penpot/render-wasm/src/wasm/text_editor.rs

use macros::{wasm_error, ToJs};

use crate::math::{Matrix, Point, Rect};
use crate::mem;
use crate::shapes::{Shape, TextContent, TextPositionWithAffinity, Type, VerticalAlign};
use crate::state::TextSelection;
use crate::utils::uuid_from_u32_quartet;
use crate::utils::uuid_to_u32_quartet;
use crate::wasm::text::helpers as text_helpers;
use crate::{with_state, with_state_mut, STATE};
use skia_safe::{textlayout::TextDirection, Color};

#[derive(PartialEq, ToJs)]
#[repr(u8)]
#[allow(dead_code)]
pub enum CursorDirection {
    Backward = 0,
    Forward = 1,
    LineBefore = 2,
    LineAfter = 3,
    LineStart = 4,
    LineEnd = 5,
}

// ============================================================================
// STATE MANAGEMENT
// ============================================================================

#[no_mangle]
pub extern "C" fn text_editor_apply_theme(
    selection_color: u32,
    cursor_width: f32,
    cursor_color: u32,
) {
    with_state_mut!(state, {
        // NOTE: In the future could be interesting to fill al this data from
        // a structure pointer.
        state.text_editor_state.theme.selection_color = Color::new(selection_color);
        state.text_editor_state.theme.cursor_width = cursor_width;
        state.text_editor_state.theme.cursor_color = Color::new(cursor_color);
    })
}

#[no_mangle]
pub extern "C" fn text_editor_start(a: u32, b: u32, c: u32, d: u32) -> bool {
    with_state_mut!(state, {
        let shape_id = uuid_from_u32_quartet(a, b, c, d);

        let Some(shape) = state.shapes.get(&shape_id) else {
            return false;
        };

        if !matches!(shape.shape_type, Type::Text(_)) {
            return false;
        }

        state.text_editor_state.start(shape_id);
        true
    })
}

#[no_mangle]
pub extern "C" fn text_editor_stop() -> bool {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return false;
        }
        state.text_editor_state.stop();
        true
    })
}

#[no_mangle]
pub extern "C" fn text_editor_is_active() -> bool {
    with_state!(state, { state.text_editor_state.is_active })
}

#[no_mangle]
pub extern "C" fn text_editor_is_active_with_id(a: u32, b: u32, c: u32, d: u32) -> bool {
    with_state!(state, {
        let shape_id = uuid_from_u32_quartet(a, b, c, d);
        let Some(active_shape_id) = state.text_editor_state.active_shape_id else {
            return false;
        };
        state.text_editor_state.is_active && active_shape_id == shape_id
    })
}

#[no_mangle]
pub extern "C" fn text_editor_get_active_shape_id(buffer_ptr: *mut u32) {
    with_state!(state, {
        if let Some(shape_id) = state.text_editor_state.active_shape_id {
            let (a, b, c, d) = uuid_to_u32_quartet(&shape_id);
            unsafe {
                *buffer_ptr = a;
                *buffer_ptr.add(1) = b;
                *buffer_ptr.add(2) = c;
                *buffer_ptr.add(3) = d;
            }
        }
    })
}

#[no_mangle]
pub extern "C" fn text_editor_select_all() -> bool {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return false;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return false;
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return false;
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return false;
        };
        state.text_editor_state.select_all(text_content)
    })
}

#[no_mangle]
pub extern "C" fn text_editor_select_word_boundary(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };

        let point = Point::new(x, y);
        if let Some(position) = text_content.get_caret_position_from_shape_coords(&point) {
            state
                .text_editor_state
                .select_word_boundary(text_content, &position);
        }
    })
}

#[no_mangle]
pub extern "C" fn text_editor_poll_event() -> u8 {
    with_state_mut!(state, { state.text_editor_state.poll_event() as u8 })
}

// ============================================================================
// SELECTION MANAGEMENT
// ============================================================================

#[no_mangle]
pub extern "C" fn text_editor_pointer_down(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };
        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };
        let point = Point::new(x, y);
        state.text_editor_state.start_pointer_selection();
        if let Some(position) = text_content.get_caret_position_from_shape_coords(&point) {
            state.text_editor_state.set_caret_from_position(&position);
        }
    });
}

