wip: handle range resets when switching sheets

* show what you are selecting in range mode
* Fix error with cell edit not updating after Enter

docs/index.md

@@ -22,11 +22,14 @@ Options:
 
 ## User Interface
 
-The sheetui user interface is loosely inspired by vim. It is a modal interface that is entirely keyboard driven. At nearly any time you can type `Alt-h` to get some context sensitive help.
+The sheetui user interface is loosely inspired by vim. It is a modal interface
+that is entirely keyboard driven. At nearly any time you can type `Alt-h` to
+get some context sensitive help.
 
 ### Navigation Mode
 
-The interface will start out in navigation mode. You can navigate around the table and between the sheets using the following keybinds:
+The interface will start out in navigation mode. You can navigate around the
+table and between the sheets using the following keybinds:
 
 **Cell Navigation**
 
@@ -44,7 +47,9 @@ Sheet navigation moving will loop around when you reach the ends.
 
 **Numeric prefixes**
 
-You can prefix each of the keybinds above with a numeric prefix to do them that many times. So typing `123h` will move to the left 123 times. Hitting `Esc` will clear the numeric prefix if you want to cancel it.
+You can prefix each of the keybinds above with a numeric prefix to do them that
+many times. So typing `123h` will move to the left 123 times. Hitting `Esc`
+will clear the numeric prefix if you want to cancel it.
 
 **Modifying the Sheet or Cells**
 
@@ -54,33 +59,51 @@ You can prefix each of the keybinds above with a numeric prefix to do them that
 
 **Other Keybindings**
 
+* `Ctrl-r` will enter range selection mode
 * `Ctrl-s` will save the sheet.
 * `q` will exit the application.
 * `:` will enter CommandMode.
 
-<aside>Note that for `q` this will not currently prompt you if the sheet is not saved.</aside>
+Range selections made from navigation mode will be available to paste into a Cell Edit.
+
+<aside>Note that for `q` this will not currently prompt you if the sheet is not
+saved.</aside>
 
 ### CellEdit Mode
 
-You enter CellEdit mode by hitting `e` or `i` while in navigation mode. Type what you want into the cell.
+You enter CellEdit mode by hitting `e` or `i` while in navigation mode. Type
+what you want into the cell.
 
 Starting with:
 
 * `=` will treat what you type as a formula.
 * `$` will treat it as us currency.
 
-Typing a number will treat the contents as a number. While typing non-numeric text will treat it as text content. <aside>We do not yet support modifying the type of a cell after the fact. We may add this in the future.</aside>
+Typing a number will treat the contents as a number. While typing non-numeric
+text will treat it as text content.
 
-For the most part this should work the same way you expect a spreadsheet to work.
+<aside>We do not yet support modifying the type of a cell after the fact. We
+may add this in the future.</aside>
+
+For the most part this should work the same way you expect a spreadsheet to
+work.
 
 * `Enter` will update the cell contents.
 * `Esc` will cancel editing the cell and leave it unedited.
+* `Ctrl-p` will paste the range selection if it exists into the cell.
 
-You can find the functions we support documented here: [ironcalc docs](https://docs.ironcalc.com/functions/lookup-and-reference.html)
+`Ctrl-r` will enter range select mode when editing a formula. You can navigate
+around the sheet and hit space to select that cell in the sheet to set the
+start of the range. Navigate some more and hit space to set the end of the
+range.
+
+You can find the functions we support documented here:
+[ironcalc docs](https://docs.ironcalc.com/functions/lookup-and-reference.html)
 
 ### Command Mode
 
-You enter command mode by typing `:` while in navigation mode. You can then type a command and hit `Enter` to execute it or `Esc` to cancel.
+You enter command mode by typing `:` while in navigation mode. You can then
+type a command and hit `Enter` to execute it or `Esc` to cancel.
 
