//! IPC stuff for starting to split things into a client and server model.
use crate::{
    cli::CliArgs,
    data::{ClientId, InputMode, Style},
    errors::{get_current_ctx, prelude::*, ErrorContext},
    input::keybinds::Keybinds,
    input::{actions::Action, layout::Layout, options::Options, plugins::PluginsConfig},
    pane_size::{Size, SizeInPixels},
};
use interprocess::local_socket::LocalSocketStream;
use log::warn;
use nix::unistd::dup;
use serde::{Deserialize, Serialize};
use std::{
    fmt::{Display, Error, Formatter},
    io::{self, Write},
    marker::PhantomData,
    os::unix::io::{AsRawFd, FromRawFd},
};

type SessionId = u64;

#[derive(PartialEq, Eq, Serialize, Deserialize, Hash)]
pub struct Session {
    // Unique ID for this session
    id: SessionId,
    // Identifier for the underlying IPC primitive (socket, pipe)
    conn_name: String,
    // User configured alias for the session
    alias: String,
}

// How do we want to connect to a session?
#[derive(Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ClientType {
    Reader,
    Writer,
}

#[derive(Default, Serialize, Deserialize, Debug, Clone)]
pub struct ClientAttributes {
    pub size: Size,
    pub style: Style,
    pub keybinds: Keybinds,
}

#[derive(Default, Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
pub struct PixelDimensions {
    pub text_area_size: Option<SizeInPixels>,
    pub character_cell_size: Option<SizeInPixels>,
}

impl PixelDimensions {
    pub fn merge(&mut self, other: PixelDimensions) {
        if let Some(text_area_size) = other.text_area_size {
            self.text_area_size = Some(text_area_size);
        }
        if let Some(character_cell_size) = other.character_cell_size {
            self.character_cell_size = Some(character_cell_size);
        }
    }
}

// Types of messages sent from the client to the server
#[allow(clippy::large_enum_variant)]
#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum ClientToServerMsg {
    /*// List which sessions are available
    ListSessions,
    // Create a new session
    CreateSession,
    // Attach to a running session
    AttachToSession(SessionId, ClientType),
    // Force detach
    DetachSession(SessionId),
    // Disconnect from the session we're connected to
    DisconnectFromSession,*/
    DetachSession(Vec<ClientId>),
    TerminalPixelDimensions(PixelDimensions),
    BackgroundColor(String),
    ForegroundColor(String),
    ColorRegisters(Vec<(usize, String)>),
    TerminalResize(Size),
    NewClient(
        ClientAttributes,
        Box<CliArgs>,
        Box<Options>,
        Box<Layout>,
        Option<PluginsConfig>,
    ),
    AttachClient(ClientAttributes, Options),
    Action(Action, Option<ClientId>),
    ClientExited,
    KillSession,
    ConnStatus,
    ListClients,
}

// Types of messages sent from the server to the client
#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum ServerToClientMsg {
    /*// Info about a particular session
    SessionInfo(Session),
    // A list of sessions
    SessionList(HashSet<Session>),*/
    Render(String),
    UnblockInputThread,
    Exit(ExitReason),
    SwitchToMode(InputMode),
    Connected,
    ActiveClients(Vec<ClientId>),
}

#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum ExitReason {
    Normal,
    NormalDetached,
    ForceDetached,
    CannotAttach,
    Error(String),
}

impl Display for ExitReason {
    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
        match self {
            Self::Normal => write!(f, "Bye from Zellij!"),
            Self::NormalDetached => write!(f, "Session detached"),
            Self::ForceDetached => write!(
                f,
                "Session was detached from this client (possibly because another client connected)"
            ),
            Self::CannotAttach => write!(
                f,
                "Session attached to another client. Use --force flag to force connect."
            ),
            Self::Error(e) => write!(f, "Error occurred in server:\n{}", e),
        }
    }
}

/// Sends messages on a stream socket, along with an [`ErrorContext`].
pub struct IpcSenderWithContext<T: Serialize> {
    sender: io::BufWriter<LocalSocketStream>,
    _phantom: PhantomData<T>,
}

impl<T: Serialize> IpcSenderWithContext<T> {
    /// Returns a sender to the given [LocalSocketStream](interprocess::local_socket::LocalSocketStream).
    pub fn new(sender: LocalSocketStream) -> Self {
        Self {
            sender: io::BufWriter::new(sender),
            _phantom: PhantomData,
        }
    }

    /// Sends an event, along with the current [`ErrorContext`], on this [`IpcSenderWithContext`]'s socket.
    pub fn send(&mut self, msg: T) -> Result<()> {
        let err_ctx = get_current_ctx();
        if rmp_serde::encode::write(&mut self.sender, &(msg, err_ctx)).is_err() {
            Err(anyhow!("failed to send message to client"))
        } else {
            // TODO: unwrapping here can cause issues when the server disconnects which we don't mind
            // do we need to handle errors here in other cases?
            let _ = self.sender.flush();
            Ok(())
        }
    }

    /// Returns an [`IpcReceiverWithContext`] with the same socket as this sender.
    pub fn get_receiver<F>(&self) -> IpcReceiverWithContext<F>
    where
        F: for<'de> Deserialize<'de> + Serialize,
    {
        let sock_fd = self.sender.get_ref().as_raw_fd();
        let dup_sock = dup(sock_fd).unwrap();
        let socket = unsafe { LocalSocketStream::from_raw_fd(dup_sock) };
        IpcReceiverWithContext::new(socket)
    }
}

/// Receives messages on a stream socket, along with an [`ErrorContext`].
pub struct IpcReceiverWithContext<T> {
    receiver: io::BufReader<LocalSocketStream>,
    _phantom: PhantomData<T>,
}

impl<T> IpcReceiverWithContext<T>
where
    T: for<'de> Deserialize<'de> + Serialize,
{
    /// Returns a receiver to the given [LocalSocketStream](interprocess::local_socket::LocalSocketStream).
    pub fn new(receiver: LocalSocketStream) -> Self {
        Self {
            receiver: io::BufReader::new(receiver),
            _phantom: PhantomData,
        }
    }

    /// Receives an event, along with the current [`ErrorContext`], on this [`IpcReceiverWithContext`]'s socket.
    pub fn recv(&mut self) -> Option<(T, ErrorContext)> {
        match rmp_serde::decode::from_read(&mut self.receiver) {
            Ok(msg) => Some(msg),
            Err(e) => {
                warn!("Error in IpcReceiver.recv(): {:?}", e);
                None
            },
        }
    }

    /// Returns an [`IpcSenderWithContext`] with the same socket as this receiver.
    pub fn get_sender<F: Serialize>(&self) -> IpcSenderWithContext<F> {
        let sock_fd = self.receiver.get_ref().as_raw_fd();
        let dup_sock = dup(sock_fd).unwrap();
        let socket = unsafe { LocalSocketStream::from_raw_fd(dup_sock) };
        IpcSenderWithContext::new(socket)
    }
}