use std::cell::RefCell;
use std::collections::BTreeMap;

use anyhow::Result;
use maplit::btreemap;
use rand::seq::{IteratorRandom, SliceRandom};

use abstio::MapName;
use abstutil::Timer;
use geom::{Bounds, Circle, Distance, Duration, FindClosest, Polygon, Pt2D, Time};
use map_gui::colors::ColorScheme;
use map_gui::options::Options;
use map_gui::render::{unzoomed_agent_radius, AgentCache, DrawMap, DrawOptions, Renderable};
use map_gui::tools::CameraState;
use map_gui::ID;
use map_model::AreaType;
use map_model::{BufferType, IntersectionID, LaneType, Map, Traversable};
use sim::{AgentID, Analytics, Scenario, Sim, SimCallback, SimFlags, VehicleType};
use widgetry::mapspace::ToggleZoomed;
use widgetry::{Cached, Canvas, EventCtx, GfxCtx, Prerender, SharedAppState, State};

use crate::challenges::HighScore;
use crate::common::Warping;
use crate::edit::apply_map_edits;
use crate::layer::Layer;
use crate::sandbox::dashboards::DashTab;
use crate::sandbox::{GameplayMode, TutorialState};

// Convenient typedef
pub type Transition = widgetry::Transition<App>;

/// The top-level data that lasts through the entire game, no matter what state the game is in.
pub struct App {
    pub primary: PerMap,
    /// This is only used right now for a debug mode to compare two versions of the same map. In
    /// the future, it might be used for some kind of live "side-by-side" comparison.
    pub secondary: Option<PerMap>,
    pub cs: ColorScheme,
    pub opts: Options,

    pub per_obj: PerObjectActions,

    /// Static data that lasts the entire session. Use sparingly.
    pub session: SessionState,
}

impl App {
    // TODO Should the prebaked methods be on primary along with the data?
    pub fn has_prebaked(&self) -> Option<(&MapName, &String)> {
        self.primary.prebaked.as_ref().map(|(m, s, _)| (m, s))
    }
    pub fn prebaked(&self) -> &Analytics {
        &self.primary.prebaked.as_ref().unwrap().2
    }
    pub fn set_prebaked(&mut self, prebaked: Option<(MapName, String, Analytics)>) {
        self.primary.prebaked = prebaked;

        if false {
            if let Some((_, _, ref a)) = self.primary.prebaked {
                use abstutil::{prettyprint_usize, serialized_size_bytes};
                println!(
                    "- road_thruput: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.road_thruput))
                );
                println!(
                    "- intersection_thruput: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.intersection_thruput))
                );
                println!(
                    "- traffic_signal_thruput: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.traffic_signal_thruput))
                );
                println!(
                    "- demand : {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.demand))
                );
                println!(
                    "- bus_arrivals : {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.bus_arrivals))
                );
                println!(
                    "- passengers_boarding: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.passengers_boarding))
                );
                println!(
                    "- passengers_alighting: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.passengers_alighting))
                );
                println!(
                    "- started_trips: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.started_trips))
                );
                println!(
                    "- finished_trips: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.finished_trips))
                );
                println!(
                    "- trip_log: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.trip_log))
                );
                println!(
                    "- intersection_delays: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.intersection_delays))
                );
                println!(
                    "- parking_lane_changes: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.parking_lane_changes))
                );
                println!(
                    "- parking_lot_changes: {} bytes",
                    prettyprint_usize(serialized_size_bytes(&a.parking_lot_changes))
                );
            }
        }
    }

    pub fn draw(&self, g: &mut GfxCtx, opts: DrawOptions, show_objs: &dyn ShowObject) {
        let map = &self.primary.map;
        let draw_map = &self.primary.draw_map;

        let mut sample_intersection: Option<String> = None;

        g.clear(self.cs.void_background);
        g.redraw(&draw_map.boundary_polygon);

        if g.canvas.is_unzoomed() {
            let layers = show_objs.layers();
            if layers.show_areas {
                g.redraw(&draw_map.draw_all_areas);
            }
            if layers.show_parking_lots {
                g.redraw(&draw_map.draw_all_unzoomed_parking_lots);
            }
            if layers.show_intersections || layers.show_lanes {
                g.redraw(
                    &self
                        .primary
                        .draw_map
                        .draw_all_unzoomed_roads_and_intersections,
                );
            }
            if layers.show_buildings {
                g.redraw(&draw_map.draw_all_buildings);
                g.redraw(&draw_map.draw_all_building_outlines);
            }