 The currently supported commands are:
 
@@ -93,4 +116,22 @@ The currently supported commands are:
 * `edit <path>` Edit a new spreadsheet at the current path. `e` is a shorthand alias for this command. 
 * `quit` Quits the application. `q` is a shorthand alias for this command.
 
-<aside>Note that in the case of `quit` and `edit` that we do not currently prompt you if the current spreadsheet has not been saved yet. So your changes will be discarded if you have not saved first.</aside>
+<aside>Note that in the case of `quit` and `edit` that we do not currently
+prompt you if the current spreadsheet has not been saved yet. So your changes
+will be discarded if you have not saved first.</aside>
+
+### Range Select Mode
+
+Range Select mode copies a range reference for use later. You can enter range
+select mode from CellEdit mode with `CTRL-r`.
+
+* `h`, `j`, `k`, `l` will navigate around the sheet.
+* `Ctrl-n`, `Ctrl-p` will navigate between sheets.
+* `The spacebar will select the start and end of the range respectively.
+
+When you have selected the end of the range you will exit range select mode and
+the range reference will be placed into the cell contents you are editing.
+
+<aside>We only support continuous ranges for the moment. Planned for
+discontinuous ranges still needs the interaction interface to be
+determined.</aside>

src/book/mod.rs

@@ -287,6 +287,13 @@ impl Book {
             .map_err(|s| anyhow!("Invalid Worksheet: {}", s))?)
     }
     
+    pub(crate) fn get_sheet_name_by_idx(&self, idx: usize) -> Result<&str> {
+        Ok(&self
+            .model
+            .workbook
+            .worksheet(idx as u32)
+            .map_err(|s| anyhow!("Invalid Worksheet: {}", s))?.name)
+    }
     pub(crate) fn get_sheet_by_idx_mut(&mut self, idx: usize) -> Result<&mut Worksheet> {
         Ok(self
             .model

src/ui/mod.rs

@@ -30,6 +30,40 @@ pub enum Modality {
     CellEdit,
     Command,
     Dialog,
+    RangeSelect,
+}
+
+#[derive(Debug, Default)]
+pub struct RangeSelection {
+    pub original_location: Option<Address>,
+    pub original_sheet: Option<u32>,
+    pub sheet: Option<u32>,
+    pub start: Option<Address>,
+    pub end: Option<Address>,
+}
+
+impl RangeSelection {
+    pub fn get_range(&self) -> Option<(Address, Address)> {
+        if let (Some(start), Some(end)) = (&self.start, &self.end) {
+            return Some((
+                Address {
+                    row: std::cmp::min(start.row, end.row),
+                    col: std::cmp::min(start.col, end.col),
+                },
+                Address {
+                    row: std::cmp::max(start.row, end.row),
+                    col: std::cmp::max(start.col, end.col),
+                },
+            ));
+        }
+        None
+    }
+
+    pub fn reset_range_selection(&mut self) {
+        self.start = None;
+        self.end = None;
+        self.sheet = None;
+    }
 }
 
 #[derive(Debug)]
@@ -38,6 +72,7 @@ pub struct AppState<'ws> {
     pub viewport_state: ViewportState,
     pub command_state: TextState<'ws>,
     pub numeric_prefix: Vec<char>,
+    pub range_select: RangeSelection,
     dirty: bool,
     popup: Vec<String>,
 }
@@ -49,6 +84,7 @@ impl<'ws> Default for AppState<'ws> {
             viewport_state: Default::default(),
             command_state: Default::default(),
             numeric_prefix: Default::default(),
+            range_select: Default::default(),
             dirty: Default::default(),
             popup: Default::default(),
         }
@@ -97,6 +133,19 @@ impl Address {
     pub fn new(row: usize, col: usize) -> Self {
         Self { row, col }
     }
+
+    pub fn to_range_part(&self) -> String {
+        let count = if self.col == 26 {
+            1
+        } else {
+            (self.col / 26) + 1
+        };
+        format!(
+            "{}{}",
+            render::viewport::COLNAMES[(self.col - 1) % 26].repeat(count),
+            self.row
+        )
+    }
 }
 
 impl Default for Address {
@@ -149,6 +198,26 @@ impl<'ws> Workspace<'ws> {
         Ok(())
     }
 
