Swizzle.swift

import ObjectiveC

nonisolated(unsafe) public var swizzleLogs = false

@MainActor
public func swizzle(_ type: AnyObject.Type, _ original: Selector, _ swizzled: Selector) {
	guard !swizzlingHistory.contains(type, original, swizzled) else {
		return
	}

	swizzlingHistory.add(type, original, swizzled)

	guard let originalMethod = class_getInstanceMethod(type, original) else {
		assertionFailure("[Swizzling] Instance method \(type).\(original) not found.")
		return
	}

	guard let swizzledMethod = class_getInstanceMethod(type, swizzled) else {
		assertionFailure("[Swizzling] Instance method \(type).\(swizzled) not found.")
		return
	}

	if swizzleLogs {
		print("[Swizzling] [\(type) \(original) <~> \(swizzled)]")
	}

	method_exchangeImplementations(originalMethod, swizzledMethod)
}

private struct SwizzlingHistory {
	private var map: [Int: Void] = [:]

	func contains(_ type: AnyObject.Type, _ original: Selector, _ swizzled: Selector) -> Bool {
		map[hash(type, original, swizzled)] != nil
	}

	mutating func add(_ type: AnyObject.Type, _ original: Selector, _ swizzled: Selector) {
		map[hash(type, original, swizzled)] = ()
	}

	private func hash(_ type: AnyObject.Type, _ original: Selector, _ swizzled: Selector) -> Int {
		var hasher = Hasher()
		hasher.combine(ObjectIdentifier(type))
		hasher.combine(original)
		hasher.combine(swizzled)
		return hasher.finalize()
	}
}

nonisolated(unsafe) private var swizzlingHistory = SwizzlingHistory()