use bytes::Bytes;
use common_types::{Class, Type, classes};
use errors::*;
use ser::packet::{DnsPacketData, DnsPacketWriteContext};
use ser::text::{DnsTextData, DnsTextFormatter, DnsTextContext};
use std::borrow::Cow;
use std::fmt;
use std::io::Cursor;
use records::UnknownRecord;

pub trait RRDataPacket {
	fn deserialize_rr_data(ttl: u32, rr_class: Class, rr_type: Type, data: &mut Cursor<Bytes>) -> Result<Self>
	where
		Self: Sized,
	;

	fn rr_type(&self) -> Type;

	fn serialize_rr_data(&self, context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()>;
}

impl<T: DnsPacketData + StaticRRData> RRDataPacket for T {
	fn deserialize_rr_data(_ttl: u32, rr_class: Class, rr_type: Type, data: &mut Cursor<Bytes>) -> Result<Self> {
		ensure!(rr_type == T::TYPE, "type mismatch");
		if T::CLASS != classes::ANY {
			ensure!(rr_class == T::CLASS, "class mismatch: got {}, need {}", rr_class, T::CLASS);
		}
		T::deserialize(data)
	}

	fn rr_type(&self) -> Type {
		T::TYPE
	}

	fn serialize_rr_data(&self, context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()> {
		self.serialize(context, packet)
	}
}

pub trait RRDataText {
	fn dns_parse_rr_data(context: &DnsTextContext, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	;

	// format might fail if there is no (known) text representation.
	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result;

	fn rr_type_txt(&self) -> Cow<'static, str>;

	// (type, rrdata)
	fn text(&self) -> Result<(String, String)>
	where
		Self: RRDataPacket,
	{
		let mut buf = String::new();
		match self.dns_format_rr_data(&mut DnsTextFormatter::new(&mut buf)) {
			Ok(()) => {
				return Ok((self.rr_type_txt().into(), buf))
			},
			Err(_) => (),
		}
		let mut raw = Vec::new();
		self.serialize_rr_data(&mut DnsPacketWriteContext::new(), &mut raw)?;
		let ur = UnknownRecord::new(self.rr_type(), raw.into());
		// formatting UnknownRecord should not fail
		buf.clear();
		self.dns_format_rr_data(&mut DnsTextFormatter::new(&mut buf)).unwrap();
		Ok((ur.rr_type_txt().into(), buf))
	}
}

impl<T: DnsTextData + StaticRRData> RRDataText for T {
	fn dns_parse_rr_data(context: &DnsTextContext, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	{
		ensure!(context.record_type() == Some(T::TYPE), "type mismatch");
		let rr_class = context.zone_class().expect("require zone CLASS to parse record");
		if T::CLASS != classes::ANY {
			ensure!(rr_class == T::CLASS, "class mismatch: got {}, need {}", rr_class, T::CLASS);
		}
		ensure!(context.last_ttl().is_some(), "require TTL to parse record");
		T::dns_parse(context, data)
	}

	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		self.dns_format(f)
	}

	fn rr_type_txt(&self) -> Cow<'static, str> {
		Cow::Borrowed(T::NAME)
	}
}

pub trait RRData: RRDataPacket + RRDataText + fmt::Debug {
	fn clone_box(&self) -> Box<RRData>;
}

impl Clone for Box<RRData> {
	fn clone(&self) -> Self {
		self.clone_box()
	}
}

pub trait StaticRRData: RRData {
	const TYPE: Type;
	const NAME: &'static str;
	// classes::ANY marks class independent types
	const CLASS: Class;
}