use bytes::{Bytes, Buf, BufMut};
use errors::*;
use common_types::*;
use failure::ResultExt;
use ser::packet::{DnsPacketData, DnsPacketWriteContext, remaining_bytes};
use ser::text::{DnsTextData, DnsTextFormatter, DnsTextContext, next_field};
use std::fmt;
use std::io::Read;
use std::net::{Ipv4Addr, Ipv6Addr};

// deriving RRData will add a unit test to make sure the type is
// registered; there must be a records::types::$name `Type` constant
// with the same name as the struct.

#[derive(Clone, PartialEq, Eq, Debug, RRData)]
#[RRClass(ANY)]
pub enum LOC {
	Version0(LOC0),
	UnknownVersion{
		version: u8,
		data: Bytes,
	},
}

impl DnsPacketData for LOC {
	fn deserialize(data: &mut ::std::io::Cursor<Bytes>) -> Result<Self> {
		let version: u8 = DnsPacketData::deserialize(data)?;
		if 0 == version {
			Ok(LOC::Version0(DnsPacketData::deserialize(data)?))
		} else {
			Ok(LOC::UnknownVersion{
				version: version,
				data: remaining_bytes(data),
			})
		}
	}

	fn serialize(&self, context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()> {
		match *self {
			LOC::Version0(ref l0) => {
				packet.reserve(1);
				packet.put_u8(0);
				l0.serialize(context, packet)
			},
			LOC::UnknownVersion{version, ref data} => {
				packet.reserve(data.len() + 1);
				packet.put_u8(version);
				packet.put_slice(data);
				Ok(())
			},
		}
	}
}

impl DnsTextData for LOC {
	fn dns_parse(_context: &DnsTextContext, data: &mut &str) -> Result<Self> {
		let degrees_latitude = next_field(data)?.parse::<u8>()?;
		ensure!(degrees_latitude <= 90, "degrees latitude out of range: {}", degrees_latitude);
		let mut minutes_latitude = 0;
		let mut seconds_latitude = 0.0;
		let mut field = next_field(data)?;
		if field != "N" && field != "n" && field != "S" && field != "s" {
			minutes_latitude = field.parse::<u8>()?;
			ensure!(minutes_latitude < 60, "minutes latitude out of range: {}", minutes_latitude);
			field = next_field(data)?;
			if field != "N" && field != "n" && field != "S" && field != "s" {
				seconds_latitude = field.parse::<f32>()?;
				ensure!(seconds_latitude >= 0.0 && seconds_latitude < 60.0, "seconds latitude out of range: {}", seconds_latitude);
				field = next_field(data)?;
			}
		}
		let latitude_off = (3600_000 * degrees_latitude as u32) + (60_000 * minutes_latitude as u32) + (1_000.0 * seconds_latitude).round() as u32;
		ensure!(latitude_off <= 3600_000 * 180, "latitude out of range");
		let latitude = match field {
			"N"|"n" => 0x8000_0000 + latitude_off,
			"S"|"s" => 0x8000_0000 - latitude_off,
			_ => bail!("invalid latitude orientation [NS]: {}", field),
		};

		let degrees_longitude = next_field(data)?.parse::<u8>()?;
		ensure!(degrees_longitude <= 180, "degrees longitude out of range: {}", degrees_longitude);
		let mut minutes_longitude = 0;
		let mut seconds_longitude = 0.0;
		let mut field = next_field(data)?;
		if field != "E" && field != "e" && field != "W" && field != "w" {
			minutes_longitude = field.parse::<u8>()?;
			ensure!(minutes_longitude < 60, "minutes longitude out of range: {}", minutes_longitude);
			field = next_field(data)?;
			if field != "E" && field != "e" && field != "W" && field != "w" {
				seconds_longitude = field.parse::<f32>()?;
				ensure!(seconds_longitude >= 0.0 && seconds_longitude < 60.0, "seconds longitude out of range: {}", seconds_longitude);
				field = next_field(data)?;
			}
		}
		let longitude_off = (3600_000 * degrees_longitude as u32) + (60_000 * minutes_longitude as u32) + (1_000.0 * seconds_longitude).round() as u32;
		ensure!(longitude_off <= 3600_000 * 180, "longitude out of range");
		let longitude = match field {
			"E"|"e" => 0x8000_0000 + longitude_off,
			"W"|"w" => 0x8000_0000 - longitude_off,
			_ => bail!("invalid longitude orientation [EW]: {}", field),
		};

		fn trim_unit_m(s: &str) -> &str {
			if s.ends_with('m') { &s[..s.len()-1] } else { s }
		}

