1 files changed, 735 insertions, 0 deletions
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
new file mode 100644
index 00000000..b345d2e8
--- /dev/null
+++ b/helix-term/src/commands.rs
@@ -0,0 +1,735 @@
+use helix_core::{
+    graphemes,
+    indent::TAB_WIDTH,
+    regex::Regex,
+    register, selection,
+    state::{Direction, Granularity, State},
+    ChangeSet, Range, Selection, Tendril, Transaction,
+};
+
+use once_cell::sync::Lazy;
+
+use crate::compositor::Compositor;
+use crate::ui::Prompt;
+
+use helix_view::{
+    document::Mode,
+    view::{View, PADDING},
+    Editor,
+};
+
+pub struct Context<'a, 'b> {
+    pub count: usize,
+    pub view: &'a mut View,
+    pub executor: &'a smol::Executor<'b>,
+
+    pub callback: Option<crate::compositor::Callback>,
+}
+
+/// A command is a function that takes the current state and a count, and does a side-effect on the
+/// state (usually by creating and applying a transaction).
+pub type Command = fn(cx: &mut Context);
+
+pub fn move_char_left(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .move_selection(Direction::Backward, Granularity::Character, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_char_right(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .move_selection(Direction::Forward, Granularity::Character, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_line_up(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .move_selection(Direction::Backward, Granularity::Line, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_line_down(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .move_selection(Direction::Forward, Granularity::Line, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_line_end(cx: &mut Context) {
+    let lines = selection_lines(&cx.view.doc.state);
+
+    let positions = lines
+        .into_iter()
+        .map(|index| {
+            // adjust all positions to the end of the line.
+
+            // Line end is pos at the start of next line - 1
+            // subtract another 1 because the line ends with \n
+            cx.view.doc.text().line_to_char(index + 1).saturating_sub(2)
+        })
+        .map(|pos| Range::new(pos, pos));
+
+    let selection = Selection::new(positions.collect(), 0);
+
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_line_start(cx: &mut Context) {
+    let lines = selection_lines(&cx.view.doc.state);
+
+    let positions = lines
+        .into_iter()
+        .map(|index| {
+            // adjust all positions to the start of the line.
+            cx.view.doc.text().line_to_char(index)
+        })
+        .map(|pos| Range::new(pos, pos));
+
+    let selection = Selection::new(positions.collect(), 0);
+
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn move_next_word_start(cx: &mut Context) {
+    let pos = cx.view.doc.state.move_pos(
+        cx.view.doc.selection().cursor(),
+        Direction::Forward,
+        Granularity::Word,
+        cx.count,
+    );
+
+    cx.view.doc.set_selection(Selection::point(pos));
+}
+
+pub fn move_prev_word_start(cx: &mut Context) {
+    let pos = cx.view.doc.state.move_pos(
+        cx.view.doc.selection().cursor(),
+        Direction::Backward,
+        Granularity::Word,
+        cx.count,
+    );
+
+    cx.view.doc.set_selection(Selection::point(pos));
+}
+
+pub fn move_next_word_end(cx: &mut Context) {
+    let pos = State::move_next_word_end(
+        &cx.view.doc.text().slice(..),
+        cx.view.doc.selection().cursor(),
+        cx.count,
+    );
+
+    cx.view.doc.set_selection(Selection::point(pos));
+}
+
+pub fn move_file_start(cx: &mut Context) {
+    cx.view.doc.set_selection(Selection::point(0));
+
+    cx.view.doc.mode = Mode::Normal;
+}
+
+pub fn move_file_end(cx: &mut Context) {
+    let text = &cx.view.doc.text();
+    let last_line = text.line_to_char(text.len_lines().saturating_sub(2));
+    cx.view.doc.set_selection(Selection::point(last_line));
+
+    cx.view.doc.mode = Mode::Normal;
+}
+
+pub fn check_cursor_in_view(view: &View) -> bool {
+    let cursor = view.doc.selection().cursor();
+    let line = view.doc.text().char_to_line(cursor);
+    let document_end = view.first_line + view.size.1.saturating_sub(1) as usize;
+
+    if (line > document_end.saturating_sub(PADDING)) | (line < view.first_line + PADDING) {
+        return false;
+    }
+    true
+}
+
+pub fn page_up(cx: &mut Context) {
+    if cx.view.first_line < PADDING {
+        return;
+    }
+
+    cx.view.first_line = cx.view.first_line.saturating_sub(cx.view.size.1 as usize);
+
+    if !check_cursor_in_view(cx.view) {
+        let text = cx.view.doc.text();
+        let pos = text.line_to_char(cx.view.last_line().saturating_sub(PADDING));
+        cx.view.doc.set_selection(Selection::point(pos));
