import Foundation
import Darwin

/// Resolves a pid to its real executable name via `proc_pidpath`, because
/// nettop's name column is unreliable (it reported `claude` as `2.1.177`).
/// Results are cached; drive from a single thread/actor.
public final class ProcessNamer {
    private var cache: [Int32: String] = [:]

    public init() {}

    public func name(for pid: Int32) -> String? {
        guard pid > 0 else { return nil }
        if let hit = cache[pid] { return hit }

        var buffer = [CChar](repeating: 0, count: 4096)   // PROC_PIDPATHINFO_MAXSIZE
        let length = proc_pidpath(pid, &buffer, UInt32(buffer.count))
        guard length > 0 else { return nil }

        let path = String(cString: buffer)
        // `/Applications/Google Chrome.app/.../Google Chrome Helper` -> last component
        let name = (path as NSString).lastPathComponent
        cache[pid] = name
        return name
    }
}