re_viewer 0.5.1

use eframe::emath::RectTransform;
use egui::{pos2, vec2, Align2, Color32, NumExt as _, Pos2, Rect, ScrollArea, Shape, Vec2};
use macaw::IsoTransform;
use re_data_store::{EntityPath, EntityPropertyMap};
use re_renderer::view_builder::{TargetConfiguration, ViewBuilder};

use super::{
    eye::Eye,
    ui::{create_labels, picking, screenshot_context_menu},
    SpatialNavigationMode, ViewSpatialState,
};
use crate::{
    gpu_bridge,
    misc::{HoveredSpace, SpaceViewHighlights},
    ui::{
        view_spatial::{
            ui::outline_config,
            ui_renderer_bridge::{fill_view_builder, ScreenBackground},
            SceneSpatial,
        },
        SpaceViewId,
    },
    ViewerContext,
};

// ---

#[derive(Clone, Default, serde::Deserialize, serde::Serialize)]
#[serde(default)]
pub struct View2DState {
    /// The zoom and pan state, which is either a zoom/center or `Auto` which will fill the screen
    #[serde(skip)]
    zoom: ZoomState2D,
}

#[derive(Clone, Copy, Default)]
/// Sub-state specific to the Zoom/Scale/Pan engine
pub enum ZoomState2D {
    #[default]
    Auto,

    Scaled {
        /// Number of ui points per scene unit
        scale: f32,

        /// Which scene coordinate will be at the center of the zoomed region.
        center: Pos2,

        /// Whether to allow the state to be updated by the current `ScrollArea` offsets
        accepting_scroll: bool,
    },
}

impl View2DState {
    /// Determine the optimal sub-region and size based on the `ZoomState` and
    /// available size. This will generally be used to construct the painter and
    /// subsequent transforms
    ///
    /// Returns `(desired_size, scroll_offset)` where:
    ///   - `desired_size` is the size of the painter necessary to capture the zoomed view in ui points
    ///   - `scroll_offset` is the position of the `ScrollArea` offset in ui points
    fn desired_size_and_offset(
        &self,
        available_size: Vec2,
        scene_rect_accum: Rect,
    ) -> (Vec2, Vec2) {
        match self.zoom {
            ZoomState2D::Scaled { scale, center, .. } => {
                let desired_size = scene_rect_accum.size() * scale;

                // Try to keep the center of the scene in the middle of the available size
                let scroll_offset = (center.to_vec2() - scene_rect_accum.left_top().to_vec2())
                    * scale
                    - available_size / 2.0;

                (desired_size, scroll_offset)
            }
            ZoomState2D::Auto => {
                // Otherwise, we autoscale the space to fit available area while maintaining aspect ratio
                let scene_bbox = if scene_rect_accum.is_positive() {
                    scene_rect_accum
                } else {
                    Rect::from_min_max(Pos2::ZERO, Pos2::new(1.0, 1.0))
                };
                let mut desired_size = scene_bbox.size();
                desired_size *= available_size.x / desired_size.x; // fill full width
                desired_size *= (available_size.y / desired_size.y).at_most(1.0); // shrink so we don't fill more than full height

                if desired_size.is_finite() {
                    (desired_size, Vec2::ZERO)
                } else {
                    (available_size, Vec2::ZERO)
                }
            }
        }
    }

    /// Update our zoom state based on response
    /// If nothing else happens this will reset `accepting_scroll` to true when appropriate
    fn update(
        &mut self,
        response: &egui::Response,
        ui_to_space: egui::emath::RectTransform,
        scene_rect_accum: Rect,
        available_size: Vec2,
    ) {
        // Determine if we are zooming
        let zoom_delta = response.ctx.input(|i| i.zoom_delta());
        let hovered_zoom = if response.hovered() && zoom_delta != 1.0 {
            Some(zoom_delta)
        } else {
            None
        };

