/*
 * 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.
 */

//! start of authority record defining ownership and defaults for the zone

use crate::error::*;
use crate::rr::domain::Name;
use crate::serialize::binary::*;

/// [RFC 1035, DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION, November 1987](https://tools.ietf.org/html/rfc1035)
///
/// ```text
/// 3.3.13. SOA RDATA format
///
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     /                     MNAME                     /
///     /                                               /
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     /                     RNAME                     /
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     |                    SERIAL                     |
///     |                                               |
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     |                    REFRESH                    |
///     |                                               |
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     |                     RETRY                     |
///     |                                               |
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     |                    EXPIRE                     |
///     |                                               |
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     |                    MINIMUM                    |
///     |                                               |
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///
/// where:
///
/// SOA records cause no additional section processing.
///
/// All times are in units of seconds.
///
/// Most of these fields are pertinent only for name server maintenance
/// operations.  However, MINIMUM is used in all query operations that
/// retrieve RRs from a zone.  Whenever a RR is sent in a response to a
/// query, the TTL field is set to the maximum of the TTL field from the RR
/// and the MINIMUM field in the appropriate SOA.  Thus MINIMUM is a lower
/// bound on the TTL field for all RRs in a zone.  Note that this use of
/// MINIMUM should occur when the RRs are copied into the response and not
/// when the zone is loaded from a master file or via a zone transfer.  The
/// reason for this provison is to allow future dynamic update facilities to
/// change the SOA RR with known semantics.
/// ```
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct SOA {
    mname: Name,
    rname: Name,
    serial: u32,
    refresh: i32,
    retry: i32,
    expire: i32,
    minimum: u32,
}

impl SOA {
    /// Creates a new SOA record data.
    ///
    /// # Arguments
    ///
    /// * `mname` - the name of the master, primary, authority for this zone.
    /// * `rname` - the name of the responsible party for this zone, e.g. an email address.
    /// * `serial` - the serial number of the zone, used for caching purposes.
    /// * `refresh` - the amount of time to wait before a zone is resynched.
    /// * `retry` - the minimum period to wait if there is a failure during refresh.
    /// * `expire` - the time until this master is no longer authoritative for the zone.
    /// * `minimum` - no zone records should have time-to-live values less than this minimum.
    ///
    /// # Return value
    ///
    /// The newly created SOA record data.
    pub fn new(
        mname: Name,
        rname: Name,
        serial: u32,
        refresh: i32,
        retry: i32,
        expire: i32,
        minimum: u32,
    ) -> Self {
        SOA {
            mname,
            rname,
            serial,
            refresh,
            retry,
            expire,
            minimum,
        }
    }

    /// Increments the serial number by one
    pub fn increment_serial(&mut self) {
        self.serial += 1; // TODO: what to do on overflow?
    }

    /// ```text
    /// MNAME           The <domain-name> of the name server that was the
    ///                 original or primary source of data for this zone.
    /// ```
    ///
    /// # Return value
    ///
    /// The `domain-name` of the name server that was the original or primary source of data for
    /// this zone, i.e. the master name server.
    pub fn mname(&self) -> &Name {
        &self.mname
    }

    /// ```text
    /// RNAME           A <domain-name> which specifies the mailbox of the
    ///                 person responsible for this zone.
    /// ```
    ///
    /// # Return value
    ///
    /// A `domain-name` which specifies the mailbox of the person responsible for this zone, i.e.
    /// the responsible name.
    pub fn rname(&self) -> &Name {
        &self.rname
    }

    /// ```text
    /// SERIAL          The unsigned 32 bit version number of the original copy
    ///                 of the zone.  Zone transfers preserve this value.  This
    ///                 value wraps and should be compared using sequence space
    ///                 arithmetic.
    /// ```
    ///
    /// # Return value
    ///
    /// The unsigned 32 bit version number of the original copy of the zone. Zone transfers
    /// preserve this value. This value wraps and should be compared using sequence space arithmetic.
    pub fn serial(&self) -> u32 {
        self.serial
    }

    /// ```text
    /// REFRESH         A 32 bit time interval before the zone should be
    ///                 refreshed.
    /// ```
    ///
    /// # Return value
    ///
    /// A 32 bit time interval before the zone should be refreshed, in seconds.
    pub fn refresh(&self) -> i32 {
        self.refresh
    }

