class_name QuarryShell
extends RefCounted

const STEPS := 512
const LEVELS := [-6.0, 0.0, 2.4, 3.0, 5.4, 6.1, 8.7, 9.4, 12.2, 13.0, 16.2, 17.0, 20.4, 21.1, 24.0, 25.2, 28.2, 30.0]

static func perimeter(t: float) -> Vector3:
 var corners := [Vector3(-50, 0, -69), Vector3(50, 0, -69), Vector3(50, 0, 69), Vector3(-50, 0, 69)]
 var edge := floori(t * 4) % 4
 return corners[edge].lerp(corners[(edge + 1) % 4], fmod(t * 4, 1.0))

static func point(i: int, level: int) -> Vector3:
 var t := float(i % STEPS) / STEPS
 var p := perimeter(t)
 var direction := p.normalized()
 var along := t * TAU
 var erosion := 3.8 + sin(along * 13 + sin(along * 5) * 0.6 + level * 0.06) * 2.8 + sin(along * 31 + level * 0.15) * 0.65
 var terrace := level * 0.23 + sin(along * 9 + level * 0.7) * 1.2 + sin(along * 57 + level * 2.3) * 0.65
 p += direction * (terrace + erosion + sin(along * 83 + level * 0.3) * 0.28 + sin(along * 137 + level) * 0.13)
 var height_scale := 1.0 + 0.15 * sin(along * 3 + 0.6) + 0.065 * cos(along * 7)
 p.y = LEVELS[level] * height_scale * 0.76 + (sin(along * 17) * 0.38 + sin(along * 37 + level * 0.35) * 0.32 if level > 1 else 0.0)
 if level >= LEVELS.size() - 2: p.y += sin(along * 23) * 1.1 + sin(along * 41) * 0.45
 return p

static func build(root: Node3D) -> void:
 # Closed contiguous rock surface. Shared vertices at every seam, including corners.
 var tool := SurfaceTool.new()
 tool.begin(Mesh.PRIMITIVE_TRIANGLES)
 for i in STEPS:
  for j in LEVELS.size() - 1:
   tool.set_smooth_group(0)
   for p in [point(i, j), point(i + 1, j + 1), point(i + 1, j), point(i, j), point(i, j + 1), point(i + 1, j + 1)]:
    tool.set_uv(Vector2(p.x + p.z, p.y) * 0.2)
    tool.add_vertex(p)
 tool.generate_normals()
 var mesh := MeshInstance3D.new()
 mesh.name = "ContinuousStrataWall"
 mesh.mesh = tool.commit()
 mesh.material_override = QuarryLandscape.sandstone(null)
 root.add_child(mesh)
 # Extend visual ground beneath the complete perimeter; no collider or route changes.
 var floor_mesh := MeshInstance3D.new()
 floor_mesh.name = "BuriedQuarryApron"
 var plane := PlaneMesh.new()
 plane.size = Vector2(220, 250)
 floor_mesh.mesh = plane
 floor_mesh.position.y = -0.045
 floor_mesh.material_override = UrbanMaterials.get_surface("sand", Color("d0b895"))
 root.add_child(floor_mesh)
 build_scree(root)

static func build_scree(root: Node3D) -> void:
 var tool := SurfaceTool.new()
 tool.begin(Mesh.PRIMITIVE_TRIANGLES)
 for i in STEPS:
  var a := perimeter(float(i) / STEPS)
  var b := perimeter(float((i + 1) % STEPS) / STEPS)
  var near_a := a * Vector3(0.915, 1, 0.94)
  var near_b := b * Vector3(0.915, 1, 0.94)
  near_a.y = -0.02
  near_b.y = -0.02
  a.y = 2.0 + sin(i * 0.83) * 0.55
  b.y = 2.0 + sin(((i + 1) % STEPS) * 0.83) * 0.55
  for p in [near_a, b, near_b, near_a, a, b]:
   tool.set_uv(Vector2(p.x, p.z))
   tool.add_vertex(p)
 tool.generate_normals()
 var mesh := MeshInstance3D.new()
 mesh.name = "ContinuousScreeFoot"
 mesh.mesh = tool.commit()
 mesh.material_override = UrbanMaterials.get_surface("sand", Color("c6aa83")).duplicate()
 mesh.material_override.cull_mode = BaseMaterial3D.CULL_DISABLED
 root.add_child(mesh)