feat: discard changes per file, hunk or line, after confirming

README.md

@@ -49,6 +49,7 @@ with that one.
   coloured lanes, branch and tag labels and the uncommitted changes on top. Arrow keys walk it.
 - **Commits**: message, author, parents and the files they changed, with the diff of each file.
 - **Staging**: stage or unstage files, whole hunks or single lines, then commit or amend.
+- **Discard**: throw away the changes to a file, a hunk or single lines, after you confirm.
 - **Branches and tags**: create, check out, merge, rebase, delete, from the sidebar or a right click.
 - **Commits from the graph**: check out, cherry-pick, revert, reset (soft, mixed, hard), copy the SHA.
 - **Remotes**: fetch, pull and push, with how far ahead and behind you are.

ROADMAP.md

@@ -22,27 +22,27 @@ drive it the way a user does, and keeps every benchmark as fast as before.
 - [x] Clone and init from the start screen, with progress
 - [x] Tabs: several repositories open at once, remembered between runs
 - [x] Live refresh: watch the working tree and refs, and reload by itself
+- [x] Discard changes per file, hunk or line, after a confirmation
 
 ## Next
 
-1. **Discard** changes per file, hunk or line.
-2. **Confirm destructive actions**: hard reset, deleting a branch with unmerged commits, force push.
-3. **Undo and redo** of the last action, through the reflog.
-4. **Conflicts**: list conflicted files, resolve them in a three-way view (ours, theirs, result),
+1. **Confirm destructive actions**: hard reset, deleting a branch with unmerged commits, force push.
+2. **Undo and redo** of the last action, through the reflog.
+3. **Conflicts**: list conflicted files, resolve them in a three-way view (ours, theirs, result),
    mark them resolved, and continue or abort a merge, rebase or cherry-pick.
-5. **Interactive rebase**: reorder, squash, fix up, reword and drop commits, by dragging in the
+4. **Interactive rebase**: reorder, squash, fix up, reword and drop commits, by dragging in the
    graph.
-6. **Credentials**: ask for a username, password or passphrase when git needs one.
-7. **Push and pull options**: force with lease, push tags, pick the remote, pull with rebase.
-8. **Remotes**: add, edit and remove.
-9. **Search the graph** by message, author or SHA, and jump to any branch or tag.
-10. **File history and blame.**
-11. **Better diffs**: side by side, word-level changes, syntax colouring, images.
-12. **Keyboard**: shortcuts for everything, and a command palette.
-13. **Settings**: light and dark theme, font size, date format, default pull mode.
-14. **Graph polish**: resizable columns, compact lanes, author avatars (optional, never by default
+5. **Credentials**: ask for a username, password or passphrase when git needs one.
+6. **Push and pull options**: force with lease, push tags, pick the remote, pull with rebase.
+7. **Remotes**: add, edit and remove.
+8. **Search the graph** by message, author or SHA, and jump to any branch or tag.
+9. **File history and blame.**
+10. **Better diffs**: side by side, word-level changes, syntax colouring, images.
+11. **Keyboard**: shortcuts for everything, and a command palette.
+12. **Settings**: light and dark theme, font size, date format, default pull mode.
+13. **Graph polish**: resizable columns, compact lanes, author avatars (optional, never by default
     over the network).
-15. **Packaging**: installers with the icon for Windows (MSI), macOS (.app in a .dmg) and Linux
+14. **Packaging**: installers with the icon for Windows (MSI), macOS (.app in a .dmg) and Linux
     (AppImage, .deb, Flatpak), signed where the platform expects it.
 
 ## After 1.0

crates/app/src/app.rs

@@ -38,6 +38,8 @@ pub enum Action {
     ToggleLine(usize, usize),
     /// Ask for a name first.
     Prompt(Prompt),
+    /// Ask whether to go ahead first.
+    Confirm(Confirm),
     /// Open a repository in a tab of its own, or show its tab if it is open.
     OpenRepo(PathBuf),
     /// Show a tab, or the start screen for `None`.
@@ -80,6 +82,17 @@ impl Prompt {
     }
 }
 