#[no_mangle]
pub extern "C" fn text_editor_pointer_move(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }
        let point = Point::new(x, y);
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };
        if !state.text_editor_state.is_pointer_selection_active {
            return;
        }
        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };

        if let Some(position) = text_content.get_caret_position_from_shape_coords(&point) {
            state
                .text_editor_state
                .extend_selection_from_position(&position);
        }
    });
}

#[no_mangle]
pub extern "C" fn text_editor_pointer_up(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }
        let point = Point::new(x, y);
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };
        if !state.text_editor_state.is_pointer_selection_active {
            return;
        }
        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };
        if let Some(position) = text_content.get_caret_position_from_shape_coords(&point) {
            state
                .text_editor_state
                .extend_selection_from_position(&position);
        }
        state.text_editor_state.stop_pointer_selection();
    });
}

#[no_mangle]
pub extern "C" fn text_editor_set_cursor_from_offset(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let point = Point::new(x, y);
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };
        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };
        if let Some(position) = text_content.get_caret_position_from_shape_coords(&point) {
            state.text_editor_state.set_caret_from_position(&position);
        }
    });
}

#[no_mangle]
pub extern "C" fn text_editor_set_cursor_from_point(x: f32, y: f32) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let view_matrix: Matrix = state.render_state.viewbox.get_matrix();
        let point = Point::new(x, y);
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };
        let shape_matrix = shape.get_matrix();
        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };
        if let Some(position) =
            text_content.get_caret_position_from_screen_coords(&point, &view_matrix, &shape_matrix)
        {
            state.text_editor_state.set_caret_from_position(&position);
        }
    });
}

// ============================================================================
// TEXT OPERATIONS
// ============================================================================

// FIXME: Review if all the return Ok(()) should be Err instead.
#[no_mangle]
#[wasm_error]
pub extern "C" fn text_editor_insert_text() -> Result<()> {
    let bytes = crate::mem::bytes();
    let text = match String::from_utf8(bytes) {
        Ok(text) => text,
        Err(_) => return Ok(()),
    };

    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return Ok(());
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return Ok(());
        };

        let Some(shape) = state.shapes.get_mut(&shape_id) else {
            return Ok(());
        };

        let Type::Text(text_content) = &mut shape.shape_type else {
            return Ok(());
        };

        let selection = state.text_editor_state.selection;

        if selection.is_selection() {
            text_helpers::delete_selection_range(text_content, &selection);
            let start = selection.start();
            state.text_editor_state.selection.set_caret(start);
        }

        let cursor = state.text_editor_state.selection.focus;

        if let Some(new_cursor) =
            text_helpers::insert_text_with_newlines(text_content, &cursor, &text)
        {
            state.text_editor_state.selection.set_caret(new_cursor);
        }

        text_content.layout.paragraphs.clear();
        text_content.layout.paragraph_builders.clear();

        state.text_editor_state.reset_blink();
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::ContentChanged);
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::NeedsLayout);

        state.render_state.mark_touched(shape_id);
    });

    crate::mem::free_bytes()?;
    Ok(())
}

#[no_mangle]
pub extern "C" fn text_editor_delete_backward(word_boundary: bool) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        let Some(shape) = state.shapes.get_mut(&shape_id) else {
            return;
        };

        let Type::Text(text_content) = &mut shape.shape_type else {
            return;
        };

        let selection = state.text_editor_state.selection;

        if selection.is_selection() {
            text_helpers::delete_selection_range(text_content, &selection);
            let start = selection.start();
            let clamped = text_helpers::clamp_cursor(start, text_content.paragraphs());
            state.text_editor_state.selection.set_caret(clamped);
        } else if word_boundary {
            let cursor = selection.focus;
            if let Some(new_cursor) = text_helpers::delete_word_before(text_content, &cursor) {
                state.text_editor_state.selection.set_caret(new_cursor);
            }
        } else {
            let cursor = selection.focus;
            if let Some(new_cursor) = text_helpers::delete_char_before(text_content, &cursor) {
                state.text_editor_state.selection.set_caret(new_cursor);
            }
        }