		fn parse_precision(s: &str) -> Result<u8> {
			let s = trim_unit_m(s);
			let mut m = 0;
			let mut e = 0;
			let mut dec_point = None;
			for &b in s.as_bytes() {
				if b == b'.' {
					ensure!(dec_point.is_none(), "invalid precision (double decimal point): {:?}", s);
					dec_point = Some(0);
					continue;
				}
				ensure!(b >= b'0' && b <= b'9', "invalid precision (invalid character): {:?}", s);
				if let Some(ref mut dp) = dec_point {
					if *dp == 2 { continue; } // ignore following digits
					*dp += 1;
				}
				let d = b - b'0';
				if 0 == m {
					m = d;
				} else {
					e += 1;
					ensure!(e <= 9, "invalid precision (overflow): {:?}", s);
				}
			}
			e += 2 - dec_point.unwrap_or(0);
			ensure!(e <= 9, "invalid precision (overflow): {:?}", s);
			Ok(m << 4 | e)
		}

		let altitude = match next_field(data) {
			Ok(field) => {
				let f_altitude = trim_unit_m(field).parse::<f64>()?;
				let altitude = (f_altitude * 100.0 + 10000000.0).round() as i64;
				ensure!(altitude > 0 && (altitude as u32) as i64 == altitude, "altitude out of range");
				altitude as u32
			},
			// standard requires the field, but the example parser doesn't..
			Err(_) => 10000000, // 0m
		};

		let size = match next_field(data) {
			Ok(field) => parse_precision(field)?,
			Err(_) => 0x12, // => 1e2 cm = 1m
		};

		let horizontal_precision = match next_field(data) {
			Ok(field) => parse_precision(field)?,
			Err(_) => 0x16, // 1e6 cm = 10km */
		};

		let vertical_precision = match next_field(data) {
			Ok(field) => parse_precision(field)?,
			Err(_) => 0x13, // 1e3 cm = 10m */
		};

		Ok(LOC::Version0(LOC0{
			size,
			horizontal_precision,
			vertical_precision,
			latitude,
			longitude,
			altitude,
		}))
	}

	fn dns_format(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		let this = match *self {
			LOC::Version0(ref t) => t,
			_ => return Err(fmt::Error),
		};
		const MAX_LAT_OFFSET: u32 = 3600_000 * 180;
		const MAX_LON_OFFSET: u32 = 3600_000 * 180;
		const LATLON_MID: u32 = 0x8000_0000;
		if this.latitude < LATLON_MID - MAX_LAT_OFFSET || this.latitude > LATLON_MID + MAX_LAT_OFFSET {
			return Err(fmt::Error);
		}
		if this.longitude < LATLON_MID - MAX_LON_OFFSET || this.longitude > LATLON_MID + MAX_LON_OFFSET {
			return Err(fmt::Error);
		}

		fn is_invalid_prec(v: u8) -> bool {
			// "leading-digit" << 4 | "exponent(base 10)"
			// if the leading digit is 0, the exponent must be 0 too.
			(v > 0x00 && v < 0x10) || (v >> 4) > 9 || (v & 0xf) > 9
		}
		if is_invalid_prec(this.size) || is_invalid_prec(this.horizontal_precision) || is_invalid_prec(this.vertical_precision) {
			return Err(fmt::Error);
		}

		fn putlatlon2(v: u32, f: &mut DnsTextFormatter) -> fmt::Result {
			let msecs = v % 1000;
			let fullsecs = v / 1000;
			let secs = fullsecs % 60;
			let fullmins = fullsecs / 60;
			let mins = fullmins % 60;
			let deg = fullmins / 60;
			write!(f, "{} {} {}.{:03}", deg, mins, secs, msecs)
		}

		fn putlatlon(v: u32, f: &mut DnsTextFormatter, pos: char, neg: char) -> fmt::Result {
			if v >= LATLON_MID {
				putlatlon2(v - LATLON_MID, f)?;
				write!(f, "{}", pos)
			} else {
				putlatlon2(LATLON_MID - v, f)?;
				write!(f, "{}", neg)
			}
		}

		putlatlon(this.latitude, f, 'N', 'S')?;
		putlatlon(this.longitude, f, 'E', 'W')?;

		write!(f, "{:.2}m", (this.altitude as f64 - 10000000.0) / 100.0)?;

		fn put_prec(v: u8, f: &mut DnsTextFormatter) -> fmt::Result {
			let m = v >> 4;
			debug_assert!(m < 10);
			let e = v & 0xf;
			if e >= 2 {
				write!(f, "{:0<width$}.00m", m, width = e as usize - 1)
			} else if e == 1 {
				write!(f, ".{}0m", m)
			} else { // e == 0
				write!(f, ".0{}m", m)
			}
		}

		put_prec(this.size, f)?;
		put_prec(this.horizontal_precision, f)?;
		put_prec(this.vertical_precision, f)?;

