use tokio::io::AsyncWrite;
use tokio::io::AsyncWriteExt;

use super::*;

/// Server-to-client message.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct ServerMessage {
    /// Optional tags section, prefixed with `@`
    pub tags: Vec<Tag>,
    /// Optional server name, prefixed with `:`.
    pub sender: Option<ByteVec>,
    pub body: ServerMessageBody,
}

impl ServerMessage {
    pub async fn write_async(&self, writer: &mut (impl AsyncWrite + Unpin)) -> std::io::Result<()> {
        match &self.sender {
            Some(ref sender) => {
                writer.write_all(b":").await?;
                writer.write_all(sender.as_slice()).await?;
                writer.write_all(b" ").await?;
            }
            None => {}
        }
        self.body.write_async(writer).await?;
        writer.write_all(b"\n").await?;
        Ok(())
    }
}

pub fn server_message(input: &[u8]) -> IResult<&[u8], ServerMessage> {
    let (input, command) = server_message_body(input)?;
    let (input, _) = tag(b"\n")(input)?;

    let message = ServerMessage {
        tags: vec![],
        sender: None,
        body: command,
    };
    Ok((input, message))
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum ServerMessageBody {
    Notice {
        first_target: ByteVec,
        rest_targets: Vec<ByteVec>,
        text: ByteVec,
    },
    Ping {
        token: ByteVec,
    },
    Pong {
        from: ByteVec,
        token: ByteVec,
    },
    PrivateMessage {
        target: Recipient,
        body: ByteVec,
    },
    Join(Chan),
    Part(Chan),
    N001Welcome {
        client: ByteVec,
        text: ByteVec,
    },
    N002YourHost {
        client: ByteVec,
        text: ByteVec,
    },
    N003Created {
        client: ByteVec,
        text: ByteVec,
    },
    N004MyInfo {
        client: ByteVec,
        hostname: ByteVec,
        softname: ByteVec,
        // TODO user modes, channel modes, channel modes with a parameter
    },
    N005ISupport {
        client: ByteVec,
        params: ByteVec, // TODO make this a datatype
    },
    /// Reply to a client's [Mode](crate::protos::irc::client::ClientMessage::Mode) request.
    N221UserModeIs {
        client: ByteVec,
        modes: ByteVec,
    },
    /// Final reply to a client's [Who](crate::protos::irc::client::ClientMessage::Who) request.
    N315EndOfWho {
        client: ByteVec,
        mask: Recipient,
        /// Usually `b"End of WHO list"`
        msg: ByteVec,
    },
    N332Topic {
        client: ByteVec,
        chat: Chan,
        topic: ByteVec,
    },
    /// A reply to a client's [Who](crate::protos::irc::client::ClientMessage::Who) request.
    N352WhoReply {
        client: ByteVec,
        // chan = *
        username: ByteVec,
        /// User's hostname
        host: ByteVec,
        /// Hostname of the server the user is connected to
        server: ByteVec,
        nickname: ByteVec,
        /// Flags
        flags: AwayStatus,
        hops: u8,
        realname: ByteVec,
    },
    N353NamesReply {
        client: ByteVec,
        chan: Chan,
        members: ByteVec, // TODO make this a non-empty list with prefixes
    },
    N366NamesReplyEnd {
        client: ByteVec,
        chan: Chan,
    },
}

