clankerdiff-ratatui 0.1.0

//! Crossterm keyboard, mouse, and paste input helpers.

use crate::{
    DiffReviewState, FocusPane,
    state::{RepositoryOperationStatus, RepositoryPrompt},
    theme_picker::{ThemePicker, ThemePickerAction},
};
use clankerdiff_core::{DiffReviewEvent, DiffSide, RepositoryAction, RevealAmount};
use crossterm::event::{
    Event, KeyCode, KeyEvent, KeyEventKind, KeyModifiers, MouseEvent, MouseEventKind,
};
use ratatui::layout::Position;

/// Files one wheel notch scrolls the drawer. A notch is a line, not a file, so
/// the drawer moves one entry at a time.
const DRAWER_WHEEL_ROWS: isize = 1;

/// Framework-neutral input accepted by [`DiffReviewState::handle_input`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DiffReviewInput {
    /// A Crossterm key event.
    Key(KeyEvent),
    /// Pasted text.
    Paste(String),
    /// A Crossterm mouse event.
    Mouse(MouseEvent),
}

/// Converts one Crossterm event and applies it to state.
///
/// Non-input events and key releases are ignored.
#[must_use]
pub fn handle_crossterm_event(
    state: &mut DiffReviewState,
    event: Event,
) -> Option<DiffReviewEvent> {
    match event {
        Event::Key(key) if matches!(key.kind, KeyEventKind::Press | KeyEventKind::Repeat) => {
            state.handle_input(DiffReviewInput::Key(key))
        }
        Event::Paste(text) => state.handle_input(DiffReviewInput::Paste(text)),
        Event::Mouse(mouse) => state.handle_input(DiffReviewInput::Mouse(mouse)),
        Event::Resize(..) => {
            state.mark_dirty();
            None
        }
        _ => None,
    }
}

impl DiffReviewState {
    #[must_use]
    pub fn handle_input(&mut self, input: DiffReviewInput) -> Option<DiffReviewEvent> {
        match input {
            DiffReviewInput::Key(key) => {
                self.mark_dirty();
                self.handle_key(key)
            }
            DiffReviewInput::Paste(text) => {
                if let Some(draft) = self.session.draft_mut() {
                    draft.insert(&text);
                    self.request_follow();
                }
                None
            }
            DiffReviewInput::Mouse(mouse) => self.handle_mouse(mouse),
        }
    }

    fn handle_key(&mut self, key: KeyEvent) -> Option<DiffReviewEvent> {
        if let Some(picker) = self.theme_picker.as_mut() {
            let action = picker.handle_key(key);
            match action {
                ThemePickerAction::Preview(theme) => self.set_theme(theme),
                ThemePickerAction::Restore(theme) => {
                    self.set_theme(theme);
                    self.theme_picker = None;
                }
                ThemePickerAction::Commit => self.theme_picker = None,
                ThemePickerAction::None => {}
            }
            return None;
        }
        if self.repository_prompt.is_some() {
            return self.handle_repository_prompt_key(key);
        }
        if self.help {
            if matches!(key.code, KeyCode::Esc | KeyCode::Char('?')) {
                self.help = false;
            }
            return None;
        }
        if self.session.draft().is_some() {
            self.handle_draft_key(key);
            return None;
        }
        let cancels = key.code == KeyCode::Esc
            || (key.code == KeyCode::Char('g') && key.modifiers.contains(KeyModifiers::CONTROL));
        if cancels {
            return Some(DiffReviewEvent::Cancel);
        }
        if key
            .modifiers
            .intersects(KeyModifiers::ALT | KeyModifiers::SUPER | KeyModifiers::CONTROL)
        {
            return None;
        }
        self.handle_browse_key(key)
    }

