@tool
extends Node3D
class_name GridPlaneManager

enum GridType { SQUARE, HEX }

signal grid_layout_changed(cells: Dictionary)

var _grid_type: GridType = GridType.SQUARE
@export var grid_type: GridType = GridType.SQUARE:
	set(value):
		if value == _grid_type:
			return
		_grid_type = value as GridType
		_queue_rebuild()
	get:
		return _grid_type

var _columns: int = 10
@export_range(1, 256, 1) var columns: int:
	set(value):
		value = max(value, 1)
		if value == _columns:
			return
		_columns = value
		_queue_rebuild()
	get:
		return _columns

var _rows: int = 10
@export_range(1, 256, 1) var rows: int:
	set(value):
		value = max(value, 1)
		if value == _rows:
			return
		_rows = value
		_queue_rebuild()
	get:
		return _rows

var _cell_size: float = 1.0
@export_range(0.1, 10.0, 0.1) var cell_size: float:
	set(value):
		value = max(value, 0.25)
		if is_equal_approx(value, _cell_size):
			return
		_cell_size = value
		_queue_rebuild()
	get:
		return _cell_size

var _ground_thickness: float = 0.4
@export_range(0.1, 2.0, 0.05) var ground_thickness: float:
	set(value):
		value = clamp(value, 0.1, 2.0)
		if is_equal_approx(value, _ground_thickness):
			return
		_ground_thickness = value
		_queue_rebuild()
	get:
		return _ground_thickness

var _ground_padding: float = 20.0
@export_range(0.0, 200.0, 1.0) var ground_padding: float:
	set(value):
		value = max(value, 0.0)
		if is_equal_approx(value, _ground_padding):
			return
		_ground_padding = value
		emit_signal("grid_layout_changed", _cells)
	get:
		return _ground_padding

var _show_grid_lines: bool = true
@export var show_grid_lines: bool:
	set(value):
		if value == _show_grid_lines:
			return
		_show_grid_lines = value
		if is_node_ready():
			_update_grid_visibility()
	get:
		return _show_grid_lines

var _grid_line_color: Color = Color(0.2, 0.7, 1.0, 0.65)
@export var grid_line_color: Color:
	set(value):
		if value == _grid_line_color:
			return
		_grid_line_color = value
		_queue_rebuild()
	get:
		return _grid_line_color

const _LINE_HEIGHT_OFFSET := 0.02
const _SQRT3 := 1.7320508075688772

@onready var _grid_lines: MeshInstance3D = %GridLines

var _grid_size: Vector2 = Vector2.ZERO
var _cells: Dictionary = {}
var _queued_rebuild: bool = false
var _hex_center_offset_local: Vector3 = Vector3.ZERO

func _ready() -> void:
	_queue_rebuild()

func get_cells() -> Dictionary:
	return _cells.duplicate()

func get_grid_size() -> Vector2:
	return _grid_size

func get_grid_type() -> GridType:
	return _grid_type

func get_cell_center(index: Vector2i) -> Vector3:
	return _cells.get(index, Vector3.ZERO)

func has_cell(index: Vector2i) -> bool:
	return _cells.has(index)

func cell_to_world(index: Vector2i) -> Vector3:
	return get_cell_center(index)

func world_to_cell(world_position: Vector3, clamp_to_bounds: bool = true) -> Vector2i:
	var local_position: Vector3 = to_local(world_position)
	if _grid_type == GridType.HEX:
		return _world_to_hex_cell(local_position, clamp_to_bounds)
	return _world_to_square_cell(local_position, clamp_to_bounds)

func for_each_cell(callback: Callable) -> void:
	for index in _cells.keys():
		callback.call(index, _cells[index])

func get_cell_size_value() -> float:
	return _cell_size

func get_ground_thickness() -> float:
	return _ground_thickness

func get_ground_padding() -> float:
	return _ground_padding

func make_highlight_mesh() -> Mesh:
	if _grid_type == GridType.HEX:
		return _build_hex_highlight_mesh()
	var plane := PlaneMesh.new()
	plane.size = Vector2(_cell_size, _cell_size)
	return plane

