rmux-core 0.10.0

use std::collections::BTreeMap;
use std::ops::Bound::{Excluded, Unbounded};
use std::path::PathBuf;
use std::time::{SystemTime, UNIX_EPOCH};

use rmux_proto::{RmuxError, SessionName, SplitDirection, TerminalSize};

use crate::{AlertFlags, Pane, PaneGeometry, PaneId, SessionId, Window, WindowId};

#[path = "session/accessors.rs"]
mod accessors;
#[path = "session/layout_cycle.rs"]
mod layout_cycle;
#[path = "session/pane_transfer.rs"]
mod pane_transfer;
#[path = "session/pane_transfer_cross.rs"]
mod pane_transfer_cross;
#[path = "session/pane_transfer_shared.rs"]
mod pane_transfer_shared;
#[path = "session/recency.rs"]
mod recency;
#[path = "session/resize.rs"]
mod resize;
#[path = "session/store.rs"]
mod store;
#[path = "session/target_error.rs"]
mod target_error;
#[path = "session/types.rs"]
mod types;
#[path = "session/window_ops.rs"]
mod window_ops;

pub use recency::SessionRecency;
pub use store::SessionStore;
use target_error::{invalid_pane_target, invalid_window_target};
pub(crate) use types::WindowIdAllocator;
pub use types::{
    BreakPaneOptions, KillPaneOutcome, PaneJoinOptions, PaneSwapOptions, SessionPaneTarget,
};

/// A single detached RMUX session.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Session {
    id: SessionId,
    name: SessionName,
    group_name: Option<SessionName>,
    terminal_size: TerminalSize,
    windows: BTreeMap<u32, Window>,
    winlink_alert_flags: BTreeMap<u32, AlertFlags>,
    active_window: u32,
    last_window: Option<u32>,
    /// First grouped-peer winlink by stable identity, retained until real local navigation.
    group_initial_window_id: Option<WindowId>,
    next_pane_id: u32,
    next_window_id: WindowIdAllocator,
    created_at: i64,
    activity_at: i64,
    last_attached_at: Option<i64>,
    /// Internal total order behind the whole-second `activity_at`/`created_at`
    /// pair, so same-second lifetime and interaction events stay orderable.
    recency: SessionRecency,
    cwd: Option<PathBuf>,
}

impl Session {
    /// Creates a new session with its initial pane active.
    #[must_use]
    pub fn new(name: SessionName, size: TerminalSize) -> Self {
        Self::new_with_initial_window(name, size, 0, PaneId::new(0), WindowId::new(0))
    }

    /// Creates a new session with an explicitly seeded initial window and pane identity.
    #[must_use]
    pub(crate) fn new_with_initial_window(
        name: SessionName,
        size: TerminalSize,
        window_index: u32,
        pane_id: PaneId,
        window_id: WindowId,
    ) -> Self {
        let now = current_unix_timestamp();
        Self {
            id: SessionId::new(0),
            name,
            group_name: None,
            terminal_size: size,
            windows: BTreeMap::from([(
                window_index,
                Window::new_with_initial_pane(size, pane_id, window_id),
            )]),
            winlink_alert_flags: BTreeMap::from([(window_index, AlertFlags::empty())]),
            active_window: window_index,
            last_window: None,
            group_initial_window_id: None,
            next_pane_id: pane_id.as_u32().saturating_add(1),
            next_window_id: WindowIdAllocator::new(window_id.as_u32().saturating_add(1)),
            created_at: now,
            activity_at: now,
            last_attached_at: None,
            recency: SessionRecency::next(),
            cwd: None,
        }
    }

    /// Splits the current active pane and returns the new pane index, making the new pane active.
    pub fn split_active_pane(&mut self) -> Result<u32, RmuxError> {
        self.split_active_pane_with_direction(SplitDirection::Vertical)
    }

    /// Splits the current active pane in the requested direction.
    pub fn split_active_pane_with_direction(
        &mut self,
        direction: SplitDirection,
    ) -> Result<u32, RmuxError> {
        self.split_pane_with_direction(self.active_pane_index(), direction)
    }

