edamame 0.1.1

A fast TUI Markdown editor and viewer
Documentation 
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use crate::document::EditDelta;
use crate::editor::list_edit;
use crate::editor::{EditorState, Mode};

use super::coord::click_to_char_offset;

/// If `(col, row)` falls on a task-list checkbox glyph, toggle it and return
/// `true`.  Otherwise returns `false` so the caller can fall through to
/// cursor-placement behaviour.
pub(super) fn toggle_checkbox_at(
    state: &mut EditorState,
    col: usize,
    row: usize,
    viewport_width: usize,
) -> bool {
    if state.mode == Mode::Raw {
        return false;
    }
    // Locate the source line under the click by reusing the click-to-offset
    // translation, then ask the list machinery whether the click sits inside
    // a checkbox glyph.
    let Some(offset) = click_to_char_offset(state, col, row, viewport_width) else {
        return false;
    };
    let source = state.buffer.contents();
    let click_byte = state.buffer.rope().char_to_byte(offset);
    let Some(info) = list_edit::find_list_at(&source, click_byte) else {
        return false;
    };
    // Find which item this is.  `cursor_item_idx` does the work.
    let Some(item_idx) = list_edit::cursor_item_idx(&info, click_byte) else {
        return false;
    };
    let item = &info.items[item_idx];
    let Some(task_box) = item.task_box else {
        return false;
    };

    // Toggle hitbox spans the entire bullet+checkbox prefix — `• [ ]`
    // (i.e. `item.start..task_box + 3` in source bytes).  Clicks anywhere
    // on the bullet, the leading marker space, or the `[x]` glyph itself
    // toggle the checkbox; clicks on the trailing space after `]` fall
    // through to normal cursor placement so the user can put the caret
    // immediately before the task's text.
    let hit_start = item.start;
    let hit_end = task_box + 3;
    if click_byte >= hit_start && click_byte < hit_end {
        if let Some(res) = list_edit::toggle_checkbox(&info, &source, click_byte) {
            // Checkbox toggle is a 1-for-1 char replacement, so existing
            // offsets stay valid.  Apply the edit without touching cursor
            // tracking state (`update_cursor_block` would reset the reveal
            // timer, causing the current cursor block to briefly re-render
            // as "rendered" before snapping back to "raw").
            let offset_char = state.buffer.rope().byte_to_char(res.delta.offset);
            let delta = EditDelta {
                offset: offset_char,
                removed: res.delta.removed,
                inserted: res.delta.inserted,
            };
            let saved_offset = state.cursor.offset;
            let saved_preferred = state.cursor.preferred_col;
            let saved_block_idx = state.cursor_block_idx;
            let saved_line_idx = state.cursor_line_idx;
            let saved_entered_at = state.cursor_block_entered_at;
            state.apply_delta(delta);
            state.cursor.offset = saved_offset.min(state.buffer.len_chars());
            state.cursor.preferred_col = saved_preferred;
            state.cursor_block_idx = saved_block_idx;
            state.cursor_line_idx = saved_line_idx;
            state.cursor_block_entered_at = saved_entered_at;
            return true;
        }
    }
    false
}