use rand::Rng;
pub fn generate(rng: &mut rand::rngs::ThreadRng) -> String {
loop {
let mut digits: Vec<u8> = vec![5];
for _ in 0..7 {
digits.push(rng.gen_range(0..=9));
}
let weights = [9, 8, 7, 6, 5, 4, 3, 2];
let sum: u32 = digits
.iter()
.zip(weights.iter())
.map(|(&d, &w)| d as u32 * w as u32)
.sum();
let r = sum % 11;
let check = if r < 2 { 0 } else { 11 - r };
if check > 9 {
continue;
}
digits.push(check as u8);
let s: String = digits.iter().map(|d| (b'0' + d) as char).collect();
return format!("PT{}", s);
}
}
pub fn validate(code: &str) -> bool {
let clean: String = if let Some(stripped) = code.strip_prefix("PT") {
stripped.to_string()
} else {
code.chars().filter(|c| c.is_ascii_digit()).collect()
};
if clean.len() != 9 || !clean.chars().all(|c| c.is_ascii_digit()) {
return false;
}
let digits: Vec<u8> = clean.bytes().map(|b| b - b'0').collect();
let weights = [9, 8, 7, 6, 5, 4, 3, 2];
let sum: u32 = digits[..8]
.iter()
.zip(weights.iter())
.map(|(&d, &w)| d as u32 * w as u32)
.sum();
let r = sum % 11;
let expected = if r < 2 { 0 } else { 11 - r };
expected == digits[8] as u32
}