func _queue_rebuild() -> void:
	if _queued_rebuild:
		return
	_queued_rebuild = true
	call_deferred("_process_rebuild_request")

func _process_rebuild_request() -> void:
	_queued_rebuild = false
	if not is_node_ready():
		return
	_rebuild_grid()

func _rebuild_grid() -> void:
	match _grid_type:
		GridType.HEX:
			_generate_hex_grid()
		_:
			_generate_square_grid()
	_update_grid_lines()
	emit_signal("grid_layout_changed", _cells)

func _generate_square_grid() -> void:
	_hex_center_offset_local = Vector3.ZERO
	_cells.clear()
	_grid_size = Vector2(_columns * _cell_size, _rows * _cell_size)
	var start_x := -_grid_size.x * 0.5 + _cell_size * 0.5
	var start_z := -_grid_size.y * 0.5 + _cell_size * 0.5
	for row in range(_rows):
		for column in range(_columns):
			var center := Vector3(
				start_x + float(column) * _cell_size,
				0.0,
				start_z + float(row) * _cell_size
			)
			_cells[Vector2i(column, row)] = center

func _generate_hex_grid() -> void:
	_cells.clear()
	if _columns <= 0 or _rows <= 0:
		_grid_size = Vector2.ZERO
		return
	var radius: float = max(_cell_size * 0.5, 0.001)
	var min_corner_x: float = INF
	var max_corner_x: float = -INF
	var min_corner_z: float = INF
	var max_corner_z: float = -INF
	for row in range(_rows):
		for column in range(_columns):
			var x := radius * 1.5 * float(column)
			var z := radius * _SQRT3 * (float(row) + float(column) * 0.5)
			var center := Vector3(x, 0.0, z)
			_cells[Vector2i(column, row)] = center
			var corners := _compute_hex_corners(center, radius)
			for corner in corners:
				min_corner_x = min(min_corner_x, corner.x)
				max_corner_x = max(max_corner_x, corner.x)
				min_corner_z = min(min_corner_z, corner.z)
				max_corner_z = max(max_corner_z, corner.z)
	if min_corner_x == INF:
		_grid_size = Vector2.ZERO
		return
	var size_x: float = max_corner_x - min_corner_x
	var size_z: float = max_corner_z - min_corner_z
	var center_offset: Vector3 = Vector3(min_corner_x + size_x * 0.5, 0.0, min_corner_z + size_z * 0.5)
	for key in _cells.keys():
		_cells[key] -= center_offset
	_hex_center_offset_local = center_offset
	_grid_size = Vector2(size_x, size_z)

func _update_grid_lines() -> void:
	if not _grid_lines:
		return
	if not _show_grid_lines:
		_grid_lines.visible = false
		_grid_lines.mesh = null
		return
	_grid_lines.visible = true
	if _grid_type == GridType.HEX:
		_grid_lines.mesh = _build_hex_grid_mesh()
	else:
		_grid_lines.mesh = _build_square_grid_mesh()

func _update_grid_visibility() -> void:
	if not _grid_lines:
		return
	_grid_lines.visible = _show_grid_lines

func _build_square_grid_mesh() -> ArrayMesh:
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_LINES)
	var half_width := _grid_size.x * 0.5
	var half_depth := _grid_size.y * 0.5
	var color := _grid_line_color
	for column in range(_columns + 1):
		var x := -half_width + float(column) * _cell_size
		st.set_color(color)
		st.add_vertex(Vector3(x, _LINE_HEIGHT_OFFSET, -half_depth))
		st.set_color(color)
		st.add_vertex(Vector3(x, _LINE_HEIGHT_OFFSET, half_depth))
	for row in range(_rows + 1):
		var z := -half_depth + float(row) * _cell_size
		st.set_color(color)
		st.add_vertex(Vector3(-half_width, _LINE_HEIGHT_OFFSET, z))
		st.set_color(color)
		st.add_vertex(Vector3(half_width, _LINE_HEIGHT_OFFSET, z))
	var mesh := st.commit()
	return mesh