+    }
+}
+
+pub fn page_down(cx: &mut Context) {
+    cx.view.first_line += cx.view.size.1 as usize + PADDING;
+
+    if cx.view.first_line < cx.view.doc.text().len_lines() {
+        let text = cx.view.doc.text();
+        let pos = text.line_to_char(cx.view.first_line as usize);
+        cx.view.doc.set_selection(Selection::point(pos));
+    }
+}
+
+pub fn half_page_up(cx: &mut Context) {
+    if cx.view.first_line < PADDING {
+        return;
+    }
+
+    cx.view.first_line = cx
+        .view
+        .first_line
+        .saturating_sub(cx.view.size.1 as usize / 2);
+
+    if !check_cursor_in_view(cx.view) {
+        let text = &cx.view.doc.text();
+        let pos = text.line_to_char(cx.view.last_line() - PADDING);
+        cx.view.doc.set_selection(Selection::point(pos));
+    }
+}
+
+pub fn half_page_down(cx: &mut Context) {
+    let lines = cx.view.doc.text().len_lines();
+    if cx.view.first_line < lines.saturating_sub(cx.view.size.1 as usize) {
+        cx.view.first_line += cx.view.size.1 as usize / 2;
+    }
+    if !check_cursor_in_view(cx.view) {
+        let text = cx.view.doc.text();
+        let pos = text.line_to_char(cx.view.first_line as usize);
+        cx.view.doc.set_selection(Selection::point(pos));
+    }
+}
+// avoid select by default by having a visual mode switch that makes movements into selects
+
+pub fn extend_char_left(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .extend_selection(Direction::Backward, Granularity::Character, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn extend_char_right(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .extend_selection(Direction::Forward, Granularity::Character, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn extend_line_up(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .extend_selection(Direction::Backward, Granularity::Line, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn extend_line_down(cx: &mut Context) {
+    let selection =
+        cx.view
+            .doc
+            .state
+            .extend_selection(Direction::Forward, Granularity::Line, cx.count);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn split_selection_on_newline(cx: &mut Context) {
+    let text = &cx.view.doc.text().slice(..);
+    // only compile the regex once
+    #[allow(clippy::trivial_regex)]
+    static REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"\n").unwrap());
+    let selection = selection::split_on_matches(text, cx.view.doc.selection(), &REGEX);
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn select_line(cx: &mut Context) {
+    // TODO: count
+    let pos = cx.view.doc.selection().primary();
+    let text = cx.view.doc.text();
+    let line = text.char_to_line(pos.head);
+    let start = text.line_to_char(line);
+    let end = text.line_to_char(line + 1).saturating_sub(1);
+
+    cx.view.doc.set_selection(Selection::single(start, end));
+}
+
+pub fn delete_selection(cx: &mut Context) {
+    let transaction = Transaction::change_by_selection(&cx.view.doc.state, |range| {
+        (range.from(), range.to() + 1, None)
+    });
+    cx.view.doc.apply(&transaction);
+
+    append_changes_to_history(cx);
+}
+
+pub fn change_selection(cx: &mut Context) {
+    delete_selection(cx);
+    insert_mode(cx);
+}
+
+pub fn collapse_selection(cx: &mut Context) {
+    let selection = cx
+        .view
+        .doc
+        .selection()
+        .transform(|range| Range::new(range.head, range.head));
+
+    cx.view.doc.set_selection(selection);
+}
+
+pub fn flip_selections(cx: &mut Context) {
+    let selection = cx
+        .view
+        .doc
+        .selection()
+        .transform(|range| Range::new(range.head, range.anchor));
+
+    cx.view.doc.set_selection(selection);
+}
+
+fn enter_insert_mode(cx: &mut Context) {
+    cx.view.doc.mode = Mode::Insert;
+
+    append_changes_to_history(cx);
+}
+// inserts at the start of each selection
+pub fn insert_mode(cx: &mut Context) {
+    enter_insert_mode(cx);
+
+    let selection = cx
+        .view
+        .doc
+        .selection()
+        .transform(|range| Range::new(range.to(), range.from()));
+    cx.view.doc.set_selection(selection);
+}
+
+// inserts at the end of each selection
+pub fn append_mode(cx: &mut Context) {
+    enter_insert_mode(cx);
+    cx.view.doc.restore_cursor = true;
+
+    // TODO: as transaction
+    let text = &cx.view.doc.text().slice(..);
+    let selection = cx.view.doc.selection().transform(|range| {
+        // TODO: to() + next char
+        Range::new(
+            range.from(),
+            graphemes::next_grapheme_boundary(text, range.to()),
+        )
+    });
+    cx.view.doc.set_selection(selection);
+}
+
+// TODO: I, A, o and O can share a lot of the primitives.