+    pub fn selected_range_to_string(&self) -> String {
+        let state = &self.state;
+        if let Some((start, end)) = state.range_select.get_range() {
+            let a1 = format!("{}{}", start.to_range_part(), format!(":{}", end.to_range_part()));
+            if let Some(range_sheet) = state.range_select.sheet {
+                if range_sheet != self.book.current_sheet {
+                    return format!(
+                        "{}!{}",
+                        self.book
+                            .get_sheet_name_by_idx(range_sheet as usize)
+                            .expect("No such sheet index"),
+                        a1
+                    );
+                }
+            }
+            return a1;
+        }
+        return String::new()
+    }
+
     /// Move a row down in the current sheet.
     pub fn move_down(&mut self) -> Result<()> {
         let mut loc = self.book.location.clone();
@@ -197,6 +266,7 @@ impl<'ws> Workspace<'ws> {
                 Modality::CellEdit => self.handle_edit_input(key)?,
                 Modality::Command => self.handle_command_input(key)?,
                 Modality::Dialog => self.handle_dialog_input(key)?,
+                Modality::RangeSelect => self.handle_range_select_input(key)?,
             };
             return Ok(result);
         }
@@ -217,13 +287,14 @@ impl<'ws> Workspace<'ws> {
                 "* CTRl-h: Shrink column width by 1".to_string(),
                 "* CTRl-n: Next sheet. Starts over at beginning if at end.".to_string(),
                 "* CTRl-p: Previous sheet. Starts over at end if at beginning.".to_string(),
-                "* CTRl-?: Previous sheet. Starts over at end if at beginning.".to_string(),
+                "* ALT-h: Previous sheet. Starts over at end if at beginning.".to_string(),
                 "* q exit".to_string(),
                 "* Ctrl-S Save sheet".to_string(),
             ],
             Modality::CellEdit => vec![
                 "Edit Mode:".to_string(),
                 "* ENTER/RETURN: Exit edit mode and save changes".to_string(),
+                "* Ctrl-r: Enter Range Selection mode".to_string(),
                 "* ESC: Exit edit mode and discard changes".to_string(),
                 "Otherwise edit as normal".to_string(),
             ],
@@ -233,6 +304,14 @@ impl<'ws> Workspace<'ws> {
                 "* CTRL-?: Exit command mode".to_string(),
                 "* ENTER/RETURN: run command and exit command mode".to_string(),
             ],
+            Modality::RangeSelect => vec![
+                "Range Selection Mode:".to_string(),
+                "* ESC: Exit command mode".to_string(),
+                "* h,j,k,l: vim style navigation".to_string(),
+                "* Spacebar: Select start and end of range".to_string(),
+                "* CTRl-n: Next sheet. Starts over at beginning if at end.".to_string(),
+                "* CTRl-p: Previous sheet. Starts over at end if at beginning.".to_string(),
+            ],
             _ => vec!["General help".to_string()],
         }
     }
@@ -276,6 +355,17 @@ impl<'ws> Workspace<'ws> {
                     self.enter_dialog_mode(self.render_help_text());
                     return Ok(None);
                 }
+                KeyCode::Char('r') if key.modifiers == KeyModifiers::CONTROL => {
+                    self.enter_range_select_mode();
+                    return Ok(None);
+                }
+                KeyCode::Char('p') if key.modifiers == KeyModifiers::CONTROL => {
+                    self.text_area
+                        .set_yank_text(self.selected_range_to_string());
+                    self.text_area.paste();
+                    self.state.dirty = true;
+                    return Ok(None);
+                }
                 KeyCode::Enter => self.exit_edit_mode(true)?,
                 KeyCode::Esc => self.exit_edit_mode(false)?,
                 _ => {
@@ -363,6 +453,91 @@ impl<'ws> Workspace<'ws> {
         self.state.numeric_prefix.push(digit);
     }
 
