truce-gui 0.1.1

//! Built-in editor using the CPU render backend.
//!
//! Renders parameter widgets via `RenderBackend`. Uses tiny-skia and blits
//! RGBA pixels to a CALayer. For GPU rendering, see the `truce-gpu` crate
//! which provides `GpuEditor` wrapping this editor with wgpu.

use std::ffi::c_void;
use std::sync::Arc;

use truce_core::editor::{Editor, EditorContext, RawWindowHandle};
use truce_params::Params;

use crate::backend_cpu::CpuBackend;
use crate::interaction::InteractionState;
use crate::layout::{GridLayout, Layout, PluginLayout, compute_section_offsets,
                     GRID_GAP, GRID_PADDING, GRID_HEADER_H, GRID_SECTION_H};
use crate::platform::{PlatformView, ViewCallbacks};
use crate::render::RenderBackend;
use crate::theme::Theme;
use crate::widgets;

/// Built-in editor that renders parameter widgets to a pixel buffer.
///
/// Uses the CPU backend (tiny-skia) for software rasterization. When
/// `open()` is called, creates a platform view and blits pixels at ~60fps.
pub struct BuiltinEditor<P: Params> {
    params: Arc<P>,
    layout: Layout,
    theme: Theme,
    backend: Option<CpuBackend>,
    interaction: InteractionState,
    context: Option<EditorContext>,
    view: Option<PlatformView>,
    /// Leaked self-pointer for C callbacks. Cleaned up on close().
    self_ptr: *mut c_void,
}

// Raw window handles and self_ptr are only accessed from the host UI thread.
unsafe impl<P: Params> Send for BuiltinEditor<P> {}

impl<P: Params + 'static> BuiltinEditor<P> {
    pub fn new(params: Arc<P>, layout: PluginLayout) -> Self {
        Self {
            params,
            layout: Layout::Rows(layout),
            theme: Theme::dark(),
            backend: None,
            interaction: InteractionState::new(),
            context: None,
            view: None,
            self_ptr: std::ptr::null_mut(),
        }
    }

    pub fn new_with_layout(params: Arc<P>, layout: Layout) -> Self {
        Self {
            params,
            layout,
            theme: Theme::dark(),
            backend: None,
            interaction: InteractionState::new(),
            context: None,
            view: None,
            self_ptr: std::ptr::null_mut(),
        }
    }

    pub fn new_grid(params: Arc<P>, layout: GridLayout) -> Self {
        Self {
            params,
            layout: Layout::Grid(layout),
            theme: Theme::dark(),
            backend: None,
            interaction: InteractionState::new(),
            context: None,
            view: None,
            self_ptr: std::ptr::null_mut(),
        }
    }

    pub fn with_theme(mut self, theme: Theme) -> Self {
        self.theme = theme;
        self
    }

    /// Render the full UI to the internal CPU pixel buffer.
    pub fn render(&mut self) {
        let (w, h) = (self.layout.width(), self.layout.height());
        let backend = self
            .backend
            .get_or_insert_with(|| CpuBackend::new(w, h).expect("Failed to create backend"));
        // SAFETY: we split the borrow — backend is a separate field from layout/params/etc.
        let backend_ptr = backend as *mut CpuBackend;
        self.render_widgets(unsafe { &mut *backend_ptr });
    }

    /// Render all widgets to any `RenderBackend`.
    fn render_widgets(&mut self, backend: &mut dyn RenderBackend) {
        if matches!(self.layout, Layout::Grid(_)) {
            self.render_grid_inner(backend);
        } else {
            self.render_rows_inner(backend);
        }
    }

    fn render_rows_inner(&mut self, backend: &mut dyn RenderBackend) {
        let pl = match &self.layout {
            Layout::Rows(pl) => pl,
            _ => return,
        };
        let w = pl.width;
        let knob_size = pl.knob_size;
        let title = pl.title;
        let version = pl.version;

