ferrule-sql 0.1.0-alpha

#![allow(unused_imports, unused_variables)]

use crate::backends;
use crate::connection::{AsyncConnection, ConnectOptions, Connection};
use crate::error::SqlError;
use crate::sync::SyncConnection;
use crate::url::DatabaseUrl;

/// Supported database backends.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Backend {
    #[cfg(feature = "postgres")]
    Postgres,
    #[cfg(feature = "mysql")]
    MySql,
    #[cfg(feature = "mssql")]
    MsSql,
    #[cfg(feature = "sqlite")]
    Sqlite,
    #[cfg(feature = "oracle")]
    Oracle,
}

impl Backend {
    /// Resolve a backend from a URL scheme.
    pub fn from_scheme(scheme: &str) -> Option<Self> {
        match scheme {
            #[cfg(feature = "postgres")]
            "postgres" | "postgresql" => Some(Self::Postgres),
            #[cfg(feature = "mysql")]
            "mysql" | "mariadb" => Some(Self::MySql),
            #[cfg(feature = "mssql")]
            "mssql" | "sqlserver" | "tds" => Some(Self::MsSql),
            #[cfg(feature = "sqlite")]
            "sqlite" => Some(Self::Sqlite),
            #[cfg(feature = "oracle")]
            "oracle" => Some(Self::Oracle),
            _ => None,
        }
    }

    /// Human-readable name.
    pub fn name(&self) -> &'static str {
        match *self {
            #[cfg(feature = "postgres")]
            Self::Postgres => "PostgreSQL",
            #[cfg(feature = "mysql")]
            Self::MySql => "MySQL",
            #[cfg(feature = "mssql")]
            Self::MsSql => "Microsoft SQL Server",
            #[cfg(feature = "sqlite")]
            Self::Sqlite => "SQLite",
            #[cfg(feature = "oracle")]
            Self::Oracle => "Oracle",
        }
    }
}

/// Establish a direct (non-proxied) connection to the given URL.
///
/// Internal async helper. Returns the inner [`AsyncConnection`]; the
/// public [`connect`] wraps it in a [`SyncConnection`] that owns the
/// driving runtime.
async fn connect_direct(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
) -> Result<Box<dyn AsyncConnection>, SqlError> {
    let backend = Backend::from_scheme(url.scheme())
        .ok_or_else(|| SqlError::UnsupportedScheme(url.scheme().to_string()))?;

    match backend {
        #[cfg(feature = "postgres")]
        Backend::Postgres => {
            let conn = backends::postgres::connect(url, opts).await?;
            Ok(Box::new(conn))
        }
        #[cfg(feature = "mysql")]
        Backend::MySql => {
            let conn = backends::mysql::connect(url, opts).await?;
            Ok(Box::new(conn))
        }
        #[cfg(feature = "mssql")]
        Backend::MsSql => {
            let conn = backends::mssql::connect(url, opts).await?;
            Ok(Box::new(conn))
        }
        #[cfg(feature = "sqlite")]
        Backend::Sqlite => {
            let conn = backends::sqlite::connect(url, opts).await?;
            Ok(Box::new(conn))
        }
        #[cfg(feature = "oracle")]
        Backend::Oracle => {
            let conn = backends::oracle::connect(url, opts).await?;
            Ok(Box::new(conn))
        }
    }
}

/// Build the private current-thread runtime that drives one
/// connection handle's driver futures for its whole lifetime.
///
/// Current-thread (not multi-thread) by design: a single embedded
/// connection needs exactly one driver task plus the in-flight
/// statement future, both polled cooperatively on the calling thread
/// during `block_on`. `enable_all` turns on the I/O and time drivers
/// the network backends need.
fn build_runtime() -> Result<tokio::runtime::Runtime, SqlError> {
    tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .map_err(|e| SqlError::ConnectionFailed(format!("failed to build connection runtime: {e}")))
}