    /// Splits the addressed pane, inserting the new pane immediately after the split target in window order.
    pub fn split_pane(&mut self, pane_index: u32) -> Result<u32, RmuxError> {
        self.split_pane_with_direction(pane_index, SplitDirection::Vertical)
    }

    /// Splits the addressed pane in the active window using the requested direction.
    pub fn split_pane_with_direction(
        &mut self,
        pane_index: u32,
        direction: SplitDirection,
    ) -> Result<u32, RmuxError> {
        self.split_pane_in_window_with_direction(self.active_window, pane_index, direction)
    }

    /// Splits the addressed pane in the addressed window and returns the new pane index.
    pub fn split_pane_in_window(
        &mut self,
        window_index: u32,
        pane_index: u32,
    ) -> Result<u32, RmuxError> {
        self.split_pane_in_window_with_direction(window_index, pane_index, SplitDirection::Vertical)
    }

    /// Splits the addressed pane in the addressed window using the requested direction.
    pub fn split_pane_in_window_with_direction(
        &mut self,
        window_index: u32,
        pane_index: u32,
        direction: SplitDirection,
    ) -> Result<u32, RmuxError> {
        self.split_pane_in_window_with_direction_before(window_index, pane_index, direction, false)
    }

    /// Splits the addressed pane in the addressed window using the requested
    /// direction, controlling whether the new pane is inserted before the
    /// target on the chosen axis (tmux `-b`).
    pub fn split_pane_in_window_with_direction_before(
        &mut self,
        window_index: u32,
        pane_index: u32,
        direction: SplitDirection,
        before: bool,
    ) -> Result<u32, RmuxError> {
        let pane_id = self.allocate_pane_id();
        self.split_pane_in_window_with_id_and_direction_before(
            window_index,
            pane_index,
            pane_id,
            direction,
            before,
        )
    }

    /// Splits the addressed pane in the addressed window using the provided pane identity.
    ///
    /// The new pane is inserted after the target on the chosen axis. Callers
    /// that need tmux `-b` semantics (insert before) should use
    /// [`Session::split_pane_in_window_with_id_and_direction_before`].
    pub fn split_pane_in_window_with_id_and_direction(
        &mut self,
        window_index: u32,
        pane_index: u32,
        pane_id: PaneId,
        direction: SplitDirection,
    ) -> Result<u32, RmuxError> {
        self.split_pane_in_window_with_id_and_direction_before(
            window_index,
            pane_index,
            pane_id,
            direction,
            false,
        )
    }

    /// Splits the addressed pane, controlling whether the new pane lands
    /// before (`-b`) or after the target on the chosen axis.
    pub fn split_pane_in_window_with_id_and_direction_before(
        &mut self,
        window_index: u32,
        pane_index: u32,
        pane_id: PaneId,
        direction: SplitDirection,
        before: bool,
    ) -> Result<u32, RmuxError> {
        self.split_pane_in_window_with_id_and_direction_before_detached(
            window_index,
            pane_index,
            pane_id,
            direction,
            before,
            false,
        )
    }

    /// Splits like [`Self::split_pane_in_window_with_id_and_direction_before`]
    /// but honors tmux `-d`: a detached spawn leaves the active pane, the
    /// last pane, and the active_point counters untouched.
    pub fn split_pane_in_window_with_id_and_direction_before_detached(
        &mut self,
        window_index: u32,
        pane_index: u32,
        pane_id: PaneId,
        direction: SplitDirection,
        before: bool,
        detached: bool,
    ) -> Result<u32, RmuxError> {
        let window = self
            .window_at(window_index)
            .ok_or_else(|| invalid_window_target(&self.name, window_index))?;
        let position = window.pane_position(pane_index).ok_or_else(|| {
            invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            )
        })?;
        if !window.can_split_pane(pane_index, direction) {
            return Err(RmuxError::Message("no space for new pane".to_owned()));
        }
        Ok(self
            .window_at_mut(window_index)
            .expect("addressed session window must exist")
            .split_at_position_with_id_and_direction_detached(
                position, pane_id, direction, before, detached,
            ))
    }

