//! Sbot type and associated methods.
use std::fmt::Debug;
use async_std::net::TcpStream;
use async_std::stream::{Stream, StreamExt};
use async_stream::stream;

use kuska_handshake::async_std::BoxStream;
use kuska_sodiumoxide::crypto::{auth, sign::ed25519};
use kuska_ssb::{
    api::{
        dto::{CreateHistoryStreamIn},
        ApiCaller,
    },
    discovery, keystore,
    keystore::OwnedIdentity,
    rpc::{RpcReader, RpcWriter, RecvMsg},
};

use crate::error::GolgiError;
use crate::messages::{SsbMessageKVT, SsbMessageContent, SsbMessageValue, SsbMessageContentType};
use crate::utils;

// re-export types from kuska
pub use kuska_ssb::api::dto::content::SubsetQuery;
use kuska_ssb::rpc::RequestNo;

pub struct SbotConnection {
    client: ApiCaller<TcpStream>,
    rpc_reader: RpcReader<TcpStream>,
}

/// The Scuttlebutt identity, keys and configuration parameters for connecting to a local sbot
/// instance, as well as handles for calling RPC methods and receiving responses.
pub struct Sbot {
    id: String,
    public_key: ed25519::PublicKey,
    private_key: ed25519::SecretKey,
    address: String,
    // aka caps key (scuttleverse identifier)
    network_id: auth::Key,
    client: ApiCaller<TcpStream>,
    rpc_reader: RpcReader<TcpStream>,
    sbot_connections: Vec<SbotConnection>,
}

impl Sbot {
    /// Initiate a connection with an sbot instance. Define the IP address, port and network key
    /// for the sbot, then retrieve the public key, private key (secret) and identity from the
    /// `.ssb-go/secret` file. Open a TCP stream to the sbot and perform the secret handshake. If successful, create a box stream and split it into a writer and reader. Return RPC handles to the sbot as part of the `struct` output.
    pub async fn init(ip_port: Option<String>, net_id: Option<String>) -> Result<Sbot, GolgiError> {
        let address = if ip_port.is_none() {
            "127.0.0.1:8008".to_string()
        } else {
            ip_port.unwrap()
        };

        let network_id = if net_id.is_none() {
            discovery::ssb_net_id()
        } else {
            auth::Key::from_slice(&hex::decode(net_id.unwrap()).unwrap()).unwrap()
        };

        let OwnedIdentity { pk, sk, id } = keystore::from_gosbot_local()
            .await
            .expect("couldn't read local secret");

        let socket = TcpStream::connect(&address)
            .await
            .map_err(|source| GolgiError::Io {
                source,
                context: "socket error; failed to initiate tcp stream connection".to_string(),
            })?;

        let handshake = kuska_handshake::async_std::handshake_client(
            &mut &socket,
            network_id.clone(),
            pk,
            sk.clone(),
            pk,
        )
        .await
        .map_err(GolgiError::Handshake)?;

        let (box_stream_read, box_stream_write) =
            BoxStream::from_handshake(socket.clone(), socket, handshake, 0x8000).split_read_write();

        let rpc_reader = RpcReader::new(box_stream_read);
        let client = ApiCaller::new(RpcWriter::new(box_stream_write));
        let mut sbot_connections = Vec::new();

        Ok(Self {
            id,
            public_key: pk,
            private_key: sk,
            address,
            network_id,
            client,
            rpc_reader,
            sbot_connections
        })
    }

    pub async fn get_sbot_connection(&self, ip_port: Option<String>, net_id: Option<String>) -> Result<SbotConnection, GolgiError> {
        let address = if ip_port.is_none() {
            "127.0.0.1:8008".to_string()
        } else {
            ip_port.unwrap()
        };

        let network_id = if net_id.is_none() {
            discovery::ssb_net_id()
        } else {
            auth::Key::from_slice(&hex::decode(net_id.unwrap()).unwrap()).unwrap()
        };

        let socket = TcpStream::connect(&address)
            .await
            .map_err(|source| GolgiError::Io {
                source,
                context: "socket error; failed to initiate tcp stream connection".to_string(),
            })?;

        let handshake = kuska_handshake::async_std::handshake_client(
            &mut &socket,
            network_id.clone(),
            self.public_key,
            self.private_key.clone(),
            self.public_key,
        )
            .await
            .map_err(GolgiError::Handshake)?;

        let (box_stream_read, box_stream_write) =
            BoxStream::from_handshake(socket.clone(), socket, handshake, 0x8000).split_read_write();

        let rpc_reader = RpcReader::new(box_stream_read);
        let client = ApiCaller::new(RpcWriter::new(box_stream_write));
        let sbot_connection = SbotConnection {
            rpc_reader,
            client,
        };
        Ok(sbot_connection)
    }