        backend.clear(self.theme.background);
        let theme = &self.theme;

        widgets::draw_header(backend, 0.0, 0.0, w as f32, 30.0, title, version, theme);

        let pl = match &self.layout {
            Layout::Rows(pl) => pl,
            _ => return,
        };
        let mut y = 35.0;
        let mut render_widget_idx = 0usize;

        for row in &pl.rows {
            if let Some(label) = row.label {
                widgets::draw_section_label(backend, 0.0, y, w as f32, label, theme);
                y += 18.0;
            }

            let total_cols: u32 = row.knobs.iter().map(|k| k.span.max(1)).sum();
            let total_w = total_cols as f32 * (knob_size + 10.0) - 10.0;
            let start_x = (w as f32 - total_w) / 2.0;

            let mut col = 0u32;
            for knob_def in row.knobs.iter() {
                let span = knob_def.span.max(1);
                let x = start_x + col as f32 * (knob_size + 10.0);
                let widget_w = span as f32 * (knob_size + 10.0) - 10.0;

                let (normalized, value_text) = if let Some(ref ctx) = self.context {
                    let n = (ctx.get_param)(knob_def.param_id) as f32;
                    let t = (ctx.format_param)(knob_def.param_id);
                    (n, t)
                } else {
                    let n = self.params.get_normalized(knob_def.param_id).unwrap_or(0.0) as f32;
                    let p = self.params.get_plain(knob_def.param_id).unwrap_or(0.0);
                    let t = self
                        .params
                        .format_value(knob_def.param_id, p)
                        .unwrap_or_else(|| format!("{:.1}", p));
                    (n, t)
                };

                let region_idx = render_widget_idx;
                render_widget_idx += 1;
                let is_hovered = self.interaction.hover_idx == Some(region_idx);

                let wtype = resolve_widget_type(knob_def.widget, knob_def.param_id, &*self.params);

                match wtype {
                    widgets::WidgetType::Toggle => widgets::draw_toggle(
                        backend, x, y, widget_w, knob_size,
                        normalized, knob_def.label, &value_text,
                        theme, is_hovered,
                    ),
                    widgets::WidgetType::Slider => widgets::draw_slider(
                        backend, x, y, widget_w, knob_size,
                        normalized, knob_def.label, &value_text,
                        theme, is_hovered,
                    ),
                    widgets::WidgetType::Selector => widgets::draw_selector(
                        backend, x, y, widget_w, knob_size,
                        normalized, knob_def.label, &value_text,
                        theme, is_hovered,
                    ),
                    widgets::WidgetType::Meter => {
                        let default_ids = vec![knob_def.param_id];
                        let ids = knob_def.meter_ids.as_deref()
                            .unwrap_or(&default_ids);
                        let levels: Vec<f32> = if let Some(ref ctx) = self.context {
                            ids.iter().map(|&id| (ctx.get_meter)(id)).collect()
                        } else {
                            vec![0.0; ids.len()]
                        };
                        widgets::draw_meter(
                            backend, x, y, widget_w, knob_size,
                            &levels, knob_def.label, theme,
                        );
                    },
                    widgets::WidgetType::XYPad => {
                        let val_y_id = knob_def.param_id_y.unwrap_or(knob_def.param_id);
                        let (vx, vy) = if let Some(ref ctx) = self.context {
                            ((ctx.get_param)(knob_def.param_id) as f32,
                             (ctx.get_param)(val_y_id) as f32)
                        } else {
                            (self.params.get_normalized(knob_def.param_id).unwrap_or(0.0) as f32,
                             self.params.get_normalized(val_y_id).unwrap_or(0.0) as f32)
                        };
                        let infos = self.params.param_infos();
                        let x_name = infos.iter().find(|i| i.id == knob_def.param_id)
                            .map(|i| i.name).unwrap_or(knob_def.label);
                        let y_name = infos.iter().find(|i| i.id == val_y_id)
                            .map(|i| i.name).unwrap_or("");
                        widgets::draw_xy_pad(
                            backend, x, y, widget_w, knob_size,
                            vx, vy, x_name, y_name, theme, is_hovered,
                        );
                    },
                    widgets::WidgetType::Knob => widgets::draw_knob(
                        backend, x, y, knob_size, normalized,
                        knob_def.label, &value_text, theme, is_hovered,
                    ),
                }
                col += span;
            }

