use std::str::FromStr;
use super::NetworkingErr;

#[derive(Debug, PartialEq, Eq)]
pub struct InvalidIPErr;

/// Ip address enum that includes associated type
/// 
/// # Example
/// ```
/// //Loopback Addresses:
/// IpAddr::V4(127, 0, 0, 1)
/// IpAddr::V6(String::from("::1"))
/// ```
#[allow(unused)]
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum IpAddr {
    V4(u8, u8, u8, u8),
    V6(String)
}

impl IpAddr {
    /// Function that generates ar array of 4 octets / error 
    /// from an IpAddr
    /// 
    /// # Limitation
    /// Currently only works for IPs of type IPv4 
    /// # Example
    /// ```
    /// let ip: IpAddr = IpAddr::V4(127, 0, 0, 1);
    /// 
    /// let ip_add: [u8; 4] = ip.to_arr();
    /// >>> ip_add = [127, 0, 0, 1]
    /// ```
    pub fn to_arr(&self) -> Result<[u8; 4], NetworkingErr> {
        match self {
            IpAddr::V4(o1, o2, o3, o4) => {
                Ok([*o1, *o2, *o3, *o4])
            }
            _ => Err(NetworkingErr::InvalidIPErr)
        }
    }

    /// Function that generates a IpAddr / Err from an array of 
    /// a octests
    /// 
    /// # Limitation
    /// Currently only works for IPs of type IPv4 
    /// # Example
    /// ```
    /// let ip_add: [u8; 4] = [127, 0, 0, 1];
    /// 
    /// let ip: IpAddr = IpAddr::V4(127, 0, 0, 1);
    /// >>> ip_add = [127, 0, 0, 1]
    /// ```
    pub fn from_arr(arr: &[u8; 4]) -> Result<IpAddr, NetworkingErr> {
        Ok(IpAddr::V4(arr[0], arr[1], arr[2], arr[3]))
    }
}

/// Function that converts an Unsigned 32-bit Ip address
    /// into an IpAddr
    /// 
    /// # Limitation
    /// Currently only works for IPs of type IPv4 
    /// # Example
    /// ```
    /// let ip: u32 = 2_130_706_433;
    /// 
    /// let ip_u32: u32 = u32::from(ip);
    /// ip_u32 = 2130706433;
    /// ```
impl From<IpAddr> for u32 {
    fn from(ip: IpAddr) -> Self {
        u32::from_be_bytes(ip.to_arr().unwrap())
    }
}

impl ToString for IpAddr {
    /// Function that returns an IP address in string form
    fn to_string(&self) -> String {
        match self {
            IpAddr::V4(oct1, oct2, oct3, oct4) => format!("{}.{}.{}.{}", oct1, oct2, oct3, oct4),
            IpAddr::V6(addr) => format!("{}", addr)
        }
    }
}

impl FromStr for IpAddr {
    type Err = NetworkingErr;
    /// Function that generates a IpAddr / Err from a string
    /// 
    /// # Limitation
    /// Currently only works for IPs of type IPv4 
    /// # Example
    /// ```
    /// let ip: &str = "127.0.0.1";
    /// 
    /// let parsed_ip: IpAddr = IpAddr::from_str(ip);
    /// ///parsed_ip = IpAddr::V4(127,0,0,1)
    /// ```
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let split_ip = s.split('.');
        if split_ip.clone().count() != 4 {
            //Invalid IP address entered
            return Err(super::NetworkingErr::InvalidIPErr)
        }
        let mut ip: [u8; 4] = Default::default();
        //Go through each octet and ensure it can be parsed;
        for (i, oct) in split_ip.into_iter().enumerate() {
            if i > ip.len() {
                //Ip string is out of the range of the 4 octets in an IPv4 Address
                return Err(NetworkingErr::InvalidIPErr)
            }
            match oct.parse::<u8>() {
                Ok(parsed_oct) => ip[i] = parsed_oct,
                Err(_) => return Err(NetworkingErr::InvalidIPErr)
            }
        }
        Ok(IpAddr::from_arr(&ip)?)
    }
}

/// Function that takes in an IP address and then prints a formatted string to the CLI
/// 
/// # Example
/// ```
/// let ip = IpAddr::V4(127, 0, 0, 1);
/// 
/// print_ip(ip);
/// //Output: IP Address: 127.0.0.1
/// ```
#[allow(unused)]
pub fn print_ip(ip_address: IpAddr) {
    println!("IP Address: {}", ip_address.to_string())
}

mod tests {
    #[test]
    /// Tests if an IP is converted to a string 
    /// correctly using the ToString trait
    fn ip_to_string() {
        use super::*;
        let ip = IpAddr::V4(192, 168, 0, 1);
        assert_eq!(ip.to_string(), "192.168.0.1")
    }

    #[test]
    /// Tests if an IP is converted from a string
    /// correctly using the FromString trait
    fn string_to_ip() {
        use super::*;
        let ip = "127.0.0.1";
        assert_eq!(IpAddr::from_str(ip).unwrap(), IpAddr::V4(127, 0, 0, 1))
    }

    #[test]
    #[should_panic]
    ///Tests if an invalid Ip will cause a panic when
    /// converting from a string to an IpAddr
    fn invalid_string_to_ip() {
        use super::*;
        let ip = "127.0.0.0.1";
        IpAddr::from_str(ip).unwrap();
        assert_eq!(IpAddr::from_str(ip), Err(NetworkingErr::InvalidIPErr))
    }

    #[test]
    /// Tests the conversion of an IPv4 Address to
    /// an array
    fn ipaddr_to_arr() {
        use super::*;
        let mut ip_addr = IpAddr::V4(127, 0, 0, 1);
        assert_eq!(ip_addr.to_arr().unwrap(), [127, 0, 0, 1]);
        ip_addr = IpAddr::V6("::".to_string());
        assert_eq!(ip_addr.to_arr().unwrap_err(), NetworkingErr::InvalidIPErr);
    }

    #[test]
    /// Tests the conversion of an array to
    // an IPv4 Address
    fn arr_to_ipaddr() {
        use super::*;
        let ip_addr: [u8; 4] = [127, 0, 0, 1];
        assert_eq!(IpAddr::from_arr(&ip_addr).unwrap(), IpAddr::V4(127, 0, 0, 1));
    }

    #[test]
    /// Tests the conversion of an IPv4 Address to
    /// an unsigned 32-bit integer
    fn ipaddr_to_u32() {
        use super::*;
        let ip = IpAddr::V4(0, 0, 0, 0);
        assert_eq!(0, u32::from(ip));
        
        let ip = IpAddr::V4(127, 0, 0, 1);
        assert_eq!(2_130_706_433, u32::from(ip));

        let ip = IpAddr::V4(10, 10, 10, 0);
        assert_eq!(168_430_080, u32::from(ip));

        let ip = IpAddr::V4(255, 255, 255, 255);
        assert_eq!(u32::MAX, u32::from(ip));
    }
}