# HitCollision —— CLIENT-GAP §3.5 修改 2：`CActorInstance::__NormalAttackProcess` 用到的碰撞几何，
# 逐行移植（单位 = Metin2 cm，Z 为高度）：
#   IntersectLineSegments / FindNearestPointOnLineSegment / FindNearestPointOfParallelLineSegments /
#   AdjustNearestPoints（EterLib/lineintersect_utils.cpp，MY_EPSILON 0.1）
#   DetectCollisionDynamicZCylinderVSDynamicZCylinder（GameLib/GameUtil.cpp）
#   .msm AttachingData CollisionType 3 = m_DefendingPointInstanceList 的防御球
extends RefCounted

const MY_EPSILON := 0.1
const COLLISION_TYPE_DEFENDING := 3   # NRaceData::COLLISION_TYPE_DEFENDING
const HUGE_RACE_VNUM := 2493          # IS_HUGE_RACE（InstanceBase.cpp）

static var _msm_cache := {}

# FindNearestPointOnLineSegment：|L|² < ε² 时 Nearest = A1，parameter 保持调用方原值。
# 返回 [Nearest, parameter]。
static func _nearest_on_segment(a1: Vector3, l: Vector3, b: Vector3, parameter: float) -> Array:
	var d := l.length_squared()
	if d < MY_EPSILON * MY_EPSILON:
		return [a1, parameter]
	var p := clampf((b - a1).dot(l) / d, 0.0, 1.0)
	return [a1 + p * l, p]

static func _out_of_range(a: float) -> bool:
	return a < 0.0 or a > 1.0

# FindNearestPointOfParallelLineSegments（s[] 已被 FindNearestPointOnLineSegment 夹到 [0,1]，
# 所以前两个分支在出货代码里实际走不到；照抄保留）。
static func _parallel(a1: Vector3, a2: Vector3, la: Vector3, b1: Vector3, b2: Vector3, lb: Vector3) -> Array:
	var r0 := _nearest_on_segment(a1, la, b1, 0.0)
	var out_a: Vector3 = r0[0]
	var s0: float = r0[1]
	var s1: float = _nearest_on_segment(a1, la, b2, 0.0)[1]
	var out_b := Vector3.ZERO
	if s0 < 0.0 and s1 < 0.0:
		out_a = a1
		out_b = b2 if s0 < s1 else b1
	elif s0 > 1.0 and s1 > 1.0:
		out_a = a2
		out_b = b1 if s0 < s1 else b2
	else:
		var temp := 0.5 * (clampf(s0, 0.0, 1.0) + clampf(s1, 0.0, 1.0))
		out_a = a1 + temp * la
		out_b = _nearest_on_segment(b1, lb, out_a, temp)[0]
	return [out_a, out_b]

static func _adjust(a1: Vector3, la: Vector3, b1: Vector3, lb: Vector3, s: float, t: float) -> Array:
	var out_a := a1 + s * la
	var out_b := b1 + t * lb
	var r: Array
	if _out_of_range(s) and _out_of_range(t):
		s = clampf(s, 0.0, 1.0)
		out_a = a1 + s * la
		r = _nearest_on_segment(b1, lb, out_a, t)
		out_b = r[0]
		t = r[1]
		if _out_of_range(t):
			t = clampf(t, 0.0, 1.0)
			out_b = b1 + t * lb
			r = _nearest_on_segment(a1, la, out_b, s)
			out_a = r[0]
			s = r[1]
			r = _nearest_on_segment(b1, lb, out_a, t)
			out_b = r[0]
	elif _out_of_range(s):
		s = clampf(s, 0.0, 1.0)
		out_a = a1 + s * la
		out_b = _nearest_on_segment(b1, lb, out_a, t)[0]
	elif _out_of_range(t):
		t = clampf(t, 0.0, 1.0)
		out_b = b1 + t * lb
		out_a = _nearest_on_segment(a1, la, out_b, s)[0]
	return [out_a, out_b]