func _build_hex_grid_mesh() -> ArrayMesh:
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_LINES)
	var color := _grid_line_color
	var radius: float = max(_cell_size * 0.5, 0.001)
	for center in _cells.values():
		var center_vec: Vector3 = center
		var corners := _compute_hex_corners(center_vec, radius)
		for i in range(corners.size()):
			var a: Vector3 = corners[i]
			var b: Vector3 = corners[(i + 1) % corners.size()]
			st.set_color(color)
			st.add_vertex(a + Vector3(0, _LINE_HEIGHT_OFFSET, 0))
			st.set_color(color)
			st.add_vertex(b + Vector3(0, _LINE_HEIGHT_OFFSET, 0))
	var mesh := st.commit()
	return mesh

func _compute_hex_corners(center: Vector3, radius: float) -> Array[Vector3]:
	var corners: Array[Vector3] = []
	for i in range(6):
		var angle_deg := 60.0 * i
		var angle := deg_to_rad(angle_deg)
		var x := center.x + radius * cos(angle)
		var z := center.z + radius * sin(angle)
		corners.append(Vector3(x, 0.0, z))
	return corners

func _update_highlight_mesh() -> void:
	# Deprecated internally; kept for compatibility.
	pass

func _build_hex_highlight_mesh() -> ArrayMesh:
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_TRIANGLES)
	var radius: float = max(_cell_size * 0.5, 0.001)
	var corners := _compute_hex_corners(Vector3.ZERO, radius)
	for i in range(1, corners.size() - 1):
		st.add_vertex(corners[0])
		st.add_vertex(corners[i])
		st.add_vertex(corners[i + 1])
	var mesh := st.commit()
	return mesh

func _world_to_square_cell(local_position: Vector3, clamp_to_bounds: bool) -> Vector2i:
	var half_width := _grid_size.x * 0.5
	var half_depth := _grid_size.y * 0.5
	var normalized_x := (local_position.x + half_width) / _cell_size
	var normalized_z := (local_position.z + half_depth) / _cell_size
	var x := int(floor(normalized_x))
	var z := int(floor(normalized_z))
	if clamp_to_bounds:
		x = clamp(x, 0, _columns - 1)
		z = clamp(z, 0, _rows - 1)
	return Vector2i(x, z)

func _world_to_hex_cell(local_position: Vector3, clamp_to_bounds: bool) -> Vector2i:
	var adjusted: Vector3 = local_position + _hex_center_offset_local
	var axial: Vector2 = _local_hex_to_axial(adjusted)
	var cube: Vector3 = _axial_to_cube(axial)
	var rounded: Vector3 = _cube_round(cube)
	var q: int = int(rounded.x)
	var r: int = int(rounded.z)
	if clamp_to_bounds:
		q = clamp(q, 0, _columns - 1)
		r = clamp(r, 0, _rows - 1)
	elif q < 0 or q >= _columns or r < 0 or r >= _rows:
		return Vector2i(-1, -1)
	return Vector2i(q, r)

func _local_hex_to_axial(local_position: Vector3) -> Vector2:
	var radius: float = max(_cell_size * 0.5, 0.0001)
	var q: float = (2.0 / 3.0 * local_position.x) / radius
	var r: float = ((-1.0 / 3.0) * local_position.x + (_SQRT3 / 3.0) * local_position.z) / radius
	return Vector2(q, r)

func _axial_to_cube(axial: Vector2) -> Vector3:
	var x: float = axial.x
	var z: float = axial.y
	var y: float = -x - z
	return Vector3(x, y, z)

func _cube_round(cube: Vector3) -> Vector3:
	var rx: float = round(cube.x)
	var ry: float = round(cube.y)
	var rz: float = round(cube.z)
	var x_diff: float = abs(rx - cube.x)
	var y_diff: float = abs(ry - cube.y)
	var z_diff: float = abs(rz - cube.z)
	if x_diff > y_diff and x_diff > z_diff:
		rx = -ry - rz
	elif y_diff > z_diff:
		ry = -rx - rz
	else:
		rz = -rx - ry
	return Vector3(rx, ry, rz)