#[cfg(feature = "std")]
use crate::std_identity::Keystore;

#[cfg(not(feature = "std"))]
use crate::no_std_identity::Keystore;

use crate::{
    anon_req::ClearAnonRequest, packet_content::PacketContent, request::ClearRequest,
    response::ClearResponse, text::ClearText,
};
use bytes::{Buf, Bytes};
use tinyvec::ArrayVec;

#[derive(PartialEq, Clone, core::fmt::Debug)]
pub struct Packet {
    pub route_type: RouteType,
    pub version: PayloadVersion,
    pub path: ArrayVec<[u16; 64]>,
    pub transport: [u16; 2],
    pub raw_content: Bytes,
    pub content: PacketContent,
    pub incomplete: bool,
}

impl core::str::FromStr for Packet {
    type Err = hex::FromHexError;

    fn from_str(hex_str: &str) -> Result<Self, Self::Err> {
        let hex = hex::decode(hex_str)?;
        Ok(Packet::from(Bytes::copy_from_slice(&hex)))
    }
}

impl From<Bytes> for Packet {
    fn from(bytes_in: Bytes) -> Self {
        let mut bytes = bytes_in;

        // This is the packet we'll build as we begin to parse
        let mut packet = Packet::default();

        if bytes.len() < 2 {
            return packet;
        }

        let header = bytes.get_u8();

        // Parse the header byte
        packet.route_type = RouteType::from(header);
        packet.version = PayloadVersion::from(header);

        // Get the transport if it's provided
        packet.transport = match packet.route_type {
            RouteType::TransportFlood | RouteType::TransportDirect => {
                // The packet isn't long enough to contain the transport
                if bytes.len() < 4 {
                    return packet;
                }

                let t1 = bytes.get_u16_le();
                let t2 = bytes.get_u16_le();
                [t1, t2]
            }
            _ => [0, 0],
        };

        // Get the route
        if bytes.is_empty() {
            return packet;
        }
        let path_length = bytes.get_u8() as usize;

        packet.path = match packet.version {
            PayloadVersion::VersionOne => {
                // The packet isn't long enough for the indicated route
                if bytes.len() < path_length {
                    return packet;
                }

                let mut route = ArrayVec::new();
                for _ in 0..path_length {
                    let path_element = bytes.get_u8() as u16;
                    route.push(path_element);
                }

                route
            }

            PayloadVersion::VersionTwo => {
                // The packet isn't long enough for the indicated route
                if bytes.len() < path_length * 2 {
                    return packet;
                }

                let mut route = ArrayVec::new();
                for i in 0..path_length {
                    let path_element = bytes.get_u16();
                    route[i] = path_element;
                }

                route
            }
            _ => {
                return packet;
            }
        };

        // Get the rest of the payload and pass the parsing to the other structs
        packet.raw_content = bytes.clone();

        packet.content = PacketContent::new(header, bytes);

        // Unfortunately, the trace packet is a bit weird.
        // So, if this is a trace packet, move things back into the right place.
        if let PacketContent::Trace(trace) = packet.content {
            let mut trace = trace;
            let path_snr = packet.path;

            for (index, element) in trace.temp_path.iter().enumerate() {
                packet.path[index] = *element as u16;
            }

            for u in path_snr.iter() {
                let i = *u as i8;
                let f = i as f32;

                trace.path_snr.push(f / 4.0);
            }

            // DON'T delete the temp path, so Trace has access to the path
            // when it prints the SNR results in its Display function.
            packet.content = PacketContent::Trace(trace);
        }