+    fn handle_range_select_input(&mut self, key: event::KeyEvent) -> Result<Option<ExitCode>> {
+        if key.kind == KeyEventKind::Press {
+            match key.code {
+                KeyCode::Esc => {
+                    if self.state.numeric_prefix.len() > 0 {
+                        self.state.reset_n_prefix();
+                    } else {
+                        self.state.range_select.start = None;
+                        self.state.range_select.end = None;
+                        self.exit_range_select_mode()?;
+                    }
+                }
+                KeyCode::Char('h') if key.modifiers == KeyModifiers::ALT => {
+                    self.enter_dialog_mode(self.render_help_text());
+                    return Ok(None);
+                }
+                KeyCode::Char(d) if d.is_ascii_digit() => {
+                    self.handle_numeric_prefix(d);
+                }
+                KeyCode::Char('h') => {
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.move_left()?;
+                        Ok(())
+                    })?;
+                    self.maybe_update_range_end();
+                }
+                KeyCode::Char('j') => {
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.move_down()?;
+                        Ok(())
+                    })?;
+                    self.maybe_update_range_end();
+                }
+                KeyCode::Char('k') => {
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.move_up()?;
+                        Ok(())
+                    })?;
+                    self.maybe_update_range_end();
+                }
+                KeyCode::Char('l') => {
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.move_right()?;
+                        Ok(())
+                    })?;
+                    self.maybe_update_range_end();
+                }
+                KeyCode::Char(' ') | KeyCode::Enter => {
+                    if self.state.range_select.start.is_none() {
+                        self.state.range_select.start = Some(self.book.location.clone());
+                    } else {
+                        self.state.range_select.end = Some(self.book.location.clone());
+                        self.exit_range_select_mode()?;
+                    }
+                }
+                KeyCode::Char('n') if key.modifiers == KeyModifiers::CONTROL => {
+                    self.state.range_select.reset_range_selection();
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.book.select_next_sheet();
+                        Ok(())
+                    })?;
+                    self.state.range_select.sheet = Some(self.book.current_sheet);
+                }
+                KeyCode::Char('p') if key.modifiers == KeyModifiers::CONTROL => {
+                    self.state.range_select.reset_range_selection();
+                    self.run_with_prefix(|ws: &mut Workspace<'_>| -> Result<()> {
+                        ws.book.select_prev_sheet();
+                        Ok(())
+                    })?;
+                    self.state.range_select.sheet = Some(self.book.current_sheet);
+                }
+                _ => {
+                    // moop
+                }
+            }
+        }
+        Ok(None)
+    }
+
+    fn maybe_update_range_end(&mut self) {
+        if self.state.range_select.start.is_some() {
+            self.state.range_select.end = Some(self.book.location.clone());
+        }
+    }
+
     fn handle_navigation_input(&mut self, key: event::KeyEvent) -> Result<Option<ExitCode>> {
         if key.kind == KeyEventKind::Press {
             match key.code {
@@ -381,6 +556,9 @@ impl<'ws> Workspace<'ws> {
                 KeyCode::Char('s') if key.modifiers == KeyModifiers::CONTROL => {
                     self.save_file()?;
                 }
+                KeyCode::Char('r') if key.modifiers == KeyModifiers::CONTROL => {
+                    self.enter_range_select_mode();
+                }
                 KeyCode::Char('h') if key.modifiers == KeyModifiers::ALT => {
                     self.enter_dialog_mode(self.render_help_text());
                 }
@@ -487,7 +665,10 @@ impl<'ws> Workspace<'ws> {
         return Ok(None);
     }
 
