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//! SUBACK

use std::cmp::Ordering;

use std::io::{self, Read, Write};

use byteorder::{ReadBytesExt, WriteBytesExt};

use crate::control::variable_header::PacketIdentifier;
use crate::control::{ControlType, FixedHeader, PacketType};
use crate::packet::{DecodablePacket, PacketError};
use crate::qos::QualityOfService;
use crate::{Decodable, Encodable};

/// Subscribe code
#[repr(u8)]
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
pub enum SubscribeReturnCode {
    MaximumQoSLevel0 = 0x00,
    MaximumQoSLevel1 = 0x01,
    MaximumQoSLevel2 = 0x02,
    Failure = 0x80,
}

impl PartialOrd for SubscribeReturnCode {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        use self::SubscribeReturnCode::*;
        match (self, other) {
            (&Failure, _) => None,
            (_, &Failure) => None,
            (&MaximumQoSLevel0, &MaximumQoSLevel0) => Some(Ordering::Equal),
            (&MaximumQoSLevel1, &MaximumQoSLevel1) => Some(Ordering::Equal),
            (&MaximumQoSLevel2, &MaximumQoSLevel2) => Some(Ordering::Equal),
            (&MaximumQoSLevel0, _) => Some(Ordering::Less),
            (&MaximumQoSLevel1, &MaximumQoSLevel0) => Some(Ordering::Greater),
            (&MaximumQoSLevel1, &MaximumQoSLevel2) => Some(Ordering::Less),
            (&MaximumQoSLevel2, _) => Some(Ordering::Greater),
        }
    }
}

impl From<QualityOfService> for SubscribeReturnCode {
    fn from(qos: QualityOfService) -> Self {
        match qos {
            QualityOfService::Level0 => SubscribeReturnCode::MaximumQoSLevel0,
            QualityOfService::Level1 => SubscribeReturnCode::MaximumQoSLevel1,
            QualityOfService::Level2 => SubscribeReturnCode::MaximumQoSLevel2,
        }
    }
}

/// `SUBACK` packet
#[derive(Debug, Eq, PartialEq, Clone)]
pub struct SubackPacket {
    fixed_header: FixedHeader,
    packet_identifier: PacketIdentifier,
    payload: SubackPacketPayload,
}

encodable_packet!(SubackPacket(packet_identifier, payload));

impl SubackPacket {
    pub fn new(pkid: u16, subscribes: Vec<SubscribeReturnCode>) -> SubackPacket {
        let mut pk = SubackPacket {
            fixed_header: FixedHeader::new(PacketType::with_default(ControlType::SubscribeAcknowledgement), 0),
            packet_identifier: PacketIdentifier(pkid),
            payload: SubackPacketPayload::new(subscribes),
        };
        pk.fix_header_remaining_len();
        pk
    }

    pub fn packet_identifier(&self) -> u16 {
        self.packet_identifier.0
    }

    pub fn set_packet_identifier(&mut self, pkid: u16) {
        self.packet_identifier.0 = pkid;
    }

    pub fn subscribes(&self) -> &[SubscribeReturnCode] {
        &self.payload.subscribes[..]
    }
}

impl DecodablePacket for SubackPacket {
    type DecodePacketError = SubackPacketError;

    fn decode_packet<R: Read>(reader: &mut R, fixed_header: FixedHeader) -> Result<Self, PacketError<Self>> {
        let packet_identifier = PacketIdentifier::decode(reader)?;
        let payload: SubackPacketPayload = SubackPacketPayload::decode_with(
            reader,
            fixed_header.remaining_length - packet_identifier.encoded_length(),
        )
        .map_err(PacketError::PayloadError)?;
        Ok(SubackPacket {
            fixed_header,
            packet_identifier,
            payload,
        })
    }
}

#[derive(Debug, Eq, PartialEq, Clone)]
struct SubackPacketPayload {
    subscribes: Vec<SubscribeReturnCode>,
}

impl SubackPacketPayload {
    pub fn new(subs: Vec<SubscribeReturnCode>) -> SubackPacketPayload {
        SubackPacketPayload { subscribes: subs }
    }
}

impl Encodable for SubackPacketPayload {
    fn encode<W: Write>(&self, writer: &mut W) -> Result<(), io::Error> {
        for code in self.subscribes.iter() {
            writer.write_u8(*code as u8)?;
        }

        Ok(())
    }

    fn encoded_length(&self) -> u32 {
        self.subscribes.len() as u32
    }
}

impl Decodable for SubackPacketPayload {
    type Error = SubackPacketError;
    type Cond = u32;

    fn decode_with<R: Read>(reader: &mut R, payload_len: u32) -> Result<SubackPacketPayload, SubackPacketError> {
        let mut subs = Vec::new();

        for _ in 0..payload_len {
            let retcode = match reader.read_u8()? {
                0x00 => SubscribeReturnCode::MaximumQoSLevel0,
                0x01 => SubscribeReturnCode::MaximumQoSLevel1,
                0x02 => SubscribeReturnCode::MaximumQoSLevel2,
                0x80 => SubscribeReturnCode::Failure,
                code => return Err(SubackPacketError::InvalidSubscribeReturnCode(code)),
            };

            subs.push(retcode);
        }

        Ok(SubackPacketPayload::new(subs))
    }
}

#[derive(Debug, thiserror::Error)]
pub enum SubackPacketError {
    #[error(transparent)]
    IoError(#[from] io::Error),
    #[error("invalid subscribe return code {0}")]
    InvalidSubscribeReturnCode(u8),
}