#if os(macOS)
import Foundation
import MachO

/// Information about this executable.
public enum ExecutableInfo {
    /// A stable identifier for this executable. Uses the Mach-O header UUID on macOS. Nil on Linux.
    public static let buildID: String? = {
        if let handle = dlopen(nil, RTLD_LAZY) {
            defer { dlclose(handle) }

            if let ptr = dlsym(handle, MH_EXECUTE_SYM) {
                return getUUID(pointer: ptr)?.uuidString
            }
        }

        return nil
    }()

    private static func getUUID(pointer: UnsafeRawPointer) -> UUID? {
        var offset: UInt64 = 0
        let header = pointer.bindMemory(to: mach_header_64.self, capacity: 1)
        offset += UInt64(MemoryLayout<mach_header_64>.size)
        for _ in 0..<header.pointee.ncmds {
            let loadCommand = pointer.load(fromByteOffset: Int(offset), as: load_command.self)
            if loadCommand.cmd == LC_UUID {
                let uuidCommand = pointer.load(fromByteOffset: Int(offset), as: uuid_command.self)
                return UUID(uuid: uuidCommand.uuid)
            }
            offset += UInt64(loadCommand.cmdsize)
        }
        return nil
    }
}

#else
/// Information about this executable.
public enum ExecutableInfo {
    /// A stable identifier for this executable. Uses the Mach-O header UUID on macOS. Nil on Linux.
    public static let buildID: String? = nil
}
#endif