use crate::MqttString;

use super::{
    len_len, length, property, read_mqtt_string, read_u16, read_u8, write_mqtt_string,
    write_remaining_length, Debug, Error, FixedHeader, PropertyType,
};
use bytes::{Buf, BufMut, Bytes, BytesMut};

/// Acknowledgement to unsubscribe
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct UnsubAck {
    pub pkid: u16,
    pub reasons: Vec<UnsubAckReason>,
    pub properties: Option<UnsubAckProperties>,
}

impl UnsubAck {
    fn len(&self) -> usize {
        let mut len = 2 + self.reasons.len();

        if let Some(p) = &self.properties {
            let properties_len = p.len();
            let properties_len_len = len_len(properties_len);
            len += properties_len_len + properties_len;
        } else {
            // just 1 byte representing 0 len
            len += 1;
        }

        len
    }

    #[must_use]
    pub fn size(&self) -> usize {
        let len = self.len();
        let remaining_len_size = len_len(len);

        1 + remaining_len_size + len
    }

    pub fn read(fixed_header: FixedHeader, mut bytes: Bytes) -> Result<UnsubAck, Error> {
        let variable_header_index = fixed_header.fixed_header_len;
        bytes.advance(variable_header_index);

        let pkid = read_u16(&mut bytes)?;
        let properties = UnsubAckProperties::read(&mut bytes)?;

        if !bytes.has_remaining() {
            return Err(Error::MalformedPacket);
        }

        let mut reasons = Vec::new();
        while bytes.has_remaining() {
            let r = read_u8(&mut bytes)?;
            reasons.push(reason(r)?);
        }

        let unsuback = UnsubAck {
            pkid,
            reasons,
            properties,
        };

        Ok(unsuback)
    }

    pub fn write(&self, buffer: &mut BytesMut) -> Result<usize, Error> {
        buffer.put_u8(0xB0);
        let remaining_len = self.len();
        let remaining_len_bytes = write_remaining_length(buffer, remaining_len)?;

        buffer.put_u16(self.pkid);

        if let Some(p) = &self.properties {
            p.write(buffer)?;
        } else {
            write_remaining_length(buffer, 0)?;
        }

        let p: Vec<u8> = self.reasons.iter().map(|&c| code(c)).collect();
        buffer.extend_from_slice(&p);
        Ok(1 + remaining_len_bytes + remaining_len)
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum UnsubAckReason {
    Success,
    NoSubscriptionExisted,
    UnspecifiedError,
    ImplementationSpecificError,
    NotAuthorized,
    TopicFilterInvalid,
    PacketIdentifierInUse,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct UnsubAckProperties {
    pub reason_string: Option<MqttString>,
    pub user_properties: Vec<(MqttString, MqttString)>,
}

impl UnsubAckProperties {
    fn len(&self) -> usize {
        let mut len = 0;

        if let Some(reason) = &self.reason_string {
            len += 1 + 2 + reason.len();
        }

        for (key, value) in &self.user_properties {
            len += 1 + 2 + key.len() + 2 + value.len();
        }

        len
    }

    pub fn read(bytes: &mut Bytes) -> Result<Option<UnsubAckProperties>, Error> {
        let mut reason_string = None;
        let mut user_properties = Vec::new();

        let (properties_len_len, properties_len) = length(bytes.iter())?;
        bytes.advance(properties_len_len);
        if properties_len == 0 {
            return Ok(None);
        }

        let mut cursor = 0;
        // read until cursor reaches property length. properties_len = 0 will skip this loop
        while cursor < properties_len {
            let prop = read_u8(bytes)?;
            cursor += 1;

            match property(prop)? {
                PropertyType::ReasonString => {
                    let reason = read_mqtt_string(bytes)?;
                    cursor += 2 + reason.len();
                    reason_string = Some(reason);
                }
                PropertyType::UserProperty => {
                    let key = read_mqtt_string(bytes)?;
                    let value = read_mqtt_string(bytes)?;
                    cursor += 2 + key.len() + 2 + value.len();
                    user_properties.push((key, value));
                }
                _ => return Err(Error::InvalidPropertyType(prop)),
            }
        }

