ced/src/ui/central_panel/editor.rs

use crate::app::TextEditor;
use eframe::egui;

use super::find_highlight;

pub(super) fn editor_view_ui(ui: &mut egui::Ui, app: &mut TextEditor) -> egui::Response {
    let _current_match_position = app.get_current_match_position();
    let show_find = app.show_find;
    let _prev_show_find = app.prev_show_find;
    let show_preferences = app.show_preferences;
    let show_about = app.show_about;
    let show_shortcuts = app.show_shortcuts;
    let word_wrap = app.word_wrap;
    let font_size = app.font_size;

    let reset_zoom_key = egui::Id::new("editor_reset_zoom");
    let should_reset_zoom = ui
        .ctx()
        .memory_mut(|mem| mem.data.get_temp::<bool>(reset_zoom_key).unwrap_or(false));

    if should_reset_zoom {
        app.zoom_factor = 1.0;
        ui.ctx().set_zoom_factor(1.0);
        ui.ctx().memory_mut(|mem| {
            mem.data.insert_temp(reset_zoom_key, false);
        });
    }

    let estimated_width = if !word_wrap {
        app.calculate_content_based_width(ui)
    } else {
        0.0
    };

    let find_data = if show_find && !app.find_matches.is_empty() {
        app.get_active_tab().map(|tab| {
            (
                tab.content.to_owned(),
                app.find_matches.to_owned(),
                app.current_match_index,
            )
        })
    } else {
        None
    };

    let Some(active_tab) = app.get_active_tab_mut() else {
        return ui.label("No file open, how did you get here?");
    };

    let bg_color = ui.visuals().extreme_bg_color;
    let editor_rect = ui.available_rect_before_wrap();
    ui.painter().rect_filled(editor_rect, 0.0, bg_color);

    if let Some((content, matches, current_match_index)) = &find_data {
        let font_id = ui
            .style()
            .text_styles
            .get(&egui::TextStyle::Monospace)
            .unwrap_or(&egui::FontId::monospace(font_size))
            .to_owned();

        let desired_width = if word_wrap {
            ui.available_width()
        } else {
            f32::INFINITY
        };

        let temp_galley = ui.fonts(|fonts| {
            fonts.layout(
                content.to_owned(),
                font_id.to_owned(),
                ui.visuals().text_color(),
                desired_width,
            )
        });

        let text_area_left = editor_rect.left() + 4.0;
        let text_area_top = editor_rect.top() + 2.0;

        find_highlight::draw_find_highlights(
            ui,
            content,
            matches,
            *current_match_index,
            &temp_galley,
            text_area_left,
            text_area_top,
            font_size,
        );
    }

    let desired_width = if word_wrap {
        ui.available_width()
    } else {
        f32::INFINITY
    };

    let text_edit = egui::TextEdit::multiline(&mut active_tab.content)
        .frame(false)
        .font(egui::TextStyle::Monospace)
        .code_editor()
        .desired_width(desired_width)
        .desired_rows(0)
        .lock_focus(!show_find)
        .cursor_at_end(false)
        .id(egui::Id::new("main_text_editor"));

    let output = if word_wrap {
        text_edit.show(ui)
    } else {
        egui::ScrollArea::horizontal()
            .auto_shrink([false; 2])
            .show(ui, |ui| {
                ui.allocate_ui_with_layout(
                    egui::Vec2::new(estimated_width, ui.available_height()),
                    egui::Layout::left_to_right(egui::Align::TOP),
                    |ui| text_edit.show(ui),
                )
            })
            .inner
            .inner
    };

    let content_changed = output.response.changed();
    let content_for_processing = if content_changed {
        active_tab.update_modified_state();
        Some(active_tab.content.to_owned())
    } else {
        None
    };

    // Save state cache when content changes (after releasing the borrow)
    if content_changed {
        if let Err(e) = app.save_state_cache() {
            eprintln!("Failed to save state cache: {e}");
        }
    }

    if content_changed && app.show_find && !app.find_query.is_empty() {
        app.update_find_matches();
    }

    let current_cursor_pos = output
        .state
        .cursor
        .char_range()
        .map(|range| range.primary.index);

    if let Some(content) = content_for_processing {
        let previous_content = app.previous_content.to_owned();
        let previous_cursor_pos = app.previous_cursor_char_index;

        if !previous_content.is_empty() {
            if let (Some(prev_cursor_pos), Some(curr_cursor_pos)) =
                (previous_cursor_pos, current_cursor_pos)
            {
                app.process_incremental_change(
                    &previous_content,
                    &content,
                    prev_cursor_pos,
                    curr_cursor_pos,
                    ui,
                );
            }
        } else {
            app.process_text_for_rendering(&content, ui);
        }

        app.previous_content = content.to_owned();
        app.previous_cursor_char_index = current_cursor_pos;

    }

    if app.font_settings_changed || app.text_needs_processing {
        if let Some(active_tab) = app.get_active_tab() {
            let content = active_tab.content.to_owned();
            app.process_text_for_rendering(&content, ui);
        }
        app.font_settings_changed = false;
        app.text_needs_processing = false;
    }

    if !word_wrap {
        if let Some(cursor_pos) = current_cursor_pos {
            let cursor_moved = Some(cursor_pos) != app.previous_cursor_position;
            let text_changed = output.response.changed();

            if cursor_moved || text_changed {
                if let Some(active_tab) = app.get_active_tab() {
                    let content = &active_tab.content;
                    let cursor_line = content
                        .char_indices()
                        .take_while(|(byte_pos, _)| *byte_pos < cursor_pos)
                        .filter(|(_, ch)| *ch == '\n')
                        .count();

                    let font_id = ui
                        .style()
                        .text_styles
                        .get(&egui::TextStyle::Monospace)
                        .unwrap_or(&egui::FontId::monospace(font_size))
                        .to_owned();
                    let line_height = ui.fonts(|fonts| fonts.row_height(&font_id));

                    let y_pos = output.response.rect.top() + (cursor_line as f32 * line_height);
                    let cursor_rect = egui::Rect::from_min_size(
                        egui::pos2(output.response.rect.left(), y_pos),
                        egui::vec2(2.0, line_height),
                    );

                    let visible_area = ui.clip_rect();
                    if !visible_area.intersects(cursor_rect) {
                        ui.scroll_to_rect(cursor_rect, Some(egui::Align::Center));
                    }
                }
            }
            app.previous_cursor_position = Some(cursor_pos);
        }
    }

    if !output.response.has_focus()
        && !show_preferences
        && !show_about
        && !show_shortcuts
        && !show_find
    {
        output.response.request_focus();
    }

    output.response
}