        // Mark the packet as complete and valid
        packet.incomplete = false;

        packet
    }
}

impl Default for Packet {
    fn default() -> Self {
        Packet {
            route_type: RouteType::Invalid,
            version: PayloadVersion::Invalid,
            path: ArrayVec::new(),
            transport: [0, 0],
            raw_content: Bytes::new(),
            content: PacketContent::Invalid,
            incomplete: true,
        }
    }
}

impl core::fmt::Display for Packet {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        core::fmt::Display::fmt(&self.route_type, f)?;
        f.write_str(" | ")?;
        core::fmt::Display::fmt(&self.version, f)?;

        if self.route_type == RouteType::TransportDirect
            || self.route_type == RouteType::TransportFlood
        {
            f.write_fmt(format_args!(
                " | {:4x?}, {:4x?} | ",
                self.transport[0], self.transport[1]
            ))?
        } else {
            f.write_fmt(format_args!(" |            |"))?
        }

        let len = self.path.len();
        match self.path.len() {
            0 => f.write_fmt(format_args!("          []          | ")),
            1 => f.write_fmt(format_args!("         [{:02x?}]         | ", self.path[0])),
            2 => f.write_fmt(format_args!(
                "       [{:02x?}, {:02x?}]       | ",
                self.path[0], self.path[1]
            )),
            3 => f.write_fmt(format_args!(
                "     [{:02x?}, {:02x?}, {:02x?}]     | ",
                self.path[0], self.path[1], self.path[2]
            )),
            _ => f.write_fmt(format_args!(
                " [{:02x?}, {:02x?}, ... {:02x?}, {:02x?}] | ",
                self.path[0],
                self.path[1],
                self.path[len - 2],
                self.path[len - 1]
            )),
        }?;

        if self.incomplete {
            f.write_str("x | ")
        } else {
            f.write_str("  | ")
        }?;

        core::fmt::Display::fmt(&self.content, f)
    }
}

impl Packet {
    #[cfg(feature = "std")]
    pub fn try_decrypt(&mut self, keystore: &Keystore) -> bool {
        match self.content {
            // Encrypted packet types
            PacketContent::Path(ref mut path) => path.cipher.try_decrypt(keystore),
            PacketContent::Request(ref mut request) => {
                let result = request.cipher.try_decrypt(keystore);

                if let Some(cleartext) = &request.cipher.cleartext {
                    let cleartext = ClearRequest::from(cleartext.clone());
                    request.cleartext = Some(cleartext);

                    result
                } else {
                    false
                }
            }
            PacketContent::Response(ref mut response) => {
                response.cipher.try_decrypt(keystore);

                if let Some(cleartext) = &response.cipher.cleartext {
                    response.cleartext = Some(ClearResponse::from(cleartext.to_owned()));
                    true
                } else {
                    false
                }
            }

            PacketContent::Text(ref mut text) => {
                text.cipher.try_decrypt(keystore);

                if let Some(cleartext) = &text.cipher.cleartext {
                    text.cleartext = Some(ClearText::from(cleartext.to_owned()));
                    true
                } else {
                    false
                }
            }

            PacketContent::AnonReq(ref mut anon_req) => {
                let decrypt_result = keystore.decrypt_anon(
                    anon_req.dest,
                    &anon_req.public_key,
                    anon_req.mac,
                    &anon_req.ciphertext,
                );

                if let Some(cleartext) = decrypt_result {
                    anon_req.request = Some(ClearAnonRequest::from(cleartext.0));
                    true
                } else {
                    false
                }
            }

            PacketContent::GroupText(ref mut group_text) => group_text.try_decrypt(keystore),

            // None of the other packets implement any encryption
            _ => false,
        }
    }
}

#[derive(PartialEq, Debug, Clone)]
pub enum RouteType {
    TransportFlood,
    Flood,
    Direct,
    TransportDirect,
    Invalid,
}

impl core::fmt::Display for RouteType {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            RouteType::TransportFlood => f.write_str("T-Flood "),
            RouteType::Flood => f.write_str("  Flood "),
            RouteType::Direct => f.write_str("  Direct"),
            RouteType::TransportDirect => f.write_str("T-Direct"),
            RouteType::Invalid => f.write_str("INVALID "),
        }
    }
}

impl From<u8> for RouteType {
    fn from(value: u8) -> Self {
        match value & 0x03 {
            0x00 => RouteType::TransportFlood,
            0x01 => RouteType::Flood,
            0x02 => RouteType::Direct,
            0x03 => RouteType::TransportDirect,
            _ => RouteType::Invalid,
        }
    }
}

