use bytes::{Bytes, BufMut};
use common_types::*;
use common_types::binary::HEXLOWER_PERMISSIVE_ALLOW_WS;
use errors::*;
use failure::{ResultExt, Fail};
use ser::packet::{DnsPacketWriteContext, remaining_bytes};
use ser::{RRData, RRDataPacket, RRDataText};
use ser::text::{DnsTextFormatter, DnsTextContext, next_field};
use std::borrow::Cow;
use std::fmt;
use std::io::Cursor;

#[derive(Clone, PartialEq, Eq, Debug)]
pub struct UnknownRecord {
	rr_type: Type,
	raw: Bytes,
}

impl UnknownRecord {
	pub fn new(rr_type: Type, raw: Bytes) -> Self {
		UnknownRecord {
			rr_type: rr_type,
			raw: raw,
		}
	}

	pub fn deserialize(rr_type: Type, data: &mut ::std::io::Cursor<Bytes>) -> Result<Self> {
		Ok(UnknownRecord::new(rr_type, remaining_bytes(data)))
	}

	pub fn dns_parse(rr_type: Type, data: &mut &str) -> Result<Self> {
		let field = next_field(data)?;
		ensure!(field == r"\#", "expect \\# token to mark generic encoding");
		let field = next_field(data).context("generic record data length")?;
		let len: usize = field.parse()?;

		let result = HEXLOWER_PERMISSIVE_ALLOW_WS.decode(data.as_bytes())
			.with_context(|e| e.context(format!("invalid hex: {:?}", data)))?;
		ensure!(len == result.len(), "length {} doesn't match length of encoded data {}", len, result.len());
		*data = ""; // read all data

		Ok(UnknownRecord {
			rr_type,
			raw: result.into(),
		})
	}
}

impl RRDataPacket for UnknownRecord {
	fn deserialize_rr_data(_ttl: u32, _rr_class: Class, rr_type: Type, data: &mut Cursor<Bytes>) -> Result<Self> {
		UnknownRecord::deserialize(rr_type, data)
	}

	fn rr_type(&self) -> Type {
		self.rr_type
	}

	fn serialize_rr_data(&self, _context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()> {
		packet.reserve(self.raw.len());
		packet.put_slice(&self.raw);
		Ok(())
	}
}

impl RRDataText for UnknownRecord {
	fn dns_parse_rr_data(context: &DnsTextContext, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	{
		let t = match context.record_type() {
			Some(t) => t,
			None => bail!("must parse DNS record with record type context"),
		};

		UnknownRecord::dns_parse(t, data)
	}

	/// this must never fail unless the underlying buffer fails.
	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		write!(f, "\\# {} {}", self.raw.len(), HEXLOWER_PERMISSIVE_ALLOW_WS.encode(&self.raw))
	}

	fn rr_type_txt(&self) -> Cow<'static, str> {
		Cow::Owned(self.rr_type.generic_name())
	}
}

impl RRData for UnknownRecord {
	fn clone_box(&self) -> Box<RRData> {
		Box::new(self.clone()) as _
	}
}