using Unity.Mathematics;

namespace ProjectM.Simulation
{
    /// <summary>
    /// Pure, deterministic respawn-timer math (no RNG, no wall-clock) — unit-testable in EditMode without a netcode
    /// world (mirrors <see cref="PlayerSpawnMath"/> / <see cref="EnemyAIMath"/>). Ticks are the server's monotonic
    /// simulation ticks; a stored value of 0 means "no respawn pending / alive". Comparisons use a wrap-safe signed-delta (modular) compare — matching
    /// <see cref="Unity.NetCode.NetworkTick.IsNewerThan"/> semantics — so they hold across the uint tick wraparound.
    /// </summary>
    public static class RespawnMath
    {
        /// <summary>
        /// The tick at which a death at <paramref name="deathTick"/> should respawn, given
        /// <paramref name="delayTicks"/> (clamped to &gt;= 1). Never returns 0 (0 is the "no respawn pending"
        /// sentinel), so a death exactly at tick 0 still schedules a recovery.
        /// </summary>
        public static uint RespawnTick(uint deathTick, int delayTicks)
        {
            uint delay = (uint)math.max(1, delayTicks);
            uint t = deathTick + delay;
            return t == 0u ? 1u : t;
        }

        /// <summary>
        /// True when <paramref name="now"/> has reached/passed a scheduled <paramref name="respawnTick"/> (and one
        /// is actually scheduled, i.e. non-zero).
        /// </summary>
        public static bool IsDue(uint now, uint respawnTick)
        {
            // Wrap-safe modular compare (signed delta), NOT a raw `now >= respawnTick` (which is unsafe at the
            // uint tick wraparound). Matches NetworkTick.IsNewerThan; keeps this helper pure-uint + unit-testable.
            return respawnTick != 0u && (int)(now - respawnTick) >= 0;
        }
    }
}