Fix file history for all sizes

Replace temporary fix by proper fix

Author: cruessler

src/components/file_revlog.rs

@@ -152,10 +152,9 @@ impl FileRevlogComponent {
 				git_log.fetch()? == FetchStatus::Started;
 
 			let table_state = self.table_state.take();
-			let start = table_state.selected().unwrap_or(0);
-			self.table_state.set(table_state);
+			let offset = table_state.offset();
 
-			if self.items.needs_data(start, git_log.count()?)
+			if self.items.needs_data(offset, git_log.count()?)
 				|| log_changed
 			{
 				self.fetch_commits()?;
@@ -225,44 +224,18 @@ impl FileRevlogComponent {
 	fn fetch_commits(&mut self) -> Result<()> {
 		if let Some(git_log) = &mut self.git_log {
 			let table_state = self.table_state.take();
+			let offset = table_state.offset();
 
 			let commits = get_commits_info(
 				&self.repo_path.borrow(),
-				&git_log.get_slice(0, SLICE_SIZE)?,
+				&git_log.get_slice(offset, SLICE_SIZE)?,
 				self.current_width.get(),
 			);
 
 			if let Ok(commits) = commits {
-				// 2023-04-12
-				//
-				// There is an issue with how windowing works in `self.items` and
-				// `self.table_state`. Because of that issue, we currently have to pass
-				// `0` as the first argument to `set_items`. If we did not do that, the
-				// offset that is kept separately in `self.items` and `self.table_state`
-				// would get out of sync, resulting in the table showing the wrong rows.
-				//
-				// The offset determines the number of rows `render_stateful_widget`
-				// skips when rendering a table. When `set_items` is called, it clears
-				// its internal `Vec` of items and sets `index_offset` based on the
-				// parameter passed. Unfortunately, there is no way for us to pass this
-				// information, `index_offset`, to `render_stateful_widget`. Because of
-				// that, `render_stateful_widget` assumes that the rows provided by
-				// `Table` are 0-indexed while in reality they are
-				// `index_offset`-indexed.
-				//
-				// This fix makes the `FileRevlog` unable to show histories that have
-				// more than `SLICE_SIZE` items, but since it is broken for larger
-				// histories anyway, this seems acceptable for the time being.
-				//
-				// This issue can only properly be fixed upstream, in `tui-rs`. See
-				// [tui-issue].
-				//
-				// [gitui-issue]: https://github.com/extrawurst/gitui/issues/1560
-				// [tui-issue]: https://github.com/fdehau/tui-rs/issues/626
-				self.items.set_items(0, commits);
+				self.items.set_items(offset, commits);
 			}
 
-			self.table_state.set(table_state);
 			self.count_total = git_log.count()?;
 		}
 
@@ -374,6 +347,13 @@ impl FileRevlogComponent {
 			self.queue.push(InternalEvent::Update(NeedsUpdate::DIFF));
 		}
 
+		let height_in_items = self.current_height.get() / 2;
+		let new_offset =
+			new_selection.saturating_sub(height_in_items);
+
+		let offset = table_state.offset_mut();
+		*offset = new_offset;
+
 		table_state.select(Some(new_selection));
 		self.table_state.set(table_state);