use std::time::Duration;
use std::u64;

pub const REKEY_AFTER_MESSAGES: u64 = 1 << 60;
pub const REJECT_AFTER_MESSAGES: u64 = u64::MAX - (1 << 4);

pub const REKEY_AFTER_TIME: Duration = Duration::from_secs(120);
pub const REJECT_AFTER_TIME: Duration = Duration::from_secs(180);
pub const REKEY_ATTEMPT_TIME: Duration = Duration::from_secs(90);
pub const REKEY_TIMEOUT: Duration = Duration::from_secs(5);
pub const KEEPALIVE_TIMEOUT: Duration = Duration::from_secs(10);

pub const MAX_TIMER_HANDSHAKES: usize =
    (REKEY_ATTEMPT_TIME.as_secs() / REKEY_TIMEOUT.as_secs()) as usize;

// Semantics:
// Maximum number of buffered handshake requests
// (either from outside message or handshake requests triggered locally)
pub const MAX_QUEUED_INCOMING_HANDSHAKES: usize = 4096;

// Semantics:
// When the number of queued handshake requests exceeds this number
// the device is considered under load and DoS mitigation is triggered.
pub const THRESHOLD_UNDER_LOAD: usize = MAX_QUEUED_INCOMING_HANDSHAKES / 8;

// Semantics:
// When a device is detected to go under load,
// it will remain under load for at least the following duration.
pub const DURATION_UNDER_LOAD: Duration = Duration::from_secs(1);

// Semantics:
// The payload of transport messages are padded to this multiple
pub const MESSAGE_PADDING_MULTIPLE: usize = 16;

// Semantics:
// Longest possible duration of any WireGuard timer
pub const TIMER_MAX_DURATION: Duration = Duration::from_secs(200);

// Semantics:
// Resolution of the timer-wheel
pub const TIMERS_TICK: Duration = Duration::from_millis(100);

// Semantics:
// Resulting number of slots in the wheel
pub const TIMERS_SLOTS: usize = (TIMER_MAX_DURATION.as_micros() / TIMERS_TICK.as_micros()) as usize;

// Performance:
// Initial capacity of timer-wheel (grows to accommodate more timers).
pub const TIMERS_CAPACITY: usize = 16;

/* A long duration (compared to the WireGuard time constants),
 * used in places to avoid Option<Instant> by instead using a long "expired" Instant:
 * (Instant::now() - TIME_HORIZON)
 *
 * Note, this duration need not fit inside the timer wheel.
 */
pub const TIME_HORIZON: Duration = Duration::from_secs(TIMER_MAX_DURATION.as_secs() * 2);