            y += knob_size + 30.0;
        }
    }

    fn render_grid_inner(&mut self, backend: &mut dyn RenderBackend) {
        let grid = match &self.layout {
            Layout::Grid(g) => g,
            _ => return,
        };
        let w = grid.width;
        let title = grid.title;
        let version = grid.version;

        backend.clear(self.theme.background);
        let theme = &self.theme;

        widgets::draw_header(backend, 0.0, 0.0, w as f32, 30.0, title, version, theme);

        let grid = match &self.layout {
            Layout::Grid(g) => g,
            _ => return,
        };

        let section_offsets = compute_section_offsets(grid);

        // Section labels
        for &(row_idx, label) in &grid.sections {
            let y = GRID_HEADER_H + GRID_PADDING
                + row_idx as f32 * (grid.cell_size + GRID_GAP)
                + section_offsets[row_idx as usize]
                - GRID_SECTION_H;
            widgets::draw_section_label(backend, 0.0, y, w as f32, label, theme);
        }

        // Widgets
        for (idx, gw) in grid.widgets.iter().enumerate() {
            let x = GRID_PADDING + gw.col as f32 * (grid.cell_size + GRID_GAP);
            let y = GRID_HEADER_H + GRID_PADDING
                + gw.row as f32 * (grid.cell_size + GRID_GAP)
                + section_offsets[gw.row as usize];
            let widget_w = gw.col_span as f32 * (grid.cell_size + GRID_GAP) - GRID_GAP;
            let widget_h = gw.row_span as f32 * (grid.cell_size + GRID_GAP) - GRID_GAP;

            let (normalized, value_text) = if let Some(ref ctx) = self.context {
                let n = (ctx.get_param)(gw.param_id) as f32;
                let t = (ctx.format_param)(gw.param_id);
                (n, t)
            } else {
                let n = self.params.get_normalized(gw.param_id).unwrap_or(0.0) as f32;
                let p = self.params.get_plain(gw.param_id).unwrap_or(0.0);
                let t = self
                    .params
                    .format_value(gw.param_id, p)
                    .unwrap_or_else(|| format!("{:.1}", p));
                (n, t)
            };

            let is_hovered = self.interaction.hover_idx == Some(idx);
            let wtype = resolve_widget_type(gw.widget, gw.param_id, &*self.params);

