// Enumerates running Claude processes and their --user-data-dir, without
// spawning pgrep (avoids both the subprocess-per-check overhead and an
// assumption that /usr/bin/pgrep exists at a fixed path). Uses the same
// sysctl(KERN_PROC_ALL)/sysctl(KERN_PROCARGS2) technique ps/pgrep use
// internally for same-user processes — no extra entitlement needed.
//
// Called on demand from live-state notification handlers (see AppDelegate),
// never on a timer.
import Darwin
import Foundation

struct RunningClaude {
    let pid: pid_t
    // nil means launched with no --user-data-dir flag at all (i.e. the
    // "default" profile).
    let userDataDir: String?
}

enum ProcessInspector {
    static func listRunningClaude(binaryPath: String) -> [RunningClaude] {
        allPIDs().compactMap { pid in
            guard let info = execInfo(pid: pid), info.execPath == binaryPath else { return nil }
            let flagPrefix = "--user-data-dir="
            let dir = info.args.first(where: { $0.hasPrefix(flagPrefix) }).map { String($0.dropFirst(flagPrefix.count)) }
            return RunningClaude(pid: pid, userDataDir: dir)
        }
    }

    static func pid(forUserDataDir dir: String?, binaryPath: String) -> pid_t? {
        listRunningClaude(binaryPath: binaryPath).first { $0.userDataDir == dir }?.pid
    }

    private static func allPIDs() -> [pid_t] {
        var mib: [Int32] = [CTL_KERN, KERN_PROC, KERN_PROC_ALL, 0]
        var size = 0
        guard sysctl(&mib, 4, nil, &size, nil, 0) == 0, size > 0 else { return [] }

        let capacity = size / MemoryLayout<kinfo_proc>.stride + 1
        var procs = [kinfo_proc](repeating: kinfo_proc(), count: capacity)
        var actualSize = capacity * MemoryLayout<kinfo_proc>.stride
        guard sysctl(&mib, 4, &procs, &actualSize, nil, 0) == 0 else { return [] }

        let actualCount = actualSize / MemoryLayout<kinfo_proc>.stride
        return procs[0..<actualCount].map { $0.kp_proc.p_pid }
    }

    private struct ExecInfo { let execPath: String; let args: [String] }

    // KERN_PROCARGS2 buffer layout: argc (Int32), then the exec path
    // (NUL-terminated, followed by NUL padding), then argv[0..<argc] each
    // NUL-terminated, then envp (which we don't read). Same layout `ps`
    // itself parses.
    private static func execInfo(pid: pid_t) -> ExecInfo? {
        var mib: [Int32] = [CTL_KERN, KERN_PROCARGS2, pid]
        var size = 0
        guard sysctl(&mib, 3, nil, &size, nil, 0) == 0, size > MemoryLayout<Int32>.size else { return nil }

        var buffer = [UInt8](repeating: 0, count: size)
        guard sysctl(&mib, 3, &buffer, &size, nil, 0) == 0 else { return nil }

        var argc = Int32(0)
        withUnsafeMutableBytes(of: &argc) { dst in
            dst.copyBytes(from: buffer[0..<MemoryLayout<Int32>.size])
        }

        var offset = MemoryLayout<Int32>.size
        func readCString() -> String? {
            guard offset < size else { return nil }
            let start = offset
            while offset < size, buffer[offset] != 0 { offset += 1 }
            guard offset > start else { return nil }
            let string = String(decoding: buffer[start..<offset], as: UTF8.self)
            while offset < size, buffer[offset] == 0 { offset += 1 } // skip padding NULs
            return string
        }

        guard let execPath = readCString() else { return nil }
        var args: [String] = []
        var i: Int32 = 0
        while i < argc, let arg = readCString() {
            args.append(arg)
            i += 1
        }
        return ExecInfo(execPath: execPath, args: args)
    }
}