use core::fmt::{Debug, Display};
use core::hash::Hash;
use core::str::FromStr;

use super::{Address, Mask};
use crate::{concrete, error::Error};

mod len;
pub use self::len::Length;

mod range;
pub use self::range::Range;

mod set;
pub use self::set::Set;

/// Address-family independent interface for IP prefixes
///
/// Methods on `Prefix` types that are well defined for all address-families
/// are implemented via this trait.
///
/// In general, methods on this trait have signatures and semantics compatible
/// with methods of the same names on the [`ipnet`] network types. Where
/// there is deviation, this is noted in the method documentation.
///
/// See also [`concrete::Prefix<A>`][crate::concrete::Prefix] and
/// [`any::Prefix`][crate::any::Prefix] for address-family specific items.
pub trait Prefix:
    Sized + Copy + Clone + Debug + Display + FromStr<Err = Error> + Hash + PartialEq + Eq + PartialOrd
{
    /// The type of IP address represented by this prefix type.
    type Address: Address;

    /// The type used to represent lengths for this IP prefix type.
    type Length: Length;

    /// The type of IP hostmask corresponding to this prefix type.
    type Hostmask: Mask;

    /// The type of IP netmask corresponding to this prefix type.
    type Netmask: Mask;

    /// The [`Iterator`] type returned by the [`Self::subprefixes`] method.
    type Subprefixes: Iterator<Item = Self>;
    // TODO:
    // type Hosts: Iterator<Item = Self::Address>;

    /// Returns the network address of the IP subnet represented by this
    /// prefix.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Address, Any, Ipv4, Ipv6, Prefix};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16".parse::<Prefix<Ipv4>>()?.network(),
    ///     "172.16.0.0".parse::<Address<Ipv4>>()?,
    /// );
    ///
    /// assert_eq!(
    ///     "2001:db8:f00::/48".parse::<Prefix<Ipv6>>()?.network(),
    ///     "2001:db8:f00::".parse::<Address<Ipv6>>()?,
    /// );
    ///
    /// assert_eq!(
    ///     "10.255.0.0/16".parse::<Prefix<Any>>()?.network(),
    ///     Address::<Any>::Ipv4("10.255.0.0".parse()?),
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn network(&self) -> Self::Address;

    /// Returns the hostmask of the IP subnet represented by this prefix.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv4, Prefix};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16"
    ///         .parse::<Prefix<Ipv4>>()?
    ///         .hostmask()
    ///         .to_string(),
    ///     "0.0.255.255",
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn hostmask(&self) -> Self::Hostmask;

    /// Returns the netmask of the IP subnet represented by this prefix.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv4, Prefix};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16"
    ///         .parse::<Prefix<Ipv4>>()?
    ///         .netmask()
    ///         .to_string(),
    ///     "255.255.0.0",
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn netmask(&self) -> Self::Netmask;

    /// Returns the maximum valid prefix length for prefixes of this type.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Any, Ipv4, Ipv6, Prefix, PrefixLength};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16".parse::<Prefix<Any>>()?.max_prefix_len(),
    ///     PrefixLength::<Ipv4>::MAX.into(),
    /// );
    ///
    /// assert_eq!(
    ///     "2001:db8:f00::/48".parse::<Prefix<Any>>()?.max_prefix_len(),
    ///     PrefixLength::<Ipv6>::MAX.into(),
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn max_prefix_len(&self) -> Self::Length;

    /// Returns the length of this prefix.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv4, Ipv6, Prefix, PrefixLength};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16".parse::<Prefix<Ipv4>>()?.prefix_len(),
    ///     PrefixLength::<Ipv4>::from_primitive(16)?,
    /// );
    ///
    /// assert_eq!(
    ///     "2001:db8:f00::/48".parse::<Prefix<Ipv6>>()?.prefix_len(),
    ///     PrefixLength::<Ipv6>::from_primitive(48)?,
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn prefix_len(&self) -> Self::Length;

    /// Returns the broadcast address of the IP subnet represented by this
    /// prefix.
    ///
    /// # [`ipnet`] Compatibility
    ///
    /// The term "broadcast address" has no meaning when applied to IPv6
    /// subnets. However, for compatibility with [`ipnet::Ipv6Net`], this
    /// method will return the last address covered by the prefix in all
    /// cases.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Address, Any, Ipv4, Ipv6, Prefix};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16".parse::<Prefix<Ipv4>>()?.broadcast(),
    ///     "172.16.255.255".parse::<Address<Ipv4>>()?,
    /// );
    ///
    /// assert_eq!(
    ///     "2001:db8:f00::/48".parse::<Prefix<Ipv6>>()?.broadcast(),
    ///     "2001:db8:f00:ffff:ffff:ffff:ffff:ffff".parse::<Address<Ipv6>>()?,
    /// );
    ///
    /// assert_eq!(
    ///     "2001:db8:dead:beef::/64"
    ///         .parse::<Prefix<Any>>()?
    ///         .broadcast(),
    ///     Address::<Any>::Ipv6("2001:db8:dead:beef:ffff:ffff:ffff:ffff".parse()?),
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn broadcast(&self) -> Self::Address;

