use rand::RngExt;

const CHARSET: &[u8] =
  b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
const ID_LENGTH: usize = 16;

/// Generate a random 16-character alphanumeric pakku ID
pub fn generate_pakku_id() -> String {
  let mut rng = rand::rng();
  (0..ID_LENGTH)
    .map(|_| {
      let idx = rng.random_range(0..CHARSET.len());
      CHARSET[idx] as char
    })
    .collect()
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn test_generate_pakku_id() {
    let id = generate_pakku_id();
    assert_eq!(id.len(), ID_LENGTH);
    assert!(id.chars().all(|c| c.is_alphanumeric()));
  }

  #[test]
  fn test_unique_ids() {
    let id1 = generate_pakku_id();
    let id2 = generate_pakku_id();
    assert_ne!(id1, id2);
  }
}