-    fn run_with_prefix(&mut self, action: impl Fn(&mut Workspace<'_>) -> std::result::Result<(), anyhow::Error>) -> Result<(), anyhow::Error> {
+    fn run_with_prefix(
+        &mut self,
+        action: impl Fn(&mut Workspace<'_>) -> std::result::Result<(), anyhow::Error>,
+    ) -> Result<(), anyhow::Error> {
         for _ in 1..=self.state.get_n_prefix() {
             action(self)?;
         }
@@ -495,10 +676,6 @@ impl<'ws> Workspace<'ws> {
         Ok(())
     }
 
-    fn enter_navigation_mode(&mut self) {
-        self.state.modality_stack.push(Modality::Navigate);
-    }
-
     fn enter_command_mode(&mut self) {
         self.state.modality_stack.push(Modality::Command);
         self.state.command_state.truncate();
@@ -511,6 +688,15 @@ impl<'ws> Workspace<'ws> {
         self.state.modality_stack.push(Modality::Dialog);
     }
 
+    fn enter_range_select_mode(&mut self) {
+        self.state.range_select.sheet = Some(self.book.current_sheet);
+        self.state.range_select.original_sheet = Some(self.book.current_sheet);
+        self.state.range_select.original_location = Some(self.book.location.clone());
+        self.state.range_select.start = None;
+        self.state.range_select.end = None;
+        self.state.modality_stack.push(Modality::RangeSelect);
+    }
+
     fn enter_edit_mode(&mut self) {
         self.state.modality_stack.push(Modality::CellEdit);
         self.text_area
@@ -535,6 +721,30 @@ impl<'ws> Workspace<'ws> {
         Ok(())
     }
 
+    fn exit_range_select_mode(&mut self) -> Result<()> {
+        self.book.current_sheet = self
+            .state
+            .range_select
+            .original_sheet
+            .clone()
+            .expect("Missing original sheet");
+        self.book.location = self
+            .state
+            .range_select
+            .original_location
+            .clone()
+            .expect("Missing original location after range copy");
+        self.state.range_select.original_location = None;
+        self.state.pop_modality();
+        if self.state.modality() == &Modality::CellEdit {
+            self.text_area
+                .set_yank_text(self.selected_range_to_string());
+            self.text_area.paste();
+            self.state.dirty = true;
+        }
+        Ok(())
+    }
+
     fn exit_edit_mode(&mut self, keep: bool) -> Result<()> {
         self.text_area.set_cursor_line_style(Style::default());
         self.text_area.set_cursor_style(Style::default());
@@ -542,11 +752,10 @@ impl<'ws> Workspace<'ws> {
         if self.state.dirty && keep {
             self.book.edit_current_cell(contents)?;
             self.book.evaluate();
-        } else {
-            self.text_area = reset_text_area(self.book.get_current_cell_contents()?);
         }
+        self.text_area = reset_text_area(self.book.get_current_cell_contents()?);
         self.state.dirty = false;
-        self.enter_navigation_mode();
+        self.state.pop_modality();
         Ok(())
     }
 

src/ui/render/mod.rs

@@ -44,7 +44,7 @@ impl<'ws> Workspace<'ws> {
             Box::new(move |rect: Rect, buf: &mut Buffer, ws: &mut Self| {
                 let sheet_name = ws.book.get_sheet_name().unwrap_or("Unknown");
                 let table_block = Block::bordered().title_top(sheet_name);
-                let viewport = Viewport::new(&ws.book)
+                let viewport = Viewport::new(&ws.book, &ws.state.range_select)
                     .with_selected(ws.book.location.clone())
                     .block(table_block);
                 StatefulWidget::render(viewport, rect, buf, &mut ws.state.viewport_state);
@@ -95,6 +95,7 @@ impl<'widget, 'ws: 'widget> Widget for &'widget mut Workspace<'ws> {
                 Modality::CellEdit => "edit",
                 Modality::Command => "command",
                 Modality::Dialog => "",
+                Modality::RangeSelect => "range-copy",
             })
             .title_bottom(
                 Line::from(format!(

src/ui/render/test.rs

@@ -1,15 +1,23 @@
 use ironcalc::base::Model;
 
