//! Focus queries and directional/cyclic focus movement.
//! Split out of the original single `manager.rs` - see `super` (`mod.rs`) for
//! `WindowManager`'s field definitions; everything here is plain `impl WindowManager`
//! methods, unchanged from before the split.

use super::*;

impl WindowManager {
    // ---- Focus ----------------------------------------------------------

    pub fn focused_window(&self) -> Option<&Window> {
        self.focused.and_then(|id| self.windows.get(&id))
    }

    pub fn focused_id(&self) -> Option<WindowId> {
        self.focused
    }

    pub fn focus_window(&mut self, id: WindowId) {
        if let Some(workspace) = self.windows.get(&id).map(|w| w.workspace) {
            // Switch to the target's workspace first if it isn't already
            // the active one - without this, focusing a window elsewhere
            // (Alt-Tab, a dock icon, anything that ends up calling this)
            // marked it focused while leaving it genuinely off-screen:
            // `visible_windows`/rendering both gate on `workspace ==
            // current_workspace`, so keyboard focus landed on a window the
            // user could not see, while whatever was actually on screen
            // kept looking focused-ish. Reported live (relayed from the
            // AGS peer session, who measured it directly over IPC):
            // `srd dispatch focus` on a window from a different workspace
            // left `current_workspace` unchanged and the target `visible:
            // false`. Every caller of `focus_window` gets this for free
            // rather than each one remembering to switch workspaces
            // itself first - matches the convention the AGS shell was
            // already built against (Hyprland's `focuswindow` switches
            // workspace as a side effect of focusing). Guarded on
            // `w.workspace != self.current_workspace` specifically, not
            // just always calling `switch_workspace`: that function's own
            // `auto_back_and_forth` handling treats being asked to
            // "switch" to the *already*-current workspace as a deliberate
            // toggle-to-previous gesture, which an ordinary redundant
            // focus call (the common case: re-focusing whatever is
            // already focused and already visible) must not trigger as a
            // surprise workspace jump.
            if workspace != self.current_workspace {
                self.switch_workspace(workspace);
            }
            // A minimized window's dock icon (or Alt-Tab entry, or any
            // other `focus_window` caller) has to un-minimize it too, not
            // just focus it - without this, clicking a minimized app's
            // dock icon left it focused (keyboard input, `srd clients`'
            // own `focused: true`) while still `minimized: true`, still
            // excluded from `visible_windows`/rendering. Reads exactly like
            // the click did nothing, since the one visible thing "focused"
            // usually implies (the window coming to the front) never
            // happens. Every desktop's taskbar/dock has this behavior for
            // free; this compositor's `Activate` (zwlr-foreign-toplevel)
            // and `"focus"` IPC handlers both route through here already,
            // so they get it too rather than each needing their own
            // explicit restore call.
            if let Some(w) = self.windows.get_mut(&id) {
                w.minimized = false;
            }
            self.focused = Some(id);
            self.raise_window(id);
        }
    }

    pub(super) fn cycle_focus(&mut self, forward: bool) {
        let ids: Vec<WindowId> = self.windows_on_workspace(self.current_workspace).filter(|w| !w.minimized).map(|w| w.id).collect();
        if ids.is_empty() {
            self.focused = None;
            return;
        }
        let cur_pos = self.focused.and_then(|f| ids.iter().position(|&i| i == f));
        let next = match cur_pos {
            None => 0,
            Some(p) if forward => (p + 1) % ids.len(),
            Some(p) => (p + ids.len() - 1) % ids.len(),
        };
        self.focus_window(ids[next]);
    }