            // Still show some shape selection when zoomed out.
            // TODO Refactor! Ideally use get_obj
            if let Some(ID::Area(id)) = self.primary.current_selection {
                g.draw_polygon(self.cs.selected, draw_map.get_a(id).get_outline(map));
            } else if let Some(ID::Road(id)) = self.primary.current_selection {
                g.draw_polygon(self.cs.selected, draw_map.get_r(id).get_outline(map));
            } else if let Some(ID::Intersection(id)) = self.primary.current_selection {
                // Actually, don't use get_outline here! Full polygon is easier to see.
                g.draw_polygon(self.cs.selected, map.get_i(id).polygon.clone());
            } else if let Some(ID::Building(id)) = self.primary.current_selection {
                g.draw_polygon(self.cs.selected, map.get_b(id).polygon.clone());
            }

            let mut cache = self.primary.agents.borrow_mut();
            cache.draw_unzoomed_agents(g, self);

            if let Some(a) = self
                .primary
                .current_selection
                .as_ref()
                .and_then(|id| id.agent_id())
            {
                if let Some(pt) = self.primary.sim.canonical_pt_for_agent(a, map) {
                    // Usually we show selection with an outline, but no thickness/color is really
                    // visible for these tiny crowded dots.
                    g.draw_polygon(
                        self.cs.selected,
                        Circle::new(pt, unzoomed_agent_radius(a.to_vehicle_type())).to_polygon(),
                    );
                }
            }
        } else {
            let mut cache = self.primary.agents.borrow_mut();
            let objects = self.get_renderables_back_to_front(
                g.get_screen_bounds(),
                g.prerender,
                &mut cache,
                show_objs,
            );

            let mut drawn_all_buildings = false;
            let mut drawn_all_areas = false;

            for obj in objects {
                obj.draw(g, self, &opts);

                match obj.get_id() {
                    ID::Building(_) => {
                        if !drawn_all_buildings {
                            g.redraw(&draw_map.draw_all_buildings);
                            g.redraw(&draw_map.draw_all_building_outlines);
                            drawn_all_buildings = true;
                        }
                    }
                    ID::Area(_) => {
                        if !drawn_all_areas {
                            g.redraw(&draw_map.draw_all_areas);
                            drawn_all_areas = true;
                        }
                    }
                    _ => {}
                }

                if self.primary.current_selection == Some(obj.get_id()) {
                    g.draw_polygon(self.cs.selected, obj.get_outline(map));
                }

                if g.is_screencap() && sample_intersection.is_none() {
                    if let ID::Intersection(id) = obj.get_id() {
                        sample_intersection = Some(format!("_i{}", id.0));
                    }
                }
            }
        }

        if let Some(i) = sample_intersection {
            g.set_screencap_naming_hint(i);
        }
    }

    /// Assumes some defaults.
    pub fn recalculate_current_selection(&mut self, ctx: &EventCtx) {
        self.primary.current_selection =
            self.calculate_current_selection(ctx, &ShowEverything::new(), false, false, false);
    }

    pub fn mouseover_unzoomed_roads_and_intersections(&self, ctx: &EventCtx) -> Option<ID> {
        self.calculate_current_selection(ctx, &ShowEverything::new(), false, true, false)
    }
    pub fn mouseover_unzoomed_intersections(&self, ctx: &EventCtx) -> Option<ID> {
        self.calculate_current_selection(ctx, &ShowEverything::new(), false, true, false)
            .filter(|id| matches!(id, ID::Intersection(_)))
    }
    pub fn mouseover_unzoomed_buildings(&self, ctx: &EventCtx) -> Option<ID> {
        self.calculate_current_selection(ctx, &ShowEverything::new(), false, false, true)
    }
    pub fn mouseover_unzoomed_everything(&self, ctx: &EventCtx) -> Option<ID> {
        self.calculate_current_selection(ctx, &ShowEverything::new(), false, true, true)
    }
    pub fn mouseover_debug_mode(&self, ctx: &EventCtx, show_objs: &dyn ShowObject) -> Option<ID> {
        self.calculate_current_selection(ctx, show_objs, true, false, false)
    }