/// Establish a blocking connection to the given URL.
///
/// When `proxy` is `Some`, the connection is routed through the proxy
/// via HTTP CONNECT. For Postgres this means `connect_raw` with a
/// pre-built stream; for MySQL/MSSQL/Oracle a local TCP listener is
/// bound and bytes are pumped through the proxy; for SQLite the proxy is
/// ignored (local file, no network).
///
/// **Blocking:** this call blocks until the connection is established.
/// The returned [`Connection`] owns a private current-thread runtime
/// that drives every later blocking call; it never exposes a `Future`.
/// Do not call from inside another `block_on` on the same thread.
#[must_use = "a connection handle must be used or the connection is dropped immediately"]
pub fn connect(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
    proxy: Option<&crate::proxy::ProxyConfig>,
) -> Result<Box<dyn Connection>, SqlError> {
    let rt = build_runtime()?;
    let inner = rt.block_on(connect_inner(url, opts, proxy))?;
    Ok(Box::new(SyncConnection::new(rt, inner)))
}

/// Async core of [`connect`]: resolve the backend and establish the
/// inner [`AsyncConnection`], honoring an optional HTTP CONNECT proxy.
/// Must be driven on the same runtime that [`connect`] later moves into
/// the returned [`SyncConnection`].
async fn connect_inner(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
    proxy: Option<&crate::proxy::ProxyConfig>,
) -> Result<Box<dyn AsyncConnection>, SqlError> {
    let backend = Backend::from_scheme(url.scheme())
        .ok_or_else(|| SqlError::UnsupportedScheme(url.scheme().to_string()))?;

    match backend {
        #[cfg(feature = "postgres")]
        Backend::Postgres => {
            if let Some(proxy) = proxy {
                let target_host = url.host().ok_or_else(|| {
                    SqlError::ConnectionFailed(
                        "URL has no host — proxy requires a network target".to_string(),
                    )
                })?;
                let target_port = url.port().unwrap_or(5432);
                let stream = crate::proxy::http_connect(proxy, target_host, target_port).await?;
                let conn = backends::postgres::connect_with_stream(url, opts, stream).await?;
                Ok(Box::new(conn))
            } else {
                connect_direct(url, opts).await
            }
        }
        #[cfg(feature = "mysql")]
        Backend::MySql => {
            if let Some(proxy) = proxy {
                connect_via_proxy_listener(url, opts, proxy, backend).await
            } else {
                connect_direct(url, opts).await
            }
        }
        #[cfg(feature = "mssql")]
        Backend::MsSql => {
            if let Some(proxy) = proxy {
                connect_via_proxy_listener(url, opts, proxy, backend).await
            } else {
                connect_direct(url, opts).await
            }
        }
        #[cfg(feature = "sqlite")]
        Backend::Sqlite => {
            // SQLite is a local-file backend; proxy is irrelevant.
            connect_direct(url, opts).await
        }
        #[cfg(feature = "oracle")]
        Backend::Oracle => {
            if let Some(proxy) = proxy {
                connect_via_proxy_listener(url, opts, proxy, backend).await
            } else {
                connect_direct(url, opts).await
            }
        }
    }
}

/// Bind a local TCP listener, pump each accepted connection through
/// a fresh HTTP CONNECT tunnel to the original host:port.
#[cfg(any(feature = "mysql", feature = "mssql", feature = "oracle"))]
async fn connect_via_proxy_listener(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
    proxy: &crate::proxy::ProxyConfig,
    backend: Backend,
) -> Result<Box<dyn AsyncConnection>, SqlError> {
    let target_host = url
        .host()
        .ok_or_else(|| {
            SqlError::ConnectionFailed(
                "URL has no host — proxy requires a network target".to_string(),
            )
        })?
        .to_string();
    let target_port = url.port().unwrap_or_else(|| default_port_for(backend));

    let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
        .await
        .map_err(|e| SqlError::ConnectionFailed(format!("proxy listener bind: {e}")))?;
    let port = listener.local_addr()?.port();