            match wtype {
                widgets::WidgetType::Toggle => widgets::draw_toggle(
                    backend, x, y, widget_w, widget_h,
                    normalized, gw.label, &value_text, theme, is_hovered,
                ),
                widgets::WidgetType::Slider => widgets::draw_slider(
                    backend, x, y, widget_w, widget_h,
                    normalized, gw.label, &value_text, theme, is_hovered,
                ),
                widgets::WidgetType::Selector => widgets::draw_selector(
                    backend, x, y, widget_w, widget_h,
                    normalized, gw.label, &value_text, theme, is_hovered,
                ),
                widgets::WidgetType::Meter => {
                    let default_ids = vec![gw.param_id];
                    let ids = gw.meter_ids.as_deref().unwrap_or(&default_ids);
                    let levels: Vec<f32> = if let Some(ref ctx) = self.context {
                        ids.iter().map(|&id| (ctx.get_meter)(id)).collect()
                    } else {
                        vec![0.0; ids.len()]
                    };
                    widgets::draw_meter(
                        backend, x, y, widget_w, widget_h,
                        &levels, gw.label, theme,
                    );
                },
                widgets::WidgetType::XYPad => {
                    let val_y_id = gw.param_id_y.unwrap_or(gw.param_id);
                    let (vx, vy) = if let Some(ref ctx) = self.context {
                        ((ctx.get_param)(gw.param_id) as f32,
                         (ctx.get_param)(val_y_id) as f32)
                    } else {
                        (self.params.get_normalized(gw.param_id).unwrap_or(0.0) as f32,
                         self.params.get_normalized(val_y_id).unwrap_or(0.0) as f32)
                    };
                    let infos = self.params.param_infos();
                    let x_name = infos.iter().find(|i| i.id == gw.param_id)
                        .map(|i| i.name).unwrap_or(gw.label);
                    let y_name = infos.iter().find(|i| i.id == val_y_id)
                        .map(|i| i.name).unwrap_or("");
                    widgets::draw_xy_pad(
                        backend, x, y, widget_w, widget_h,
                        vx, vy, x_name, y_name, theme, is_hovered,
                    );
                },
                widgets::WidgetType::Knob => {
                    let knob_size = widget_w.min(widget_h);
                    let kx = x + (widget_w - knob_size) / 2.0;
                    let ky = y + (widget_h - knob_size) / 2.0;
                    widgets::draw_knob(
                        backend, kx, ky, knob_size, normalized,
                        gw.label, &value_text, theme, is_hovered,
                    );
                },
            }
        }
    }

    /// Get the raw pixel data after rendering (RGBA premultiplied).
    pub fn pixel_data(&self) -> Option<&[u8]> {
        self.backend.as_ref().map(|b| b.data())
    }

    /// Get the KnobDef at a flattened index (Rows layout only).
    fn knob_def_at(&self, idx: usize) -> Option<&crate::layout::KnobDef> {
        if let Layout::Rows(pl) = &self.layout {
            let mut i = 0;
            for row in &pl.rows {
                for kd in &row.knobs {
                    if i == idx { return Some(kd); }
                    i += 1;
                }
            }
        }
        None
    }

    /// Get the Y-axis param ID for an XY pad at the given region index.
    fn param_id_y_at(&self, idx: usize) -> Option<u32> {
        match &self.layout {
            Layout::Rows(_) => self.knob_def_at(idx).and_then(|kd| kd.param_id_y),
            Layout::Grid(g) => g.widgets.get(idx).and_then(|w| w.param_id_y),
        }
    }

    // --- Public API for external backends (truce-gpu) ---

    /// Set the editor context (host callbacks) without opening the CPU view.
    pub fn set_context(&mut self, context: EditorContext) {
        self.context = Some(context);
        match &self.layout {
            Layout::Rows(pl) => self.interaction.build_regions(pl),
            Layout::Grid(gl) => self.interaction.build_regions_grid(gl),
        }
    }

    /// Render all widgets to an external `RenderBackend`.
    ///
    /// Used by `truce-gpu` to draw through the GPU backend instead of
    /// the internal CPU backend.
    pub fn render_to(&mut self, backend: &mut dyn RenderBackend) {
        unsafe { update_interaction(self) };
        self.render_widgets(backend);
    }

