xdg-shell: honor client move/resize requests

 river/Cursor.zig      |  2 +-
 river/XdgToplevel.zig | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/river/Cursor.zig b/river/Cursor.zig
index 3f9d986..52fbecf 100644
--- a/river/Cursor.zig
+++ b/river/Cursor.zig
@@ -741,7 +741,7 @@ fn computeEdges(cursor: *const Self, view: *const View) wlr.Edges {
 }
 
 fn enterMode(cursor: *Self, mode: Mode, view: *View, image: Image) void {
-    assert(cursor.mode == .passthrough);
+    assert(cursor.mode == .passthrough or cursor.mode == .down);
     assert(mode == .move or mode == .resize);
 
     log.debug("enter {s} cursor mode", .{@tagName(mode)});
diff --git a/river/XdgToplevel.zig b/river/XdgToplevel.zig
index 91bee57..9aa68bd 100644
--- a/river/XdgToplevel.zig
+++ b/river/XdgToplevel.zig
@@ -53,6 +53,10 @@ ack_configure: wl.Listener(*wlr.XdgSurface.Configure) =
     wl.Listener(*wlr.XdgSurface.Configure).init(handleAckConfigure),
 commit: wl.Listener(*wlr.Surface) = wl.Listener(*wlr.Surface).init(handleCommit),
 request_fullscreen: wl.Listener(void) = wl.Listener(void).init(handleRequestFullscreen),
+request_move: wl.Listener(*wlr.XdgToplevel.event.Move) =
+    wl.Listener(*wlr.XdgToplevel.event.Move).init(handleRequestMove),
+request_resize: wl.Listener(*wlr.XdgToplevel.event.Resize) =
+    wl.Listener(*wlr.XdgToplevel.event.Resize).init(handleRequestResize),
 set_title: wl.Listener(void) = wl.Listener(void).init(handleSetTitle),
 set_app_id: wl.Listener(void) = wl.Listener(void).init(handleSetAppId),
 
@@ -161,6 +165,8 @@ fn handleMap(listener: *wl.Listener(void)) void {
     self.xdg_toplevel.base.events.ack_configure.add(&self.ack_configure);
     self.xdg_toplevel.base.surface.events.commit.add(&self.commit);
     self.xdg_toplevel.events.request_fullscreen.add(&self.request_fullscreen);
+    self.xdg_toplevel.events.request_move.add(&self.request_move);
+    self.xdg_toplevel.events.request_resize.add(&self.request_resize);
     self.xdg_toplevel.events.set_title.add(&self.set_title);
     self.xdg_toplevel.events.set_app_id.add(&self.set_app_id);
 
@@ -202,6 +208,8 @@ fn handleUnmap(listener: *wl.Listener(void)) void {
     self.ack_configure.link.remove();
     self.commit.link.remove();
     self.request_fullscreen.link.remove();
+    self.request_move.link.remove();
+    self.request_resize.link.remove();
     self.set_title.link.remove();
     self.set_app_id.link.remove();
 
@@ -297,6 +305,47 @@ fn handleRequestFullscreen(listener: *wl.Listener(void)) void {
     }
 }
 
+fn handleRequestMove(
+    listener: *wl.Listener(*wlr.XdgToplevel.event.Move),
+    event: *wlr.XdgToplevel.event.Move,
+) void {
+    const self = @fieldParentPtr(Self, "request_move", listener);
+    const seat = @intToPtr(*Seat, event.seat.seat.data);
+    const view = self.view;
+
+    if (view.current.output == null or view.pending.output == null) return;
+    if (view.current.tags & view.current.output.?.current.tags == 0) return;
+    if (view.pending.fullscreen) return;
+    if (!(view.pending.float or view.pending.output.?.layout == null)) return;
+
+    seat.cursor.startMove(view);
+}
+
+fn handleRequestResize(listener: *wl.Listener(*wlr.XdgToplevel.event.Resize), event: *wlr.XdgToplevel.event.Resize) void {
+    const self = @fieldParentPtr(Self, "request_resize", listener);
+    const seat = @intToPtr(*Seat, event.seat.seat.data);
+    const view = self.view;
+
+    {
+        // TODO(wlroots) remove this after updating to the next wlroots version
+        // https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4041
+        if ((event.edges.top and event.edges.bottom) or (event.edges.left and event.edges.right)) {
+            self.xdg_toplevel.resource.postError(
+                .invalid_resize_edge,
+                "provided value is not a valid variant of the resize_edge enum",
+            );
+            return;
+        }
+    }
+
+    if (view.current.output == null or view.pending.output == null) return;
+    if (view.current.tags & view.current.output.?.current.tags == 0) return;
+    if (view.pending.fullscreen) return;
+    if (!(view.pending.float or view.pending.output.?.layout == null)) return;
+
+    seat.cursor.startResize(view, event.edges);
+}
+
 /// Called when the client sets / updates its title
 fn handleSetTitle(listener: *wl.Listener(void)) void {
     const self = @fieldParentPtr(Self, "set_title", listener);