+use crate::ui::AppState;
+
 use super::{Address, Book, Viewport, ViewportState};
 
 #[test]
 fn test_viewport_get_visible_columns() {
     let mut state = ViewportState::default();
-    let book = Book::new(Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"));
+    let book = Book::new(
+        Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"),
+    );
     let default_size = book.get_col_size(1).expect("Failed to get column size");
     let width = dbg!(dbg!(default_size) * 12 / 2);
-    let viewport = Viewport::new(&book).with_selected(Address { row: 1, col: 17 });
-    let cols = viewport.get_visible_columns((width + 5) as u16, &mut state).expect("Failed to get visible columns");
+    let app_state = AppState::default();
+    let viewport =
+        Viewport::new(&book, &app_state.range_select).with_selected(Address { row: 1, col: 17 });
+    let cols = viewport
+        .get_visible_columns((width + 5) as u16, &mut state)
+        .expect("Failed to get visible columns");
     assert_eq!(5, cols.len());
     assert_eq!(17, cols.last().expect("Failed to get last column").idx);
 }
@@ -17,32 +25,50 @@ fn test_viewport_get_visible_columns() {
 #[test]
 fn test_viewport_get_visible_rows() {
     let mut state = dbg!(ViewportState::default());
-    let book = Book::new(Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"));
+    let book = Book::new(
+        Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"),
+    );
     let height = 6;
-    let viewport = Viewport::new(&book).with_selected(Address { row: 17, col: 1 });
+    let app_state = AppState::default();
+    let viewport =
+        Viewport::new(&book, &app_state.range_select).with_selected(Address { row: 17, col: 1 });
     let rows = dbg!(viewport.get_visible_rows(height as u16, &mut state));
     assert_eq!(height - 1, rows.len());
-    assert_eq!(17 - (height - 2), *rows.first().expect("Failed to get first row"));
+    assert_eq!(
+        17 - (height - 2),
+        *rows.first().expect("Failed to get first row")
+    );
     assert_eq!(17, *rows.last().expect("Failed to get last row"));
 }
 
 #[test]
 fn test_viewport_visible_columns_after_length_change() {
     let mut state = ViewportState::default();
-    let mut book = Book::new(Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"));
+    let mut book = Book::new(
+        Model::new_empty("test", "en", "America/New_York").expect("Failed to make model"),
+    );
     let default_size = book.get_col_size(1).expect("Failed to get column size");
     let width = dbg!(dbg!(default_size) * 12 / 2);
     {
-        let viewport = Viewport::new(&book).with_selected(Address { row: 1, col: 17 });
-        let cols = viewport.get_visible_columns((width + 5) as u16, &mut state).expect("Failed to get visible columns");
+        let app_state = AppState::default();
+        let viewport = Viewport::new(&book, &app_state.range_select)
+            .with_selected(Address { row: 1, col: 17 });
+        let cols = viewport
+            .get_visible_columns((width + 5) as u16, &mut state)
+            .expect("Failed to get visible columns");
         assert_eq!(5, cols.len());
         assert_eq!(17, cols.last().expect("Failed to get last column").idx);
     }
 
-    book.set_col_size(1, default_size * 6).expect("Failed to set column size");
+    book.set_col_size(1, default_size * 6)
+        .expect("Failed to set column size");
     {
-        let viewport = Viewport::new(&book).with_selected(Address { row: 1, col: 1 });
-        let cols = viewport.get_visible_columns((width + 5) as u16, &mut state).expect("Failed to get visible columns");
+        let app_state = AppState::default();
+        let viewport =
+            Viewport::new(&book, &app_state.range_select).with_selected(Address { row: 1, col: 1 });
+        let cols = viewport
+            .get_visible_columns((width + 5) as u16, &mut state)
+            .expect("Failed to get visible columns");
         assert_eq!(1, cols.len());
         assert_eq!(1, cols.last().expect("Failed to get last column").idx);
     }

src/ui/render/viewport.rs

@@ -7,7 +7,7 @@ use ratatui::{
     widgets::{Block, Cell, Row, StatefulWidget, Table, Widget},
 };
 