    // --- Mouse event handlers (public for external backends) ---

    pub fn on_mouse_down(&mut self, x: f32, y: f32) {
        if let Some(idx) = self.interaction.hit_test(x, y) {
            let param_id = self.interaction.knob_regions[idx].param_id;
            let wtype = self.interaction.widget_type_at(idx);
            if wtype == Some(crate::widgets::WidgetType::Toggle) {
                let norm = self.params.get_normalized(param_id).unwrap_or(0.0);
                let new_norm = if norm > 0.5 { 0.0 } else { 1.0 };
                self.params.set_normalized(param_id, new_norm);
                if let Some(ref ctx) = self.context {
                    (ctx.begin_edit)(param_id);
                    (ctx.set_param)(param_id, new_norm);
                    (ctx.end_edit)(param_id);
                }
            } else if wtype == Some(crate::widgets::WidgetType::Selector) {
                if let Some(info) = self.params.param_infos().into_iter().find(|i| i.id == param_id) {
                    let plain = self.params.get_plain(param_id).unwrap_or(0.0);
                    let max = info.range.max();
                    let next = if plain >= max { 0.0 } else { plain + 1.0 };
                    let new_norm = info.range.normalize(next);
                    self.params.set_normalized(param_id, new_norm);
                    if let Some(ref ctx) = self.context {
                        (ctx.begin_edit)(param_id);
                        (ctx.set_param)(param_id, new_norm);
                        (ctx.end_edit)(param_id);
                    }
                }
            } else {
                let norm = self.params.get_normalized(param_id).unwrap_or(0.0);
                self.interaction.begin_drag(idx, norm, y);
                if let Some(ref ctx) = self.context {
                    (ctx.begin_edit)(param_id);
                    if wtype == Some(crate::widgets::WidgetType::XYPad) {
                        if let Some(y_id) = self.param_id_y_at(idx) {
                            (ctx.begin_edit)(y_id);
                        }
                    }
                }
            }
        }
    }

    pub fn on_mouse_dragged(&mut self, x: f32, y: f32) {
        if let Some(drag) = &self.interaction.dragging {
            if drag.widget_type == crate::widgets::WidgetType::XYPad {
                let pad_margin = 4.0;
                let label_h = 18.0;
                let pad_x = drag.region_x + pad_margin;
                let pad_w = drag.region_w - pad_margin * 2.0;
                let pad_y_start = drag.region_y + pad_margin;
                let pad_h = drag.region_h - pad_margin * 2.0 - label_h;

                let norm_x = ((x - pad_x) / pad_w).clamp(0.0, 1.0) as f64;
                let norm_y = (1.0 - (y - pad_y_start) / pad_h).clamp(0.0, 1.0) as f64;

                let param_id = drag.param_id;
                let region_idx = drag.region_idx;
                self.params.set_normalized(param_id, norm_x);
                if let Some(ref ctx) = self.context {
                    (ctx.set_param)(param_id, norm_x);
                }

                if let Some(y_id) = self.param_id_y_at(region_idx) {
                    self.params.set_normalized(y_id, norm_y);
                    if let Some(ref ctx) = self.context {
                        (ctx.set_param)(y_id, norm_y);
                    }
                }
            } else if drag.widget_type == crate::widgets::WidgetType::Slider {
                if let Some((param_id, new_norm)) = self.interaction.update_slider_drag(x) {
                    self.params.set_normalized(param_id, new_norm);
                    if let Some(ref ctx) = self.context {
                        (ctx.set_param)(param_id, new_norm);
                    }
                }
            } else {
                if let Some((param_id, new_norm)) = self.interaction.update_drag(y) {
                    self.params.set_normalized(param_id, new_norm);
                    if let Some(ref ctx) = self.context {
                        (ctx.set_param)(param_id, new_norm);
                    }
                }
            }
        }
    }

    pub fn on_mouse_up(&mut self, _x: f32, _y: f32) {
        if let Some(drag) = &self.interaction.dragging {
            let param_id = drag.param_id;
            let was_xy = drag.widget_type == crate::widgets::WidgetType::XYPad;
            let region_idx = drag.region_idx;
            self.interaction.end_drag();
            if let Some(ref ctx) = self.context {
                (ctx.end_edit)(param_id);
                if was_xy {
                    if let Some(y_id) = self.param_id_y_at(region_idx) {
                        (ctx.end_edit)(y_id);
                    }
                }
            }
        }
    }