    /// Splits the full addressed window root and returns the new pane index.
    pub fn split_pane_full_size_in_window_with_id_and_direction_before(
        &mut self,
        window_index: u32,
        pane_index: u32,
        pane_id: PaneId,
        direction: SplitDirection,
        before: bool,
    ) -> Result<u32, RmuxError> {
        self.split_pane_full_size_in_window_with_id_and_direction_before_detached(
            window_index,
            pane_index,
            pane_id,
            direction,
            before,
            false,
        )
    }

    /// Full-size split honoring tmux `-d` like
    /// [`Self::split_pane_in_window_with_id_and_direction_before_detached`].
    pub fn split_pane_full_size_in_window_with_id_and_direction_before_detached(
        &mut self,
        window_index: u32,
        pane_index: u32,
        pane_id: PaneId,
        direction: SplitDirection,
        before: bool,
        detached: bool,
    ) -> Result<u32, RmuxError> {
        let window = self
            .window_at(window_index)
            .ok_or_else(|| invalid_window_target(&self.name, window_index))?;
        if window.pane(pane_index).is_none() {
            return Err(invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            ));
        }

        let window = self
            .window_at_mut(window_index)
            .expect("addressed session window must exist");
        let previous_active_pane_id = window.active_pane().map(Pane::id);
        let previous_last_pane_id = window
            .last_pane_index()
            .and_then(|pane_index| window.pane(pane_index))
            .map(Pane::id);
        let new_index = window
            .panes()
            .iter()
            .map(Pane::index)
            .max()
            .unwrap_or(0)
            .saturating_add(1);
        window.insert_pane_full_size(
            Pane::new_with_id(pane_id, new_index, PaneGeometry::new(0, 0, 0, 0)),
            direction,
            before,
        )?;
        window.commit_split_renumber(
            pane_id,
            previous_active_pane_id,
            previous_last_pane_id,
            detached,
        );
        window
            .panes()
            .iter()
            .find(|pane| pane.id() == pane_id)
            .map(Pane::index)
            .ok_or_else(|| {
                RmuxError::Server(format!(
                    "pane id {} disappeared after full-size split",
                    pane_id.as_u32()
                ))
            })
    }

    /// Removes the addressed pane in the active window.
    pub fn kill_pane(&mut self, pane_index: u32) -> Result<KillPaneOutcome, RmuxError> {
        self.kill_pane_in_window(self.active_window, pane_index)
    }

    /// Removes the addressed pane or destroys its window when it is the last pane there.
    pub fn kill_pane_in_window(
        &mut self,
        window_index: u32,
        pane_index: u32,
    ) -> Result<KillPaneOutcome, RmuxError> {
        let window = self
            .window_at(window_index)
            .ok_or_else(|| invalid_window_target(&self.name, window_index))?;
        let pane_id = window.pane_id(pane_index).ok_or_else(|| {
            invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            )
        })?;

        if window.pane_count() == 1 {
            let removed_window = self.remove_window(window_index)?;
            let removed_pane_ids = removed_window.panes().iter().map(Pane::id).collect();
            return Ok(KillPaneOutcome::new(removed_pane_ids, true));
        }

        let removed_pane = self
            .window_at_mut(window_index)
            .expect("addressed session window must exist")
            .remove_pane(pane_index)
            .expect("prevalidated pane removal must succeed");
        debug_assert_eq!(removed_pane.id(), pane_id);

        Ok(KillPaneOutcome::new(vec![removed_pane.id()], false))
    }

    /// Removes every pane except the addressed pane, matching `kill-pane -a`.
    pub fn kill_other_panes_in_window(
        &mut self,
        window_index: u32,
        pane_index: u32,
    ) -> Result<KillPaneOutcome, RmuxError> {
        let window = self
            .window_at(window_index)
            .ok_or_else(|| invalid_window_target(&self.name, window_index))?;
        if window.pane(pane_index).is_none() {
            return Err(invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            ));
        }

        let removed_pane_ids = self
            .window_at_mut(window_index)
            .expect("addressed session window must exist")
            .remove_other_panes(pane_index)
            .expect("prevalidated pane removal must succeed");