    /// Call the `partialReplication getSubset` RPC method and return a vector
    /// of messages as KVTs (key, value, timestamp).
    // TODO: add args for `descending` and `page` (max number of msgs in response)
    pub async fn get_subset(&mut self, query: SubsetQuery) -> Result<Vec<SsbMessageKVT>, GolgiError> {
        let req_id = self.client.getsubset_req_send(query).await?;

        utils::get_source_until_eof(&mut self.rpc_reader, req_id, utils::kvt_res_parse).await
    }

    /// Call the `whoami` RPC method and return an `id`.
    pub async fn whoami(&mut self) -> Result<String, GolgiError> {
        let req_id = self.client.whoami_req_send().await?;

        utils::get_async(&mut self.rpc_reader, req_id, utils::string_res_parse).await
    }

    /// Call the `publish` RPC method and return a message reference.
    ///
    /// # Arguments
    ///
    /// * `msg` - A `SsbMessageContent` `enum` whose variants include `Pub`, `Post`, `Contact`, `About`,
    /// `Channel` and `Vote`. See the `kuska_ssb` documentation for further details such as field
    /// names and accepted values for each variant.
    pub async fn publish(&mut self, msg: SsbMessageContent) -> Result<String, GolgiError> {
        let req_id = self.client.publish_req_send(msg).await?;

        utils::get_async(&mut self.rpc_reader, req_id, utils::string_res_parse).await
    }

    /// Wrapper for publish which constructs and publishes a post message appropriately from a string.
    ///
    /// # Arguments
    ///
    /// * `text` - A reference to a string slice which represents the text to be published in the post
    pub async fn publish_post(&mut self, text: &str) -> Result<String, GolgiError> {
        let msg = SsbMessageContent::Post {
            text: text.to_string(),
            mentions: None,
        };
        self.publish(msg).await
    }

    /// Wrapper for publish which constructs and publishes an about description message appropriately from a string.
    ///
    /// # Arguments
    ///
    /// * `description` - A reference to a string slice which represents the text to be published as an about description.
    pub async fn publish_description(&mut self, description: &str) -> Result<String, GolgiError> {
        let msg = SsbMessageContent::About {
            about: self.id.to_string(),
            name: None,
            title: None,
            branch: None,
            image: None,
            description: Some(description.to_string()),
            location: None,
            start_datetime: None,
        };
        self.publish(msg).await
    }

    /// Wrapper for publish which constructs and publishes an about name message appropriately from a string.
    ///
    /// # Arguments
    ///
    /// * `name` - A reference to a string slice which represents the text to be published as an about name.
    pub async fn publish_name(&mut self, name: &str) -> Result<String, GolgiError> {
        let msg = SsbMessageContent::About {
            about: self.id.to_string(),
            name: Some(name.to_string()),
            title: None,
            branch: None,
            image: None,
            description: None,
            location: None,
            start_datetime: None,
        };
        self.publish(msg).await
    }

    /// Get the about messages for a particular user in order of recency.
    pub async fn get_about_messages(&mut self, ssb_id: &str) -> Result<Vec<SsbMessageValue>, GolgiError> {
        let query = SubsetQuery::Author{
            op: "author".to_string(),
            feed: ssb_id.to_string(),
        };
        let kvts: Vec<SsbMessageKVT> = self.get_subset(query).await?;
        let messages: Vec<SsbMessageValue> = kvts.into_iter().map(|kvt| kvt.value).collect();
        // TODO: after fixing sbot regression,
        // change this subset query to filter by type about in addition to author
        // and remove this filter section
        // filter down to about  messages
        let mut about_messages: Vec<SsbMessageValue> = messages.into_iter().filter(|msg| {
            msg.is_message_type(SsbMessageContentType::About)
        }).collect();
        // TODO: use subset query to order messages instead of doing it this way
        about_messages.sort_by(|a, b| {
            b.timestamp.partial_cmp(&a.timestamp).unwrap()
        });
        // return about messages
        Ok(about_messages)
    }