		Ok(())
	}
}

#[derive(Clone, PartialEq, Eq, Debug, DnsPacketData)]
pub struct LOC0 {
	size: u8,
	horizontal_precision: u8,
	vertical_precision: u8,
	latitude: u32,
	longitude: u32,
	altitude: u32,
}

#[derive(Clone, PartialEq, Eq, Debug, RRData)]
#[RRClass(IN)]
pub struct A6 {
	prefix: u8, // [0...128]
	// might include non-zero padding
	dirty_suffix: Ipv6Addr,
	suffix: Ipv6Addr,
	prefix_name: Option<DnsCanonicalName>,
}

impl DnsPacketData for A6 {
	fn deserialize(data: &mut ::std::io::Cursor<Bytes>) -> Result<Self> {
		let prefix: u8 = DnsPacketData::deserialize(data)
			.context("failed parsing field A6::prefix")?;
		ensure!(prefix <= 128, "invalid A6::prefix {}", prefix);
		let suffix_offset = (prefix / 8) as usize;
		debug_assert!(suffix_offset <= 16);
		let suffix_len = 16 - suffix_offset;
		check_enough_data!(data, suffix_len, "A6::suffix");
		let mut addr = [0u8; 16];
		data.read_exact(&mut addr[suffix_offset..16])?;

		let dirty_suffix = Ipv6Addr::from(addr);
		if suffix_offset < 16 {
			let mask = 0xff >> (prefix % 8);
			addr[suffix_offset] &= mask;
		}
		let suffix = Ipv6Addr::from(addr);

		let prefix_name = if data.has_remaining() {
			Some(DnsPacketData::deserialize(data)?)
		} else {
			None
		};

		Ok(A6 {
			prefix,
			dirty_suffix,
			suffix,
			prefix_name,
		})
	}

	fn serialize(&self, context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()> {
		let suffix_offset = (self.prefix / 8) as usize;
		debug_assert!(suffix_offset <= 16);
		let suffix = self.dirty_suffix.octets();
		let suffix_data = &suffix[suffix_offset..];
		packet.reserve(1 /* prefix */ + suffix_data.len());
		packet.put_u8(self.prefix);
		packet.put_slice(suffix_data);
		if let Some(ref n) = self.prefix_name {
			n.serialize(context, packet)?;
		}
		Ok(())
	}
}

impl DnsTextData for A6 {
	fn dns_parse(context: &DnsTextContext, data: &mut &str) -> Result<Self> {
		let prefix: u8 = DnsTextData::dns_parse(context, data)
			.context("failed parsing field A6::prefix")?;
		ensure!(prefix <= 128, "invalid A6::prefix {}", prefix);

		let suffix_offset = (prefix / 8) as usize;
		debug_assert!(suffix_offset <= 16);

		let suffix: Ipv6Addr = DnsTextData::dns_parse(context, data)
			.context("failed parsing field A6::suffix")?;

		// clear prefix bits
		let mut suffix = suffix.octets();
		for i in 0..suffix_offset {
			suffix[i] = 0;
		}
		if suffix_offset < 16 {
			let mask = 0xff >> (prefix % 8);
			suffix[suffix_offset] &= mask;
		}
		let suffix = Ipv6Addr::from(suffix);

		let prefix_name = if !data.is_empty() {
			Some(DnsTextData::dns_parse(context, data)
				.context("failed parsing field A6::prefix_name")?)
		} else {
			None
		};

		Ok(A6 {
			prefix,
			dirty_suffix: suffix.clone(),
			suffix,
			prefix_name,
		})
	}

	fn dns_format(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		if self.dirty_suffix != self.suffix {
			// parsing text clears the padding, so we would loose data.
			// use binary representation instead.
			return Err(fmt::Error);
		}
		write!(f, "{} {}", self.prefix, self.suffix)?;
		if let Some(ref prefix_name) = self.prefix_name {
			write!(f, "{}", prefix_name)?;
		}
		Ok(())
	}
}

#[derive(Clone, PartialEq, Eq, Debug)]
pub enum IpsecKeyGateway {
	None,
	Ipv4(Ipv4Addr),
	Ipv6(Ipv6Addr),
	Name(DnsName),
}

