// vtest retry: 5

// This test case runs concurrent 3 instances of `do_select` that
// communicate with 6 other threads doing send and receive operations.
// There are buffered and unbuffered channels - handled by one or two
// concurrend threads on the other side

fn do_select(ch1 chan int, ch2 chan int, chf1 chan f64, chf2 chan f64, sumch1 chan i64, sumch2 chan i64) {
    mut sum1 := i64(0)
    mut sum2 := i64(0)
    f1 := 17.0
    f2 := 7.0
    for _ in 0 .. 20000 + chf1.cap / 3 {
        select {
            chf1 <- f1 {}
            i := <-ch1 {
                sum1 += i
            }
            j := <-ch2 {
                sum2 += j
            }
            chf2 <- f2 {}
        }
    }
    sumch1 <- sum1
    sumch2 <- sum2
}

fn do_send_int(ch chan int, factor int) {
    for i in 0 .. 10000 {
        ch <- (i * factor)
    }
}

fn do_rec_f64(ch chan f64, sumch chan f64) {
    mut sum := 0.0
    for _ in 0 .. 10000 {
        sum += <-ch
    }
    sumch <- sum
}

fn test_select() {
    ch1 := chan int{cap: 3}
    ch2 := chan int{}
    // buffer length of chf1 mus be multiple of 3 (# select threads)
    chf1 := chan f64{cap: 30}
    chf2 := chan f64{}
    chsum1 := chan i64{}
    chsum2 := chan i64{}
    chsumf1 := chan f64{}
    chsumf2 := chan f64{}
    spawn do_send_int(ch1, 3)
    spawn do_select(ch1, ch2, chf1, chf2, chsum1, chsum2)
    spawn do_rec_f64(chf1, chsumf1)
    spawn do_rec_f64(chf2, chsumf2)
    spawn do_rec_f64(chf2, chsumf2)
    spawn do_select(ch1, ch2, chf1, chf2, chsum1, chsum2)
    spawn do_send_int(ch2, 7)
    spawn do_send_int(ch2, 17)
    spawn do_select(ch1, ch2, chf1, chf2, chsum1, chsum2)

    sum1 := <-chsum1 + <-chsum1 + <-chsum1
    sum2 := <-chsum2 + <-chsum2 + <-chsum2
    mut sumf1 := <-chsumf1
    // empty channel buffer
    for _ in 0 .. chf1.cap {
        sumf1 += <-chf1
    }
    sumf2 := <-chsumf2 + <-chsumf2
    // Use Gauß' formula
    expected_sum := i64(10000) * (10000 - 1) / 2
    assert sum1 == 3 * expected_sum
    assert sum2 == (7 + 17) * expected_sum
    assert sumf1 == 17.0 * f64(10000 + chf1.cap)
    assert sumf2 == 7.0 * 20000
}