        text_content.layout.paragraphs.clear();
        text_content.layout.paragraph_builders.clear();

        state.text_editor_state.reset_blink();
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::ContentChanged);
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::NeedsLayout);

        state.render_state.mark_touched(shape_id);
    });
}

#[no_mangle]
pub extern "C" fn text_editor_delete_forward(word_boundary: bool) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        let Some(shape) = state.shapes.get_mut(&shape_id) else {
            return;
        };

        let Type::Text(text_content) = &mut shape.shape_type else {
            return;
        };

        let selection = state.text_editor_state.selection;

        if selection.is_selection() {
            text_helpers::delete_selection_range(text_content, &selection);
            let start = selection.start();
            let clamped = text_helpers::clamp_cursor(start, text_content.paragraphs());
            state.text_editor_state.selection.set_caret(clamped);
        } else if word_boundary {
            let cursor = selection.focus;
            text_helpers::delete_word_after(text_content, &cursor);
            let clamped = text_helpers::clamp_cursor(cursor, text_content.paragraphs());
            state.text_editor_state.selection.set_caret(clamped);
        } else {
            let cursor = selection.focus;
            text_helpers::delete_char_after(text_content, &cursor);
            let clamped = text_helpers::clamp_cursor(cursor, text_content.paragraphs());
            state.text_editor_state.selection.set_caret(clamped);
        }

        text_content.layout.paragraphs.clear();
        text_content.layout.paragraph_builders.clear();

        state.text_editor_state.reset_blink();
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::ContentChanged);
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::NeedsLayout);

        state.render_state.mark_touched(shape_id);
    });
}

#[no_mangle]
pub extern "C" fn text_editor_insert_paragraph() {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        let Some(shape) = state.shapes.get_mut(&shape_id) else {
            return;
        };

        let Type::Text(text_content) = &mut shape.shape_type else {
            return;
        };

        let selection = state.text_editor_state.selection;

        if selection.is_selection() {
            text_helpers::delete_selection_range(text_content, &selection);
            let start = selection.start();
            state.text_editor_state.selection.set_caret(start);
        }

        let cursor = state.text_editor_state.selection.focus;

        if text_helpers::split_paragraph_at_cursor(text_content, &cursor) {
            let new_cursor =
                TextPositionWithAffinity::new_without_affinity(cursor.paragraph + 1, 0);
            state.text_editor_state.selection.set_caret(new_cursor);
        }

        text_content.layout.paragraphs.clear();
        text_content.layout.paragraph_builders.clear();

        state.text_editor_state.reset_blink();
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::ContentChanged);
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::NeedsLayout);

        state.render_state.mark_touched(shape_id);
    });
}

// ============================================================================
// NAVIGATION
// ============================================================================

#[no_mangle]
pub extern "C" fn text_editor_move_cursor(
    direction: CursorDirection,
    word_boundary: bool,
    extend_selection: bool,
) {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return;
        };

        let paragraphs = text_content.paragraphs();
        if paragraphs.is_empty() {
            return;
        }

        let current = state.text_editor_state.selection.focus;

        // Get the text direction of the span at the current cursor position
        let span_text_direction = if current.paragraph < paragraphs.len() {
            text_helpers::get_span_text_direction_at_offset(
                &paragraphs[current.paragraph],
                current.offset,
            )
        } else {
            TextDirection::LTR
        };

        // For horizontal navigation, swap Backward/Forward when in RTL text
        let adjusted_direction = if span_text_direction == TextDirection::RTL {
            match direction {
                CursorDirection::Backward => CursorDirection::Forward,
                CursorDirection::Forward => CursorDirection::Backward,
                other => other,
            }
        } else {
            direction
        };