+pub fn command_mode(cx: &mut Context) {
+    cx.callback = Some(Box::new(|compositor: &mut Compositor| {
+        let prompt = Prompt::new(
+            ":".to_owned(),
+            |_input: &str| {
+                // TODO: i need this duplicate list right now to avoid borrow checker issues
+                let command_list = vec![
+                    String::from("q"),
+                    String::from("aaa"),
+                    String::from("bbb"),
+                    String::from("ccc"),
+                    String::from("ddd"),
+                    String::from("eee"),
+                    String::from("averylongcommandaverylongcommandaverylongcommandaverylongcommandaverylongcommand"),
+                    String::from("q"),
+                    String::from("aaa"),
+                    String::from("bbb"),
+                    String::from("ccc"),
+                    String::from("ddd"),
+                    String::from("eee"),
+                    String::from("q"),
+                    String::from("aaa"),
+                    String::from("bbb"),
+                    String::from("ccc"),
+                    String::from("ddd"),
+                    String::from("eee"),
+                    String::from("q"),
+                    String::from("aaa"),
+                    String::from("bbb"),
+                    String::from("ccc"),
+                    String::from("ddd"),
+                    String::from("eee"),
+                    String::from("q"),
+                    String::from("aaa"),
+                    String::from("bbb"),
+                    String::from("ccc"),
+                    String::from("ddd"),
+                    String::from("eee"),
+                    ];
+                command_list
+                    .into_iter()
+                    .filter(|command| command.contains(_input))
+                    .collect()
+            }, // completion
+            |editor: &mut Editor, input: &str| match input {
+                "q" => editor.should_close = true,
+                _ => (),
+            },
+        );
+        compositor.push(Box::new(prompt));
+    }));
+}
+
+// calculate line numbers for each selection range
+fn selection_lines(state: &State) -> Vec<usize> {
+    let mut lines = state
+        .selection
+        .ranges()
+        .iter()
+        .map(|range| state.doc.char_to_line(range.head))
+        .collect::<Vec<_>>();
+
+    lines.sort_unstable(); // sorting by usize so _unstable is preferred
+    lines.dedup();
+
+    lines
+}
+
+// I inserts at the start of each line with a selection
+pub fn prepend_to_line(cx: &mut Context) {
+    enter_insert_mode(cx);
+
+    move_line_start(cx);
+}
+
+// A inserts at the end of each line with a selection
+pub fn append_to_line(cx: &mut Context) {
+    enter_insert_mode(cx);
+
+    move_line_end(cx);
+}
+
+// o inserts a new line after each line with a selection
+pub fn open_below(cx: &mut Context) {
+    enter_insert_mode(cx);
+
+    let lines = selection_lines(&cx.view.doc.state);
+
+    let positions: Vec<_> = lines
+        .into_iter()
+        .map(|index| {
+            // adjust all positions to the end of the line/start of the next one.
+            cx.view.doc.text().line_to_char(index + 1)
+        })
+        .collect();
+
+    // TODO: use same logic as insert_newline for indentation
+    let changes = positions.iter().copied().map(|index|
+        // generate changes
+        (index, index, Some(Tendril::from_char('\n'))));
+
+    // TODO: count actually inserts "n" new lines and starts editing on all of them.
+    // TODO: append "count" newlines and modify cursors to those lines
+
+    let selection = Selection::new(
+        positions
+            .iter()
+            .copied()
+            .map(|pos| Range::new(pos, pos))
+            .collect(),
+        0,
+    );
+
+    let transaction = Transaction::change(&cx.view.doc.state, changes).with_selection(selection);
+
+    cx.view.doc.apply(&transaction);
+}
+
+// O inserts a new line before each line with a selection
+
+fn append_changes_to_history(cx: &mut Context) {
+    if cx.view.doc.changes.is_empty() {
+        return;
+    }
+
+    let new_changeset = ChangeSet::new(cx.view.doc.text());
+    let changes = std::mem::replace(&mut cx.view.doc.changes, new_changeset);
+    // Instead of doing this messy merge we could always commit, and based on transaction
+    // annotations either add a new layer or compose into the previous one.
