using AcDream.Core.Items;

namespace AcDream.Core.Combat;

/// <summary>
/// Eligibility policy for automatic monster acquisition.
/// </summary>
public static class CombatTargetPolicy
{
    /// <summary>
    /// Returns true only for a live-data creature that is attackable, is not a
    /// player, and is not a pet. Friendly NPCs and non-creatures are rejected.
    /// </summary>
    /// <remarks>
    /// The attackability core is retail
    /// <c>ClientCombatSystem::ObjectIsAttackable @ 0x0056A600</c>. Retail
    /// <c>AutoTarget @ 0x0056BC80</c> falls back to
    /// <c>SelectNext(SELECTION_TYPE_COMPASS_ITEM)</c>, whose combat filter also
    /// uses ObjectIsAttackable. acdream deliberately narrows that set to
    /// non-player monsters for its automatic acquisition policy; explicit
    /// player-selection commands remain separate.
    /// </remarks>
    public static bool IsHostileMonster(
        uint playerId,
        ClientObject? player,
        ClientObject? candidate)
    {
        if (candidate is null
            || candidate.ObjectId == playerId
            || (candidate.Type & ItemType.Creature) == 0
            || (candidate.PublicWeenieBitfield.GetValueOrDefault()
                & SelectedObjectHealthPolicy.BfPlayer) != 0
            || candidate.PetOwnerId != 0)
            return false;

        return SelectedObjectHealthPolicy.ObjectIsAttackable(
            playerId,
            player,
            candidate.ObjectId,
            candidate);
    }
}