#[cfg(target_os = "windows")]
pub fn get_unique_identifier() -> Option<String> {
    use std::os::windows::process::CommandExt;
    use std::process::Command;
    let output = match Command::new("wmic")
        .creation_flags(0x08000000)
        .args(&["csproduct", "get", "UUID"])
        .output()
    {
        Ok(output) => output,
        Err(_) => {
            return None;
        }
    };

    let result = String::from_utf8_lossy(&output.stdout);
    let identifier = result.lines().nth(1).unwrap_or("").trim();
    if identifier.is_empty() {
        None
    } else {
        Some(identifier.to_string())
    }
}

#[cfg(target_os = "macos")]
pub fn get_unique_identifier() -> Option<String> {
    use std::process::Command;
    let output = match Command::new("ioreg")
        .args(&["-rd1", "-c", "IOPlatformExpertDevice"])
        .output()
    {
        Ok(output) => output,
        Err(_) => {
            return None;
        }
    };

    let result = String::from_utf8_lossy(&output.stdout);
    let identifier = result
        .lines()
        .find(|line| line.contains("IOPlatformUUID"))
        .unwrap_or("")
        .trim();
    if identifier.is_empty() {
        None
    } else {
        Some(identifier.to_string())
    }
}

#[cfg(target_os = "linux")]
pub fn get_unique_identifier() -> Option<String> {
    use std::process::Command;

    // Try to execute 'dmidecode' command to get the system identifier first.
    if let Ok(output) = Command::new("dmidecode")
        .arg("-s")
        .arg("system-uuid")
        .output()
    {
        let identifier = String::from_utf8_lossy(&output.stdout).trim().to_owned();
        if !identifier.is_empty() {
            return Some(identifier.to_string());
        }
    }

    // Try to read file /etc/machine-id if 'dmidecode' command cannot be executed or get nothing.
    // 对 linux 或 wsl 来说，读取 /etc/machine-id 即可获取当前操作系统的
    // 唯一标识，而且某些环境没有预装`dmidecode`命令
    if let Ok(identifier) = std::fs::read_to_string("/etc/machine-id") {
        let identifier = identifier.trim();
        if !identifier.is_empty() {
            return Some(identifier.to_string());
        }
    }

    None
}