    /// Get value of latest about message with given key from given user
    pub async fn get_latest_about_message(&mut self, ssb_id: &str, key: &str) -> Result<Option<String>, GolgiError> {
        // vector of about messages with most recent at the front of the vector
        let about_messages = self.get_about_messages(ssb_id).await?;
        // iterate through the vector looking for most recent about message with the given key
        let latest_about = about_messages
            .iter()
            // find the first msg that contains the field `key`
            .find(|msg| msg.content.get(key).is_some())
            // map the found msg (`Some(SsbMessageValue)`) to a `Some(Some(&Value))`
            .map(|msg| msg.content.get(key))
            // flatten `Some(Some(&Value))` into `Some(&Value)`
            .flatten()
            // map `Some(&Value)` to `Some(Some(&str))`
            .map(|msg_val| msg_val.as_str())
            // flatten `Some(Some(&str))` to `Some(&str)`
            .flatten()
            // map `Some(&str))` to `Some(String)`
            .map(|msg_str| msg_str.to_string());

        // return value is either `Ok(Some(String))` or `Ok(None)`
        Ok(latest_about)
    }

    pub async fn get_name(&mut self, ssb_id: &str) -> Result<Option<String>, GolgiError> {
        self.get_latest_about_message(ssb_id, "name").await
    }

    pub async fn get_description(&mut self, ssb_id: &str) -> Result<Option<String>, GolgiError> {
        self.get_latest_about_message(ssb_id, "description").await
    }

    /// Call the `createHistoryStream` RPC method
    /// and return a Stream of Result<SsbMessageValue, GolgiError>
    pub async fn create_history_stream(
        &mut self,
        id: String,
    ) -> Result<impl Stream<Item = Result<SsbMessageValue, GolgiError>>, GolgiError> {
        let mut sbot_connection = self.get_sbot_connection(None, None).await.unwrap();
        let args = CreateHistoryStreamIn::new(id);
        let req_id = sbot_connection.client.create_history_stream_req_send(&args).await?;
        let history_stream = Sbot::get_source_stream(sbot_connection.rpc_reader, req_id, utils::ssb_message_res_parse).await;
        Ok(history_stream)
    }

    /// Takes in an rpc request number, and a handling function (parsing results of type T),
    /// and produces an async_std::stream::Stream
    /// of results of type T where the handling functions is called
    /// on all rpc_reader responses which match the request number
    ///
    /// # Arguments
    ///
    /// * `req_no` - A `RequestNo` of the response to listen for
    /// * `f` - A function which takes in an array of u8 and returns a Result<T, GolgiError>.
    /// This is a function which parses the response from the RpcReader. T is a generic type,
    /// so this parse function can return multiple possible types (String, json, custom struct etc.)
    pub async fn get_source_stream<'a, F, T>(mut rpc_reader: RpcReader<TcpStream>, req_no: RequestNo, f: F) -> impl Stream<Item = Result<T, GolgiError>>
    where
        F: Fn(&[u8]) -> Result<T, GolgiError>,
        T: Debug + serde::Deserialize<'a>,
    {
        // we use the async_stream::stream macro to allow for creating a stream which calls async functions
        // see https://users.rust-lang.org/t/how-to-create-async-std-stream-which-calls-async-function-in-poll-next/69760

        let source_stream = stream! {
        loop {
            // get the next message from the rpc_reader
            let (id, msg) = rpc_reader.recv().await?;
            let x : i32 = id.clone();
            // check if the next message from rpc_reader matches the req_no we are looking for
            // if it matches, then this rpc response is for the given request
            // and if it doesn't match, then we ignore it
            if x == req_no {
                match msg {
                    RecvMsg::RpcResponse(_type, body) => {
                        // parse an item of type T from the message body using the provided
                        // function for parsing
                        let item = f(&body)?;
                        // return Ok(item) as the next value in the stream
                        yield Ok(item)
                    }
                    RecvMsg::ErrorResponse(message) => {
                        // if an error is received
                        // return an Err(err) as the next value in the stream
                        yield Err(GolgiError::Sbot(message.to_string()));
                    }
                    // if we find a CancelStreamResponse
                    // this is the end of the stream
                    RecvMsg::CancelStreamRespose() => break,
                    // if we find an unknown response, we just continue the loop
                    _ => {}
                }
            }
        }
    };
    // finally return the stream object
    source_stream
    }
}