basemind 0.10.1

//! Session operations over the rmux SDK.
//!
//! Thin, typed wrappers around the verified rmux-sdk 0.6.1 surface:
//! [`rmux_sdk::EnsureSession`] to create a detached headless session,
//! [`rmux_sdk::Session::pane`] / [`rmux_sdk::Pane`] to drive stdin + capture
//! output, and [`rmux_sdk::Rmux::list_sessions`] / [`rmux_sdk::Session::kill`]
//! for lifecycle. Errors are surfaced as [`anyhow::Error`] so callers (the MCP
//! helpers) can map them to MCP errors at the boundary.

use anyhow::{Context, Result};
use rmux_sdk::{
    EnsureSession, Input, Pane, Rmux, RmuxError, Session, SessionName, TerminalSizeSpec,
};

/// Fallback terminal geometry for a headless session. Wide enough that typical
/// command output is not wrapped, tall enough to hold a screenful for snapshot
/// capture. Headless sessions have no attached client driving a resize, so this
/// is the geometry the pane keeps for its whole life.
///
/// The configured `[shells].default_cols` normally supplies the width; this const
/// is the floor applied when a caller passes `0`, so a degenerate zero-sized PTY
/// can never reach the daemon. The config default mirrors this value.
pub(crate) const DEFAULT_COLS: u16 = 200;
/// See [`DEFAULT_COLS`]. The configured `[shells].default_rows` normally supplies
/// the height; this const is the floor applied when a caller passes `0`.
pub(crate) const DEFAULT_ROWS: u16 = 50;

/// How a shell session's program is specified.
///
/// `Shell` runs the string through the login shell (rmux's `ProcessCommandSpec::Shell`);
/// `Argv` execs the argument vector directly with no shell interpretation.
#[derive(Debug, Clone)]
pub enum ShellCommand {
    /// Run `command` via the login shell, e.g. `bash -lc '<command>'`.
    Shell(String),
    /// Exec this argument vector directly with no shell interpretation; the first
    /// element is the program and the rest are its arguments.
    Argv(Vec<String>),
}

/// Inputs for spawning one detached headless shell session.
#[derive(Debug, Clone)]
pub struct SpawnSpec {
    /// The rmux session name to create (already minted + sanitized by the caller).
    pub name: SessionName,
    /// The program to run in the session's initial pane.
    pub command: ShellCommand,
    /// Optional working directory for the spawned process.
    pub working_directory: Option<String>,
    /// Environment overrides as `"KEY=VALUE"` strings.
    pub environment: Vec<String>,
    /// Terminal width in columns for the headless pane. Sourced from `[shells].default_cols` so an
    /// operator can widen the geometry; [`DEFAULT_COLS`] is the fallback the config default mirrors.
    pub cols: u16,
    /// Terminal height in rows for the headless pane. Sourced from `[shells].default_rows`;
    /// [`DEFAULT_ROWS`] is the fallback the config default mirrors.
    pub rows: u16,
}

/// Create a detached headless session per `spec` and return the live handle.
///
/// The session is created with `detached(true)` so no client is attached — it
/// runs purely under the daemon. The pane geometry is taken from `spec.cols` ×
/// `spec.rows` (the configured `[shells]` defaults), falling back to
/// `DEFAULT_COLS` × `DEFAULT_ROWS` at the config layer.
pub async fn spawn_session(rmux: &Rmux, spec: SpawnSpec) -> Result<Session> {
    // Apply the documented fallback for a degenerate zero-sized request, so the daemon never gets a
    // 0×0 PTY even if a caller threads through an unset geometry.
    let cols = if spec.cols == 0 {
        DEFAULT_COLS
    } else {
        spec.cols
    };
    let rows = if spec.rows == 0 {
        DEFAULT_ROWS
    } else {
        spec.rows
    };
    let mut ensure = EnsureSession::named(spec.name)
        .detached(true)
        .size(TerminalSizeSpec::new(cols, rows));

    ensure = match spec.command {
        ShellCommand::Shell(command) => ensure.shell(command),
        ShellCommand::Argv(argv) => ensure.argv(argv),
    };

    if let Some(cwd) = spec.working_directory {
        ensure = ensure.working_directory(cwd);
    }
    if !spec.environment.is_empty() {
        ensure = ensure.environment(spec.environment);
    }

    ensure
        .ensure(rmux)
        .await
        .context("create detached rmux session")
}

