Path.swift

import Foundation
import ArgumentParser

public enum Path {
    static let path = ProcessInfo.processInfo.environment["PATH"]!.components(separatedBy: ":")

    public static func find(_ command: String) throws -> URL {
        let files = FileManager.default
        for path in Self.path {
            let executable = URL(fileURLWithPath: path).appendingPathComponent(command, isDirectory: false)
            guard files.fileExists(atPath: executable.path) else {
                continue
            }
            let metadata = try executable.resourceValues(forKeys: [.isRegularFileKey, .isSymbolicLinkKey,
                                                                   .isExecutableKey])
            if metadata.isRegularFile! || metadata.isSymbolicLink!, metadata.isExecutable! {
                return executable
            }
        }
        throw POSIXError(.ENOENT)
    }
    
    public static func run(_ command: String, _ arguments: String...) throws -> String {
        let process = Process()
        process.executableURL = try Self.find(command)
        process.arguments = arguments
        let pipe = Pipe()
        process.standardOutput = pipe
        try process.run()
        process.waitUntilExit()
        guard process.terminationStatus == EX_OK else {
            throw ExitCode(process.terminationStatus)
        }
        return try pipe.fileHandleForReading.readToEnd().flatMap {
            String(data: $0, encoding: .utf8)
        } ?? String()
    }
}