impl ServerMessageBody {
    pub async fn write_async(&self, writer: &mut (impl AsyncWrite + Unpin)) -> std::io::Result<()> {
        match self {
            ServerMessageBody::Notice {
                first_target,
                rest_targets,
                text,
            } => {
                writer.write_all(b"NOTICE ").await?;
                writer.write_all(&first_target).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&text).await?;
            }
            ServerMessageBody::Ping { token } => {
                writer.write_all(b"PING ").await?;
                writer.write_all(&token).await?;
            }
            ServerMessageBody::Pong { from, token } => {
                writer.write_all(b"PONG ").await?;
                writer.write_all(&from).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&token).await?;
            }
            ServerMessageBody::PrivateMessage { target, body } => {
                writer.write_all(b"PRIVMSG ").await?;
                target.write_async(writer).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&body).await?;
            }
            ServerMessageBody::Join(chan) => {
                writer.write_all(b"JOIN ").await?;
                chan.write_async(writer).await?;
            }
            ServerMessageBody::Part(chan) => {
                writer.write_all(b"PART ").await?;
                chan.write_async(writer).await?;
            }
            ServerMessageBody::N001Welcome { client, text } => {
                writer.write_all(b"001 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" :").await?;
                writer.write_all(text).await?;
            }
            ServerMessageBody::N002YourHost { client, text } => {
                writer.write_all(b"002 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" :").await?;
                writer.write_all(text).await?;
            }
            ServerMessageBody::N003Created { client, text } => {
                writer.write_all(b"003 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" :").await?;
                writer.write_all(text).await?;
            }
            ServerMessageBody::N004MyInfo {
                client,
                hostname,
                softname,
            } => {
                writer.write_all(b"004 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&hostname).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&softname).await?;
                writer
                    .write_all(b" r CFILPQbcefgijklmnopqrstvz")
                    .await?;
                // TODO remove hardcoded modes
            }
            ServerMessageBody::N005ISupport { client, params } => {
                writer.write_all(b"005 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&params).await?;
                writer.write_all(b" :are supported by this server").await?;
            }
            ServerMessageBody::N221UserModeIs { client, modes } => {
                writer.write_all(b"221 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&modes).await?;
            },
            ServerMessageBody::N315EndOfWho { client, mask, msg } => {
                writer.write_all(b"315 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                mask.write_async(writer).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&msg).await?;
            }
            ServerMessageBody::N332Topic {
                client,
                chat,
                topic,
            } => {
                writer.write_all(b"332 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                chat.write_async(writer).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&topic).await?;
            }
            ServerMessageBody::N352WhoReply {
                client,
                username,
                host,
                server,
                flags,
                nickname,
                hops,
                realname,
            } => {
                writer.write_all(b"352 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" * ").await?;
                writer.write_all(&username).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&host).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&server).await?;
                writer.write_all(b" ").await?;
                match flags {
                    AwayStatus::Here => writer.write_all(b"H").await?,
                    AwayStatus::Gone => writer.write_all(b"G").await?,
                }
                writer.write_all(b" ").await?;
                writer.write_all(&nickname).await?;
                writer.write_all(b" :").await?;
                writer.write_all(hops.to_string().as_bytes()).await?;
                writer.write_all(b" ").await?;
                writer.write_all(&realname).await?;
            }
            ServerMessageBody::N353NamesReply {
                client,
                chan,
                members,
            } => {
                writer.write_all(b"353 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" = ").await?;
                chan.write_async(writer).await?;
                writer.write_all(b" :").await?;
                writer.write_all(&members).await?;
            }
            ServerMessageBody::N366NamesReplyEnd { client, chan } => {
                writer.write_all(b"366 ").await?;
                writer.write_all(&client).await?;
                writer.write_all(b" ").await?;
                chan.write_async(writer).await?;
                writer.write_all(b" :End of /NAMES list").await?;
            }
        }
        Ok(())
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum AwayStatus {
    Here,
    Gone,
}

fn server_message_body(input: &[u8]) -> IResult<&[u8], ServerMessageBody> {
    alt((
        server_message_body_notice,
        server_message_body_ping,
        server_message_body_pong,
    ))(input)
}

fn server_message_body_notice(input: &[u8]) -> IResult<&[u8], ServerMessageBody> {
    let (input, _) = tag("NOTICE ")(input)?;
    let (input, first_target) = receiver(input)?;
    let (input, _) = tag(" :")(input)?;
    let (input, text) = token(input)?;

    let first_target = first_target.to_owned();
    let text = text.to_owned();
    Ok((
        input,
        ServerMessageBody::Notice {
            first_target,
            rest_targets: vec![],
            text,
        },
    ))
}

fn server_message_body_ping(input: &[u8]) -> IResult<&[u8], ServerMessageBody> {
    let (input, _) = tag("PING ")(input)?;
    let (input, token) = token(input)?;

    Ok((
        input,
        ServerMessageBody::Ping {
            token: token.to_owned(),
        },
    ))
}

fn server_message_body_pong(input: &[u8]) -> IResult<&[u8], ServerMessageBody> {
    let (input, _) = tag("PONG ")(input)?;
    let (input, from) = receiver(input)?;
    let (input, _) = tag(" :")(input)?;
    let (input, token) = token(input)?;

    Ok((
        input,
        ServerMessageBody::Pong {
            from: from.to_owned(),
            token: token.to_owned(),
        },
    ))
}

#[cfg(test)]
mod test {
    use assert_matches::*;

    use super::*;
    use crate::util::testkit::*;

    #[test]
    fn test_server_message_notice() {
        let input = b"NOTICE * :*** Looking up your hostname...\n";
        let expected = ServerMessage {
            tags: vec![],
            sender: None,
            body: ServerMessageBody::Notice {
                first_target: b"*".to_vec(),
                rest_targets: vec![],
                text: b"*** Looking up your hostname...".to_vec(),
            },
        };

        let result = server_message(input);
        assert_matches!(result, Ok((_, result)) => assert_eq!(expected, result));

        let mut bytes = vec![];
        sync_future(expected.write_async(&mut bytes))
            .unwrap()
            .unwrap();
        assert_eq!(bytes, input);
    }

    #[test]
    fn test_server_message_pong() {
        let input = b"PONG server.example :LAG004911\n";
        let expected = ServerMessage {
            tags: vec![],
            sender: None,
            body: ServerMessageBody::Pong {
                from: b"server.example".to_vec(),
                token: b"LAG004911".to_vec(),
            },
        };

        let result = server_message(input);
        assert_matches!(result, Ok((_, result)) => assert_eq!(expected, result));

        let mut bytes = vec![];
        sync_future(expected.write_async(&mut bytes))
            .unwrap()
            .unwrap();
        assert_eq!(bytes, input);
    }
}