+/// An operation that throws work away, waiting for the user to go ahead.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Confirm {
+    /// What will be lost, as a question.
+    pub question: String,
+    /// The button that goes ahead.
+    pub verb: &'static str,
+    /// The operation.
+    pub op: Op,
+}
+
 /// Everything read in the background after a change.
 #[derive(Debug, Default)]
 pub struct Snapshot {
@@ -158,6 +171,8 @@ pub struct Workspace {
     pub amend: bool,
     /// A name being asked for.
     pub prompt: Option<(Prompt, String)>,
+    /// An operation waiting for the user to go ahead.
+    pub confirm: Option<Confirm>,
     /// The last thing that went wrong.
     pub error: Option<String>,
     /// A graph row to scroll to.
@@ -187,6 +202,7 @@ impl Workspace {
             description: String::new(),
             amend: false,
             prompt: None,
+            confirm: None,
             error: None,
             scroll_to: None,
             visible: 0..0,
@@ -248,6 +264,7 @@ impl Workspace {
                 }
             }
             Action::Prompt(prompt) => self.prompt = Some((prompt, String::new())),
+            Action::Confirm(confirm) => self.confirm = Some(confirm),
             Action::OpenRepo(_) | Action::ShowTab(_) | Action::CloseTab(_) => unreachable!("the app handles tabs"),
         }
     }
@@ -340,7 +357,15 @@ impl Workspace {
             }
         }
         if let Some(file) = &mut self.open_file {
+            // A file in the working tree without changes left, or gone altogether, closes.
+            let entries = &self.snapshot.status.entries;
+            if !matches!(file.source, Source::Commit { .. }) && !entries.iter().any(|e| e.path == file.source.path()) {
+                self.open_file = None;
+                return;
+            }
+            // The picked lines stay picked as long as the diff stays the same.
             match diff::read(&self.repo.git, &file.source) {
+                Ok(diff) if diff == file.diff => {}
                 Ok(diff) => (file.diff, file.lines) = (diff, BTreeSet::new()),
                 Err(error) => self.error = Some(error.to_string()),
             }

crates/app/src/details.rs

@@ -1,12 +1,12 @@
 //! The panel on the right: the uncommitted changes with the commit form, or a commit.
 
-use eframe::egui::{self, Button, Layout, RichText, TextEdit, Ui};
+use eframe::egui::{self, Button, Layout, RichText, Role, TextEdit, Ui, WidgetInfo};
 use gitcraft_core::ObjectId;
 use gitcraft_core::diff::Source;
 use gitcraft_core::git::Op;
 use gitcraft_core::status::Change;
 
-use crate::app::{Action, Selection, Workspace};
+use crate::app::{Action, Confirm, Selection, Workspace};
 use crate::theme;
 
 /// Shows the panel.
@@ -20,16 +20,16 @@ pub fn show(ui: &mut Ui, ws: &mut Workspace, actions: &mut Vec<Action>) {
     }
 }
 
-/// One changed file: its kind of change, its path, and a button.
-fn file(ui: &mut Ui, change: Change, path: &str, open: bool, button: Option<&str>) -> (bool, bool) {
+/// One changed file: its kind of change, its path, and `buttons` on the right, right to left.
+/// Returns whether the path was clicked.
+fn file(ui: &mut Ui, change: Change, path: &str, open: bool, buttons: impl FnOnce(&mut Ui)) -> bool {
     let (letter, colour) = theme::change(change);
     ui.horizontal(|ui| {
         ui.with_layout(Layout::right_to_left(egui::Align::Center), |ui| {
-            let pressed = button.is_some_and(|text| ui.small_button(text).clicked());
+            buttons(ui);
             ui.with_layout(Layout::left_to_right(egui::Align::Center), |ui| {
                 ui.label(RichText::new(letter).monospace().strong().color(colour));
-                let clicked = ui.add(Button::selectable(open, path).truncate()).clicked();
-                (clicked, pressed)
+                ui.add(Button::selectable(open, path).truncate()).clicked()
             })
             .inner
         })
@@ -38,6 +38,16 @@ fn file(ui: &mut Ui, change: Change, path: &str, open: bool, button: Option<&str
     .inner
 }
 