#[derive(Clone, PartialEq, Eq, Debug, RRData)]
#[RRClass(ANY)]
pub enum IPSECKEY {
	Known{
		precedence: u8,
		algorithm: u8,
		gateway: IpsecKeyGateway,
		public_key: Base64RemainingBlob,
	},
	UnknownGateway{
		precedence: u8,
		gateway_type: u8,
		algorithm: u8,
		// length of gateway is unknown, can't split gateway and public key
		remaining: Bytes,
	}
}

impl DnsPacketData for IPSECKEY {
	fn deserialize(data: &mut ::std::io::Cursor<Bytes>) -> Result<Self> {
		let precedence = u8::deserialize(data)?;
		let gateway_type = u8::deserialize(data)?;
		let algorithm = u8::deserialize(data)?;
		let gateway = match gateway_type {
			0 => IpsecKeyGateway::None,
			1 => IpsecKeyGateway::Ipv4(Ipv4Addr::deserialize(data)?),
			2 => IpsecKeyGateway::Ipv6(Ipv6Addr::deserialize(data)?),
			3 => IpsecKeyGateway::Name(DnsName::deserialize(data)?),
			_ => return Ok(IPSECKEY::UnknownGateway{
				precedence,
				gateway_type,
				algorithm,
				remaining: remaining_bytes(data),
			}),
		};
		Ok(IPSECKEY::Known{
			precedence,
			algorithm,
			gateway,
			public_key: Base64RemainingBlob::deserialize(data)?,
		})
	}

	fn serialize(&self, context: &mut DnsPacketWriteContext, packet: &mut Vec<u8>) -> Result<()> {
		match *self {
			IPSECKEY::Known{precedence, algorithm, ref gateway, ref public_key} => {
				packet.reserve(3);
				packet.put_u8(precedence);
				let gateway_type: u8 = match *gateway {
					IpsecKeyGateway::None => 0,
					IpsecKeyGateway::Ipv4(_) => 1,
					IpsecKeyGateway::Ipv6(_) => 2,
					IpsecKeyGateway::Name(_) => 3,
				};
				packet.put_u8(gateway_type);
				packet.put_u8(algorithm);
				match *gateway {
					IpsecKeyGateway::None => (),
					IpsecKeyGateway::Ipv4(ref a) => a.serialize(context, packet)?,
					IpsecKeyGateway::Ipv6(ref a) => a.serialize(context, packet)?,
					IpsecKeyGateway::Name(ref n) => n.serialize(context, packet)?,
				};
				public_key.serialize(context, packet)?;
			},
			IPSECKEY::UnknownGateway{precedence, gateway_type, algorithm, ref remaining} => {
				packet.reserve(3 + remaining.len());
				packet.put_u8(precedence);
				packet.put_u8(gateway_type);
				packet.put_u8(algorithm);
				packet.put_slice(remaining);
			}
		}
		Ok(())
	}
}

impl DnsTextData for IPSECKEY {
	fn dns_parse(context: &DnsTextContext, data: &mut &str) -> Result<Self> {
		let precedence = u8::dns_parse(context, data)?;
		let gateway_type = u8::dns_parse(context, data)?;
		let algorithm = u8::dns_parse(context, data)?;
		let gateway = match gateway_type {
			0 => IpsecKeyGateway::None,
			1 => IpsecKeyGateway::Ipv4(Ipv4Addr::dns_parse(context, data)?),
			2 => IpsecKeyGateway::Ipv6(Ipv6Addr::dns_parse(context, data)?),
			3 => IpsecKeyGateway::Name(DnsName::dns_parse(context, data)?),
			_ => bail!("unknown gateway type {} for IPSECKEY", gateway_type),
		};
		Ok(IPSECKEY::Known{
			precedence,
			algorithm,
			gateway,
			public_key: Base64RemainingBlob::dns_parse(context, data)?,
		})
	}

	fn dns_format(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		match *self {
			IPSECKEY::Known{precedence, algorithm, ref gateway, ref public_key} => {
				let gateway_type: u8 = match *gateway {
					IpsecKeyGateway::None => 0,
					IpsecKeyGateway::Ipv4(_) => 1,
					IpsecKeyGateway::Ipv6(_) => 2,
					IpsecKeyGateway::Name(_) => 3,
				};
				write!(f, "{} {} {}", precedence, gateway_type, algorithm)?;
				match *gateway {
					IpsecKeyGateway::None => (),
					IpsecKeyGateway::Ipv4(ref a) => a.dns_format(f)?,
					IpsecKeyGateway::Ipv6(ref a) => a.dns_format(f)?,
					IpsecKeyGateway::Name(ref n) => n.dns_format(f)?,
				};
				public_key.dns_format(f)?;
				Ok(())
			},
			IPSECKEY::UnknownGateway{..} => Err(fmt::Error),
		}
	}
}