    fn calculate_current_selection(
        &self,
        ctx: &EventCtx,
        show_objs: &dyn ShowObject,
        debug_mode: bool,
        unzoomed_roads_and_intersections: bool,
        unzoomed_buildings: bool,
    ) -> Option<ID> {
        let unzoomed = ctx.canvas.is_unzoomed();

        // Unzoomed mode. Ignore when debugging areas.
        if unzoomed && !(debug_mode || unzoomed_roads_and_intersections || unzoomed_buildings) {
            return None;
        }

        let pt = ctx.canvas.get_cursor_in_map_space()?;

        let mut cache = self.primary.agents.borrow_mut();
        let mut objects = self.get_renderables_back_to_front(
            Circle::new(pt, Distance::meters(3.0)).get_bounds(),
            ctx.prerender,
            &mut cache,
            show_objs,
        );
        objects.reverse();

        let mut small_agents: Vec<(ID, Pt2D)> = Vec::new();

        // In most cases, this loop is greedy -- as soon as we find the first object containing the
        // cursor, return it. But if we happen to match a pedestrian or bike while zoomed in, there
        // might be several overlapping hitboxes. Collect them all in small_agents, then pick the
        // closest to the cursor.
        for obj in objects {
            let id = obj.get_id();
            match id {
                ID::Area(_) => {
                    if !debug_mode {
                        continue;
                    }
                }
                ID::Road(_) => {
                    if !unzoomed_roads_and_intersections || !unzoomed {
                        continue;
                    }
                }
                ID::Intersection(_) => {
                    if unzoomed && !unzoomed_roads_and_intersections {
                        continue;
                    }
                }
                ID::Building(_) => {
                    if unzoomed && !unzoomed_buildings {
                        continue;
                    }
                }
                _ => {
                    if unzoomed {
                        continue;
                    }
                }
            }
            if obj.contains_pt(pt, &self.primary.map) {
                if unzoomed {
                    // If we're selecting agents unzoomed, they're all tiny circles, and we really
                    // don't care about picking the one closest to the cursor.
                    return Some(id);
                }

                match id {
                    ID::Pedestrian(_) => {}
                    ID::Car(c) => {
                        if c.vehicle_type != VehicleType::Bike {
                            return Some(id);
                        }
                    }
                    _ => {
                        // Once we match at least one small agent, keep scanning through all
                        // possible hits. Ignore lanes and intersections and other thngs; they have
                        // a lower z-order.
                        if small_agents.is_empty() {
                            return Some(id);
                        } else {
                            continue;
                        }
                    }
                }

                small_agents.push((id, obj.get_outline(&self.primary.map).center()));
            }
        }

        let (id, _) = small_agents
            .into_iter()
            .min_by_key(|(_, center)| center.fast_dist(pt))?;
        Some(id)
    }

    // TODO This could probably belong to DrawMap again, but it's annoying to plumb things that
    // State does, like show_icons_for() and show().
    fn get_renderables_back_to_front<'a>(
        &'a self,
        bounds: Bounds,
        prerender: &Prerender,
        agents: &'a mut AgentCache,
        show_objs: &dyn ShowObject,
    ) -> Vec<&'a (dyn Renderable + 'a)> {
        let map = &self.primary.map;
        let draw_map = &self.primary.draw_map;

        let mut areas: Vec<&dyn Renderable> = Vec::new();
        let mut parking_lots: Vec<&dyn Renderable> = Vec::new();
        let mut lanes: Vec<&dyn Renderable> = Vec::new();
        let mut roads: Vec<&dyn Renderable> = Vec::new();
        let mut intersections: Vec<&dyn Renderable> = Vec::new();
        let mut buildings: Vec<&dyn Renderable> = Vec::new();
        let mut bus_stops: Vec<&dyn Renderable> = Vec::new();
        let mut agents_on: Vec<Traversable> = Vec::new();