        Ok(Some(UnsubAckProperties {
            reason_string,
            user_properties,
        }))
    }

    pub fn write(&self, buffer: &mut BytesMut) -> Result<(), Error> {
        let len = self.len();
        write_remaining_length(buffer, len)?;

        if let Some(reason) = &self.reason_string {
            buffer.put_u8(PropertyType::ReasonString as u8);
            write_mqtt_string(buffer, reason)?;
        }

        for (key, value) in &self.user_properties {
            buffer.put_u8(PropertyType::UserProperty as u8);
            write_mqtt_string(buffer, key)?;
            write_mqtt_string(buffer, value)?;
        }

        Ok(())
    }
}

/// Connection return code type
fn reason(num: u8) -> Result<UnsubAckReason, Error> {
    let code = match num {
        0x00 => UnsubAckReason::Success,
        0x11 => UnsubAckReason::NoSubscriptionExisted,
        0x80 => UnsubAckReason::UnspecifiedError,
        0x83 => UnsubAckReason::ImplementationSpecificError,
        0x87 => UnsubAckReason::NotAuthorized,
        0x8F => UnsubAckReason::TopicFilterInvalid,
        0x91 => UnsubAckReason::PacketIdentifierInUse,
        num => return Err(Error::InvalidSubscribeReasonCode(num)),
    };

    Ok(code)
}

fn code(reason: UnsubAckReason) -> u8 {
    match reason {
        UnsubAckReason::Success => 0x00,
        UnsubAckReason::NoSubscriptionExisted => 0x11,
        UnsubAckReason::UnspecifiedError => 0x80,
        UnsubAckReason::ImplementationSpecificError => 0x83,
        UnsubAckReason::NotAuthorized => 0x87,
        UnsubAckReason::TopicFilterInvalid => 0x8F,
        UnsubAckReason::PacketIdentifierInUse => 0x91,
    }
}

#[cfg(test)]
mod test {
    use crate::test::read_write_packets;
    use crate::Packet;

    use super::super::test::{USER_PROP_KEY, USER_PROP_VAL};
    use super::*;
    use bytes::BytesMut;
    use pretty_assertions::assert_eq;

    #[test]
    fn length_calculation() {
        let mut dummy_bytes = BytesMut::new();
        // Use user_properties to pad the size to exceed ~128 bytes to make the
        // remaining_length field in the packet be 2 bytes long.
        let unsuback_props = UnsubAckProperties {
            reason_string: None,
            user_properties: vec![(USER_PROP_KEY.into(), USER_PROP_VAL.into())],
        };

        let unsuback_pkt = UnsubAck {
            pkid: 1,
            reasons: vec![UnsubAckReason::Success],
            properties: Some(unsuback_props),
        };

        let size_from_size = unsuback_pkt.size();
        let size_from_write = unsuback_pkt.write(&mut dummy_bytes).unwrap();
        let size_from_bytes = dummy_bytes.len();

        assert_eq!(size_from_write, size_from_bytes);
        assert_eq!(size_from_size, size_from_bytes);
    }

    #[test]
    fn test_write_read() {
        read_write_packets(write_read_provider());
    }

    fn write_read_provider() -> Vec<Packet> {
        vec![
            Packet::UnsubAck(UnsubAck {
                pkid: 42,
                reasons: vec![UnsubAckReason::Success],
                properties: None,
            }),
            Packet::UnsubAck(UnsubAck {
                pkid: 42,
                reasons: vec![UnsubAckReason::Success],
                properties: Some(UnsubAckProperties {
                    reason_string: Some("Resaon".into()),
                    user_properties: vec![(USER_PROP_KEY.into(), USER_PROP_VAL.into())],
                }),
            }),
        ]
    }
}