    pub fn on_double_click(&mut self, x: f32, y: f32) {
        if let Some(idx) = self.interaction.hit_test(x, y) {
            let param_id = self.interaction.knob_regions[idx].param_id;
            // Reset to default value
            let infos = self.params.param_infos();
            if let Some(info) = infos.iter().find(|i| i.id == param_id) {
                let default_norm = info.range.normalize(info.default_plain);
                self.params.set_normalized(param_id, default_norm);
                if let Some(ref ctx) = self.context {
                    (ctx.begin_edit)(param_id);
                    (ctx.set_param)(param_id, default_norm);
                    (ctx.end_edit)(param_id);
                }
            }
        }
    }

    pub fn on_scroll(&mut self, x: f32, y: f32, delta_y: f32) {
        if let Some(idx) = self.interaction.hit_test(x, y) {
            let param_id = self.interaction.knob_regions[idx].param_id;
            let norm = self.params.get_normalized(param_id).unwrap_or(0.0);
            let step = delta_y as f64 / 200.0; // 200 pixels of scroll = full range
            let new_norm = (norm + step).clamp(0.0, 1.0);
            self.params.set_normalized(param_id, new_norm);
            if let Some(ref ctx) = self.context {
                (ctx.begin_edit)(param_id);
                (ctx.set_param)(param_id, new_norm);
                (ctx.end_edit)(param_id);
            }
        }
    }

    pub fn on_mouse_moved(&mut self, x: f32, y: f32) -> bool {
        self.interaction.hover_idx = self.interaction.hit_test(x, y);
        self.interaction.hover_idx.is_some()
    }
}

// ---------------------------------------------------------------------------
// C callbacks — thin wrappers that cast the context pointer back to &mut Self
// ---------------------------------------------------------------------------

/// Update interaction regions and live param values.
///
/// # Safety
/// The editor must be valid and not concurrently accessed.
pub unsafe fn update_interaction<P: Params + 'static>(editor: &mut BuiltinEditor<P>) {
    match &editor.layout {
        Layout::Rows(pl) => {
            editor.interaction.build_regions(pl);
            let mut flat_idx = 0usize;
            for row in &pl.rows {
                for knob_def in &row.knobs {
                    if let Some(region) = editor.interaction.knob_regions.get_mut(flat_idx) {
                        region.widget_type = resolve_widget_type(
                            knob_def.widget, knob_def.param_id, &*editor.params,
                        );
                    }
                    flat_idx += 1;
                }
            }
        }
        Layout::Grid(gl) => {
            editor.interaction.build_regions_grid(gl);
            for (idx, gw) in gl.widgets.iter().enumerate() {
                if let Some(region) = editor.interaction.knob_regions.get_mut(idx) {
                    region.widget_type = resolve_widget_type(
                        gw.widget, gw.param_id, &*editor.params,
                    );
                }
            }
        }
    }
    for region in &mut editor.interaction.knob_regions {
        if let Some(ref ctx) = editor.context {
            region.normalized_value = (ctx.get_param)(region.param_id) as f32;
        } else {
            region.normalized_value =
                editor.params.get_normalized(region.param_id).unwrap_or(0.0) as f32;
        }
    }
}

unsafe extern "C" fn cb_render<P: Params + 'static>(
    ctx: *mut c_void,
    out_w: *mut u32,
    out_h: *mut u32,
) -> *const u8 {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    update_interaction(editor);
    editor.render();
    let backend = match editor.backend.as_ref() {
        Some(b) => b,
        None => return std::ptr::null(),
    };
    *out_w = backend.width();
    *out_h = backend.height();
    backend.data().as_ptr()
}

unsafe extern "C" fn cb_mouse_down<P: Params + 'static>(ctx: *mut c_void, x: f32, y: f32) {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_mouse_down(x, y);
}

unsafe extern "C" fn cb_mouse_dragged<P: Params + 'static>(ctx: *mut c_void, x: f32, y: f32) {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_mouse_dragged(x, y);
}

unsafe extern "C" fn cb_mouse_up<P: Params + 'static>(ctx: *mut c_void, x: f32, y: f32) {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_mouse_up(x, y);
}