-use super::{Address, Book};
+use super::{Address, Book, RangeSelection};
 
 // TODO(zaphar): Move this to the book module.
 // NOTE(zaphar): This is stolen from ironcalc but ironcalc doesn't expose it
@@ -34,10 +34,11 @@ pub struct ViewportState {
 }
 
 /// A renderable viewport over a book.
-pub struct Viewport<'book> {
+pub struct Viewport<'ws> {
     pub(crate) selected: Address,
-    book: &'book Book,
-    block: Option<Block<'book>>,
+    book: &'ws Book,
+    range_selection: &'ws RangeSelection,
+    block: Option<Block<'ws>>,
 }
 
 pub(crate) const COLNAMES: [&'static str; 26] = [
@@ -45,10 +46,11 @@ pub(crate) const COLNAMES: [&'static str; 26] = [
     "T", "U", "V", "W", "X", "Y", "Z",
 ];
 
-impl<'book> Viewport<'book> {
-    pub fn new(book: &'book Book) -> Self {
+impl<'ws> Viewport<'ws> {
+    pub fn new(book: &'ws Book, app_state: &'ws RangeSelection) -> Self {
         Self {
             book,
+            range_selection: app_state,
             selected: Default::default(),
             block: None,
         }
@@ -127,7 +129,7 @@ impl<'book> Viewport<'book> {
         return Ok(visible);
     }
 
-    pub fn block(mut self, block: Block<'book>) -> Self {
+    pub fn block(mut self, block: Block<'ws>) -> Self {
         self.block = Some(block);
         self
     }
@@ -158,7 +160,17 @@ impl<'book> Viewport<'book> {
                                 .book
                                 .get_cell_addr_rendered(&Address { row: ri, col: *ci })
                                 .unwrap();
-                            let cell = Cell::new(Text::raw(content));
+                            let mut cell = Cell::new(Text::raw(content));
+                            if let Some((start, end)) = &self.range_selection.get_range() {
+                                if ri >= start.row
+                                    && ri <= end.row
+                                    && *ci >= start.col
+                                    && *ci <= end.col
+                                {
+                                    // This is a selected range
+                                    cell = cell.fg(Color::Black).bg(Color::LightBlue)
+                                }
+                            }
                             match (self.book.location.row == ri, self.book.location.col == *ci) {
                                 (true, true) => cell.fg(Color::White).bg(Color::Rgb(57, 61, 71)),
                                 _ => cell,
@@ -197,7 +209,7 @@ impl<'book> Viewport<'book> {
     }
 }
 
-impl<'book> StatefulWidget for Viewport<'book> {
+impl<'ws> StatefulWidget for Viewport<'ws> {
     type State = ViewportState;
 
     fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {

src/ui/test.rs

@@ -1,6 +1,6 @@
 use crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
 
-use crate::ui::Modality;
+use crate::ui::{Address, Modality};
 
