use crate::Uuid;

impl Uuid {

    /// Creates a random UUID.

    ///

    /// This uses the [`getrandom`] crate to utilise the operating system's RNG

    /// as the source of random numbers. If you'd like to use a custom

    /// generator, don't use this method: generate random bytes using your

    /// custom generator and pass them to the

    /// [`uuid::Builder::from_random_bytes`][from_random_bytes] function

    /// instead.

    ///

    /// Note that usage of this method requires the `v4` feature of this crate

    /// to be enabled.

    ///

    /// # Examples

    ///

    /// Basic usage:

    ///

    /// ```

    /// # use uuid::{Uuid, Version};

    /// let uuid = Uuid::new_v4();

    ///

    /// assert_eq!(Some(Version::Random), uuid.get_version());

    /// ```

    ///

    /// # References

    ///

    /// * [UUID Version 4 in RFC 9562](https://www.ietf.org/rfc/rfc9562.html#section-5.4)

    ///

    /// [`getrandom`]: https://crates.io/crates/getrandom

    /// [from_random_bytes]: struct.Builder.html#method.from_random_bytes

    pub fn new_v4() -> Uuid {

        // This is an optimized method for generating random UUIDs that just masks

        // out the bits for the version and variant and sets them both together

        Uuid::from_u128(

            crate::rng::u128() & 0xFFFFFFFFFFFF4FFFBFFFFFFFFFFFFFFF | 0x40008000000000000000,

        )

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    use crate::{Variant, Version};

    #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))]

    use wasm_bindgen_test::*;

    #[test]

    #[cfg_attr(

        all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")),

        wasm_bindgen_test

    )]

    fn test_new() {

        let uuid = Uuid::new_v4();

        assert_eq!(uuid.get_version(), Some(Version::Random));

        assert_eq!(uuid.get_variant(), Variant::RFC4122);

    }

    #[test]

    #[cfg_attr(

        all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")),

        wasm_bindgen_test

    )]

    fn test_get_version() {

        let uuid = Uuid::new_v4();

        assert_eq!(uuid.get_version(), Some(Version::Random));

        assert_eq!(uuid.get_version_num(), 4)

    }

}