/// Send `text` to the session's primary pane.
///
/// When `enter` is true a trailing newline is appended so the shell executes the
/// line. Targets the first pane of the first window (`pane(0, 0)`).
pub async fn send_text(session: &Session, text: &str, enter: bool) -> Result<()> {
    let pane = session.pane(0, 0);
    let payload = if enter {
        format!("{text}\n")
    } else {
        text.to_string()
    };
    pane.send_text(payload)
        .await
        .context("send text to rmux pane")
}

/// Capture the currently-visible text of the session's primary pane.
///
/// Returns the rendered screen as a single newline-joined string. When `lines`
/// is supplied, only the last `lines` non-leading-blank rows are returned (the
/// most recent output), so callers can ask for a tail rather than the whole
/// screen. Trailing all-blank rows are always trimmed.
pub async fn capture(session: &Session, lines: Option<usize>) -> Result<String> {
    let pane = session.pane(0, 0);
    let snapshot = pane
        .snapshot()
        .await
        .context("snapshot rmux pane for capture")?;
    let mut rows: Vec<String> = snapshot.visible_lines();

    // Drop trailing blank rows — a 50-row pane running a short command is mostly
    // empty, and returning 45 blank lines is pure noise.
    while rows.last().is_some_and(|row| row.trim().is_empty()) {
        rows.pop();
    }

    if let Some(tail) = lines {
        let start = rows.len().saturating_sub(tail);
        rows.drain(..start);
    }

    Ok(rows.join("\n"))
}

/// List the names of all sessions currently known to the daemon.
pub async fn list_sessions(rmux: &Rmux) -> Result<Vec<SessionName>> {
    rmux.list_sessions().await.context("list rmux sessions")
}

/// Broadcast `text` to the primary pane of each named session at once.
///
/// Resolves every `SessionName` to its first pane (`pane(0, 0)`), then delivers
/// the same input to all of them via [`Rmux::broadcast`]. When `enter` is true a
/// trailing newline is appended so each shell executes the line (matching
/// [`send_text`]). Returns the number of panes that accepted the input.
///
/// A partial failure (some panes rejected the input) is surfaced as an error that
/// reports how many of the targeted panes succeeded versus failed, so the caller
/// learns the broadcast was not fully delivered rather than silently losing it.
pub async fn broadcast(
    rmux: &Rmux,
    names: &[SessionName],
    text: &str,
    enter: bool,
) -> Result<usize> {
    if names.is_empty() {
        return Ok(0);
    }

    let mut panes: Vec<Pane> = Vec::with_capacity(names.len());
    for name in names {
        let session = rmux
            .session(name.clone())
            .await
            .with_context(|| format!("open session {:?} for broadcast", name.as_str()))?;
        panes.push(session.pane(0, 0));
    }

    let payload = if enter {
        format!("{text}\n")
    } else {
        text.to_string()
    };

    match rmux.broadcast(&panes, Input::text(&payload)).await {
        Ok(result) => Ok(result.len()),
        Err(RmuxError::PartialBroadcast { source, .. }) => {
            let delivered = source.successes().len();
            let failed = source.failures().len();
            Err(anyhow::anyhow!(
                "broadcast partially failed: {delivered} of {} panes accepted the input, \
                 {failed} rejected it",
                delivered + failed
            ))
        }
        Err(other) => Err(anyhow::Error::new(other).context("broadcast input to rmux panes")),
    }
}

/// Kill `session`. Returns `true` when a session existed and was terminated,
/// `false` when it was already gone.
pub async fn kill_session(session: &Session) -> Result<bool> {
    session.kill().await.context("kill rmux session")
}