    #[allow(clippy::too_many_lines)]
    fn handle_browse_key(&mut self, key: KeyEvent) -> Option<DiffReviewEvent> {
        if matches!(self.repository_status, RepositoryOperationStatus::Pending)
            && matches!(
                key.code,
                KeyCode::Char(' ' | 'a' | 'A' | 'C' | 'S' | 'd' | 'r')
            )
        {
            return None;
        }
        let in_diff = self.focus == FocusPane::Diff;
        match key.code {
            KeyCode::Tab => {
                self.focus = match self.focus {
                    FocusPane::Files => FocusPane::Diff,
                    FocusPane::Diff => FocusPane::Files,
                };
            }
            KeyCode::Left if in_diff && self.layout().is_split() => {
                self.session.set_selected_side(DiffSide::Old);
            }
            KeyCode::Right if in_diff && self.layout().is_split() => {
                self.session.set_selected_side(DiffSide::New);
            }
            KeyCode::Left | KeyCode::Char('h') => {
                if in_diff {
                    self.focus = FocusPane::Files;
                } else {
                    self.collapse_drawer_entry();
                }
            }
            KeyCode::Right | KeyCode::Char('l') | KeyCode::Enter if !in_diff => {
                if !self.expand_or_open_drawer_entry() {
                    self.focus = FocusPane::Diff;
                }
            }
            KeyCode::Up | KeyCode::Char('k') => self.move_focused(-1),
            KeyCode::Down | KeyCode::Char('j') => self.move_focused(1),
            KeyCode::PageUp => self.page(-1),
            KeyCode::PageDown => self.page(1),
            KeyCode::Home => self.select_boundary(false),
            KeyCode::End => self.select_boundary(true),
            KeyCode::Char('c') if in_diff => {
                self.session.begin_draft(None);
                self.request_follow();
            }
            KeyCode::Char('e') if in_diff => {
                let editing = self.session.comment_id_at_selection();
                if editing.is_some() {
                    self.session.begin_draft(editing);
                    self.request_follow();
                }
            }
            KeyCode::Char('x') if in_diff => {
                self.session.delete_comment_at_selection();
            }
            KeyCode::Char('u') if in_diff => {
                if let Some(id) = self.session.last_comment_id() {
                    self.session.review_mut().remove_comment(id);
                }
            }
            KeyCode::Char('s') if in_diff => {
                return Some(DiffReviewEvent::SubmitReview(self.session.submission()));
            }
            KeyCode::Char('y') if in_diff => {
                return Some(DiffReviewEvent::CopyFormattedReview(
                    self.session.submission().formatted,
                ));
            }
            KeyCode::Char(' ') if self.focus == FocusPane::Files => {
                if let Some(action) = self.toggle_stage_action() {
                    return Some(DiffReviewEvent::RepositoryAction(action));
                }
            }
            KeyCode::Char('a') if self.focus == FocusPane::Files => {
                return Some(DiffReviewEvent::RepositoryAction(
                    RepositoryAction::StageAll,
                ));
            }
            KeyCode::Char('A') if self.focus == FocusPane::Files => {
                return Some(DiffReviewEvent::RepositoryAction(
                    RepositoryAction::UnstageAll,
                ));
            }
            KeyCode::Char('C') => self.begin_commit(),
            KeyCode::Char('d') => self.begin_discard(),
            KeyCode::Char('t') => {
                self.theme_picker = Some(ThemePicker::new(&self.theme));
            }
            KeyCode::Enter
                if in_diff
                    && self
                        .session
                        .selected_row()
                        .is_some_and(|row| self.presentation().gap_info(row).is_some()) =>
            {
                self.reveal_selected_gap(RevealAmount::Step);
            }
            KeyCode::Char('o') if in_diff => {
                self.reveal_selected_gap(RevealAmount::Step);
            }
            KeyCode::Char('O') if in_diff => {
                self.reveal_selected_gap(RevealAmount::All);
            }
            KeyCode::Char('f') if in_diff => {
                self.toggle_full_file();
            }
            KeyCode::Char('v') => {
                if self.session.cycle_view_mode() {
                    self.scroll_to_selected_file();
                }
            }
            KeyCode::Char('S') => {
                return Some(DiffReviewEvent::SetScope(self.scope.next()));
            }
            KeyCode::Char('?') => self.help = true,
            _ => {}
        }
        None
    }

    fn move_focused(&mut self, delta: isize) {
        match self.focus {
            FocusPane::Files => self.move_drawer_entry(delta),
            FocusPane::Diff => self.move_row(delta),
        }
    }