        for id in draw_map.get_matching_objects(bounds) {
            if !show_objs.show(&id) {
                continue;
            }
            match id {
                ID::Area(id) => areas.push(draw_map.get_a(id)),
                ID::Road(id) => {
                    let road = draw_map.get_r(id);
                    for lane in &road.lanes {
                        agents_on.push(Traversable::Lane(lane.id));
                        for bs in &map.get_l(lane.id).bus_stops {
                            if show_objs.show(&ID::BusStop(*bs)) {
                                bus_stops.push(draw_map.get_bs(*bs));
                            }
                        }
                        lanes.push(lane);
                    }
                    roads.push(road);
                }
                ID::Intersection(id) => {
                    intersections.push(draw_map.get_i(id));
                    for t in &map.get_i(id).turns {
                        agents_on.push(Traversable::Turn(t.id));
                    }
                }
                ID::Building(id) => buildings.push(draw_map.get_b(id)),
                ID::ParkingLot(id) => {
                    parking_lots.push(draw_map.get_pl(id));
                    // Slight hack
                    agents_on.push(Traversable::Lane(map.get_pl(id).driving_pos.lane()));
                }

                ID::Lane(_) | ID::BusStop(_) | ID::Car(_) | ID::Pedestrian(_) | ID::PedCrowd(_) => {
                    panic!("{:?} shouldn't be in the quadtree", id)
                }
            }
        }

        // From background to foreground Z-order
        let mut borrows: Vec<&dyn Renderable> = Vec::new();
        borrows.extend(areas);
        borrows.extend(parking_lots);
        borrows.extend(lanes);
        borrows.extend(roads);
        borrows.extend(intersections);
        borrows.extend(buildings);
        borrows.extend(bus_stops);

        // Expand all of the Traversables into agents, populating the cache if needed.
        {
            for on in &agents_on {
                agents.populate_if_needed(*on, map, &self.primary.sim, &self.cs, prerender);
            }
        }

        for on in agents_on {
            for obj in agents.get(on) {
                borrows.push(obj);
            }
        }

        borrows.retain(|x| x.get_zorder() <= self.primary.draw_map.show_zorder);

        // This is a stable sort.
        borrows.sort_by_key(|x| x.get_zorder());

        borrows
    }

    /// Ensure the map edits are blank, reset the simulation, and blank out prebaked results.
    pub fn clear_everything(&mut self, ctx: &mut EventCtx) {
        ctx.loading_screen("reset map and sim", |ctx, mut timer| {
            apply_map_edits(ctx, self, self.primary.map.new_edits());
            self.primary
                .map
                .recalculate_pathfinding_after_edits(&mut timer);

            self.primary.clear_sim();
            self.set_prebaked(None);
        });
    }
}

impl App {
    /// If an intersection was clicked, return its ID.
    pub fn click_on_intersection<S: Into<String>>(
        &mut self,
        ctx: &mut EventCtx,
        label: S,
    ) -> Option<IntersectionID> {
        if let Some(ID::Intersection(i)) = self.primary.current_selection {
            if self.per_obj.left_click(ctx, label) {
                return Some(i);
            }
        }
        None
    }
}

// I haven't measured build or runtime impact of inlining vs not, but I assume for these simple
// accessors it makes sense.
impl map_gui::AppLike for App {
    #[inline]
    fn map(&self) -> &Map {
        &self.primary.map
    }
    #[inline]
    fn sim(&self) -> &Sim {
        &self.primary.sim
    }
    #[inline]
    fn cs(&self) -> &ColorScheme {
        &self.cs
    }
    #[inline]
    fn mut_cs(&mut self) -> &mut ColorScheme {
        &mut self.cs
    }
    #[inline]
    fn draw_map(&self) -> &DrawMap {
        &self.primary.draw_map
    }
    #[inline]
    fn mut_draw_map(&mut self) -> &mut DrawMap {
        &mut self.primary.draw_map
    }
    #[inline]
    fn opts(&self) -> &Options {
        &self.opts
    }
    #[inline]
    fn mut_opts(&mut self) -> &mut Options {
        &mut self.opts
    }

    fn map_switched(&mut self, ctx: &mut EventCtx, map: Map, timer: &mut Timer) {
        let sim = Sim::new(&map, self.primary.current_flags.sim_flags.opts.clone());