        let new_cursor = match adjusted_direction {
            CursorDirection::Backward => {
                text_helpers::move_cursor_backward(&current, paragraphs, word_boundary)
            }
            CursorDirection::Forward => {
                text_helpers::move_cursor_forward(&current, paragraphs, word_boundary)
            }
            CursorDirection::LineBefore => {
                text_helpers::move_cursor_up(&current, paragraphs, text_content)
            }
            CursorDirection::LineAfter => {
                text_helpers::move_cursor_down(&current, paragraphs, text_content)
            }
            CursorDirection::LineStart => {
                text_helpers::move_cursor_line_start(&current, paragraphs)
            }
            CursorDirection::LineEnd => text_helpers::move_cursor_line_end(&current, paragraphs),
        };

        if extend_selection {
            state.text_editor_state.selection.extend_to(new_cursor);
        } else {
            state.text_editor_state.selection.set_caret(new_cursor);
        }

        state.text_editor_state.reset_blink();
        state
            .text_editor_state
            .push_event(crate::state::TextEditorEvent::SelectionChanged);
    });
}

// ============================================================================
// RENDERING & EXPORT
// ============================================================================

#[no_mangle]
pub extern "C" fn text_editor_get_cursor_rect() -> *mut u8 {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active || !state.text_editor_state.cursor_visible {
            return std::ptr::null_mut();
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return std::ptr::null_mut();
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return std::ptr::null_mut();
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return std::ptr::null_mut();
        };

        let cursor = &state.text_editor_state.selection.focus;

        if let Some(rect) = get_cursor_rect(text_content, cursor, shape) {
            let mut bytes = vec![0u8; 16];
            bytes[0..4].copy_from_slice(&rect.left().to_le_bytes());
            bytes[4..8].copy_from_slice(&rect.top().to_le_bytes());
            bytes[8..12].copy_from_slice(&rect.width().to_le_bytes());
            bytes[12..16].copy_from_slice(&rect.height().to_le_bytes());
            return mem::write_bytes(bytes);
        }

        std::ptr::null_mut()
    })
}

#[no_mangle]
pub extern "C" fn text_editor_get_selection_rects() -> *mut u8 {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return std::ptr::null_mut();
        }

        if state.text_editor_state.selection.is_collapsed() {
            return std::ptr::null_mut();
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return std::ptr::null_mut();
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return std::ptr::null_mut();
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return std::ptr::null_mut();
        };

        let selection = &state.text_editor_state.selection;
        let rects = get_selection_rects(text_content, selection, shape);

        if rects.is_empty() {
            return std::ptr::null_mut();
        }

        let mut bytes = Vec::with_capacity(4 + rects.len() * 16);
        bytes.extend_from_slice(&(rects.len() as u32).to_le_bytes());
        for rect in rects {
            bytes.extend_from_slice(&rect.left().to_le_bytes());
            bytes.extend_from_slice(&rect.top().to_le_bytes());
            bytes.extend_from_slice(&rect.width().to_le_bytes());
            bytes.extend_from_slice(&rect.height().to_le_bytes());
        }
        mem::write_bytes(bytes)
    })
}

#[no_mangle]
pub extern "C" fn text_editor_update_blink(timestamp_ms: f64) {
    with_state_mut!(state, {
        state.text_editor_state.update_blink(timestamp_ms);
    });
}

#[no_mangle]
pub extern "C" fn text_editor_render_overlay() {
    with_state_mut!(state, {
        if !state.text_editor_state.is_active {
            return;
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return;
        };

        if let Some(shape) = state.shapes.get(&shape_id) {
            if let Type::Text(text_content) = &shape.shape_type {
                if text_content.needs_update_layout() {
                    let selrect = shape.selrect();
                    if let Some(shape) = state.shapes.get_mut(&shape_id) {
                        if let Type::Text(text_content) = &mut shape.shape_type {
                            text_content.update_layout(selrect);
                        }
                    }
                }
            }
        }

        let Some(shape) = state.shapes.get(&shape_id) else {
            return;
        };

        let transform = shape.get_concatenated_matrix(&state.shapes);

        use crate::render::text_editor as te_render;
        use crate::render::SurfaceId;

        let canvas = state.render_state.surfaces.canvas(SurfaceId::Target);

        canvas.save();
        let viewbox = state.render_state.viewbox;
        let zoom = viewbox.zoom * state.render_state.options.dpr();
        canvas.scale((zoom, zoom));
        canvas.translate((-viewbox.area.left, -viewbox.area.top));

        te_render::render_overlay(canvas, &state.text_editor_state, shape, &transform);

        canvas.restore();
        state.render_state.flush_and_submit();
    });
}

#[no_mangle]
pub extern "C" fn text_editor_export_content() -> *mut u8 {
    with_state!(state, {
        if !state.text_editor_state.is_active {
            return std::ptr::null_mut();
        }