    pub fn focus_next(&mut self) {
        self.cycle_focus(true);
    }

    pub fn focus_previous(&mut self) {
        self.cycle_focus(false);
    }

    /// Vim-style directional focus: picks the nearest window whose center
    /// lies in `dir` relative to the focused window's center, on the same
    /// workspace. Returns the newly focused window, if any.
    /// Nearest window to the focused one in `dir`, by a distance biased
    /// toward the requested axis so a window that's mostly to the left
    /// (small |dy|) beats a diagonally-placed one - matching how
    /// i3/sway-style directional focus feels.
    ///
    /// Shared by [`Self::focus_direction`] and [`Self::move_window_direction`]
    /// so "the window to the left" means the same thing whether you're
    /// focusing it or swapping with it.
    pub fn neighbour_in(&self, dir: Direction) -> Option<WindowId> {
        let (fx, fy, fid) = {
            let focused = self.focused_window()?;
            let (fx, fy) = focused.geometry.center();
            (fx, fy, focused.id)
        };
        let workspace = self.current_workspace;
        let mut best: Option<(WindowId, i64)> = None;
        for w in self.windows_on_workspace(workspace).filter(|w| w.id != fid && !w.minimized) {
            let (cx, cy) = w.geometry.center();
            let (dx, dy) = ((cx - fx) as i64, (cy - fy) as i64);
            let matches = match dir {
                Direction::Left => dx < 0,
                Direction::Right => dx > 0,
                Direction::Up => dy < 0,
                Direction::Down => dy > 0,
            };
            if !matches {
                continue;
            }
            let (primary, secondary) = match dir {
                Direction::Left | Direction::Right => (dx, dy),
                Direction::Up | Direction::Down => (dy, dx),
            };
            let dist = primary * primary + secondary * secondary * 4;
            if best.is_none_or(|(_, d)| dist < d) {
                best = Some((w.id, dist));
            }
        }
        best.map(|(id, _)| id)
    }

    pub fn focus_direction(&mut self, dir: Direction) -> Option<WindowId> {
        let target = self.neighbour_in(dir);
        if let Some(id) = target {
            self.focus_window(id);
        }
        target
    }

    /// Moves the focused window in `dir` by swapping places with its
    /// neighbour there - the `movewindow l/r/u/d` gesture.
    ///
    /// Swapping (rather than nudging by a fixed step) is what makes this
    /// useful in both of srdwm's modes: under tiling it reorders the layout,
    /// and in dynamic/floating mode two windows trade positions, which is
    /// predictable either way. With no neighbour in that direction the
    /// window is pushed to the corresponding edge of its monitor instead, so
    /// the key still does something sensible.
    /// How far one press moves a window, as a fraction of the monitor.
    ///
    /// An eighth crosses the screen in eight presses, which is fine
    /// control without being tedious, and passes through the middle at the
    /// fourth - the owner asked for "increments, or one side, middle,
    /// other side", and stepping gives both.
    const MOVE_STEP_FRACTION: i32 = 8;

    pub fn move_window_direction(&mut self, dir: Direction) -> Option<WindowId> {
        let focused = self.focused_id()?;
        // Only a tiling layout swaps with the neighbour. Everywhere else a
        // window has its own geometry and "move it left" means move it, not
        // trade places with whatever happens to be over there.
        let tiling = self
            .windows
            .get(&focused)
            .and_then(|w| self.workspace(w.workspace))
            .map(|ws| ws.layout == "tiling")
            .unwrap_or(false);
        if !tiling {
            self.nudge_window(focused, dir);
            return None;
        }
        match self.neighbour_in(dir) {
            Some(other) => {
                let a = self.windows.get(&focused)?.geometry;
                let b = self.windows.get(&other)?.geometry;
                if let Some(w) = self.windows.get_mut(&focused) {
                    w.geometry = b;
                }
                if let Some(w) = self.windows.get_mut(&other) {
                    w.geometry = a;
                }
                // Keep stacking order in step so a tiling layout, which
                // assigns slots from `order`, actually reflects the swap.
                let (ia, ib) = (
                    self.order.iter().position(|&id| id == focused)?,
                    self.order.iter().position(|&id| id == other)?,
                );
                self.order.swap(ia, ib);
                Some(other)
            }
            None => {
                let mon = self.windows.get(&focused).and_then(|w| self.monitor_for(w.monitor))?.geometry;
                let w = self.windows.get_mut(&focused)?;
                match dir {
                    Direction::Left => w.geometry.x = mon.x,
                    Direction::Right => w.geometry.x = mon.right() - w.geometry.width as i32,
                    Direction::Up => w.geometry.y = mon.y,
                    Direction::Down => w.geometry.y = mon.bottom() - w.geometry.height as i32,
                }
                None
            }
        }
    }

