vtcode-mcp 0.179.6

/// RMCP transport layer wrappers for VT Code
///
/// This module provides wrappers around rmcp's transport types to integrate
/// with VT Code's configuration and error handling.
use anyhow::{Context, Result};
use rmcp::transport::StreamableHttpClientTransport;
use rmcp::transport::TokioChildProcess;
use rmcp_reqwest::header::HeaderMap;
use std::ffi::OsString;
use std::path::PathBuf;
use tokio::process::Command;

use vtcode_config::mcp::McpStdioServerConfig;

/// Type alias for HTTP transport
pub type HttpTransport = StreamableHttpClientTransport<rmcp_reqwest::Client>;

/// Create a stdio-based transport from configuration
///
/// # Arguments
/// * `stdio_config` - Stdio server configuration with command and args
/// * `env` - Environment variables to pass to the process
///
/// # Returns
/// A TokioChildProcess transport ready to use with RMCP client
pub fn create_stdio_transport(
    stdio_config: &McpStdioServerConfig,
    env: &hashbrown::HashMap<OsString, OsString>,
) -> Result<TokioChildProcess> {
    let mut cmd = Command::new(&stdio_config.command);

    // Add arguments
    let _command = cmd.args(&stdio_config.args);

    // Set working directory if specified
    if let Some(working_dir) = &stdio_config.working_directory {
        let _command = cmd.current_dir(working_dir);
    }

    // Match `create_stdio_transport_with_stderr`: the child receives the
    // caller-resolved environment only, never vtcode's full process environment.
    let _command = cmd.env_clear();

    // Configure environment variables
    for (key, value) in env {
        let _command = cmd.env(key, value);
    }

    // Create the child process transport
    TokioChildProcess::new(cmd).context("Failed to create child process for MCP server")
}

/// Create a stdio transport from individual parameters (Phase 2 integration)
///
/// This is a convenience wrapper for use within RmcpClient where transport
/// parameters come from different configuration sources.
///
/// # Arguments
/// * `program` - Path to the executable
/// * `args` - Command arguments
/// * `working_dir` - Working directory (optional)
/// * `env` - Environment variables to pass
///
/// # Returns
/// A tuple of (TokioChildProcess transport, stderr reader)
/// The stderr reader can be passed to async logging tasks
pub fn create_stdio_transport_with_stderr(
    program: &OsString,
    args: &[OsString],
    working_dir: Option<&PathBuf>,
    env: &hashbrown::HashMap<OsString, OsString>,
) -> Result<(TokioChildProcess, Option<tokio::process::ChildStderr>)> {
    let mut cmd = Command::new(program);

    let _command = cmd
        .kill_on_drop(true)
        .stdin(std::process::Stdio::piped())
        .stdout(std::process::Stdio::piped())
        .stderr(std::process::Stdio::piped())
        .env_clear();

    // Add all environment variables
    for (key, value) in env {
        let _command = cmd.env(key, value);
    }

    // Set working directory if provided
    if let Some(dir) = working_dir {
        let _command = cmd.current_dir(dir);
    }

    // Add command arguments
    let _command = cmd.args(args);

    // Create transport with stderr capture for logging
    let builder = TokioChildProcess::builder(cmd);
    builder
        .stderr(std::process::Stdio::piped())
        .spawn()
        .context("Failed to create stdio transport with stderr capture")
}

/// Create an HTTP-based transport from endpoint URL (Phase 3.2)
///
/// # Arguments
/// * `endpoint` - HTTP endpoint URL (e.g., `https://api.example.com/mcp`)
/// * `bearer_token` - Optional bearer token for authentication
/// * `headers` - Custom HTTP headers to include in requests
///
/// # Returns
/// A StreamableHttpClientTransport ready to use with RMCP client
///
/// # Note
/// This is a convenience wrapper for HTTP transport creation. The actual
/// transport construction delegates to rmcp's StreamableHttpClientTransport
/// following the pattern used in RmcpClient::new_streamable_http_client().
///
/// # Example
/// ```ignore
/// let transport = create_http_transport(
///     "https://api.example.com/mcp",
///     Some("auth_token"),
///     &HeaderMap::new()
/// )?;
/// ```
pub fn create_http_transport(
    _endpoint: &str,
    _bearer_token: Option<&str>,
    _headers: &HeaderMap,
) -> Result<HttpTransport> {
    // Phase 3.2: HTTP transport wrapper
    // NOTE: Full implementation requires direct use of rmcp APIs
    // See RmcpClient::new_streamable_http_client() for reference implementation
    // This function provides the interface; actual HTTP transport is created via:
    // StreamableHttpClientTransport::with_client(http_client, config)

    anyhow::bail!(
        "HTTP transport creation requires rmcp's StreamableHttpClientTransport. \
         Use RmcpClient::new_streamable_http_client() for full implementation."
    )
}

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

    #[test]
    fn test_transport_creation() {
        // Test transport creation with configuration
        // Detailed tests in integration tests
    }

    /// MCP stdio children must receive the caller-resolved environment only. Before
    /// this was pinned, this transport inherited vtcode's whole process environment
    /// while its `_with_stderr` sibling already cleared it.
    #[tokio::test]
    async fn stdio_transport_child_receives_only_the_resolved_environment() {
        let dir = tempfile::tempdir().unwrap();
        let dump = dir.path().join("child-env.txt");
        let process_has_home = std::env::var_os("HOME").is_some();

        let config = McpStdioServerConfig {
            command: "/bin/sh".to_string(),
            args: vec!["-c".to_string(), "env > \"$MCP_DUMP\"".to_string()],
            working_directory: None,
        };
        let mut env = hashbrown::HashMap::new();
        drop(env.insert(
            OsString::from("PATH"),
            std::env::var_os("PATH").unwrap_or_else(|| OsString::from("/usr/bin:/bin")),
        ));
        drop(env.insert(OsString::from("MCP_MARKER"), OsString::from("marker-value")));
        drop(env.insert(OsString::from("MCP_DUMP"), dump.as_os_str().to_os_string()));
        // HOME is present in this process but deliberately absent from the map, so
        // inheritance stays observable in the dump below.
        assert!(!env.contains_key(&OsString::from("HOME")));

        let _transport = create_stdio_transport(&config, &env).unwrap();
        let contents = child_env_dump(&dump).await;

        assert!(contents.contains("MCP_MARKER=marker-value"), "resolved map not applied: {contents}");
        assert!(contents.lines().any(|line| line.starts_with("PATH=")), "resolved PATH not applied: {contents}");
        if process_has_home {
            assert!(
                !contents.lines().any(|line| line.starts_with("HOME=")),
                "MCP stdio child inherited the process environment: {contents}"
            );
        }
    }

    /// Wait (bounded) for the spawned child to flush its environment dump.
    async fn child_env_dump(path: &std::path::Path) -> String {
        for _ in 0..100 {
            if let Ok(contents) = tokio::fs::read_to_string(path).await {
                return contents;
            }
            tokio::time::sleep(std::time::Duration::from_millis(50)).await;
        }
        panic!("MCP stdio child never wrote {}", path.display());
    }
}