    let proxy = proxy.clone();
    let forwarder = tokio::spawn(async move {
        loop {
            let (mut tcp, _addr) = match listener.accept().await {
                Ok(pair) => pair,
                Err(e) => {
                    eprintln!("[ferrule] proxy listener accept failed: {e}");
                    return;
                }
            };
            let target_host = target_host.clone();
            let proxy = proxy.clone();
            tokio::spawn(async move {
                let mut proxy_stream =
                    match crate::proxy::http_connect(&proxy, &target_host, target_port).await {
                        Ok(s) => s,
                        Err(e) => {
                            eprintln!("[ferrule] proxy connect failed: {e}");
                            return;
                        }
                    };
                if let Err(e) = tokio::io::copy_bidirectional(&mut tcp, &mut proxy_stream).await {
                    // Normal close is expected; don't spam stderr.
                    let _ = e;
                }
            });
        }
    });

    let local_url = rewrite_url_to_local(url, port)?;
    let inner = connect_direct(&local_url, opts).await?;
    Ok(Box::new(crate::proxy::ProxiedConnection {
        inner,
        forwarder: Some(forwarder),
    }))
}

/// Establish a connection to `url` through an SSH tunnel.
///
/// An optional `proxy` routes the SSH session itself through an
/// HTTP CONNECT proxy (corporate firewall scenario: proxy → bastion
/// → SSH → direct-tcpip → DB).
///
/// Picks the transport based on the backend:
///
/// - **Postgres** — `Stream` transport. The russh channel is fed
///   directly into `tokio_postgres::Config::connect_raw`, so there
///   is no extra TCP hop. TLS (if requested via `?sslmode=...`) is
///   negotiated end-to-end inside the SSH stream.
/// - **MySQL, MSSQL, Oracle** — `LocalListener` transport. A
///   `127.0.0.1:<random>` listener is bound; bytes are pumped through
///   the SSH channel by a forwarder task. The driver opens a regular
///   TCP connection to that local port.
/// - **SQLite** — rejected. SQLite is a local-file backend, so SSH
///   tunneling is not applicable.
///
/// The returned `Box<dyn Connection>` wraps the inner backend
/// connection in a [`crate::tunnel::TunneledConnection`] that owns
/// the SSH session (and, for the LocalListener path, the forwarder
/// task) for the connection's lifetime.
#[cfg(feature = "ssh")]
async fn connect_with_tunnel_inner(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
    ssh_config: &crate::tunnel::SshConfig,
    key_source: &crate::tunnel::KeySource,
    proxy: Option<&crate::proxy::ProxyConfig>,
) -> Result<Box<dyn AsyncConnection>, SqlError> {
    use crate::tunnel::{
        TunnelError, TunnelTransport, TunnelTransportResult, TunneledConnection, setup_tunnel,
    };

    let backend = Backend::from_scheme(url.scheme())
        .ok_or_else(|| SqlError::UnsupportedScheme(url.scheme().to_string()))?;

    #[cfg(feature = "sqlite")]
    if matches!(backend, Backend::Sqlite) {
        return Err(SqlError::ConnectionFailed(
            "SSH tunneling is not applicable to SQLite (local-file backend)".to_string(),
        ));
    }

    let target_host = url
        .host()
        .ok_or_else(|| {
            SqlError::ConnectionFailed(
                "URL has no host — SSH tunneling requires a network-based backend".to_string(),
            )
        })?
        .to_string();
    let target_port = url.port().unwrap_or_else(|| default_port_for(backend));

    let transport = match backend {
        #[cfg(feature = "postgres")]
        Backend::Postgres => TunnelTransport::Stream,
        _ => TunnelTransport::LocalListener,
    };