# 返回 [OutA, OutB]：两段上的最近点对。
static func intersect_line_segments(a1: Vector3, a2: Vector3, b1: Vector3, b2: Vector3) -> Array:
	var la := a2 - a1
	var lb := b2 - b1
	var l11 := la.length_squared()
	var l22 := lb.length_squared()
	var eps2 := MY_EPSILON * MY_EPSILON
	if l11 < eps2:
		return [a1, _nearest_on_segment(b1, lb, a1, 0.0)[0]]
	elif l22 < eps2:
		return [_nearest_on_segment(a1, la, b1, 0.0)[0], b1]
	var ab := b1 - a1
	var l12 := -la.dot(lb)
	var det_l := l11 * l22 - l12 * l12
	if absf(det_l) < MY_EPSILON:
		return _parallel(a1, a2, la, b1, b2, lb)
	var ra := la.dot(ab)
	# 出货代码是 +dot(Lb, AB)（旁注写的是负号）——两段都在动时 t 会反号，1:1 保留。
	var rb := lb.dot(ab)
	var t := (l11 * rb - ra * l12) / det_l
	var s := (ra - l12 * t) / l11
	if _out_of_range(s) or _out_of_range(t):
		return _adjust(a1, la, b1, lb, s, t)
	return [a1 + s * la, b1 + t * lb]

# DetectCollisionDynamicZCylinderVSDynamicZCylinder：两个扫掠球都压到 z=0（高度不参与），
# 各自 AABB（按自身半径外扩）不相交直接 false，否则比较两段最近点距离与 r1+r2。
static func detect_z_cylinder(c1_last: Vector3, c1_pos: Vector3, r1: float,
		c2_last: Vector3, c2_pos: Vector3, r2: float) -> bool:
	c1_last.z = 0.0
	c1_pos.z = 0.0
	c2_last.z = 0.0
	c2_pos.z = 0.0
	var r := r1 + r2
	var mi1 := Vector3(minf(c1_last.x, c1_pos.x), minf(c1_last.y, c1_pos.y), minf(c1_last.z, c1_pos.z)) - Vector3.ONE * r1
	var mi2 := Vector3(maxf(c1_last.x, c1_pos.x), maxf(c1_last.y, c1_pos.y), maxf(c1_last.z, c1_pos.z)) + Vector3.ONE * r1
	var mi3 := Vector3(minf(c2_last.x, c2_pos.x), minf(c2_last.y, c2_pos.y), minf(c2_last.z, c2_pos.z)) - Vector3.ONE * r2
	var mi4 := Vector3(maxf(c2_last.x, c2_pos.x), maxf(c2_last.y, c2_pos.y), maxf(c2_last.z, c2_pos.z)) + Vector3.ONE * r2
	if mi4.x < mi1.x or mi2.x < mi3.x:
		return false
	if mi4.y < mi1.y or mi2.y < mi3.y:
		return false
	if mi4.z < mi1.z or mi2.z < mi3.z:
		return false
	var o := intersect_line_segments(c1_last, c1_pos, c2_last, c2_pos)
	return (Vector3(o[0]) - Vector3(o[1])).length_squared() <= r * r

# IS_HUGE_RACE（InstanceBase.cpp）：出货表只有 2493。
static func is_huge_race(race: int) -> bool:
	return race == HUGE_RACE_VNUM

# 解析 .msm 的防御球：[{radius, pos: Vector3(cm, 模型本地), bone}]。bone 非空 = isAttaching
# 挂骨骼（本端按模型本地坐标近似，seam）。缺文件 -> []。按路径缓存。
static func parse_msm_defending(path: String) -> Array:
	if _msm_cache.has(path):
		return _msm_cache[path]
	var out := []
	if FileAccess.file_exists(path):
		var f := FileAccess.open(path, FileAccess.READ)
		var ctype := -1
		var bone := ""
		var attaching := false
		var radius := 0.0
		while f and not f.eof_reached():
			var parts := f.get_line().strip_edges().replace("\t", " ").split(" ", false)
			if parts.is_empty():
				continue
			var key := String(parts[0]).to_lower()
			if key == "group" and parts.size() > 1 and String(parts[1]).to_lower().begins_with("attachingdata"):
				ctype = -1
				bone = ""
				attaching = false
			elif key == "collisiontype" and parts.size() > 1:
				ctype = int(parts[1])
			elif key == "isattaching" and parts.size() > 1:
				attaching = int(parts[1]) != 0
			elif key == "attachingbonename" and parts.size() > 1:
				bone = String(parts[1]).trim_prefix("\"").trim_suffix("\"")
			elif key == "radius" and parts.size() > 1:
				radius = float(parts[1])
			elif key == "position" and parts.size() > 3 and ctype == COLLISION_TYPE_DEFENDING:
				out.append({"radius": radius,
						"pos": Vector3(float(parts[1]), float(parts[2]), float(parts[3])),
						"bone": bone if attaching else ""})
	_msm_cache[path] = out
	return out