    /// Grows or shrinks the focused window one step along `dir`.
    ///
    /// The keyboard counterpart to dragging an edge. srdwm has had
    /// Super+right-drag since before this, which covers the mouse, but
    /// nothing resized a window without one - reported as a missing
    /// keybinding alongside screen lock.
    ///
    /// `grow` decides which way: growing extends the window's far edge in
    /// `dir`, shrinking pulls it back, so Right always affects the right
    /// edge whichever way it moves. The window's top-left stays put, which
    /// is what every keyboard resize does and what keeps repeated presses
    /// predictable.
    ///
    /// Bounded by the same minimums a drag is, and by the monitor's usable
    /// area, so a window can neither be resized to nothing nor grown off
    /// the screen.
    pub fn resize_window_direction(&mut self, dir: Direction, grow: bool) -> Option<WindowId> {
        let focused = self.focused_id()?;
        let area = self.windows.get(&focused).and_then(|w| self.monitor_for(w.monitor)).map(|m| m.geometry)?;
        let step_x = (area.width as i32 / Self::MOVE_STEP_FRACTION).max(1);
        let step_y = (area.height as i32 / Self::MOVE_STEP_FRACTION).max(1);
        let w = self.windows.get_mut(&focused)?;
        let (min_w, min_h) = (w.min_size.0.max(crate::placement::MIN_WINDOW_WIDTH) as i32, w.min_size.1.max(crate::placement::MIN_WINDOW_HEIGHT) as i32);
        let delta_x = if grow { step_x } else { -step_x };
        let delta_y = if grow { step_y } else { -step_y };
        match dir {
            Direction::Left | Direction::Right => {
                let room = area.right() - w.geometry.x;
                w.geometry.width = (w.geometry.width as i32 + delta_x).clamp(min_w, room.max(min_w)) as u32;
            }
            Direction::Up | Direction::Down => {
                let room = area.bottom() - w.geometry.y;
                w.geometry.height = (w.geometry.height as i32 + delta_y).clamp(min_h, room.max(min_h)) as u32;
            }
        }
        Some(focused)
    }

    /// Moves a window one step in `dir`, stopping flush against the edge of
    /// its monitor's usable area.
    ///
    /// This is what a directional move does outside a tiling layout. It used
    /// to slam the window all the way to the edge in one press, which the
    /// owner reported as "it should move in increments, one side, middle,
    /// other side - not just extreme left/up/right/down".
    ///
    /// The step is a fraction of the monitor rather than a pixel count, so
    /// the same keypress feels the same on a laptop panel and on a 4K
    /// display. Landing within one step of an edge snaps flush to it, so the
    /// window can always be put exactly against the side rather than a few
    /// pixels short of it.
    fn nudge_window(&mut self, id: WindowId, dir: Direction) {
        let Some(area) = self.windows.get(&id).and_then(|w| self.monitor_for(w.monitor)).map(|m| m.geometry) else { return };
        let step_x = (area.width as i32 / Self::MOVE_STEP_FRACTION).max(1);
        let step_y = (area.height as i32 / Self::MOVE_STEP_FRACTION).max(1);
        let Some(w) = self.windows.get_mut(&id) else { return };
        let (width, height) = (w.geometry.width as i32, w.geometry.height as i32);
        let (min_x, max_x) = (area.x, (area.right() - width).max(area.x));
        let (min_y, max_y) = (area.y, (area.bottom() - height).max(area.y));
        match dir {
            Direction::Left => w.geometry.x = (w.geometry.x - step_x).max(min_x),
            Direction::Right => w.geometry.x = (w.geometry.x + step_x).min(max_x),
            Direction::Up => w.geometry.y = (w.geometry.y - step_y).max(min_y),
            Direction::Down => w.geometry.y = (w.geometry.y + step_y).min(max_y),
        }
    }
}