/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

using CultMath;
using static CultMath.math;

// Cut 1 (docs/fire-control-cut.md): geometry only. Whether a weapon bears on a point is decided here and
// nowhere else -- no prefab, transform, ArticulationPoint or renderer may influence it (R6, R7). Mount
// direction and arc are both derived per read from catalog data and the item's authored rotation; neither
// is ever stored on the entity.
public static class FireControl
{
    // The planar unit vector a hardpoint's weapon points along, derived solely from the item's authored
    // rotation (R6, the same convention reaction thrusters already use) -- never from a live Unity
    // transform. This is the item-rotation path Behavior.Direction now uses unconditionally, after the
    // HardpointTransforms readback branch is deleted.
    public static float3 MountDirection(EquippedItem item)
    {
        var itemDirection = item.Entity.Direction.Rotate(item.EquippableItem.Rotation);
        return normalize(float3(itemDirection.x, 0, itemDirection.y));
    }

    // Full arc width in degrees: the per-hardpoint override when authored (nonzero), else
    // GameplaySettings.FiringArc. Zero on the hardpoint means "use the default," not "no arc."
    public static float ArcFor(EquippedItem item)
    {
        var hardpoint = item.Entity.Hardpoints[item.Position.x, item.Position.y];
        var arc = hardpoint?.FiringArc ?? 0f;
        return arc > 0 ? arc : item.ItemManager.GameplaySettings.FiringArc;
    }

    // Planar bearing test (R7: the simulation is 2D, the 3D is set dressing -- target height never enters
    // this). An arc of 360 degrees or more passes unconditionally, which is how a turret hardpoint
    // (authored FiringArc: 360, Q1) tracks all the way around without a second type.
    public static bool InArc(EquippedItem weapon, float3 toTarget)
    {
        var arc = ArcFor(weapon);
        if (arc >= 360f) return true;
        var planarTarget = normalize(float3(toTarget.x, 0, toTarget.z));
        return dot(MountDirection(weapon), planarTarget) >= cos(radians(arc / 2f));
    }
}