pub mod hail;

pub mod uuid {
    /// 生成一个UUID v4字符串。
    pub fn new() -> Box<String> {
        Box::from(uuid::Uuid::new_v4().to_string())
    }
}

pub mod short_uuid {
    const STR_SRC: &str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

    /// 生成一个基于UUID v4的短UUID字符串。
    pub fn new(length: i16) -> Box<String> {
        let length = if length < 2 {
            2
        } else if length > 128 {
            128
        } else {
            length
        };
        let choices = STR_SRC.as_bytes();
        let mut uuid = uuid::Uuid::new_v4().as_u128();
        let mut mask = 0_u128;
        let mut result_bits: Vec<i64> = Vec::new();
        let (mask_length, last_mask_length) = if 128 % length == 0 {
            (128 / length, 0)
        } else {
            (128 / length + 1, 128 / length - 128 % length)
        };
        for _ in 1..mask_length {
            mask = (mask << 1) | 0b1;
        }
        if last_mask_length > 0 {
            let mut last_mask = 0_u128;
            for _ in 1..last_mask_length {
                last_mask = (last_mask << 1) | 0b1;
            }
            result_bits.push(((uuid & last_mask) as i64) % choices.len() as i64);
            uuid = uuid >> last_mask_length;
        }
        for _ in 0..(length - if last_mask_length > 0 { 1 } else { 0 }) {
            result_bits.push(((uuid & mask) as i64) % choices.len() as i64);
            uuid = uuid >> mask_length;
        }
        let mut code: Vec<String> = Vec::new();
        result_bits.reverse();
        for i in result_bits {
            code.push(String::from_utf8(vec![choices[i as usize]]).unwrap());
        }
        Box::from(code.join(""))
    }
}