    /// ```text
    /// RETRY           A 32 bit time interval that should elapse before a
    ///                 failed refresh should be retried.
    /// ```
    ///
    /// # Return value
    ///
    /// A 32 bit time interval that should elapse before a failed refresh should be retried,
    /// in seconds.
    pub fn retry(&self) -> i32 {
        self.retry
    }

    /// ```text
    /// EXPIRE          A 32 bit time value that specifies the upper limit on
    ///                 the time interval that can elapse before the zone is no
    ///                 longer authoritative.
    /// ```
    ///
    /// # Return value
    ///
    /// A 32 bit time value that specifies the upper limit on the time interval that can elapse
    /// before the zone is no longer authoritative, in seconds
    pub fn expire(&self) -> i32 {
        self.expire
    }

    /// ```text
    /// MINIMUM         The unsigned 32 bit minimum TTL field that should be
    ///                 exported with any RR from this zone.
    /// ```
    ///
    /// # Return value
    ///
    /// The unsigned 32 bit minimum TTL field that should be exported with any RR from this zone.
    pub fn minimum(&self) -> u32 {
        self.minimum
    }
}

/// Read the RData from the given Decoder
pub fn read(decoder: &mut BinDecoder) -> ProtoResult<SOA> {
    Ok(SOA {
        mname: Name::read(decoder)?,
        rname: Name::read(decoder)?,
        serial: decoder.read_u32()?.unverified(/*any u32 is valid*/),
        refresh: decoder.read_i32()?.unverified(/*any i32 is valid*/),
        retry: decoder.read_i32()?.unverified(/*any i32 is valid*/),
        expire: decoder.read_i32()?.unverified(/*any i32 is valid*/),
        minimum: decoder.read_u32()?.unverified(/*any u32 is valid*/),
    })
}

/// [RFC 4034](https://tools.ietf.org/html/rfc4034#section-6), DNSSEC Resource Records, March 2005
///
/// This is accurate for all currently known name records.
///
/// ```text
/// 6.2.  Canonical RR Form
///
///    For the purposes of DNS security, the canonical form of an RR is the
///    wire format of the RR where:
///
///    ...
///
///    3.  if the type of the RR is NS, MD, MF, CNAME, SOA, MB, MG, MR, PTR,
///        HINFO, MINFO, MX, HINFO, RP, AFSDB, RT, SIG, PX, NXT, NAPTR, KX,
///        SRV, DNAME, A6, RRSIG, or (rfc6840 removes NSEC), all uppercase
///        US-ASCII letters in the DNS names contained within the RDATA are replaced
///        by the corresponding lowercase US-ASCII letters;
/// ```
pub fn emit(encoder: &mut BinEncoder, soa: &SOA) -> ProtoResult<()> {
    let is_canonical_names = encoder.is_canonical_names();

    soa.mname.emit_with_lowercase(encoder, is_canonical_names)?;
    soa.rname.emit_with_lowercase(encoder, is_canonical_names)?;
    encoder.emit_u32(soa.serial)?;
    encoder.emit_i32(soa.refresh)?;
    encoder.emit_i32(soa.retry)?;
    encoder.emit_i32(soa.expire)?;
    encoder.emit_u32(soa.minimum)?;
    Ok(())
}

#[test]
fn test() {
    use std::str::FromStr;

    let rdata = SOA::new(
        Name::from_str("m.example.com").unwrap(),
        Name::from_str("r.example.com").unwrap(),
        1,
        2,
        3,
        4,
        5,
    );

    let mut bytes = Vec::new();
    let mut encoder: BinEncoder = BinEncoder::new(&mut bytes);
    assert!(emit(&mut encoder, &rdata).is_ok());
    let bytes = encoder.into_bytes();

    println!("bytes: {:?}", bytes);

    let mut decoder: BinDecoder = BinDecoder::new(bytes);
    let read_rdata = read(&mut decoder);
    assert!(
        read_rdata.is_ok(),
        format!("error decoding: {:?}", read_rdata.unwrap_err())
    );
    assert_eq!(rdata, read_rdata.unwrap());
}