        match self.zoom {
            ZoomState2D::Auto => {
                if let Some(input_zoom) = hovered_zoom {
                    if input_zoom > 1.0 {
                        let scale = response.rect.height() / ui_to_space.to().height();
                        let center = scene_rect_accum.center();
                        self.zoom = ZoomState2D::Scaled {
                            scale,
                            center,
                            accepting_scroll: false,
                        };
                        // Recursively update now that we have initialized `ZoomState` to `Scaled`
                        self.update(response, ui_to_space, scene_rect_accum, available_size);
                    }
                }
            }
            ZoomState2D::Scaled {
                mut scale,
                mut center,
                ..
            } => {
                let mut accepting_scroll = true;

                // If we are zooming, adjust the scale and center
                if let Some(input_zoom) = hovered_zoom {
                    let new_scale = scale * input_zoom;

                    // Adjust for mouse location while executing zoom
                    if let Some(hover_pos) = response.ctx.input(|i| i.pointer.hover_pos()) {
                        let zoom_loc = ui_to_space.transform_pos(hover_pos);

                        // Space-units under the cursor will shift based on distance from center
                        let dist_from_center = zoom_loc - center;
                        // In UI points this happens based on the difference in scale;
                        let shift_in_ui = dist_from_center * (new_scale - scale);
                        // But we will compensate for it by a shift in space units
                        let shift_in_space = shift_in_ui / new_scale;

                        // Moving the center in the direction of the desired shift
                        center += shift_in_space;
                    }
                    scale = new_scale;
                    accepting_scroll = false;
                }

                // If we are dragging, adjust the center accordingly
                if response.dragged_by(egui::PointerButton::Primary) {
                    // Adjust center based on drag
                    center -= response.drag_delta() / scale;
                    accepting_scroll = false;
                }

                // Save the zoom state
                self.zoom = ZoomState2D::Scaled {
                    scale,
                    center,
                    accepting_scroll,
                };
            }
        }

        // Process things that might reset ZoomState to Auto
        if let ZoomState2D::Scaled { scale, .. } = self.zoom {
            // If the user double-clicks
            if response.double_clicked() {
                self.zoom = ZoomState2D::Auto;
            }

            // If our zoomed region is smaller than the available size
            if scene_rect_accum.size().x * scale < available_size.x
                && scene_rect_accum.size().y * scale < available_size.y
            {
                self.zoom = ZoomState2D::Auto;
            }
        }
    }

    /// Take the offset from the `ScrollArea` and apply it back to center so that other
    /// scroll interfaces work as expected.
    fn capture_scroll(&mut self, offset: Vec2, available_size: Vec2, scene_rect_accum: Rect) {
        if let ZoomState2D::Scaled {
            scale,
            accepting_scroll,
            ..
        } = self.zoom
        {
            if accepting_scroll {
                let center = scene_rect_accum.left_top() + (available_size / 2.0 + offset) / scale;
                self.zoom = ZoomState2D::Scaled {
                    scale,
                    center,
                    accepting_scroll,
                };
            }
        }
    }
}

pub const HELP_TEXT_2D: &str = "Ctrl-scroll  to zoom (⌘-scroll or Mac).\n\
    Drag to pan.\n\
    Double-click to reset the view.";

/// Create the outer 2D view, which consists of a scrollable region
/// TODO(andreas): Split into smaller parts, more re-use with `ui_3d`
#[allow(clippy::too_many_arguments)]
pub fn view_2d(
    ctx: &mut ViewerContext<'_>,
    ui: &mut egui::Ui,
    state: &mut ViewSpatialState,
    space: &EntityPath,
    scene: SceneSpatial,
    scene_rect_accum: Rect,
    space_view_id: SpaceViewId,
    highlights: &SpaceViewHighlights,
    entity_properties: &EntityPropertyMap,
) -> egui::Response {
    crate::profile_function!();