        CameraState::save(ctx.canvas, self.primary.map.get_name());
        self.primary = PerMap::map_loaded(
            map,
            sim,
            self.primary.current_flags.clone(),
            &self.opts,
            &self.cs,
            ctx,
            timer,
        );
        self.primary.init_camera_for_loaded_map(ctx, false);
    }

    fn draw_with_opts(&self, g: &mut GfxCtx, opts: DrawOptions) {
        self.draw(g, opts, &ShowEverything::new());
    }
    fn make_warper(
        &mut self,
        ctx: &EventCtx,
        pt: Pt2D,
        target_cam_zoom: Option<f64>,
        id: Option<ID>,
    ) -> Box<dyn State<App>> {
        Warping::new_state(ctx, pt, target_cam_zoom, id, &mut self.primary)
    }
}

pub struct ShowLayers {
    pub show_buildings: bool,
    pub show_parking_lots: bool,
    pub show_intersections: bool,
    pub show_lanes: bool,
    pub show_areas: bool,
    pub show_labels: bool,
}

impl ShowLayers {
    pub fn new() -> ShowLayers {
        ShowLayers {
            show_buildings: true,
            show_parking_lots: true,
            show_intersections: true,
            show_lanes: true,
            show_areas: true,
            show_labels: false,
        }
    }
}

pub trait ShowObject {
    fn show(&self, obj: &ID) -> bool;
    fn layers(&self) -> &ShowLayers;
}

pub struct ShowEverything {
    layers: ShowLayers,
}

impl ShowEverything {
    pub fn new() -> ShowEverything {
        ShowEverything {
            layers: ShowLayers::new(),
        }
    }
}

impl ShowObject for ShowEverything {
    fn show(&self, _: &ID) -> bool {
        true
    }

    fn layers(&self) -> &ShowLayers {
        &self.layers
    }
}

#[derive(Clone)]
pub struct Flags {
    pub sim_flags: SimFlags,
    /// If true, all map edits immediately apply to the live simulation. Otherwise, most edits
    /// require resetting to midnight.
    pub live_map_edits: bool,
    /// Display an extra area with this name on the map. This gets applied to every map loaded, if
    /// the area is within map bounds.
    pub study_area: Option<String>,
}

/// All of the state that's bound to a specific map.
pub struct PerMap {
    pub map: Map,
    pub draw_map: DrawMap,
    pub sim: Sim,
    pub agents: RefCell<AgentCache>,

    pub current_selection: Option<ID>,
    pub current_flags: Flags,
    pub last_warped_from: Option<(Pt2D, f64)>,
    pub sim_cb: Option<Box<dyn SimCallback>>,
    /// If we ever left edit mode and resumed without restarting from midnight, this is true.
    pub dirty_from_edits: bool,
    /// Any ScenarioModifiers in effect?
    pub has_modified_trips: bool,

    /// If the map has been edited, store the unedited version here.
    pub unedited_map: Option<Map>,

    pub layer: Option<Box<dyn Layer>>,
    /// Only filled out in edit mode. Stored here once to avoid lots of clones. Used for preview.
    pub suspended_sim: Option<Sim>,
    /// Only exists in some gameplay modes. Must be carefully reset otherwise. Has the map and
    /// scenario name too.
    // TODO Embed that in Analytics directly instead.
    prebaked: Option<(MapName, String, Analytics)>,
    /// The most recent Scenario loaded from a file. Don't depend on it always matching the current
    /// gameplay mode; always verify the name matches what's needed.
    ///
    /// Storing this may cost some memory, but otherwise resetting to midnight would require
    /// loading it again from a file. This is particularly painful on the web!
    pub scenario: Option<Scenario>,

