package floxenv

import (
	"fmt"
	"os"
	"strconv"
	"strings"
	"syscall"
)

// IsAlive returns true if the process identified by pid is still running.
// It first attempts a zero-signal delivery test, then confirms on Linux
// by inspecting /proc/<pid>/stat so that zombie processes are reported dead.
func IsAlive(pid int) bool {
	if pid <= 0 {
		return false
	}
	if err := syscall.Kill(pid, 0); err != nil {
		return false
	}
	// Linux-specific confirmation to distinguish zombies.
	data, err := os.ReadFile(fmt.Sprintf("/proc/%d/stat", pid))
	if err != nil {
		// /proc may be unavailable in restricted spaces; trust signal result.
		return true
	}
	s := string(data)
	idx := strings.LastIndexByte(s, ')')
	if idx >= 0 && idx+2 < len(s) {
		state := s[idx+2]
		if state == 'Z' { // zombie
			return false
		}
	}
	return true
}

// IsAliveString wraps IsAlive with string-to-int conversion.
// It returns false for any parse or signal error.
func IsAliveString(s string) bool {
	pid, err := strconv.Atoi(s)
	if err != nil {
		return false
	}
	return IsAlive(pid)
}