+/// Throwing away the unstaged changes to a file, or the whole file when git does not track it.
+fn discard(change: Change, path: &str) -> Confirm {
+    if change == Change::Untracked {
+        let question = format!("Delete {path}? Git does not track it.");
+        return Confirm { question, verb: "Delete", op: Op::DeleteUntracked(vec![path.into()]) };
+    }
+    let question = format!("Discard the unstaged changes to {path}?");
+    Confirm { question, verb: "Discard", op: Op::Discard(vec![path.into()]) }
+}
+
 fn changes(ui: &mut Ui, ws: &mut Workspace, actions: &mut Vec<Action>) {
     let open = ws.open_file.as_ref().map(|f| &f.source);
     let entries = &ws.snapshot.status.entries;
@@ -59,10 +69,20 @@ fn changes(ui: &mut Ui, ws: &mut Workspace, actions: &mut Vec<Action>) {
             } else {
                 Source::Unstaged(path.into())
             };
-            let (clicked, stage) = file(ui, change, path, open == Some(&source), Some("Stage"));
-            if stage {
-                actions.push(Action::Run(Op::Stage(vec![path.into()])));
-            } else if clicked {
+            let clicked = file(ui, change, path, open == Some(&source), |ui| {
+                if ui.small_button("Stage").clicked() {
+                    actions.push(Action::Run(Op::Stage(vec![path.into()])));
+                }
+                // Conflicts are resolved, not discarded.
+                if change != Change::Conflicted {
+                    let button = ui.small_button("Discard");
+                    button.widget_info(|| WidgetInfo::labeled(Role::Button, true, format!("Discard {path}")));
+                    if button.clicked() {
+                        actions.push(Action::Confirm(discard(change, path)));
+                    }
+                }
+            });
+            if clicked {
                 actions.push(Action::Open(source));
             }
         }
@@ -77,10 +97,12 @@ fn changes(ui: &mut Ui, ws: &mut Workspace, actions: &mut Vec<Action>) {
     egui::ScrollArea::vertical().id_salt("staged").max_height(half).auto_shrink([false, true]).show(ui, |ui| {
         for &(change, path) in &staged {
             let source = Source::Staged(path.into());
-            let (clicked, unstage) = file(ui, change, path, open == Some(&source), Some("Unstage"));
-            if unstage {
-                actions.push(Action::Run(Op::Unstage(vec![path.into()])));
-            } else if clicked {
+            let clicked = file(ui, change, path, open == Some(&source), |ui| {
+                if ui.small_button("Unstage").clicked() {
+                    actions.push(Action::Run(Op::Unstage(vec![path.into()])));
+                }
+            });
+            if clicked {
                 actions.push(Action::Open(source));
             }
         }
@@ -151,7 +173,7 @@ fn commit(ui: &mut Ui, ws: &mut Workspace, id: ObjectId, actions: &mut Vec<Actio
     egui::ScrollArea::vertical().auto_shrink([false, true]).show(ui, |ui| {
         for change in files {
             let source = Source::Commit { commit: sha.clone(), path: change.path.clone() };
-            if file(ui, change.change, &change.path, open == Some(&source), None).0 {
+            if file(ui, change.change, &change.path, open == Some(&source), |_| {}) {
                 actions.push(Action::Open(source));
             }
         }

crates/app/src/diff.rs

@@ -1,23 +1,41 @@
-//! The diff of one file, with staging of hunks and single lines.
+//! The diff of one file, with staging and discarding of hunks and single lines.
 
 use eframe::egui::{self, Align2, Color32, FontId, Key, Rect, RichText, Sense, Ui, Vec2};
 use gitcraft_core::diff::{LineKind, Source};
 use gitcraft_core::git::Op;
 
-use crate::app::{Action, OpenFile};
+use crate::app::{Action, Confirm, OpenFile};
 use crate::theme;
 
 const LINE: f32 = 18.0;
 const NUMBER: f32 = 44.0;
 
