using Unity.Entities;

namespace ProjectM.Simulation
{
    /// <summary>
    /// The ONE in-place frame-swap effect, shared by the editor dev tool (DebugOp.SetClass) and the player-facing
    /// frame select. Re-seeds the frame's stat band via <see cref="ClassTraits.Reapply"/>; the caller then writes
    /// FrameId/PlayerClass, re-seeds the socket loadout, and calls <see cref="HealClamp"/> (a static can't resolve
    /// singletons or SystemAPI.SetComponent, so the caller passes the resolved pieces). Server-authoritative +
    /// prediction-correct (StatRecomputeSystem refolds EffectiveCharacterStats next tick).
    ///
    /// HISTORY (2026-08-07 audit purge): this also used to strip and replay a PERMANENT-META band
    /// (MetaUpgradeCatalog + MetaTierState) so an Aether-bought upgrade followed the frame across a swap. The meta
    /// shop belonged to the superseded base/expedition direction and was deleted; only the frame band remains.
    /// </summary>
    public static class ClassSwapUtil
    {
        /// <summary>Re-seed the frame stat band for <paramref name="rawClass"/> on <paramref name="mods"/>.
        /// Returns the normalized frame id (the caller writes FrameId/PlayerClass + re-seeds the socket
        /// loadout).</summary>
        public static void Apply(byte rawClass, DynamicBuffer<StatModifier> mods, out byte newClass)
        {
            newClass = ClassTraits.Normalize(rawClass);
            ClassTraits.Reapply(newClass, mods);
        }

        /// <summary>Heal/down-clamp a LIVING player's Current to the new class's full max (blob base folded with the
        /// just-reseeded <paramref name="mods"/>, like StatRecomputeSystem). Doubles as the down-clamp when the new
        /// class's max is lower (Bathynaut +30 HP vs Harpooner -15%). No-op on a corpse (Current&lt;=0) — respawn refills.</summary>
        public static void HealClamp(ref Health health, float baseMaxHealth, DynamicBuffer<StatModifier> mods)
        {
            if (health.Current > 0f)
                health.Current = StatMath.Apply(baseMaxHealth, StatTarget.MaxHealth, mods);
        }
    }
}