rmux 0.9.0

//! Client-side terminal capability detection shared by the full and tiny CLIs.

use std::io::IsTerminal;

use rmux_proto::ClientTerminalContext;

pub(crate) const ATTACH_TERMINAL_REQUIRED_MESSAGE: &str = "open terminal failed: not a terminal";

pub(crate) fn require_attach_terminal() -> Result<(), &'static str> {
    require_attach_terminal_from(std::io::stdin().is_terminal())
}

fn require_attach_terminal_from(stdin_is_terminal: bool) -> Result<(), &'static str> {
    if stdin_is_terminal {
        Ok(())
    } else {
        Err(ATTACH_TERMINAL_REQUIRED_MESSAGE)
    }
}

pub(crate) fn client_terminal_context_from_parts(
    terminal_features: Vec<String>,
    utf8: bool,
) -> ClientTerminalContext {
    let mut context = ClientTerminalContext {
        terminal_features,
        utf8,
    };
    apply_detected_client_terminal_features(&mut context);
    context
}

pub(crate) fn apply_detected_client_terminal_features(context: &mut ClientTerminalContext) {
    #[cfg(windows)]
    apply_windows_terminal_features(
        context,
        std::env::var_os("WT_SESSION").is_some_and(|value| !value.is_empty()),
    );
    #[cfg(not(windows))]
    let _ = context;
}

#[cfg(windows)]
fn apply_windows_terminal_features(context: &mut ClientTerminalContext, is_windows_terminal: bool) {
    // rmux always drives the outer terminal as VT on Windows — a console outer
    // runs with ENABLE_VIRTUAL_TERMINAL_PROCESSING and a pipe outer is raw VT —
    // so advertise the base VT feature set for any outer, not only Windows
    // Terminal. Without this a VT outer reached without WT_SESSION
    // (OpenSSH-into-Windows, WezTerm, Alacritty, VS Code, mintty) never has
    // mouse reporting or bracketed paste enabled on it (issue #93).
    push_unique_terminal_feature(&mut context.terminal_features, "sync");
    push_unique_terminal_feature(&mut context.terminal_features, "bpaste");
    push_unique_terminal_feature(&mut context.terminal_features, "mouse");
    // Advertise clipboard (OSC 52) too so the daemon has an Ms template and can
    // emit a pane's write under `set-clipboard on` (issue #91). Actual system
    // clipboard delivery remains host-dependent: older ConPTY paths can consume
    // OSC 52 before the outer terminal sees it, and an outer may ignore it. The
    // inbound relay still depends on the daemon-side `set-clipboard on` gate.
    push_unique_terminal_feature(&mut context.terminal_features, "clipboard");
    // utf8 stays gated: Windows Terminal is known UTF-8, while other outers
    // are inferred from the console code page / locale elsewhere.
    if is_windows_terminal {
        context.utf8 = true;
    }
}

#[cfg(windows)]
fn push_unique_terminal_feature(features: &mut Vec<String>, feature: &str) {
    if !features
        .iter()
        .any(|value| value.eq_ignore_ascii_case(feature))
    {
        features.push(feature.to_owned());
    }
}

#[cfg(test)]
mod tests {
    use super::{
        client_terminal_context_from_parts, require_attach_terminal_from,
        ATTACH_TERMINAL_REQUIRED_MESSAGE,
    };

    #[test]
    fn attach_terminal_preflight_rejects_redirected_stdin() {
        assert_eq!(
            require_attach_terminal_from(false),
            Err(ATTACH_TERMINAL_REQUIRED_MESSAGE)
        );
        assert_eq!(require_attach_terminal_from(true), Ok(()));
    }

    #[test]
    fn detected_client_terminal_context_preserves_explicit_features() {
        let context = client_terminal_context_from_parts(vec!["RGB".to_owned()], true);

        assert!(context.utf8);
        assert!(context
            .terminal_features
            .iter()
            .any(|feature| feature == "RGB"));
    }

    #[cfg(windows)]
    #[test]
    fn windows_terminal_advertises_vt_features_and_utf8() {
        let mut context = rmux_proto::ClientTerminalContext::default();

        super::apply_windows_terminal_features(&mut context, true);

        assert!(context.utf8);
        assert_eq!(
            context.terminal_features,
            vec!["sync", "bpaste", "mouse", "clipboard"]
        );
    }

    #[cfg(windows)]
    #[test]
    fn non_windows_terminal_vt_outer_still_advertises_mouse_and_bpaste() {
        // Issue #93: a VT outer reached without WT_SESSION (SSH/WezTerm/…) must
        // still advertise mouse + bracketed paste so the daemon enables them on
        // the outer. utf8 is NOT forced here (only Windows Terminal is known
        // UTF-8); the console code page decides it elsewhere.
        let mut context = rmux_proto::ClientTerminalContext::default();

        super::apply_windows_terminal_features(&mut context, false);

        assert!(!context.utf8);
        assert_eq!(
            context.terminal_features,
            vec!["sync", "bpaste", "mouse", "clipboard"]
        );
    }

    #[cfg(windows)]
    #[test]
    fn detected_windows_terminal_features_are_not_duplicated() {
        let mut context = rmux_proto::ClientTerminalContext {
            terminal_features: vec!["SYNC".to_owned(), "BPASTE".to_owned(), "MOUSE".to_owned()],
            utf8: false,
        };

        super::apply_windows_terminal_features(&mut context, true);

        assert!(context.utf8);
        assert_eq!(
            context.terminal_features,
            vec!["SYNC", "BPASTE", "MOUSE", "clipboard"]
        );
    }
}