#[derive(PartialEq, Debug, Clone)]
pub enum PayloadVersion {
    VersionOne,
    VersionTwo,
    VersionThree,
    VersionFour,
    Invalid,
}

impl From<u8> for PayloadVersion {
    fn from(value: u8) -> Self {
        let value = (value & 0xC0) >> 6;
        assert!(value < 4, "Programming error in masking and bit-shifting");

        match value {
            0x00 => PayloadVersion::VersionOne,
            0x01 => PayloadVersion::VersionTwo,
            0x02 => PayloadVersion::VersionThree,
            0x03 => PayloadVersion::VersionFour,
            _ => PayloadVersion::Invalid,
        }
    }
}

impl core::fmt::Display for PayloadVersion {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            PayloadVersion::VersionOne => f.write_str("v1"),
            PayloadVersion::VersionTwo => f.write_str("v2"),
            PayloadVersion::VersionThree => f.write_str("v3"),
            PayloadVersion::VersionFour => f.write_str("v4"),
            PayloadVersion::Invalid => f.write_str("xx"),
        }
    }
}

#[cfg(test)]
mod tests {
    use core::str::FromStr;
    use tinyvec::array_vec;

    use super::*;
    use crate::packet_content::{PacketContent, Raw};

    #[test]
    fn header_route_type() {
        // The route type is the lowest-order two bits
        assert_eq!(RouteType::TransportFlood, RouteType::from(0x00));
        assert_eq!(RouteType::TransportFlood, RouteType::from(0xFC));
        assert_eq!(RouteType::Flood, RouteType::from(0x01));
        assert_eq!(RouteType::Flood, RouteType::from(0xFD));
        assert_eq!(RouteType::Direct, RouteType::from(0x02));
        assert_eq!(RouteType::Direct, RouteType::from(0xFE));
        assert_eq!(RouteType::TransportDirect, RouteType::from(0x03));
        assert_eq!(RouteType::TransportDirect, RouteType::from(0xFF));

        assert_eq!(format!("{}", RouteType::TransportFlood), "T-Flood ");
        assert_eq!(format!("{}", RouteType::Flood), "  Flood ");
        assert_eq!(format!("{}", RouteType::Direct), "  Direct");
        assert_eq!(format!("{}", RouteType::TransportDirect), "T-Direct");
        assert_eq!(format!("{}", RouteType::Invalid), "INVALID ");
    }

    #[test]
    fn header_version() {
        assert_eq!(PayloadVersion::VersionOne, PayloadVersion::from(0x00));
        assert_eq!(PayloadVersion::VersionOne, PayloadVersion::from(0x3F));
        assert_eq!(PayloadVersion::VersionTwo, PayloadVersion::from(0x40));
        assert_eq!(PayloadVersion::VersionTwo, PayloadVersion::from(0x7F));
        assert_eq!(PayloadVersion::VersionThree, PayloadVersion::from(0x80));
        assert_eq!(PayloadVersion::VersionThree, PayloadVersion::from(0xBF));
        assert_eq!(PayloadVersion::VersionFour, PayloadVersion::from(0xC0));
        assert_eq!(PayloadVersion::VersionFour, PayloadVersion::from(0xFF));

        assert_eq!(format!("{}", PayloadVersion::VersionOne), "v1");
        assert_eq!(format!("{}", PayloadVersion::VersionTwo), "v2");
        assert_eq!(format!("{}", PayloadVersion::VersionThree), "v3");
        assert_eq!(format!("{}", PayloadVersion::VersionFour), "v4");
        assert_eq!(format!("{}", PayloadVersion::Invalid), "xx");
    }

