use super::funejson::Value;
use super::validation_gs1_check_digit::gs1_check_digit;

/// Build an 18-digit SSCC: extension digit, GS1 company prefix, zero-padded
/// serial reference and GS1 mod-10 check digit.
///
/// # Panics
/// Panics on an extension digit outside 0-9, a prefix that is not 4 to 12
/// ASCII digits, or a serial reference that is negative or too long.
pub fn build_sscc(extension_digit: i64, company_prefix: &str, serial_reference: i64) -> String {
    if !(0..=9).contains(&extension_digit) {
        panic!("extensionDigit must be 0 to 9, received {}", extension_digit);
    }
    let len = company_prefix.len();
    if !(4..=12).contains(&len) || !company_prefix.bytes().all(|b| b.is_ascii_digit()) {
        panic!("companyPrefix must be 4 to 12 digits, received \"{}\"", company_prefix);
    }
    if serial_reference < 0 {
        panic!("serialReference must not be negative, received {}", serial_reference);
    }
    // Prefix and serial share 16 digits, so a longer prefix leaves less room.
    // Too large is an error: truncating would reuse another unit's number.
    let room = 16 - len;
    let serial = serial_reference.to_string();
    if serial.len() > room {
        panic!(
            "serialReference must fit in {} digits after a {}-digit company prefix, received {}",
            room, len, serial_reference
        );
    }
    let data = format!("{}{}{:0>width$}", extension_digit, company_prefix, serial, width = room);
    format!("{}{}", data, gs1_check_digit(&data))
}

pub fn fune_vector(args: &[Value]) -> Value {
    Value::str(&build_sscc(args[0].as_i64(), args[1].as_str(), args[2].as_i64()))
}