import net
import time

fn echo_server(mut c net.UdpConn) {
    mut count := 0
    for {
        eprintln('> echo_server loop count: ${count}')
        mut buf := []u8{len: 100}
        read, addr := c.read(mut buf) or { continue }
        eprintln('Server got addr ${addr}, read: ${read} | buf: ${buf}')
        c.write_to(addr, buf[..read]) or {
            println('Server: connection dropped')
            return
        }
        count++
        // Normally, after responding, the test will end, but there are sometimes  cases,
        // when the echo_server continued looping, printing messages constantly.
        // The sleep here, is a small precaution against spamming the CI with log messages,
        // when there are network problems, and it allows easier root cause diagnostic, when
        // they do happen:
        time.sleep(1000 * time.millisecond)
    }
}

const server_addr = '127.0.0.1:40003'

fn echo() ! {
    mut c := net.dial_udp(server_addr) or { panic('could not net.dial_udp: ${err}') }
    defer {
        c.close() or {}
    }
    data := 'Hello from vlib/net!'

    c.write_string(data) or { panic('could not write_string: ${err}') }

    mut buf := []u8{len: 100, init: 0}
    read, addr := c.read(mut buf) or { panic('could not read: ${err}') }

    assert read == data.len
    println('Got address ${addr}')
    // Can't test this here because loopback addresses
    // are mapped to other addresses
    // assert addr.str() == '127.0.0.1:30001'

    for i := 0; i < read; i++ {
        assert buf[i] == data[i]
    }

    println('Got "${buf.bytestr()}"')

    c.close()!
}

fn test_udp() {
    mut l := net.listen_udp(server_addr) or { panic('could not listen_udp: ${err}') }

    spawn echo_server(mut l)
    echo() or { panic('could not echo: ${err}') }

    l.close() or {}
}

fn udp_write_after_delay(addr string, delay time.Duration, payload string, done chan bool) {
    time.sleep(delay)
    mut conn := net.dial_udp(addr) or { panic(err) }
    defer {
        conn.close() or {}
    }
    conn.write_string(payload) or { panic(err) }
    done <- true
}

fn test_udp_read_timeout_is_honored_for_blocking_reads() ! {
    mut listener := net.listen_udp('127.0.0.1:0')!
    defer {
        listener.close() or {}
    }
    addr := listener.sock.address()!.str()
    delay := 200 * time.millisecond
    timeout := 20 * time.millisecond
    payload := 'late udp packet'
    done := chan bool{cap: 1}

    spawn udp_write_after_delay(addr, delay, payload, done)
    listener.set_read_timeout(timeout)

    mut buf := []u8{len: payload.len}
    if _, _ := listener.read(mut buf) {
        assert false, 'expected udp read timeout before delayed packet arrived'
    } else {
        assert err.code() == net.err_timed_out_code
    }

    _ = <-done
    listener.set_read_timeout(time.second)
    read, _ := listener.read(mut buf)!
    assert read == payload.len
    assert buf[..read].bytestr() == payload
}

fn test_udp_multicast_ipv4_socket_options() ! {
    mut listener := net.listen_udp('0.0.0.0:0')!
    defer {
        listener.close() or {}
    }

    listener.join_multicast_group('224.0.0.1', '0.0.0.0')!
    listener.leave_multicast_group('224.0.0.1', '0.0.0.0')!
    listener.set_multicast_ttl(2)!
    listener.set_multicast_loop(true)!
    listener.set_multicast_loop(false)!
    listener.set_multicast_interface('0.0.0.0')!
}

fn test_udp_multicast_validates_inputs() ! {
    mut listener := net.listen_udp('0.0.0.0:0')!
    defer {
        listener.close() or {}
    }

    mut ttl_failed := false
    listener.set_multicast_ttl(-1) or {
        ttl_failed = true
        assert err.msg().contains('multicast ttl')
    }
    assert ttl_failed

    mut non_multicast_failed := false
    listener.join_multicast_group('127.0.0.1', '') or {
        non_multicast_failed = true
        assert err.msg().contains('not an ipv4 multicast address')
    }
    assert non_multicast_failed

    mut iface_failed := false
    listener.set_multicast_interface('not-an-ip') or {
        iface_failed = true
        assert err.msg().contains('ipv4 multicast interface')
    }
    assert iface_failed
}