pub struct UDPMessage {
    id: u32,
    msg_type: u8,
    length: u16,
    body: Vec<u8>,
    signature: Vec<u8>,
}

pub struct HandshakeMessage {
    id: u32,
    msg_type: u8,
    length: u16,
    extensions: u32,
    name: Vec<u8>,
    signature: Vec<u8>,
}

impl UDPMessage {
    pub fn ping(id: u32) -> UDPMessage {
        UDPMessage {
            id: id,
            msg_type: 0,
            length: 0,
            body: vec![0; 985],
            signature: vec![0; 32],
        }
    }

    pub fn error(id: u32) -> UDPMessage {
        UDPMessage {
            id: id,
            msg_type: 129,
            length: 0,
            body: vec![0; 985],
            signature: vec![0; 32],
        }
    }

    pub fn parse(received_message: Vec<u8>) -> UDPMessage {
        let id_bytes: [u8; 4] = received_message[0..4]
            .try_into()
            .expect("Taille incorrecte");
        let length_bytes: [u8; 2] = received_message[5..7]
            .try_into()
            .expect("Taille incorrecte");
        let msg_length = u16::from_be_bytes(length_bytes);
        let name_bytes = &received_message[7..msg_length as usize + 8];
        let signature_bytes =
            &received_message[msg_length as usize + 8..msg_length as usize + 9 + 32];
        UDPMessage {
            id: u32::from_be_bytes(id_bytes),
            msg_type: received_message[4],
            length: u16::from_be_bytes(length_bytes),
            body: name_bytes.to_vec(),
            signature: signature_bytes.to_vec(),
        }
    }

    pub fn display(&self) {
        println!("ID: {:?}", self.id);
        println!("Message Type: {}", self.msg_type);
        println!("Length: {:?}", self.length);
        let good_length = usize::min(self.length as usize, 985);
        println!("name: {:?}", &self.body[..good_length]);
        println!("Signature: {:?}", self.signature);
    }
}

impl HandshakeMessage {
    pub fn display(&self) {
        println!("ID: {:?}", self.id);
        println!("Message Type: {}", self.msg_type);
        println!("Length: {:?}", self.length);
        println!("extensions: {:?}", self.extensions);
        println!("name: {:?}", &self.name[..(self.length - 4) as usize]);
        println!("Signature: {:?}", self.signature);
    }
    pub fn hello(id: u32, length: u16, username: String) -> HandshakeMessage {
        let name_vec = username.trim_end_matches(char::from(0)).as_bytes().to_vec();
        HandshakeMessage {
            id: id,
            msg_type: 1,
            length: length,
            extensions: 0,
            name: name_vec,
            signature: vec![0; 64],
        }
    }

    pub fn helloReply(id: u32, length: u16, username: String) -> HandshakeMessage {
        let name_vec = username.trim_end_matches(char::from(0)).as_bytes().to_vec();
        HandshakeMessage {
            id: id,
            msg_type: 130,
            length: length,
            extensions: 0,
            name: name_vec,
            signature: vec![0; 64],
        }
    }

    pub fn serialize(&self) -> Vec<u8> {
        let mut out = Vec::with_capacity(4 + 1 + 2 + 4 + self.name.len() + self.signature.len());

        // id: u32 little-endian
        out.extend_from_slice(&self.id.to_be_bytes());

        // msg_type: u8
        out.push(self.msg_type);

        out.extend_from_slice(&self.length.to_be_bytes());

        out.extend_from_slice(&self.extensions.to_be_bytes());

        out.extend_from_slice(&self.name);

        out.extend_from_slice(&self.signature);

        out
    }

    pub fn parse(received_message: Vec<u8>) -> HandshakeMessage {
        let id_bytes: [u8; 4] = received_message[0..4]
            .try_into()
            .expect("Taille incorrecte");
        let length_bytes: [u8; 2] = received_message[5..7]
            .try_into()
            .expect("Taille incorrecte");
        let msg_length = u16::from_be_bytes(length_bytes);
        let extensions_bytes: [u8; 4] = received_message[7..11]
            .try_into()
            .expect("Taille incorrecte");
        let name_bytes = &received_message[11..12 + msg_length as usize];
        let signature_bytes =
            &received_message[12 + msg_length as usize..(13 + msg_length + 32) as usize];
        HandshakeMessage {
            id: u32::from_be_bytes(id_bytes),
            msg_type: received_message[4],
            length: u16::from_be_bytes(length_bytes),
            extensions: u32::from_be_bytes(extensions_bytes),
            name: name_bytes.to_vec(),
            signature: signature_bytes.to_vec(),
        }
    }
}

#[cfg(test)]
mod tests {
    // Note this useful idiom: importing names from outer (for mod tests) scope.
    use super::*;

    /// creates an handshake message
    #[tokio::test]
    async fn creating_handshake_msg() {
        let username = String::from("charlie_kirk");
        let handshake = HandshakeMessage::hello(0, 12, username);
        handshake.display();
    }

    /// parses an handshake message
    #[tokio::test]
    async fn parse_handshakemessage() {
        let username = String::from("charlie_kirk");
        let handshake = HandshakeMessage::hello(0, 12, username);
        let ser = handshake.serialize();
        let parsed = HandshakeMessage::parse(ser);
        handshake.display();
        parsed.display();
    }
}