        Ok(KillPaneOutcome::new(removed_pane_ids, false))
    }

    /// Selects the active pane for the session.
    pub fn select_pane(&mut self, pane_index: u32) -> Result<(), RmuxError> {
        self.select_pane_in_window(self.active_window, pane_index)
    }

    /// Selects the active pane for the addressed window.
    pub fn select_pane_in_window(
        &mut self,
        window_index: u32,
        pane_index: u32,
    ) -> Result<(), RmuxError> {
        self.select_pane_in_window_with_zoom(window_index, pane_index, false)
    }

    /// Selects the active pane for the addressed window, preserving zoom when requested.
    pub fn select_pane_in_window_with_zoom(
        &mut self,
        window_index: u32,
        pane_index: u32,
        preserve_zoom: bool,
    ) -> Result<(), RmuxError> {
        if self.window_at(window_index).is_none() {
            return Err(invalid_window_target(&self.name, window_index));
        }

        if self
            .window_at(window_index)
            .expect("addressed session window must exist")
            .pane(pane_index)
            .is_none()
        {
            return Err(invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            ));
        }

        let window = self
            .window_at_mut(window_index)
            .expect("addressed session window must exist");
        if preserve_zoom {
            let _ = window.push_zoom(true);
        }
        let selected = window.select_pane(pane_index);
        if preserve_zoom {
            window.pop_zoom();
        }
        debug_assert!(selected, "validated pane target must be selectable");
        Ok(())
    }

    /// Selects the pane adjacent to the addressed pane in the requested direction.
    pub fn select_adjacent_pane_in_window(
        &mut self,
        window_index: u32,
        pane_index: u32,
        direction: rmux_proto::SelectPaneDirection,
    ) -> Result<u32, RmuxError> {
        self.select_adjacent_pane_in_window_with_zoom(window_index, pane_index, direction, false)
    }

    /// Selects an adjacent pane, preserving zoom when requested.
    pub fn select_adjacent_pane_in_window_with_zoom(
        &mut self,
        window_index: u32,
        pane_index: u32,
        direction: rmux_proto::SelectPaneDirection,
        preserve_zoom: bool,
    ) -> Result<u32, RmuxError> {
        if self.window_at(window_index).is_none() {
            return Err(invalid_window_target(&self.name, window_index));
        }

        if self
            .window_at(window_index)
            .expect("addressed session window must exist")
            .pane(pane_index)
            .is_none()
        {
            return Err(invalid_pane_target(
                &self.name,
                window_index,
                pane_index,
                "pane index does not exist in session",
            ));
        }

        let window = self
            .window_at_mut(window_index)
            .expect("addressed session window must exist");
        let was_zoomed = window.is_zoomed();
        let original_active_pane = window.active_pane_index();
        if was_zoomed {
            let _ = window.push_zoom(false);
        }
        let selected = window
            .select_adjacent_pane(pane_index, direction)
            .expect("validated adjacent pane anchor must be selectable");
        let moved = selected != original_active_pane;
        if was_zoomed && (preserve_zoom || !moved) {
            let _ = window.toggle_zoom(window.active_pane_index());
        }
        Ok(selected)
    }

    /// Updates the terminal and content sizes together for all windows.
    ///
    /// This is the explicit/manual-size path. Attached clients should use
    /// [`Session::resize_active_window_geometry`] so status rows never enter a
    /// window layout.
    pub fn resize_terminal(&mut self, size: TerminalSize) {
        self.terminal_size = size;
        for window in self.windows.values_mut() {
            window.set_size(size);
        }
    }

    /// Updates only the external terminal size used to render this session.
    pub fn set_terminal_size(&mut self, size: TerminalSize) {
        self.terminal_size = size;
    }