unsafe extern "C" fn cb_scroll<P: Params + 'static>(
    ctx: *mut c_void,
    x: f32,
    y: f32,
    delta_y: f32,
) {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_scroll(x, y, delta_y);
}

unsafe extern "C" fn cb_double_click<P: Params + 'static>(ctx: *mut c_void, x: f32, y: f32) {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_double_click(x, y);
}

unsafe extern "C" fn cb_mouse_moved<P: Params + 'static>(ctx: *mut c_void, x: f32, y: f32) -> u8 {
    let editor = &mut *(ctx as *mut BuiltinEditor<P>);
    editor.on_mouse_moved(x, y) as u8
}

// ---------------------------------------------------------------------------
// Editor trait implementation
// ---------------------------------------------------------------------------

/// Resolve widget type: explicit override > auto-detect from param range.
fn resolve_widget_type<P: Params>(
    widget: Option<crate::layout::WidgetKind>,
    param_id: u32,
    params: &P,
) -> widgets::WidgetType {
    match widget {
        Some(crate::layout::WidgetKind::Knob) => widgets::WidgetType::Knob,
        Some(crate::layout::WidgetKind::Slider) => widgets::WidgetType::Slider,
        Some(crate::layout::WidgetKind::Toggle) => widgets::WidgetType::Toggle,
        Some(crate::layout::WidgetKind::Selector) => widgets::WidgetType::Selector,
        Some(crate::layout::WidgetKind::Meter) => widgets::WidgetType::Meter,
        Some(crate::layout::WidgetKind::XYPad) => widgets::WidgetType::XYPad,
        None => {
            let param_info = params.param_infos().into_iter()
                .find(|i| i.id == param_id);
            match param_info.as_ref().map(|i| &i.range) {
                Some(truce_params::ParamRange::Discrete { min: 0, max: 1 }) => widgets::WidgetType::Toggle,
                Some(truce_params::ParamRange::Enum { .. }) => widgets::WidgetType::Selector,
                _ => widgets::WidgetType::Knob,
            }
        }
    }
}

impl<P: Params + 'static> Editor for BuiltinEditor<P> {
    fn size(&self) -> (u32, u32) {
        (self.layout.width(), self.layout.height())
    }

    fn open(&mut self, parent: RawWindowHandle, context: EditorContext) {
        let (w, h) = self.size();
        self.backend = CpuBackend::new(w, h);
        self.context = Some(context);

        // Build interaction regions
        match &self.layout {
            Layout::Rows(pl) => self.interaction.build_regions(pl),
            Layout::Grid(gl) => self.interaction.build_regions_grid(gl),
        }

        // Render initial frame
        self.render();

        // Create platform view if we have a parent window
        let parent_ptr = match parent {
            RawWindowHandle::AppKit(ptr) => ptr,
            #[allow(unused)]
            _ => std::ptr::null_mut(),
        };

        if !parent_ptr.is_null() {
            let self_ptr = self as *mut BuiltinEditor<P> as *mut c_void;
            self.self_ptr = self_ptr;

            let callbacks = ViewCallbacks {
                render: Some(cb_render::<P>),
                mouse_down: Some(cb_mouse_down::<P>),
                mouse_dragged: Some(cb_mouse_dragged::<P>),
                mouse_up: Some(cb_mouse_up::<P>),
                scroll: Some(cb_scroll::<P>),
                double_click: Some(cb_double_click::<P>),
                mouse_moved: Some(cb_mouse_moved::<P>),
            };

            self.view = unsafe { PlatformView::new(parent_ptr, w, h, self_ptr, &callbacks) };
        }
    }

    fn close(&mut self) {
        self.view = None;
        self.context = None;
        self.backend = None;
        self.self_ptr = std::ptr::null_mut();
    }

    fn idle(&mut self) {
        // Platform view handles its own repaint timer.
        // If no platform view (standalone mode), render for external consumption.
        if self.view.is_none() {
            self.render();
        }
    }
}