 use super::cmd::{parse, Cmd};
 use super::Workspace;
@@ -351,3 +351,77 @@ fn test_navigation_tab_next_numeric_prefix()
         .expect("Failed to handle 'Ctrl-n' key event");
     assert_eq!("Sheet1", ws.book.get_sheet_name().expect("Failed to get sheet name"));
 }
+
+#[test]
+fn test_range_copy() {
+    let mut ws =
+        Workspace::new_empty("en", "America/New_York").expect("Failed to get empty workbook");
+    assert_eq!(Some(&Modality::Navigate), ws.state.modality_stack.last());
+    
+    ws.book.move_to(&Address { row: 1, col: 1, }).expect("Failed to move to row");
+    let original_loc = ws.book.location.clone();
+    ws.handle_input(construct_modified_key_event(KeyCode::Char('r'), KeyModifiers::CONTROL))
+        .expect("Failed to handle 'Ctrl-r' key event");
+    assert_eq!(Some(&Modality::RangeSelect), ws.state.modality_stack.last());
+    assert_eq!(Some(original_loc.clone()), ws.state.range_select.original_location);
+    assert!(ws.state.range_select.start.is_none());
+    assert!(ws.state.range_select.end.is_none());
+    
+    ws.handle_input(construct_key_event(KeyCode::Char('l')))
+        .expect("Failed to handle 'l' key event");
+    ws.handle_input(construct_key_event(KeyCode::Char(' ')))
+        .expect("Failed to handle ' ' key event");
+    assert_eq!(Some(Address {row:1, col:2, }), ws.state.range_select.start);
+    
+    ws.handle_input(construct_key_event(KeyCode::Char('j')))
+        .expect("Failed to handle 'j' key event");
+    ws.handle_input(construct_key_event(KeyCode::Char(' ')))
+        .expect("Failed to handle ' ' key event");
+    
+    assert!(ws.state.range_select.original_location.is_none());
+    assert_eq!(Some(Address {row:1, col:2, }), ws.state.range_select.start);
+    assert_eq!(Some(Address {row:2, col:2, }), ws.state.range_select.end);
+    assert_eq!(original_loc, ws.book.location);
+    assert_eq!(Some(&Modality::Navigate), ws.state.modality_stack.last());
+   
+    ws.book.move_to(&Address { row: 5, col: 5, }).expect("Failed to move to row");
+    let original_loc_2 = ws.book.location.clone();
+    assert_eq!(Address { row: 5, col: 5 }, original_loc_2);
+    
+    ws.handle_input(construct_modified_key_event(KeyCode::Char('r'), KeyModifiers::CONTROL))
+        .expect("Failed to handle 'Ctrl-r' key event");
+    assert_eq!(Some(&Modality::RangeSelect), ws.state.modality_stack.last());
+    assert_eq!(Some(original_loc_2.clone()), ws.state.range_select.original_location);
+    assert!(ws.state.range_select.start.is_none());
+    assert!(ws.state.range_select.end.is_none());
+    
+    ws.handle_input(construct_key_event(KeyCode::Char('h')))
+        .expect("Failed to handle 'h' key event");
+    ws.handle_input(construct_key_event(KeyCode::Char(' ')))
+        .expect("Failed to handle ' ' key event");
+    assert_eq!(Some(Address {row:5, col:4, }), ws.state.range_select.start);
+    
+    ws.handle_input(construct_key_event(KeyCode::Char('k')))
+        .expect("Failed to handle 'k' key event");
+    ws.handle_input(construct_key_event(KeyCode::Char(' ')))
+        .expect("Failed to handle ' ' key event");
+    
+    assert!(ws.state.range_select.original_location.is_none());
+    assert_eq!(Some(Address {row:5, col:4, }), ws.state.range_select.start);
+    assert_eq!(Some(Address {row:4, col:4, }), ws.state.range_select.end);
+    assert_eq!(original_loc_2, ws.book.location);
+    assert_eq!(Some(&Modality::Navigate), ws.state.modality_stack.last());
+}
+
+#[test]
+fn test_range_copy_mode_from_edit_mode() {
+    let mut ws =
+        Workspace::new_empty("en", "America/New_York").expect("Failed to get empty workbook");
+    assert_eq!(Some(&Modality::Navigate), ws.state.modality_stack.last());
+    ws.handle_input(construct_key_event(KeyCode::Char('e')))
+        .expect("Failed to handle 'e' key event");
+    assert_eq!(Some(&Modality::CellEdit), ws.state.modality_stack.last());
+    ws.handle_input(construct_modified_key_event(KeyCode::Char('r'), KeyModifiers::CONTROL))
+        .expect("Failed to handle 'Ctrl-r' key event");
+    assert_eq!(Some(&Modality::RangeSelect), ws.state.modality_stack.last());
+}