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/*
 * Copyright (C) 2015 Benjamin Fry <benjaminfry@me.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//! class of DNS operations, in general always IN for internet

use std::convert::From;
use std::cmp::Ordering;

use ::serialize::binary::*;
use ::error::*;

#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
#[allow(dead_code)]
pub enum DNSClass {
  IN,          //	1	RFC 1035	Internet (IN)
  CH,          // 3 Chaos (CH)
  HS,          // 4 Hesiod (HS)
  NONE,        // 254 QCLASS NONE
  ANY,         // 255 QCLASS * (ANY)
  OPT(u16),    // Special class for OPT Version, it was overloaded for EDNS - RFC 6891
}

impl DNSClass {
  /// Convert from &str to DNSClass
  ///
  /// ```
  /// use trust_dns::rr::dns_class::DNSClass;
  ///
  /// let var: DNSClass = DNSClass::from_str("IN").unwrap();
  /// assert_eq!(DNSClass::IN, var);
  /// ```
  pub fn from_str(str: &str) -> DecodeResult<Self> {
    match str {
      "IN" => Ok(DNSClass::IN),
      "CH" => Ok(DNSClass::CH),
      "HS" => Ok(DNSClass::HS),
      "NONE" => Ok(DNSClass::NONE),
      "ANY" | "*" => Ok(DNSClass::ANY),
      _ => Err(DecodeError::UnknownDnsClassStr(str.to_string())),
    }
  }


  /// Convert from u16 to DNSClass
  ///
  /// ```
  /// use trust_dns::rr::dns_class::DNSClass;
  ///
  /// let var = DNSClass::from_u16(1).unwrap();
  /// assert_eq!(DNSClass::IN, var);
  /// ```
  pub fn from_u16(value: u16) -> DecodeResult<Self> {
    match value {
      1 => Ok(DNSClass::IN),
      3 => Ok(DNSClass::CH),
      4 => Ok(DNSClass::HS),
      254 => Ok(DNSClass::NONE),
      255 => Ok(DNSClass::ANY),
      _ => Err(DecodeError::UnknownDnsClassValue(value)),
    }
  }

  pub fn for_opt(value: u16) -> Self {
    DNSClass::OPT(value)
  }
}

impl BinSerializable<DNSClass> for DNSClass {
  fn read(decoder: &mut BinDecoder) -> DecodeResult<Self> {
    Self::from_u16(try!(decoder.read_u16()))
  }

  fn emit(&self, encoder: &mut BinEncoder) -> EncodeResult {
    encoder.emit_u16((*self).into())
  }
}

// TODO make these a macro or annotation

/// Convert from DNSClass to &str
///
/// ```
/// use trust_dns::rr::dns_class::DNSClass;
///
/// let var: &'static str = DNSClass::IN.into();
/// assert_eq!("IN", var);
/// ```
impl From<DNSClass> for &'static str {
  fn from(rt: DNSClass) -> &'static str {
    match rt {
      DNSClass::IN => "IN",
      DNSClass::CH => "CH",
      DNSClass::HS => "HS",
      DNSClass::NONE => "NONE",
      DNSClass::ANY => "ANY",
      DNSClass::OPT(_) => "OPT"
    }
  }
}

/// Convert from DNSClass to u16
///
/// ```
/// use trust_dns::rr::dns_class::DNSClass;
///
/// let var: u16 = DNSClass::IN.into();
/// assert_eq!(1, var);
/// ```
impl From<DNSClass> for u16 {
  fn from(rt: DNSClass) -> Self {
    match rt {
      DNSClass::IN => 1,
      DNSClass::CH => 3,
      DNSClass::HS => 4,
      DNSClass::NONE => 254,
      DNSClass::ANY => 255,
      DNSClass::OPT(version) => version,
    }
  }
}

impl PartialOrd<DNSClass> for DNSClass {
  fn partial_cmp(&self, other: &DNSClass) -> Option<Ordering> {
    Some(self.cmp(other))
  }
}

impl Ord for DNSClass {
  fn cmp(&self, other: &Self) -> Ordering {
    u16::from(*self).cmp(&u16::from(*other))
  }
}


#[test]
fn test_order() {
  let ordered = vec![DNSClass::IN, DNSClass::CH, DNSClass::HS, DNSClass::NONE, DNSClass::ANY];
  let mut unordered = vec![DNSClass::NONE, DNSClass::HS, DNSClass::CH, DNSClass::IN, DNSClass::ANY];

  unordered.sort();

  assert_eq!(unordered, ordered);
}