    let tunnel = setup_tunnel(
        ssh_config,
        key_source,
        &target_host,
        target_port,
        transport,
        proxy,
    )
    .await
    .map_err(|e| match e {
        TunnelError::HostKeyMismatch { host, port, .. } => {
            SqlError::SshHostKeyMismatch { host, port }
        }
        TunnelError::UnknownHost {
            host,
            port,
            algorithm,
            fingerprint,
            key,
            ..
        } => SqlError::SshUnknownHost {
            host,
            port,
            algorithm,
            fingerprint,
            key,
        },
        other => SqlError::ConnectionFailed(format!("SSH tunnel setup: {other}")),
    })?;

    let session = tunnel.session;
    match tunnel.transport {
        TunnelTransportResult::Stream { stream } => {
            #[cfg(feature = "postgres")]
            if matches!(backend, Backend::Postgres) {
                let pg = backends::postgres::connect_with_stream(url, opts, *stream).await?;
                return Ok(Box::new(TunneledConnection {
                    inner: Box::new(pg),
                    session,
                    forwarder: None,
                }));
            }
            Err(SqlError::ConnectionFailed(
                "Stream transport selected but no backend handler is registered \
                 (this is a ferrule bug — please report)"
                    .to_string(),
            ))
        }
        TunnelTransportResult::LocalPort { port, forwarder } => {
            let local_url = rewrite_url_to_local(url, port)?;
            let inner = connect_direct(&local_url, opts).await?;
            Ok(Box::new(TunneledConnection {
                inner,
                session,
                forwarder: Some(forwarder),
            }))
        }
    }
}

#[cfg(any(
    feature = "ssh",
    feature = "mysql",
    feature = "mssql",
    feature = "oracle"
))]
fn default_port_for(backend: Backend) -> u16 {
    match backend {
        #[cfg(feature = "postgres")]
        Backend::Postgres => 5432,
        #[cfg(feature = "mysql")]
        Backend::MySql => 3306,
        #[cfg(feature = "mssql")]
        Backend::MsSql => 1433,
        #[cfg(feature = "sqlite")]
        Backend::Sqlite => 0, // unreachable in contexts that call this
        #[cfg(feature = "oracle")]
        Backend::Oracle => 1521,
    }
}

#[cfg(any(
    feature = "ssh",
    feature = "mysql",
    feature = "mssql",
    feature = "oracle"
))]
fn rewrite_url_to_local(url: &DatabaseUrl, port: u16) -> Result<DatabaseUrl, SqlError> {
    let mut parsed = ::url::Url::parse(url.raw())
        .map_err(|e| SqlError::InvalidUrl(format!("re-parse for tunnel rewrite: {e}")))?;
    parsed
        .set_host(Some("127.0.0.1"))
        .map_err(|e| SqlError::InvalidUrl(format!("set_host(127.0.0.1): {e}")))?;
    parsed
        .set_port(Some(port))
        .map_err(|()| SqlError::InvalidUrl("set_port failed".to_string()))?;
    DatabaseUrl::parse(parsed.as_str())
}

/// Establish a blocking connection to `url` through an SSH tunnel.
///
/// An optional `proxy` routes the SSH session itself through an HTTP
/// CONNECT proxy. See [`connect`] for the runtime / blocking contract:
/// the returned handle owns the private runtime that also hosts the SSH
/// session and (for the LocalListener transport) the byte-forwarder
/// task, so all of them are driven on every later blocking call and torn
/// down together when the handle drops.
#[cfg(feature = "ssh")]
#[must_use = "a connection handle must be used or the connection is dropped immediately"]
pub fn connect_with_tunnel(
    url: &DatabaseUrl,
    opts: &ConnectOptions,
    ssh_config: &crate::tunnel::SshConfig,
    key_source: &crate::tunnel::KeySource,
    proxy: Option<&crate::proxy::ProxyConfig>,
) -> Result<Box<dyn Connection>, SqlError> {
    let rt = build_runtime()?;
    let inner = rt.block_on(connect_with_tunnel_inner(
        url, opts, ssh_config, key_source, proxy,
    ))?;
    Ok(Box::new(SyncConnection::new(rt, inner)))
}