module sync

// vtest retry: 3

// ATTENTION! Do not use this file as an example!
// For that, please look at `channel_select_2_test.v` or `channel_select_3_test.v`
// This test case uses the implementation in `sync/channels.v` directly
// in order to test it independently from the support in the core language
import os
import time

fn test_should_run_flaky_test() {
    if os.getenv('VTEST_RUN_FLAKY') != '1' {
        eprintln('> skipping running flaky test, set VTEST_RUN_FLAKY to 1, to run it')
        exit(0)
    }
    assert true
}

fn do_rec_i64(mut ch Channel) {
    mut sum := i64(0)
    for _ in 0 .. 300 {
        mut a := i64(0)
        ch.pop(&a)
        sum += a
    }
    assert sum == 300 * (300 - 1) / 2
}

fn do_send_int(mut ch Channel) {
    for i in 0 .. 300 {
        ch.push(&i)
    }
}

fn do_send_u8(mut ch Channel) {
    for i in 0 .. 300 {
        ii := u8(i)
        ch.push(&ii)
    }
}

fn do_send_i64(mut ch Channel) {
    for i in 0 .. 300 {
        ii := i64(i)
        ch.push(&ii)
    }
}

fn test_select() {
    mut chi := new_channel[int](0)
    mut chl := new_channel[i64](1)
    mut chb := new_channel[u8](10)
    mut recch := new_channel[i64](0)
    spawn do_rec_i64(mut recch)
    spawn do_send_int(mut chi)
    spawn do_send_u8(mut chb)
    spawn do_send_i64(mut chl)
    mut channels := [chi, recch, chl, chb]
    directions := [Direction.pop, .push, .pop, .pop]
    mut sum := i64(0)
    mut rl := i64(0)
    mut ri := int(0)
    mut rb := u8(0)
    mut sl := i64(0)
    mut objs := [voidptr(&ri), &sl, &rl, &rb]
    for _ in 0 .. 1200 {
        idx := channel_select(mut channels, directions, mut objs, time.infinite)
        match idx {
            0 {
                sum += ri
            }
            1 {
                sl++
            }
            2 {
                sum += rl
            }
            3 {
                sum += rb
            }
            else {
                println('got ${idx} (timeout)')
            }
        }
    }
    // Use Gauß' formula for the first 2 contributions
    // the 3rd contribution is `byte` and must be seen modulo 256
    expected_sum := 2 * (300 * (300 - 1) / 2) + 256 * (256 - 1) / 2 + 44 * (44 - 1) / 2
    assert sum == expected_sum
}