From 935063d8924c070ff83415a3eed33117f4a7c70c Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 13 Mar 2024 13:23:55 -0700
Subject: [PATCH] core: scroll to selection working

---
 src/Surface.zig           | 36 ++++++++++++++++++++----------------
 src/terminal/PageList.zig | 13 +++++++++++++
 src/terminal/Screen.zig   |  2 ++
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/src/Surface.zig b/src/Surface.zig
index 2418a535c..6ffc001e9 100644
--- a/src/Surface.zig
+++ b/src/Surface.zig
@@ -1358,14 +1358,14 @@ pub fn keyCallback(
     if (event.mods.shift) adjust_selection: {
         self.renderer_state.mutex.lock();
         defer self.renderer_state.mutex.unlock();
-        var screen = self.io.terminal.screen;
+        var screen = &self.io.terminal.screen;
         const sel = if (screen.selection) |*sel| sel else break :adjust_selection;
 
         // Silently consume key releases. We only want to process selection
         // adjust on press.
         if (event.action != .press and event.action != .repeat) return .consumed;
 
-        sel.adjust(&screen, switch (event.key) {
+        sel.adjust(screen, switch (event.key) {
             .left => .left,
             .right => .right,
             .up => .up,
@@ -1378,20 +1378,24 @@ pub fn keyCallback(
         });
 
         // If the selection endpoint is outside of the current viewpoint,
-        // scroll it in to view.
-        // TODO(paged-terminal)
-        // scroll: {
-        //     const viewport_max = terminal.Screen.RowIndexTag.viewport.maxLen(&screen) - 1;
-        //     const viewport_end = screen.viewport + viewport_max;
-        //     const delta: isize = if (sel.end.y < screen.viewport)
-        //         @intCast(screen.viewport)
-        //     else if (sel.end.y > viewport_end)
-        //         @intCast(viewport_end)
-        //     else
-        //         break :scroll;
-        //     const start_y: isize = @intCast(sel.end.y);
-        //     try self.io.terminal.scrollViewport(.{ .delta = start_y - delta });
-        // }
+        // scroll it in to view. Note we always specifically use sel.end
+        // because that is what adjust modifies.
+        scroll: {
+            const viewport_tl = screen.pages.getTopLeft(.viewport);
+            const viewport_br = screen.pages.getBottomRight(.viewport).?;
+            if (sel.end().isBetween(viewport_tl, viewport_br))
+                break :scroll;
+
+            // Our end point is not within the viewport. If the end
+            // point is after the br then we need to adjust the end so
+            // that it is at the bottom right of the viewport.
+            const target = if (sel.end().before(viewport_tl))
+                sel.end()
+            else
+                sel.end().up(screen.pages.rows - 1) orelse sel.end();
+
+            screen.scroll(.{ .pin = target });
+        }
 
         // Queue a render so its shown
         try self.queueRender();
diff --git a/src/terminal/PageList.zig b/src/terminal/PageList.zig
index 96a12513c..f0fa6168d 100644
--- a/src/terminal/PageList.zig
+++ b/src/terminal/PageList.zig
@@ -1413,6 +1413,10 @@ pub const Scroll = union(enum) {
     /// prompts. If the absolute value is greater than the number of prompts
     /// in either direction, jump to the furthest prompt in that direction.
     delta_prompt: isize,
+
+    /// Scroll directly to a specific pin in the page. This will be set
+    /// as the top left of the viewport (ignoring the pin x value).
+    pin: Pin,
 };
 
 /// Scroll the viewport. This will never create new scrollback, allocate
@@ -1422,6 +1426,15 @@ pub fn scroll(self: *PageList, behavior: Scroll) void {
     switch (behavior) {
         .active => self.viewport = .{ .active = {} },
         .top => self.viewport = .{ .top = {} },
+        .pin => |p| {
+            if (self.pinIsActive(p)) {
+                self.viewport = .{ .active = {} };
+                return;
+            }
+
+            self.viewport_pin.* = p;
+            self.viewport = .{ .pin = {} };
+        },
         .delta_prompt => |n| self.scrollPrompt(n),
         .delta_row => |n| {
             if (n == 0) return;
diff --git a/src/terminal/Screen.zig b/src/terminal/Screen.zig
index fe672bb77..571fd1541 100644
--- a/src/terminal/Screen.zig
+++ b/src/terminal/Screen.zig
@@ -552,6 +552,7 @@ pub const Scroll = union(enum) {
     /// For all of these, see PageList.Scroll.
     active,
     top,
+    pin: Pin,
     delta_row: isize,
     delta_prompt: isize,
 };
@@ -566,6 +567,7 @@ pub fn scroll(self: *Screen, behavior: Scroll) void {
     switch (behavior) {
         .active => self.pages.scroll(.{ .active = {} }),
         .top => self.pages.scroll(.{ .top = {} }),
+        .pin => |p| self.pages.scroll(.{ .pin = p }),
         .delta_row => |v| self.pages.scroll(.{ .delta_row = v }),
         .delta_prompt => |v| self.pages.scroll(.{ .delta_prompt = v }),
     }