+    let transaction = Transaction::from(changes).with_selection(cx.view.doc.selection().clone());
+
+    // increment document version
+    // TODO: needs to happen on undo/redo too
+    cx.view.doc.version += 1;
+
+    // TODO: trigger lsp/documentDidChange with changes
+
+    // HAXX: we need to reconstruct the state as it was before the changes..
+    let old_state = std::mem::replace(&mut cx.view.doc.old_state, cx.view.doc.state.clone());
+    // TODO: take transaction by value?
+    cx.view
+        .doc
+        .history
+        .commit_revision(&transaction, &old_state);
+
+    // TODO: notify LSP of changes
+}
+
+pub fn normal_mode(cx: &mut Context) {
+    cx.view.doc.mode = Mode::Normal;
+
+    append_changes_to_history(cx);
+
+    // if leaving append mode, move cursor back by 1
+    if cx.view.doc.restore_cursor {
+        let text = &cx.view.doc.text().slice(..);
+        let selection = cx.view.doc.selection().transform(|range| {
+            Range::new(
+                range.from(),
+                graphemes::prev_grapheme_boundary(text, range.to()),
+            )
+        });
+        cx.view.doc.set_selection(selection);
+
+        cx.view.doc.restore_cursor = false;
+    }
+}
+
+pub fn goto_mode(cx: &mut Context) {
+    cx.view.doc.mode = Mode::Goto;
+}
+
+// NOTE: Transactions in this module get appended to history when we switch back to normal mode.
+pub mod insert {
+    use super::*;
+    // TODO: insert means add text just before cursor, on exit we should be on the last letter.
+    pub fn insert_char(cx: &mut Context, c: char) {
+        let c = Tendril::from_char(c);
+        let transaction = Transaction::insert(&cx.view.doc.state, c);
+
+        cx.view.doc.apply(&transaction);
+    }
+
+    pub fn insert_tab(cx: &mut Context) {
+        insert_char(cx, '\t');
+    }
+
+    pub fn insert_newline(cx: &mut Context) {
+        let transaction = Transaction::change_by_selection(&cx.view.doc.state, |range| {
+            let indent_level = helix_core::indent::suggested_indent_for_pos(
+                cx.view.doc.syntax.as_ref(),
+                &cx.view.doc.state,
+                range.head,
+            );
+            let indent = " ".repeat(TAB_WIDTH).repeat(indent_level);
+            let mut text = String::with_capacity(1 + indent.len());
+            text.push('\n');
+            text.push_str(&indent);
+            (range.head, range.head, Some(text.into()))
+        });
+        cx.view.doc.apply(&transaction);
+    }
+
+    // TODO: handle indent-aware delete
+    pub fn delete_char_backward(cx: &mut Context) {
+        let text = &cx.view.doc.text().slice(..);
+        let transaction = Transaction::change_by_selection(&cx.view.doc.state, |range| {
+            (
+                graphemes::nth_prev_grapheme_boundary(text, range.head, cx.count),
+                range.head,
+                None,
+            )
+        });
+        cx.view.doc.apply(&transaction);
+    }
+
+    pub fn delete_char_forward(cx: &mut Context) {
+        let text = &cx.view.doc.text().slice(..);
+        let transaction = Transaction::change_by_selection(&cx.view.doc.state, |range| {
+            (
+                range.head,
+                graphemes::nth_next_grapheme_boundary(text, range.head, cx.count),
+                None,
+            )
+        });
+        cx.view.doc.apply(&transaction);
+    }
+}
+
+pub fn insert_char_prompt(prompt: &mut Prompt, c: char) {
+    prompt.insert_char(c);
+}
+
+// Undo / Redo
+
+pub fn undo(cx: &mut Context) {
+    if let Some(revert) = cx.view.doc.history.undo() {
+        cx.view.doc.version += 1;
+        cx.view.doc.apply(&revert);
+    }
+
+    // TODO: each command could simply return a Option<transaction>, then the higher level handles storing it?
+}
+
+pub fn redo(cx: &mut Context) {
+    if let Some(transaction) = cx.view.doc.history.redo() {
+        cx.view.doc.version += 1;
+        cx.view.doc.apply(&transaction);
+    }
+}
+
+// Yank / Paste
+
+pub fn yank(cx: &mut Context) {
+    // TODO: should selections be made end inclusive?