        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return std::ptr::null_mut();
        };

        let Some(shape) = state.shapes.get(&shape_id) else {
            return std::ptr::null_mut();
        };

        let Type::Text(text_content) = &shape.shape_type else {
            return std::ptr::null_mut();
        };

        let mut json_parts: Vec<String> = Vec::new();
        for para in text_content.paragraphs() {
            let mut span_parts: Vec<String> = Vec::new();
            for span in para.children() {
                let escaped_text = span
                    .text
                    .replace('\\', "\\\\")
                    .replace('"', "\\\"")
                    .replace('\n', "\\n")
                    .replace('\r', "\\r")
                    .replace('\t', "\\t");
                span_parts.push(format!("\"{}\"", escaped_text));
            }
            json_parts.push(format!("[{}]", span_parts.join(",")));
        }
        let json = format!("[{}]", json_parts.join(","));

        let mut bytes = json.into_bytes();
        bytes.push(0);
        crate::mem::write_bytes(bytes)
    })
}

#[no_mangle]
pub extern "C" fn text_editor_export_selection() -> *mut u8 {
    use std::ptr;
    with_state!(state, {
        if !state.text_editor_state.is_active {
            return ptr::null_mut();
        }
        let Some(shape_id) = state.text_editor_state.active_shape_id else {
            return ptr::null_mut();
        };
        let Some(shape) = state.shapes.get(&shape_id) else {
            return ptr::null_mut();
        };
        let Type::Text(text_content) = &shape.shape_type else {
            return ptr::null_mut();
        };
        let selection = &state.text_editor_state.selection;
        let start = selection.start();
        let end = selection.end();
        let paragraphs = text_content.paragraphs();
        let mut result = String::new();
        let end_paragraph = end.paragraph.min(paragraphs.len().saturating_sub(1)) + 1;
        for (para_idx, _) in paragraphs
            .iter()
            .enumerate()
            .take(end_paragraph)
            .skip(start.paragraph)
        {
            let para = &paragraphs[para_idx];
            let mut para_text = String::new();
            let para_char_count: usize = para
                .children()
                .iter()
                .map(|span| span.text.chars().count())
                .sum();
            let range_start = if para_idx == start.paragraph {
                start.offset
            } else {
                0
            };
            let range_end = if para_idx == end.paragraph {
                end.offset
            } else {
                para_char_count
            };
            if range_start < range_end {
                let mut char_pos = 0;
                for span in para.children() {
                    let span_len = span.text.chars().count();
                    let span_start = char_pos;
                    let span_end = char_pos + span_len;
                    let sel_start = range_start.max(span_start);
                    let sel_end = range_end.min(span_end);
                    if sel_start < sel_end {
                        let rel_start = sel_start - span_start;
                        let rel_end = sel_end - span_start;
                        let text: String = span
                            .text
                            .chars()
                            .skip(rel_start)
                            .take(rel_end - rel_start)
                            .collect();
                        para_text.push_str(&text);
                    }
                    char_pos += span_len;
                }
            }
            if para_idx > start.paragraph {
                result.push('\n');
            }
            result.push_str(&para_text);
        }
        let mut bytes = result.into_bytes();
        bytes.push(0);
        crate::mem::write_bytes(bytes)
    })
}

#[no_mangle]
pub extern "C" fn text_editor_get_selection(buffer_ptr: *mut u32) -> u32 {
    with_state!(state, {
        if !state.text_editor_state.is_active {
            return 0;
        }
        let sel = &state.text_editor_state.selection;
        unsafe {
            *buffer_ptr = sel.anchor.paragraph as u32;
            *buffer_ptr.add(1) = sel.anchor.offset as u32;
            *buffer_ptr.add(2) = sel.focus.paragraph as u32;
            *buffer_ptr.add(3) = sel.focus.offset as u32;
        }
        1
    })
}