    #[test]
    fn packet() {
        // Check the hex decode errors
        assert_eq!(
            Err(hex::FromHexError::InvalidHexCharacter { c: 's', index: 0 }),
            Packet::from_str("s0")
        );
        assert_eq!(Err(hex::FromHexError::OddLength), Packet::from_str("0"));

        // Check errors related to packet length issues
        assert_eq!(Packet::default(), Packet::from_str("").unwrap());
        let rhs_packet = Packet::from_str("01").unwrap();
        assert_eq!(Packet::default(), rhs_packet);

        // Packet not long enough to contain the provided path
        let mut lhs_packet = Packet::default();
        lhs_packet.route_type = RouteType::Flood;
        lhs_packet.version = PayloadVersion::VersionOne;
        let rhs_packet = Packet::from_str("0101").unwrap();
        assert_eq!(lhs_packet, rhs_packet);

        // Packet not long enough for transport
        let mut lhs_packet = Packet::default();
        lhs_packet.route_type = RouteType::TransportDirect;
        lhs_packet.version = PayloadVersion::VersionOne;
        let rhs_packet = Packet::from_str("0301").unwrap();
        assert_eq!(lhs_packet, rhs_packet);

        // Packet not long enough for version 2 path
        let mut lhs_packet = Packet::default();
        lhs_packet.route_type = RouteType::Direct;
        lhs_packet.version = PayloadVersion::VersionTwo;
        let rhs_packet = Packet::from_str("420102").unwrap();
        assert_eq!(lhs_packet, rhs_packet);

        // Ensure packet remainder is captured.  This
        // will test version 1 plus transport
        let lhs_packet = Packet {
            route_type: RouteType::TransportDirect,
            version: PayloadVersion::VersionOne,
            path: array_vec!([u16; 64] => 0x06, 0x07, 0x08, 0x09, 0x0A),
            transport: [0x0102, 0x0304],
            raw_content: Bytes::copy_from_slice(&[
                0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
            ]),
            content: PacketContent::Raw(Raw {
                bytes: Bytes::copy_from_slice(&[
                    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
                ]),
            }),
            incomplete: false,
        };

        let rhs_packet: Packet =
            Packet::from_str("3F0201040305060708090A10111213141516171819").unwrap();

        let compare_string = "T-Direct | v1 |  102,  304 |  [06, 07, ... 09, 0a] |   |     RAW    | Raw { bytes: b\"\\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\" }";
        assert_eq!(format!("{}", rhs_packet), compare_string);

        assert_eq!(lhs_packet, rhs_packet);
    }

    #[test]
    fn packet_display() {
        let mut packet = Packet {
            route_type: RouteType::Direct,
            version: PayloadVersion::VersionOne,
            path: ArrayVec::new(),
            transport: [0, 1],
            raw_content: Bytes::new(),
            content: PacketContent::Invalid,
            incomplete: false,
        };

        assert_eq!(
            format!("{}", packet),
            "  Direct | v1 |            |          []          |   |   INVALID  | INVALID"
        );

        packet.path.push(0x01);
        assert_eq!(
            format!("{}", packet),
            "  Direct | v1 |            |         [01]         |   |   INVALID  | INVALID"
        );

        packet.path.push(0x02);
        assert_eq!(
            format!("{}", packet),
            "  Direct | v1 |            |       [01, 02]       |   |   INVALID  | INVALID"
        );

        packet.path.push(0xff);
        assert_eq!(
            format!("{}", packet),
            "  Direct | v1 |            |     [01, 02, ff]     |   |   INVALID  | INVALID"
        );

        packet.incomplete = true;
        assert_eq!(
            format!("{}", packet),
            "  Direct | v1 |            |     [01, 02, ff]     | x |   INVALID  | INVALID"
        );
    }
}