) * 1000000000 + u64(ts.tv_nsec)
        }
    }
}

@[markused]
pub fn on_c_main(should_trace_c_main bool) {
    g_start_time = current_time()
    //                    > trace  2128896   714640    28148 fn
    C.fprintf(C.stderr, c'#          tid       ns      ssize name\n')
    C.fflush(C.stderr)
    if should_trace_c_main {
        on_call('C.main')
    }
}