GenericGeometry.swift

typealias GeometricValue = Numeric & Comparable

struct GenericPoint<ValueType: GeometricValue>: Equatable {
	var x: ValueType
	var y: ValueType
	
	static var zero: Self { Self(x: 0, y: 0) }
}

extension GenericPoint {
	init(_ x: ValueType, _ y: ValueType) {
		self.init(x: x, y: y)
	}
	
	static func +(lhs: Self, rhs: Self) -> Self {
		Self(x: lhs.x + rhs.x, y: lhs.y + rhs.y)
	}
	
	static func +=(lhs: inout Self, rhs: Self) {
		lhs = lhs + rhs
	}
	
	static func -(lhs: Self, rhs: Self) -> Self {
		lhs + (rhs * -1)
	}
	
	static func -=(lhs: inout Self, rhs: Self) {
		lhs = lhs - rhs
	}
	
	static func *(lhs: Self, scale: ValueType) -> Self {
		Self(x: lhs.x * scale, y: lhs.y * scale)
	}
	
	static func *=(lhs: inout Self, scale: ValueType) {
		lhs = lhs * scale
	}
	
	static prefix func - (point: Self) -> Self {
		point * -1
	}
	
	func offsetBy(dx: ValueType = 0, dy: ValueType = 0) -> Self {
		self + Self(x: dx, y: dy)
	}
}

extension GenericPoint where ValueType: FloatingPoint {
	static func /(lhs: Self, scale: ValueType) -> Self {
		lhs * (1 / scale)
	}
	
	static func /=(lhs: inout Self, scale: ValueType) {
		lhs *= (1 / scale)
	}
}

struct GenericSize<ValueType: GeometricValue>: Equatable {
	var width: ValueType
	var height: ValueType
	
	static var zero: Self { Self(width: 0, height: 0) }
}

extension GenericSize {
	init(_ w: ValueType, _ h: ValueType) {
		self.init(width: w, height: h)
	}
}

extension GenericSize: Sequence where ValueType: Strideable {
	typealias Element = GenericPoint<ValueType>
	
	func makeIterator() -> AnyIterator<Element> {
		return GenericRect(origin: .zero, size: self).makeIterator()
	}
}

struct GenericRect<ValueType: GeometricValue>: Equatable {
	typealias PointType = GenericPoint<ValueType>
	typealias SizeType = GenericSize<ValueType>
	
	var origin: PointType
	var size: SizeType
	
	var x: ValueType {
		get { origin.x }
		set { origin.x = newValue }
	}
	
	var y: ValueType {
		get { origin.y }
		set { origin.y = newValue }
	}
	
	var width: ValueType {
		get { size.width }
		set { size.width = newValue }
	}
	
	var height: ValueType {
		get { size.height }
		set { size.height = newValue }
	}
	
	var maxX: ValueType { Swift.max(x, x + width) }
	var maxY: ValueType { Swift.max(y, y + height) }
	
	var minX: ValueType { Swift.min(x, x + width) }
	var minY: ValueType { Swift.min(y, y + height) }
	
	var bottomLeft: PointType { PointType(x: minX, y: maxY) }
	var bottomRight: PointType { PointType(x: maxX, y: maxY) }
	
	var area: ValueType {
		let copy = standardized()
		return copy.width * copy.height
	}
	
	func contains(_ point: PointType) -> Bool {
		let test = standardized()
		return point.x >= test.x && point.y >= test.y && point.x < test.x + test.width && point.y < test.y + test.height
	}
	
	mutating func standardize() {
		if width < 0 {
			x += width
			width *= -1
		}
		
		if height < 0 {
			y += height
			height *= -1
		}
	}
	
	func standardized() -> Self {
		var copy = self
		copy.standardize()
		return copy
	}
	
	func translatedBy(_ v: PointType) -> Self {
		Self(origin: PointType(x: x + v.x, y: y + v.y), size: SizeType(width: width, height: height))
	}
	
	func intersection(_ r2: Self) -> Self? {
		if minX < r2.maxX, maxX > r2.minX, minY < r2.maxY, maxY > r2.minY {
			return Self(minX: Swift.max(minX, r2.minX),
						minY: Swift.max(minY, r2.minY),
						maxX: Swift.min(maxX, r2.maxX),
						maxY: Swift.min(maxY, r2.maxY))
		} else {
			return nil
		}
	}
	
	func inset(by insets: GenericInsets<ValueType>) -> Self {
		Self(minX: minX + insets.left,
			 minY: minY + insets.top,
			 maxX: maxX - insets.bottom,
			 maxY: maxY - insets.right)
	}
	
	static var zero: Self { Self(origin: .zero, size: .zero) }
}

extension GenericRect {
	init(x: ValueType, y: ValueType, width: ValueType, height: ValueType) {
		self.init(origin: PointType(x: x, y: y),
				  size: SizeType(width: width, height: height))
	}
	
	init(_ x: ValueType, _ y: ValueType, _ w: ValueType, _ h: ValueType) {
		self.init(x: x, y: y, width: w, height: h)
	}
	
	init(minX: ValueType, minY: ValueType, maxX: ValueType, maxY: ValueType) {
		self.init(minX, minY, maxX - minX, maxY - minY)
	}
	
	init(origin: PointType, bottomRight: PointType) {
		self.init(minX: origin.x, minY: origin.y, maxX: bottomRight.x, maxY: bottomRight.y)
	}
}

protocol Divisible {
	static func / (lhs: Self, rhs: Self) -> Self
}

extension Float: Divisible {}
extension Int: Divisible {}

extension GenericRect where ValueType: Divisible {
	var center: PointType {
		get { PointType(x: midX, y: midY) }
		set { midX = newValue.x; midY = newValue.y }
	}
	
	var midX: ValueType {
		get { x + (width / 2) }
		set { x = newValue - width / 2 }
	}
	
	var midY: ValueType {
		get { y + (height / 2) }
		set { y = newValue - height / 2 }
	}
	
	var bottomCenter: PointType { PointType(x: midX, y: maxY) }
}

extension GenericRect: Sequence where ValueType: Strideable {
	typealias Element = PointType
	
	func makeIterator() -> AnyIterator<PointType> {
		var at = origin
		return AnyIterator {
			if at.x == self.width {
				at.y += 1
				at.x = 0
			}
			guard at.y < self.height else { return nil }
			defer { at.x += 1 }
			return at
		}
	}
}

struct GenericInsets<ValueType: GeometricValue>: Equatable {
	var top: ValueType
	var left: ValueType
	var bottom: ValueType
	var right: ValueType
	
	static var zero: Self { Self(top: 0, left: 0, bottom: 0, right: 0) }
}

typealias Point = GenericPoint<Int>
typealias Size = GenericSize<Int>
typealias Rect = GenericRect<Int>
typealias EdgeInsets = GenericInsets<Int>

typealias PointF = GenericPoint<Float>
typealias SizeF = GenericSize<Float>
typealias RectF = GenericRect<Float>
typealias EdgeInsetsF = GenericInsets<Float>

extension Point {
	init(_ point: PointF) {
		self.init(Int(point.x.rounded(.down)), Int(point.y.rounded(.down)))
	}
}

extension PointF {
	init(_ point: Point) {
		self.init(Float(point.x), Float(point.y))
	}
}