    fn handle_repository_prompt_key(&mut self, key: KeyEvent) -> Option<DiffReviewEvent> {
        match self.repository_prompt.as_mut()? {
            RepositoryPrompt::Commit { message } => match key.code {
                KeyCode::Esc => self.repository_prompt = None,
                KeyCode::Enter => {
                    let message = message.trim().to_owned();
                    if message.is_empty() {
                        self.set_repository_error("Commit message cannot be empty");
                    } else {
                        self.repository_prompt = None;
                        return Some(DiffReviewEvent::RepositoryAction(
                            RepositoryAction::Commit { message },
                        ));
                    }
                }
                KeyCode::Backspace => {
                    message.pop();
                }
                KeyCode::Char(character)
                    if key.modifiers.is_empty() || key.modifiers == KeyModifiers::SHIFT =>
                {
                    message.push(character);
                }
                _ => {}
            },
            RepositoryPrompt::Discard { path, status } => match key.code {
                KeyCode::Char('y' | 'Y') => {
                    let action = RepositoryAction::Discard {
                        path: path.clone(),
                        status: *status,
                    };
                    self.repository_prompt = None;
                    return Some(DiffReviewEvent::RepositoryAction(action));
                }
                KeyCode::Char('n' | 'N') | KeyCode::Esc => self.repository_prompt = None,
                _ => {}
            },
        }
        None
    }

    fn handle_draft_key(&mut self, key: KeyEvent) {
        if key.code == KeyCode::Esc {
            self.session.cancel_draft();
            self.cursor_position = None;
            return;
        }
        if key.code == KeyCode::Enter && !key.modifiers.contains(KeyModifiers::SHIFT) {
            self.session.submit_draft();
            self.cursor_position = None;
            return;
        }
        let Some(draft) = self.session.draft_mut() else {
            return;
        };
        match key.code {
            KeyCode::Enter => draft.insert("\n"),
            KeyCode::Left => draft.move_cursor_left(),
            KeyCode::Right => draft.move_cursor_right(),
            KeyCode::Home => draft.move_cursor_to_start(),
            KeyCode::End => draft.move_cursor_to_end(),
            KeyCode::Backspace => draft.delete_before_cursor(),
            KeyCode::Delete => draft.delete_at_cursor(),
            KeyCode::Char(character)
                if key.modifiers.is_empty() || key.modifiers == KeyModifiers::SHIFT =>
            {
                let mut buffer = [0_u8; 4];
                draft.insert(character.encode_utf8(&mut buffer));
            }
            _ => {}
        }
        self.request_follow();
    }

    fn handle_mouse(&mut self, mouse: MouseEvent) -> Option<DiffReviewEvent> {
        let position = Position::new(mouse.column, mouse.row);
        match mouse.kind {
            MouseEventKind::ScrollUp => self.scroll_at(position, -1),
            MouseEventKind::ScrollDown => self.scroll_at(position, 1),
            MouseEventKind::Down(_) => {
                if self.hit_layout.drawer.contains(position) {
                    self.focus = FocusPane::Files;
                    let relative = usize::from(mouse.row.saturating_sub(self.hit_layout.drawer.y));
                    self.select_drawer_entry(self.drawer_scroll.saturating_add(relative));
                    self.mark_dirty();
                    if self.hit_layout.drawer_stage_column == Some(mouse.column)
                        && !matches!(self.repository_status, RepositoryOperationStatus::Pending)
                        && let Some(action) = self.toggle_stage_action()
                    {
                        return Some(DiffReviewEvent::RepositoryAction(action));
                    }
                } else if self.hit_layout.patch.contains(position) {
                    self.focus = FocusPane::Diff;
                    self.select_clicked_row(mouse.row);
                    self.mark_dirty();
                }
            }
            // Motion, drag, and button releases change nothing that is drawn,
            // and a terminal in all-motion mode reports one per pointer step.
            _ => {}
        }
        None
    }

    /// Navigates the pane under the pointer, falling back to the focused pane
    /// when the pointer is over neither. The wheel moves one diff selection or
    /// one drawer entry per notch without changing which pane has focus.
    fn scroll_at(&mut self, position: Position, direction: isize) {
        let pane = if self.hit_layout.patch.contains(position) {
            FocusPane::Diff
        } else if self.hit_layout.drawer.contains(position) {
            FocusPane::Files
        } else {
            self.focus
        };
        match pane {
            FocusPane::Diff => self.move_row(direction),
            FocusPane::Files => self.scroll_drawer(direction * DRAWER_WHEEL_ROWS),
        }
    }
}