    /// Updates the external terminal and active-window content geometry.
    ///
    /// Attached clients drive the size of the window they are currently viewing. Inactive
    /// windows can have independent policies and may share a runtime with another session, so
    /// resizing every window here would leak the active window's size into unrelated runtimes.
    pub fn resize_active_window_geometry(
        &mut self,
        terminal_size: TerminalSize,
        content_size: TerminalSize,
    ) {
        self.terminal_size = terminal_size;
        self.window_mut().set_size(content_size);
    }

    fn resolve_window_target_mut(&mut self, window_index: u32) -> Result<&mut Window, RmuxError> {
        if !self.windows.contains_key(&window_index) {
            return Err(invalid_window_target(&self.name, window_index));
        }

        Ok(self
            .window_at_mut(window_index)
            .expect("addressed session window must exist"))
    }

    pub(crate) fn lowest_available_window_index_at_or_above(
        &self,
        minimum_index: u32,
    ) -> Result<u32, RmuxError> {
        let mut next_index = minimum_index;

        for window_index in self.windows.keys().copied() {
            if window_index < next_index {
                continue;
            }
            if window_index > next_index {
                break;
            }

            if window_index == next_index {
                next_index = next_index.checked_add(1).ok_or_else(|| {
                    RmuxError::Server(format!(
                        "window index space exhausted for session {}",
                        self.name
                    ))
                })?;
            }
        }

        Ok(next_index)
    }

    fn next_active_window_after_removal(&self, removed_index: u32) -> u32 {
        if let Some(last_window) = self.last_window {
            if last_window != removed_index && self.windows.contains_key(&last_window) {
                return last_window;
            }
        }

        if let Some(group_initial_window_id) = self.group_initial_window_id {
            if let Some((window_index, _)) = self.windows.iter().find(|(window_index, window)| {
                **window_index != removed_index && window.id() == group_initial_window_id
            }) {
                return *window_index;
            }
        }

        cyclic_previous_window_index(&self.windows, removed_index)
            .expect("a non-empty session must have a replacement window")
    }

    fn allocate_pane_id(&mut self) -> PaneId {
        let mut next_pane_id = self.next_pane_id;

        loop {
            let pane_id = PaneId::new(next_pane_id);
            if !self.contains_pane_id(pane_id) {
                self.next_pane_id = next_pane_id.saturating_add(1);
                return pane_id;
            }

            assert_ne!(next_pane_id, u32::MAX, "pane id space exhausted");
            next_pane_id += 1;
        }
    }

    fn contains_pane_id(&self, pane_id: PaneId) -> bool {
        self.windows
            .values()
            .flat_map(Window::panes)
            .any(|pane| pane.id() == pane_id)
    }

    /// Resolves the owning window index for the given pane identity when present.
    pub fn window_index_for_pane_id(&self, pane_id: PaneId) -> Option<u32> {
        self.windows.iter().find_map(|(window_index, window)| {
            window
                .panes()
                .iter()
                .any(|pane| pane.id() == pane_id)
                .then_some(*window_index)
        })
    }

    fn allocate_window_id(&self) -> WindowId {
        self.next_window_id.allocate()
    }
}

fn synchronized_active_window(
    windows: &BTreeMap<u32, Window>,
    previous_active: u32,
    previous_last: Option<u32>,
) -> u32 {
    if windows.contains_key(&previous_active) {
        return previous_active;
    }

    if let Some(last_window) = previous_last {
        if last_window != previous_active && windows.contains_key(&last_window) {
            return last_window;
        }
    }

    cyclic_previous_window_index(windows, previous_active)
        .expect("group synchronization requires at least one window")
}

fn cyclic_previous_window_index(
    windows: &BTreeMap<u32, Window>,
    removed_index: u32,
) -> Option<u32> {
    windows
        .range(..removed_index)
        .next_back()
        .or_else(|| {
            windows
                .range((Excluded(removed_index), Unbounded))
                .next_back()
        })
        .map(|(window_index, _)| *window_index)
}

fn current_unix_timestamp() -> i64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .ok()
        .and_then(|duration| i64::try_from(duration.as_secs()).ok())
        .unwrap_or_default()
}

#[cfg(test)]
mod tests;

#[cfg(test)]
#[path = "session/zoom_tests.rs"]
mod zoom_tests;

#[cfg(test)]
#[path = "session/layout_tests.rs"]
mod layout_tests;