+    let values = cx
+        .view
+        .doc
+        .state
+        .selection()
+        .fragments(&cx.view.doc.text().slice(..))
+        .map(|cow| cow.into_owned())
+        .collect();
+
+    // TODO: allow specifying reg
+    let reg = '"';
+    register::set(reg, values);
+}
+
+pub fn paste(cx: &mut Context) {
+    // TODO: allow specifying reg
+    let reg = '"';
+    if let Some(values) = register::get(reg) {
+        let repeat = std::iter::repeat(
+            values
+                .last()
+                .map(|value| Tendril::from_slice(value))
+                .unwrap(),
+        );
+
+        // TODO: if any of values ends \n it's linewise paste
+        //
+        // p => paste after
+        // P => paste before
+        // alt-p => paste every yanked selection after selected text
+        // alt-P => paste every yanked selection before selected text
+        // R => replace selected text with yanked text
+        // alt-R => replace selected text with every yanked text
+        //
+        // append => insert at next line
+        // insert => insert at start of line
+        // replace => replace
+        // default insert
+
+        let linewise = values.iter().any(|value| value.ends_with('\n'));
+
+        let mut values = values.into_iter().map(Tendril::from).chain(repeat);
+
+        let transaction = if linewise {
+            // paste on the next line
+            // TODO: can simply take a range + modifier and compute the right pos without ifs
+            let text = cx.view.doc.text();
+            Transaction::change_by_selection(&cx.view.doc.state, |range| {
+                let line_end = text.line_to_char(text.char_to_line(range.head) + 1);
+                (line_end, line_end, Some(values.next().unwrap()))
+            })
+        } else {
+            Transaction::change_by_selection(&cx.view.doc.state, |range| {
+                (range.head + 1, range.head + 1, Some(values.next().unwrap()))
+            })
+        };
+
+        cx.view.doc.apply(&transaction);
+        append_changes_to_history(cx);
+    }
+}
+
+fn get_lines(view: &View) -> Vec<usize> {
+    let mut lines = Vec::new();
+
+    // Get all line numbers
+    for range in view.doc.selection().ranges() {
+        let start = view.doc.text().char_to_line(range.from());
+        let end = view.doc.text().char_to_line(range.to());
+
+        for line in start..=end {
+            lines.push(line)
+        }
+    }
+    lines.sort_unstable(); // sorting by usize so _unstable is preferred
+    lines.dedup();
+    lines
+}
+
+pub fn indent(cx: &mut Context) {
+    let lines = get_lines(cx.view);
+
+    // Indent by one level
+    let indent = Tendril::from(" ".repeat(TAB_WIDTH));
+
+    let transaction = Transaction::change(
+        &cx.view.doc.state,
+        lines.into_iter().map(|line| {
+            let pos = cx.view.doc.text().line_to_char(line);
+            (pos, pos, Some(indent.clone()))
+        }),
+    );
+    cx.view.doc.apply(&transaction);
+    append_changes_to_history(cx);
+}
+
+pub fn unindent(cx: &mut Context) {
+    let lines = get_lines(cx.view);
+    let mut changes = Vec::with_capacity(lines.len());
+
+    for line_idx in lines {
+        let line = cx.view.doc.text().line(line_idx);
+        let mut width = 0;
+
+        for ch in line.chars() {
+            match ch {
+                ' ' => width += 1,
+                '\t' => width = (width / TAB_WIDTH + 1) * TAB_WIDTH,
+                _ => break,
+            }
+
+            if width >= TAB_WIDTH {
+                break;
+            }
+        }
+
+        if width > 0 {
+            let start = cx.view.doc.text().line_to_char(line_idx);
+            changes.push((start, start + width, None))
+        }
+    }
+
+    let transaction = Transaction::change(&cx.view.doc.state, changes.into_iter());
+
+    cx.view.doc.apply(&transaction);
+    append_changes_to_history(cx);
+}
+
+pub fn indent_selection(_cx: &mut Context) {
+    // loop over each line and recompute proper indentation
+    unimplemented!()
+}
+
+//
+
+pub fn save(cx: &mut Context) {
+    // Spawns an async task to actually do the saving. This way we prevent blocking.
+
+    // TODO: handle save errors somehow?
+    cx.executor.spawn(cx.view.doc.save()).detach();
+}