    /// Returns the prefix of length `self.prefix_len() + 1` containing `self`,
    /// if it exists.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv4, Ipv6, Prefix};
    ///
    /// assert_eq!(
    ///     "172.16.123.123/16".parse::<Prefix<Ipv4>>()?.supernet(),
    ///     Some("172.16.0.0/15".parse()?),
    /// );
    ///
    /// assert_eq!("::/0".parse::<Prefix<Ipv6>>()?.supernet(), None,);
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn supernet(&self) -> Option<Self>;

    /// Returns [`true`] if `self` and `other` share the same immediate
    /// supernet. See also [`supernet()`][Self::supernet()].
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv6, Prefix};
    ///
    /// let a: Prefix<Ipv6> = "2001:db8:a::/48".parse()?;
    /// let b: Prefix<Ipv6> = "2001:db8:b::/48".parse()?;
    /// let c: Prefix<Ipv6> = "2001:db8:c::/48".parse()?;
    ///
    /// assert!(a.is_sibling(&b));
    /// assert!(!b.is_sibling(&c));
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn is_sibling(&self, other: &Self) -> bool;

    /// Returns [`true`] if `self` contains `other` (in the set-theoretic
    /// sense).
    ///
    /// # Note
    ///
    /// This method is defined for all types `T` where `Self: PartialOrd<T>`.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Address, Ipv6, Prefix};
    ///
    /// let a: Prefix<Ipv6> = "2001:db8:a::/48".parse()?;
    /// let b: Prefix<Ipv6> = "2001:db8:a:b::/64".parse()?;
    /// let c: Prefix<Ipv6> = "2001:db8::/32".parse()?;
    ///
    /// assert!(a.contains(&b));
    /// assert!(!a.contains(&c));
    ///
    /// let x: Address<Ipv6> = "2001:db8:a::1".parse()?;
    /// let y: Address<Ipv6> = "2001:db8::1".parse()?;
    ///
    /// assert!(a.contains(&x));
    /// assert!(!a.contains(&y));
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn contains<T>(&self, other: &T) -> bool
    where
        Self: PartialOrd<T>,
    {
        self.ge(other)
    }

    // TODO:
    // #[cfg(feature = "std")]
    // fn aggregate(networks: &std::vec::Vec<Self>) -> std::vec::Vec<Self>;
    // fn hosts(&self) -> Self::Hosts;

    /// Returns an iterator over the subprefixes of `self` of length
    /// `new_prefix_len`.
    ///
    /// # Errors
    ///
    /// An error is returned if `new_prefix_len < self.prefix_len()`.
    ///
    /// # Examples
    ///
    /// ``` rust
    /// use ip::{traits::Prefix as _, Ipv4, Ipv6, Prefix, PrefixLength};
    ///
    /// let prefix: Prefix<Ipv4> = "192.0.2.0/24".parse()?;
    /// let new_length = PrefixLength::<Ipv4>::from_primitive(26)?;
    ///
    /// assert_eq!(prefix.subprefixes(new_length)?.count(), 4);
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn subprefixes(&self, new_prefix_len: Self::Length) -> Result<Self::Subprefixes, Error>;

    /// Returns the address-family associated with this IP prefix.
    ///
    /// # Examples
    ///
    /// ```
    /// use ip::{traits::Prefix as _, Any, Prefix};
    ///
    /// let prefix: Prefix<Any> = "192.0.2.0/24".parse()?;
    ///
    /// assert_eq!(prefix.afi().to_string(), "ipv4");
    /// # Ok::<(), ip::Error>(())
    /// ```
    fn afi(&self) -> concrete::Afi {
        self.network().afi()
    }

    /// Try to construct a new [`Self::Length`] for the address-family
    /// associated with this IP prefix.
    ///
    /// # Errors
    ///
    /// Fails when `length` is outside of the bounds of prefix-lengths of the
    /// address-family.
    ///
    /// # Examples
    ///
    /// ```
    /// use ip::{traits::Prefix as _, Any, Ipv6, Prefix, PrefixLength};
    ///
    /// let prefix: Prefix<Any> = "2001:db8::/32".parse()?;
    ///
    /// assert_eq!(
    ///     prefix.new_prefix_length(48)?,
    ///     PrefixLength::<Ipv6>::from_primitive(48)?.into(),
    /// );
    /// # Ok::<(), ip::Error>(())
    /// ```
    // #[cfg(feature = "std")]
    fn new_prefix_length(&self, length: u8) -> Result<Self::Length, Error>;
}