    /// Is this the original "secondary" state, loaded via --diff?
    pub is_secondary: bool,
}

impl PerMap {
    pub fn map_loaded(
        mut map: Map,
        sim: Sim,
        flags: Flags,
        opts: &Options,
        cs: &ColorScheme,
        ctx: &mut EventCtx,
        timer: &mut Timer,
    ) -> PerMap {
        if let Some(ref name) = flags.study_area {
            if let Err(err) = add_study_area(&mut map, name) {
                error!("Didn't apply study area {}: {}", name, err);
            }
        }

        timer.start("draw_map");
        let draw_map = DrawMap::new(ctx, &map, opts, cs, timer);
        timer.stop("draw_map");

        PerMap {
            map,
            draw_map,
            sim,
            agents: RefCell::new(AgentCache::new_state()),
            current_selection: None,
            current_flags: flags,
            last_warped_from: None,
            sim_cb: None,
            dirty_from_edits: false,
            has_modified_trips: false,
            unedited_map: None,
            layer: None,
            suspended_sim: None,
            prebaked: None,
            scenario: None,
            is_secondary: false,
        }
    }

    pub fn init_camera_for_loaded_map(&mut self, ctx: &mut EventCtx, splash: bool) {
        let mut rng = self.current_flags.sim_flags.make_rng();
        let rand_focus_pt = self
            .map
            .all_buildings()
            .choose(&mut rng)
            .and_then(|b| self.canonical_point(ID::Building(b.id)))
            .or_else(|| {
                self.map
                    .all_lanes()
                    .choose(&mut rng)
                    .and_then(|l| self.canonical_point(ID::Lane(l.id)))
            })
            .unwrap_or_else(|| self.map.get_bounds().center());

        if splash {
            ctx.canvas.center_on_map_pt(rand_focus_pt);
        } else if !CameraState::load(ctx, self.map.get_name()) {
            info!("Couldn't load camera state, just focusing on an arbitrary building");
            ctx.canvas.center_on_map_pt(rand_focus_pt);
        }
    }

    /// Returns whatever was there
    pub fn clear_sim(&mut self) -> Sim {
        self.dirty_from_edits = false;
        std::mem::replace(
            &mut self.sim,
            Sim::new(&self.map, self.current_flags.sim_flags.opts.clone()),
        )
    }

    pub fn canonical_point(&self, id: ID) -> Option<Pt2D> {
        match id {
            ID::Road(id) => self.map.maybe_get_r(id).map(|r| r.center_pts.first_pt()),
            ID::Lane(id) => self.map.maybe_get_l(id).map(|l| l.first_pt()),
            ID::Intersection(id) => self.map.maybe_get_i(id).map(|i| i.polygon.center()),
            ID::Building(id) => self.map.maybe_get_b(id).map(|b| b.polygon.center()),
            ID::ParkingLot(id) => self.map.maybe_get_pl(id).map(|pl| pl.polygon.center()),
            ID::Car(id) => self.sim.canonical_pt_for_agent(AgentID::Car(id), &self.map),
            ID::Pedestrian(id) => self
                .sim
                .canonical_pt_for_agent(AgentID::Pedestrian(id), &self.map),
            ID::PedCrowd(ref members) => self
                .sim
                .canonical_pt_for_agent(AgentID::Pedestrian(members[0]), &self.map),
            ID::BusStop(id) => self
                .map
                .maybe_get_bs(id)
                .map(|bs| bs.sidewalk_pos.pt(&self.map)),
            ID::Area(id) => self.map.maybe_get_a(id).map(|a| a.polygon.center()),
        }
    }
}

// TODO Serialize these, but in a very careful, future-compatible way
pub struct SessionState {
    pub tutorial: Option<TutorialState>,
    pub high_scores: BTreeMap<GameplayMode, Vec<HighScore>>,
    pub info_panel_tab: BTreeMap<&'static str, &'static str>,
    pub last_gmns_timing_csv: Option<String>,
    pub dash_tab: DashTab,
    pub buffer_lane_type: LaneType,