// ============================================================================
// HELPERS: Cursor & Selection
// ============================================================================

fn get_cursor_rect(
    text_content: &TextContent,
    cursor: &TextPositionWithAffinity,
    shape: &Shape,
) -> Option<Rect> {
    let paragraphs = text_content.paragraphs();
    if cursor.paragraph >= paragraphs.len() {
        return None;
    }

    let layout_paragraphs: Vec<_> = text_content.layout.paragraphs.iter().flatten().collect();

    let total_height: f32 = layout_paragraphs.iter().map(|p| p.height()).sum();
    let valign_offset = match shape.vertical_align() {
        VerticalAlign::Center => (shape.selrect().height() - total_height) / 2.0,
        VerticalAlign::Bottom => shape.selrect().height() - total_height,
        _ => 0.0,
    };

    let mut y_offset = valign_offset;
    for (idx, laid_out_para) in layout_paragraphs.iter().enumerate() {
        if idx == cursor.paragraph {
            let char_pos = cursor.offset;

            use skia_safe::textlayout::{RectHeightStyle, RectWidthStyle};
            let rects = laid_out_para.get_rects_for_range(
                char_pos..char_pos,
                RectHeightStyle::Tight,
                RectWidthStyle::Tight,
            );

            let (x, height) = if !rects.is_empty() {
                (rects[0].rect.left(), rects[0].rect.height())
            } else {
                let pos = laid_out_para.get_glyph_position_at_coordinate((0.0, 0.0));
                let height = laid_out_para.height();
                (pos.position as f32, height)
            };

            let cursor_width = 2.0;
            let selrect = shape.selrect();
            let base_x = selrect.x();
            let base_y = selrect.y() + y_offset;

            return Some(Rect::from_xywh(base_x + x, base_y, cursor_width, height));
        }
        y_offset += laid_out_para.height();
    }

    None
}

/// Get selection rectangles for a given selection.
fn get_selection_rects(
    text_content: &TextContent,
    selection: &TextSelection,
    shape: &Shape,
) -> Vec<Rect> {
    let mut rects = Vec::new();

    let start = selection.start();
    let end = selection.end();

    let paragraphs = text_content.paragraphs();
    let layout_paragraphs: Vec<_> = text_content.layout.paragraphs.iter().flatten().collect();

    let selrect = shape.selrect();

    let total_height: f32 = layout_paragraphs.iter().map(|p| p.height()).sum();
    let valign_offset = match shape.vertical_align() {
        VerticalAlign::Center => (selrect.height() - total_height) / 2.0,
        VerticalAlign::Bottom => selrect.height() - total_height,
        _ => 0.0,
    };

    let mut y_offset = valign_offset;

    for (para_idx, laid_out_para) in layout_paragraphs.iter().enumerate() {
        let para_height = laid_out_para.height();

        if para_idx < start.paragraph || para_idx > end.paragraph {
            y_offset += para_height;
            continue;
        }

        if para_idx >= paragraphs.len() {
            y_offset += para_height;
            continue;
        }

        let para = &paragraphs[para_idx];
        let para_char_count: usize = para
            .children()
            .iter()
            .map(|span| span.text.chars().count())
            .sum();
        let range_start = if para_idx == start.paragraph {
            start.offset
        } else {
            0
        };

        let range_end = if para_idx == end.paragraph {
            end.offset
        } else {
            para_char_count
        };

        if range_start < range_end {
            use skia_safe::textlayout::{RectHeightStyle, RectWidthStyle};
            let text_boxes = laid_out_para.get_rects_for_range(
                range_start..range_end,
                RectHeightStyle::Tight,
                RectWidthStyle::Tight,
            );

            for text_box in text_boxes {
                let r = text_box.rect;
                rects.push(Rect::from_xywh(
                    selrect.x() + r.left(),
                    selrect.y() + y_offset + r.top(),
                    r.width(),
                    r.height(),
                ));
            }
        }

        y_offset += para_height;
    }

    rects
}