use axum::{
    extract::State,
    response::sse::{Event, KeepAlive, Sse},
    http::StatusCode,
};
use futures::stream::{self, Stream};
use log::{debug, info};
use std::convert::Infallible;
use std::time::Duration;

use crate::modes::server::common::AppState;
use crate::modes::server::mcp::KeepMcpServer;

#[utoipa::path(
    get,
    path = "/mcp/sse",
    operation_id = "mcp_sse",
    summary = "MCP SSE endpoint",
    description = "Server-Sent Events for Model Context Protocol. Enables AI tools to interact with Keep's storage and retrieval functions.",
    responses(
        (status = 200, description = "SSE stream established"),
        (status = 401, description = "Unauthorized"),
        (status = 500, description = "Internal server error")
    ),
    security(
        ("bearerAuth" = [])
    ),
    tag = "mcp"
)]
pub async fn handle_mcp_sse(
    State(state): State<AppState>,
) -> Result<Sse<impl Stream<Item = Result<Event, Infallible>>>, StatusCode> {
    debug!("MCP: Starting SSE endpoint");
    
    let _mcp_server = KeepMcpServer::new(state);
    
    // Create a simple message channel for SSE communication
    let (tx, rx) = tokio::sync::mpsc::unbounded_channel::<String>();
    
    // Send initial connection message
    let _ = tx.send("data: {\"type\":\"connection\",\"status\":\"connected\"}\n\n".to_string());
    
    // For now, create a simple stream that sends periodic keep-alive messages
    // In a full implementation, this would integrate with the rmcp transport layer
    let stream = stream::unfold((rx, tx), |(mut rx, tx)| async move {
        tokio::select! {
            msg = rx.recv() => {
                match msg {
                    Some(data) => {
                        let event = Event::default().data(data);
                        Some((Ok(event), (rx, tx)))
                    }
                    None => None,
                }
            }
            _ = tokio::time::sleep(Duration::from_secs(30)) => {
                let event = Event::default()
                    .event("keep-alive")
                    .data("ping");
                Some((Ok(event), (rx, tx)))
            }
        }
    });
    
    info!("MCP: SSE endpoint established");
    
    Ok(Sse::new(stream).keep_alive(
        KeepAlive::new()
            .interval(Duration::from_secs(30))
            .text("keep-alive"),
    ))
}