    // Specific to the ungap tool
    pub elevation_contours: Cached<MapName, (FindClosest<Distance>, ToggleZoomed)>,
    pub routing_preferences: crate::ungap::RoutingPreferences,
    pub ungap_current_trip_name: Option<String>,
    // Map and edit change key
    pub mode_shift: Cached<(MapName, usize), crate::ungap::ModeShiftData>,
}

impl SessionState {
    pub fn empty() -> SessionState {
        SessionState {
            tutorial: None,
            high_scores: BTreeMap::new(),
            info_panel_tab: btreemap! {
                "lane" => "info",
                "intersection" => "info",
                "bldg" => "info",
                "person" => "trips",
                "bus" => "status",
            },
            last_gmns_timing_csv: None,
            dash_tab: DashTab::TripTable,
            buffer_lane_type: LaneType::Buffer(BufferType::Stripes),

            elevation_contours: Cached::new(),
            routing_preferences: crate::ungap::RoutingPreferences::default(),
            ungap_current_trip_name: None,
            mode_shift: Cached::new(),
        }
    }
}

// TODO Reconsider this; maybe it does belong in widgetry.
pub struct PerObjectActions {
    pub click_action: Option<String>,
}

impl PerObjectActions {
    pub fn new() -> PerObjectActions {
        PerObjectActions { click_action: None }
    }

    pub fn reset(&mut self) {
        self.click_action = None;
    }

    pub fn left_click<S: Into<String>>(&mut self, ctx: &mut EventCtx, label: S) -> bool {
        assert!(self.click_action.is_none());
        self.click_action = Some(label.into());
        ctx.normal_left_click()
    }
}

pub struct FindDelayedIntersections {
    pub halt_limit: Duration,
    pub report_limit: Duration,

    pub currently_delayed: Vec<(IntersectionID, Time)>,
}

impl SimCallback for FindDelayedIntersections {
    fn run(&mut self, sim: &Sim, _: &Map) -> bool {
        self.currently_delayed = sim.delayed_intersections(self.report_limit);
        if let Some((_, t)) = self.currently_delayed.get(0) {
            sim.time() - *t >= self.halt_limit
        } else {
            false
        }
    }
}

impl SharedAppState for App {
    fn before_event(&mut self) {
        self.per_obj.reset();
    }

    fn draw_default(&self, g: &mut GfxCtx) {
        self.draw(g, DrawOptions::new(), &ShowEverything::new());
    }

    fn dump_before_abort(&self, canvas: &Canvas) {
        println!();
        println!(
            "********************************************************************************"
        );
        CameraState::save(canvas, self.primary.map.get_name());
        println!(
            "Crash! Please report to https://github.com/a-b-street/abstreet/issues/ and include \
             all output.txt; at least everything starting from the stack trace above!"
        );

        println!();
        self.primary.sim.dump_before_abort();

        println!();
        println!("Camera:");
        println!(
            r#"{{ "cam_x": {}, "cam_y": {}, "cam_zoom": {} }}"#,
            canvas.cam_x, canvas.cam_y, canvas.cam_zoom
        );

        println!();
        if self.primary.map.get_edits().commands.is_empty() {
            println!("No edits");
        } else {
            abstio::write_json(
                "edits_during_crash.json".to_string(),
                &self.primary.map.get_edits().to_permanent(&self.primary.map),
            );
            println!("Please include edits_during_crash.json in your bug report.");
        }

        // Repeat, because it can be hard to see the top of the report if it's long
        println!();
        println!(
            "Crash! Please report to https://github.com/a-b-street/abstreet/issues/ and include \
             all output.txt; at least everything above here until the start of the report!"
        );
        println!(
            "********************************************************************************"
        );
    }

    fn before_quit(&self, canvas: &Canvas) {
        CameraState::save(canvas, self.primary.map.get_name());
    }

    fn free_memory(&mut self) {
        self.primary.draw_map.free_memory();
    }
}

/// Load an extra GeoJSON file, and add the area to the map dynamically.
fn add_study_area(map: &mut Map, name: &str) -> Result<()> {
    let require_in_bounds = true;
    for (polygon, tags) in Polygon::from_geojson_bytes(
        &abstio::slurp_file(abstio::path(format!("system/study_areas/{}.geojson", name)))?,
        map.get_gps_bounds(),
        require_in_bounds,
    )? {
        map.hack_add_area(AreaType::StudyArea, polygon, tags);
    }
    Ok(())
}