ratada 0.3.0

//! Table interaction: key dispatch, cursor navigation, selection and the
//! filter/sort view rebuild.

use std::collections::HashSet;

use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};

use super::model::{filter_indices, sort_indices};
use super::{FilterScope, SelectMode, SortDir, Table, TableAction};
use crate::nav;

impl Table {
    /// Handles a key press; returns whether the host should act on it.
    pub fn handle_key(&mut self, key: KeyEvent) -> TableAction {
        if self.filtering {
            self.handle_filter_key(key);
            return TableAction::None;
        }
        let shift = key.modifiers.contains(KeyModifiers::SHIFT);
        let ctrl = key.modifiers.contains(KeyModifiers::CONTROL);
        let page = self.viewport.get().max(1) as isize;
        let last = self.view.len().saturating_sub(1);
        match key.code {
            KeyCode::Char('a') if ctrl => self.select_all(),
            KeyCode::Up | KeyCode::Char('k') => self.move_rows(-1, shift),
            KeyCode::Down | KeyCode::Char('j') => self.move_rows(1, shift),
            KeyCode::PageUp => self.move_rows(-page, shift),
            KeyCode::PageDown => self.move_rows(page, shift),
            KeyCode::Home | KeyCode::Char('g') => self.move_to(0, shift),
            KeyCode::End | KeyCode::Char('G') => self.move_to(last, shift),
            KeyCode::Left | KeyCode::Char('h') => self.move_col(-1, shift),
            KeyCode::Right | KeyCode::Char('l') => self.move_col(1, shift),
            KeyCode::Char(' ') => self.toggle_current(),
            KeyCode::Char('s') => self.sort_by_active(),
            KeyCode::Char('f') => self.toggle_filter_scope(),
            KeyCode::Char('m') => self.toggle_mode(),
            KeyCode::Char('/') => self.filtering = true,
            KeyCode::Esc => self.clear_selection(),
            KeyCode::Enter => return TableAction::Activate,
            _ => {}
        }
        TableAction::None
    }

    /// Whether the filter input is active (the host modal yields keys to it).
    pub fn is_filtering(&self) -> bool {
        self.filtering
    }

    fn handle_filter_key(&mut self, key: KeyEvent) {
        match key.code {
            KeyCode::Esc => {
                self.filtering = false;
                self.filter.clear();
                self.rebuild_view();
            }
            KeyCode::Enter => self.filtering = false,
            KeyCode::Backspace => {
                self.filter.pop();
                self.rebuild_view();
            }
            KeyCode::Char(ch) => {
                self.filter.push(ch);
                self.rebuild_view();
            }
            _ => {}
        }
    }

    fn move_rows(&mut self, delta: isize, shift: bool) {
        let target = nav::step_clamped(self.cursor, self.view.len(), delta);
        self.move_to(target, shift);
    }

    fn move_to(&mut self, target: usize, shift: bool) {
        if self.view.is_empty() {
            return;
        }
        let prev = self.cursor;
        self.cursor = target.min(self.view.len() - 1);
        self.after_move(prev, shift);
    }

    fn move_col(&mut self, delta: isize, shift: bool) {
        if self.columns.is_empty() {
            return;
        }
        let prev_cell = self.cursor_cell();
        self.active_col =
            nav::step_clamped(self.active_col, self.columns.len(), delta);
        if shift && self.mode == SelectMode::Cell {
            if let Some(cell) = prev_cell {
                self.selected_cells.insert(cell);
            }
            if let Some(cell) = self.cursor_cell() {
                self.selected_cells.insert(cell);
            }
        }
    }

    /// Applies selection side effects after the cursor row moved.
    fn after_move(&mut self, prev: usize, shift: bool) {
        if !shift {
            self.anchor = self.cursor;
            return;
        }
        match self.mode {
            SelectMode::Row => {
                let (lo, hi) = minmax(self.anchor, self.cursor);
                for view_idx in lo..=hi {
                    self.selected_rows.insert(self.view[view_idx]);
                }
            }
            SelectMode::Cell => {
                for view_idx in [prev, self.cursor] {
                    self.selected_cells
                        .insert((self.view[view_idx], self.active_col));
                }
            }
        }
    }

    fn toggle_current(&mut self) {
        match self.mode {
            SelectMode::Row => {
                if let Some(row) = self.cursor_row() {
                    toggle(&mut self.selected_rows, row);
                }
            }
            SelectMode::Cell => {
                if let Some(cell) = self.cursor_cell() {
                    toggle(&mut self.selected_cells, cell);
                }
            }
        }
    }

    fn select_all(&mut self) {
        match self.mode {
            SelectMode::Row => {
                self.selected_rows = self.view.iter().copied().collect();
            }
            SelectMode::Cell => {
                self.selected_cells = self
                    .view
                    .iter()
                    .flat_map(|&row| {
                        (0..self.columns.len()).map(move |col| (row, col))
                    })
                    .collect();
            }
        }
    }

    fn clear_selection(&mut self) {
        self.selected_rows.clear();
        self.selected_cells.clear();
    }

    fn toggle_mode(&mut self) {
        self.mode = match self.mode {
            SelectMode::Row => SelectMode::Cell,
            SelectMode::Cell => SelectMode::Row,
        };
        // Selections do not translate between the modes.
        self.clear_selection();
    }

    fn toggle_filter_scope(&mut self) {
        self.filter_scope = match self.filter_scope {
            FilterScope::AllColumns => FilterScope::ActiveColumn,
            FilterScope::ActiveColumn => FilterScope::AllColumns,
        };
        self.rebuild_view();
    }

    fn sort_by_active(&mut self) {
        let dir = match self.sort {
            Some((col, SortDir::Asc)) if col == self.active_col => {
                SortDir::Desc
            }
            _ => SortDir::Asc,
        };
        self.sort = Some((self.active_col, dir));
        self.rebuild_view();
    }

    /// Recomputes `view` (filter then sort), keeping the cursor on its row.
    fn rebuild_view(&mut self) {
        let keep = self.cursor_row();
        let mut view = filter_indices(
            &self.rows,
            &self.filter,
            self.filter_scope,
            self.active_col,
        );
        if let Some((col, dir)) = self.sort {
            view = sort_indices(&self.rows, &self.columns, view, col, dir);
        }
        self.view = view;
        self.cursor = keep
            .and_then(|row| self.view.iter().position(|&r| r == row))
            .unwrap_or(0)
            .min(self.view.len().saturating_sub(1));
        self.anchor = self.cursor;
    }
}

fn toggle<T: Eq + std::hash::Hash>(set: &mut HashSet<T>, value: T) {
    if !set.remove(&value) {
        set.insert(value);
    }
}

fn minmax(a: usize, b: usize) -> (usize, usize) {
    if a <= b { (a, b) } else { (b, a) }
}