// SPDX-FileCopyrightText: 2025 The Project Pterodactyl Developers
//
// SPDX-License-Identifier: MPL-2.0

import Foundation

struct Graph<Vertex: Hashable> {
	var edges: [Vertex: Set<Vertex>]
}

extension Graph: Codable where Vertex: Codable {}
extension Graph: Sendable where Vertex: Sendable {}

extension Graph {
	func verticesReachableFrom(_ start: Vertex) -> Set<Vertex> {
		var visited: Set<Vertex> = []
		var stack: [Vertex] = []

		if let neighbors = edges[start] {
			stack.append(contentsOf: neighbors)
		}

		while let vertex = stack.popLast() {
			guard !visited.contains(vertex) else { continue }
			visited.insert(vertex)
			if let neighbors = edges[vertex] {
				for neighbor in neighbors where !visited.contains(neighbor) {
					stack.append(neighbor)
				}
			}
		}

		return visited
	}
}