    // Save off the available_size since this is used for some of the layout updates later
    let available_size = ui.available_size();

    let (desired_size, offset) = state
        .state_2d
        .desired_size_and_offset(available_size, scene_rect_accum);

    // Bound the offset based on sizes
    // TODO(jleibs): can we derive this from the ScrollArea shape?
    let offset = offset.at_most(desired_size - available_size);
    let offset = offset.at_least(Vec2::ZERO);

    let scroll_area = ScrollArea::both()
        .scroll_offset(offset)
        .auto_shrink([false, false]);

    let scroll_out = scroll_area.show(ui, |ui| {
        view_2d_scrollable(
            desired_size,
            available_size,
            ctx,
            ui,
            state,
            space,
            scene,
            scene_rect_accum,
            space_view_id,
            highlights,
            entity_properties,
        )
    });

    // Update the scroll area based on the computed offset
    // This handles cases of dragging/zooming the space
    state
        .state_2d
        .capture_scroll(scroll_out.state.offset, available_size, scene_rect_accum);
    scroll_out.inner
}

/// Create the real 2D view inside the scrollable area
#[allow(clippy::too_many_arguments)]
fn view_2d_scrollable(
    desired_size: Vec2,
    available_size: Vec2,
    ctx: &mut ViewerContext<'_>,
    parent_ui: &mut egui::Ui,
    state: &mut ViewSpatialState,
    space: &EntityPath,
    mut scene: SceneSpatial,
    scene_rect_accum: Rect,
    space_view_id: SpaceViewId,
    highlights: &SpaceViewHighlights,
    entity_properties: &EntityPropertyMap,
) -> egui::Response {
    let (mut response, painter) =
        parent_ui.allocate_painter(desired_size, egui::Sense::click_and_drag());

    if !response.rect.is_positive() {
        return response; // protect against problems with zero-sized views
    }

    // Create our transforms.
    let ui_from_space = egui::emath::RectTransform::from_to(scene_rect_accum, response.rect);
    let space_from_ui = ui_from_space.inverse();
    let space_from_points = space_from_ui.scale().y;
    let points_from_pixels = 1.0 / painter.ctx().pixels_per_point();
    let space_from_pixel = space_from_points * points_from_pixels;

    state
        .state_2d
        .update(&response, space_from_ui, scene_rect_accum, available_size);

    let eye = Eye {
        world_from_view: IsoTransform::IDENTITY,
        fov_y: None,
    };

    let Ok(target_config) = setup_target_config(
        &painter,
        space_from_ui,
        space_from_pixel,
        &space.to_string(),
        state.auto_size_config(),
        scene
            .primitives
            .any_outlines,
    ) else {
        return response;
    };

    let mut view_builder = ViewBuilder::new(ctx.render_ctx, target_config);

    // Create labels now since their shapes participate are added to scene.ui for picking.
    let label_shapes = create_labels(
        &mut scene.ui,
        ui_from_space,
        space_from_ui,
        &eye,
        parent_ui,
        highlights,
        SpatialNavigationMode::TwoD,
    );

    if !re_ui::egui_helpers::is_anything_being_dragged(parent_ui.ctx()) {
        response = picking(
            ctx,
            response,
            space_from_ui,
            painter.clip_rect(),
            parent_ui,
            eye,
            &mut view_builder,
            space_view_id,
            state,
            &scene,
            space,
            entity_properties,
        );
    }

    // ------------------------------------------------------------------------

    // Screenshot context menu.
    let (response, screenshot_mode) = screenshot_context_menu(ctx, response);
    if let Some(mode) = screenshot_mode {
        let _ =
            view_builder.schedule_screenshot(ctx.render_ctx, space_view_id.gpu_readback_id(), mode);
    }