+/// What can be done with lines of the file.
+fn verbs(source: &Source) -> &'static [&'static str] {
+    match source {
+        Source::Unstaged(_) => &["Stage", "Discard"],
+        Source::Staged(_) => &["Unstage"],
+        Source::Untracked(_) | Source::Commit { .. } => &[],
+    }
+}
+
+/// Doing `verb` with the `selected` lines, which `what` names.
+fn act(file: &OpenFile, verb: &'static str, what: &str, selected: &dyn Fn(usize, usize) -> bool) -> Action {
+    // Unstaging and discarding both start from the lines as they are now, and take them out.
+    let reverse = verb != "Stage";
+    let patch = file.diff.patch(selected, reverse);
+    if verb == "Discard" {
+        let question = format!("Discard {what} of {}?", file.source.path());
+        return Action::Confirm(Confirm { question, verb, op: Op::DiscardLines(patch) });
+    }
+    Action::Run(Op::ApplyToIndex { patch, reverse })
+}
+
 /// Shows the open file.
 pub fn show(ui: &mut Ui, file: &OpenFile, actions: &mut Vec<Action>) {
-    let reverse = matches!(file.source, Source::Staged(_));
-    let stageable = matches!(file.source, Source::Unstaged(_) | Source::Staged(_));
-    let verb = if reverse { "Unstage" } else { "Stage" };
-    let run = |selected: &dyn Fn(usize, usize) -> bool| {
-        Action::Run(Op::ApplyToIndex { patch: file.diff.patch(selected, reverse), reverse })
-    };
+    let verbs = verbs(&file.source);
+    let picked = |h, l| file.lines.contains(&(h, l));
+    let lines = theme::count(file.lines.len(), "line");
     ui.horizontal(|ui| {
         ui.strong(file.source.path());
         ui.weak(match file.source {
@@ -30,9 +48,10 @@ pub fn show(ui: &mut Ui, file: &OpenFile, actions: &mut Vec<Action>) {
             if ui.button("Close").clicked() || ui.input(|i| i.key_pressed(Key::Escape)) {
                 actions.push(Action::CloseFile);
             }
-            if stageable && !file.lines.is_empty() && ui.button(format!("{verb} {} lines", file.lines.len())).clicked()
-            {
-                actions.push(run(&|h, l| file.lines.contains(&(h, l))));
+            for verb in verbs {
+                if !file.lines.is_empty() && ui.button(format!("{verb} {lines}")).clicked() {
+                    actions.push(act(file, verb, &lines, &picked));
+                }
             }
         });
     });
@@ -68,22 +87,21 @@ pub fn show(ui: &mut Ui, file: &OpenFile, actions: &mut Vec<Action>) {
                     font.clone(),
                     Color32::GRAY,
                 );
-                if stageable {
-                    let button = Rect::from_min_size(rect.right_top() - Vec2::X * 110.0, Vec2::new(104.0, LINE));
+                for (verb, x) in verbs.iter().zip([110.0, 220.0]) {
+                    let button = Rect::from_min_size(rect.right_top() - Vec2::X * x, Vec2::new(104.0, LINE));
                     if ui.put(button, egui::Button::new(RichText::new(format!("{verb} hunk")).small())).clicked() {
-                        actions.push(run(&|hh, _| hh == h));
+                        actions.push(act(file, verb, "this hunk", &|hh, _| hh == h));
                     }
                 }
                 continue;
             };
             let line = &hunk.lines[l];
-            let picked = file.lines.contains(&(h, l));
             let (background, marker) = match line.kind {
                 LineKind::Added => (theme::ADDED, "+"),
                 LineKind::Removed => (theme::REMOVED, "-"),
                 LineKind::Context | LineKind::NoNewline => (Color32::TRANSPARENT, " "),
             };
-            painter.rect_filled(rect, 0.0, if picked { theme::PICKED } else { background });
+            painter.rect_filled(rect, 0.0, if picked(h, l) { theme::PICKED } else { background });
             let number = |n: Option<u32>| n.map(|n| n.to_string()).unwrap_or_default();
             let at = |x: f32| rect.left_center() + Vec2::X * x;
             painter.text(at(NUMBER - 6.0), Align2::RIGHT_CENTER, number(line.old), font.clone(), Color32::DARK_GRAY);
@@ -97,7 +115,7 @@ pub fn show(ui: &mut Ui, file: &OpenFile, actions: &mut Vec<Action>) {
             let text = format!("{marker} {}", line.text.trim_end_matches('\r'));
             painter.text(at(2.0 * NUMBER + 6.0), Align2::LEFT_CENTER, text, font.clone(), ui.visuals().text_color());
             let changed = matches!(line.kind, LineKind::Added | LineKind::Removed);
-            if stageable && changed && response.clicked() {
+            if !verbs.is_empty() && changed && response.clicked() {
                 actions.push(Action::ToggleLine(h, l));
             }
         }