    // Draw a re_renderer driven view.
    // Camera & projection are configured to ingest space coordinates directly.
    {
        let command_buffer = match fill_view_builder(
            ctx.render_ctx,
            &mut view_builder,
            scene.primitives,
            &ScreenBackground::ClearColor(parent_ui.visuals().extreme_bg_color.into()),
        ) {
            Ok(command_buffer) => command_buffer,
            Err(err) => {
                re_log::error!("Failed to fill view builder: {}", err);
                return response;
            }
        };
        painter.add(gpu_bridge::renderer_paint_callback(
            ctx.render_ctx,
            command_buffer,
            view_builder,
            painter.clip_rect(),
            painter.ctx().pixels_per_point(),
        ));
    }

    painter.extend(show_projections_from_3d_space(
        ctx,
        parent_ui,
        space,
        &ui_from_space,
    ));

    // Add egui driven labels on top of re_renderer content.
    painter.extend(label_shapes);

    response
}

fn setup_target_config(
    painter: &egui::Painter,
    space_from_ui: RectTransform,
    space_from_pixel: f32,
    space_name: &str,
    auto_size_config: re_renderer::AutoSizeConfig,
    any_outlines: bool,
) -> anyhow::Result<TargetConfiguration> {
    let pixels_from_points = painter.ctx().pixels_per_point();
    let resolution_in_pixel =
        gpu_bridge::viewport_resolution_in_pixels(painter.clip_rect(), pixels_from_points);
    anyhow::ensure!(resolution_in_pixel[0] > 0 && resolution_in_pixel[1] > 0);

    let camera_position_space = space_from_ui.transform_pos(painter.clip_rect().min);

    Ok({
        let name = space_name.into();
        let top_left_position = glam::vec2(camera_position_space.x, camera_position_space.y);
        TargetConfiguration {
            name,
            resolution_in_pixel,
            view_from_world: macaw::IsoTransform::from_translation(-top_left_position.extend(0.0)),
            projection_from_view: re_renderer::view_builder::Projection::Orthographic {
                camera_mode:
                    re_renderer::view_builder::OrthographicCameraMode::TopLeftCornerAndExtendZ,
                vertical_world_size: space_from_pixel * resolution_in_pixel[1] as f32,
                far_plane_distance: 1000.0,
            },
            pixels_from_point: pixels_from_points,
            auto_size_config,
            outline_config: any_outlines.then(|| outline_config(painter.ctx())),
        }
    })
}

// ------------------------------------------------------------------------

fn show_projections_from_3d_space(
    ctx: &ViewerContext<'_>,
    ui: &egui::Ui,
    space: &EntityPath,
    ui_from_space: &RectTransform,
) -> Vec<Shape> {
    let mut shapes = Vec::new();
    if let HoveredSpace::ThreeD {
        point_in_space_cameras: target_spaces,
        ..
    } = ctx.selection_state().hovered_space()
    {
        for (space_2d, pos_2d) in target_spaces {
            if space_2d == space {
                if let Some(pos_2d) = pos_2d {
                    // User is hovering a 2D point inside a 3D view.
                    let pos_in_ui = ui_from_space.transform_pos(pos2(pos_2d.x, pos_2d.y));
                    let radius = 4.0;
                    shapes.push(Shape::circle_filled(
                        pos_in_ui,
                        radius + 2.0,
                        Color32::BLACK,
                    ));
                    shapes.push(Shape::circle_filled(pos_in_ui, radius, Color32::WHITE));

                    let text = format!("Depth: {:.3} m", pos_2d.z);
                    let font_id = egui::TextStyle::Body.resolve(ui.style());
                    let galley =
                        ui.fonts(|fonts| fonts.layout_no_wrap(text, font_id, Color32::WHITE));
                    let rect = Align2::CENTER_TOP.anchor_rect(Rect::from_min_size(
                        pos_in_ui + vec2(0.0, 5.0),
                        galley.size(),
                    ));
                    shapes.push(Shape::rect_filled(
                        rect,
                        2.0,
                        Color32::from_black_alpha(196),
                    ));
                    shapes.push(Shape::galley(rect.min, galley));
                }
            }
        }
    }
    shapes
}