scenes.ts

// Copyright 2023 the .NET Foundation

// A "scene" is an individual post that users can view.
//
// For now, scenes roughly correspond to WWT "places", with the view position,
// background, and one or more imagesets specified. We expect to accumulate
// additional kinds of scenes over time.
//
// See `SCHEMA.md` for more information about the schema used here.

import { Response } from "express";
import { Request as JwtRequest } from "express-jwt";
import { isLeft } from "fp-ts/lib/Either.js";
import * as t from "io-ts";
import axios from "axios";
import { PathReporter } from "io-ts/lib/PathReporter.js";
import { ObjectId, UpdateFilter, WithId } from "mongodb";
import { create } from "xmlbuilder2";
import { XMLBuilder } from "xmlbuilder2/lib/interfaces";

import { logClickEvent, logImpressionEvent, logLikeEvent, logShareEvent } from "./events.js";
import { State } from "./globals.js";
import { isAllowed as handleIsAllowed } from "./handles.js";
import { imageToImageset, imageToDisplayJson } from "./images.js";
import { nearbySceneIDs } from "./tessellation.js";
import { IoObjectId, UnitInterval } from "./util.js";
import { isValidSession, tryAddImpressionToSession, tryAddLikeToSession, tryRemoveLikeFromSession } from "./session.js";
import { Session } from "express-session";

const R2D = 180.0 / Math.PI;
const R2H = 12.0 / Math.PI;

export interface MongoScene {
  handle_id: ObjectId;
  creation_date: Date;
  impressions: number;
  likes: number;
  clicks: number;
  shares: number;

  place: ScenePlaceT;
  content: SceneContentT;
  previews: ScenePreviewsT;
  outgoing_url?: string;
  text: string;

  published: boolean;
  home_timeline_sort_key?: number;
}

const ScenePlace = t.type({
  ra_rad: t.number,
  dec_rad: t.number,
  roll_rad: t.number,
  roi_height_deg: t.number,
  roi_aspect_ratio: t.number,
});

type ScenePlaceT = t.TypeOf<typeof ScenePlace>;

const ImageLayer = t.type({
  image_id: IoObjectId,
  opacity: t.intersection([t.number, UnitInterval]),
});

const SceneContent = t.intersection([
  t.partial({
    background_id: IoObjectId,
  }),
  t.type({
    image_layers: t.union([t.array(ImageLayer), t.undefined]),
  })
]);

type SceneContentT = t.TypeOf<typeof SceneContent>;

const ScenePreviews = t.partial({
  video: t.string,
  thumbnail: t.string
});

type ScenePreviewsT = t.TypeOf<typeof ScenePreviews>;

const sceneShareTypes = ["facebook", "linkedin", "twitter", "email", "copy"] as const;
export type SceneShareType = typeof sceneShareTypes[number];

function isSceneShareType(type: string): type is SceneShareType {
  return (sceneShareTypes as readonly string[]).includes(type);
}

// Authorization tools

export type SceneCapability =
  "edit"
  ;

export async function isAllowed(state: State, req: JwtRequest, scene: MongoScene, cap: SceneCapability): Promise<boolean> {
  // One day we might have finer-grained permissions, but not yet. We might also
  // have some kind of caching that allows us to not always look up the owning
  // handle info.

  const owner_handle = await state.handles.findOne({ "_id": scene.handle_id });

  if (owner_handle === null) {
    throw new Error(`Internal database inconsistency: scene missing owner ${scene.handle_id}`);
  }

  switch (cap) {
    case "edit": {
      return handleIsAllowed(req, owner_handle, "editScenes");
    }

    default: {
      return false; // this is a can't-happen but might as well be safe
    }
  }
}


// Turn a Scene into a basic WWT place, if possible.
//
// "Possible" means that its content is a single imageset layer.
//
// This function is async since we need to pull the imageset info from the
// database.
export async function sceneToPlace(scene: MongoScene, desc: string, root: XMLBuilder, state: State): Promise<XMLBuilder> {
  const pl = root.ele("Place");

  // Bad hardcodings!!
  pl.att("DataSetType", "Sky");

  // Hardcodings that are probably OK:
  pl.att("Angle", "0");
  pl.att("AngularSize", "0");
  pl.att("Magnitude", "0");
  pl.att("Opacity", "100");

  // Actual settings
  pl.att("Dec", String(scene.place.dec_rad * R2D));
  pl.att("Name", desc);
  pl.att("RA", String(scene.place.ra_rad * R2H));
  pl.att("Rotation", String(scene.place.roll_rad * R2D));

  // The ZoomLevel setting is the height of the viewport in degrees, times six.
  // Padding the view out by a factor of 1.2 over the size of the ROI gives nice
  // spacing, generally.
  pl.att("ZoomLevel", String(scene.place.roi_height_deg * 7.2));

  // TODO: "Constellation" attr ? "Thumbnail" ?

  if (scene.content.image_layers && scene.content.image_layers.length == 1) {
    const fg = pl.ele("ForegroundImageSet");

    const image = await state.images.findOne({ "_id": new ObjectId(scene.content.image_layers[0].image_id) });

    if (image === null) {
      throw new Error(`database consistency failure: no image ${scene.content.image_layers[0].image_id}`);
    }

    imageToImageset(image, fg);
  }

  return pl;
}

export function requestPreviewCreation(state: State, sceneID: string | ObjectId) {
  axios.post(`${state.config.previewerUrl}/create-preview/${sceneID}`)
    .then(response => {
      // Note that a 200 OK response does NOT mean that the preview completed successfully,
      // just that the previewer successfully received our job request
      if (response.status !== 200) {
        console.error(`Previewer returned error for scene ${sceneID}`);
      }
    })
    .catch(error => console.error(error));
}

export async function sceneToJson(scene: WithId<MongoScene>, state: State, session: Session): Promise<Record<string, any>> {
  // Build up the main part of the response.

  const handle = await state.handles.findOne({ "_id": scene.handle_id });

  if (handle === null) {
    throw new Error(`Database consistency failure, scene ${scene._id} missing handle ${scene.handle_id}`);
  }

  const output: Record<string, any> = {
    id: scene._id,
    handle_id: scene.handle_id,
    handle: {
      handle: handle.handle,
      display_name: handle.display_name,
    },
    creation_date: scene.creation_date,
    likes: scene.likes,
    impressions: scene.impressions,
    clicks: scene.clicks || 0,
    shares: scene.shares || 0,
    place: scene.place,
    text: scene.text,
    liked: session?.likes?.some(x => x.scene_id == scene._id.toString()) ?? false,
    content: {},
    published: scene.published
  };

  if (scene.outgoing_url) {
    output.outgoing_url = scene.outgoing_url;
  }

  // ~"Hydrate" the content

  if (scene.content.image_layers) {
    const image_layers = [];

    for (var layer_desc of scene.content.image_layers) {
      const image = await state.images.findOne({ "_id": new ObjectId(layer_desc.image_id) });

      if (image === null) {
        throw new Error(`Database consistency failure, scene ${scene._id} missing image ${layer_desc.image_id}`);
      }

      image_layers.push({
        image: imageToDisplayJson(image),
        opacity: layer_desc.opacity,
      });
    }

    output.content.image_layers = image_layers;
  }

  // Fill in complete URLs for social-media preview links

  output.previews = {};
  for (const [key, value] of Object.entries(scene.previews)) {
    output.previews[key] = `${state.config.previewBaseUrl}/${value}`;
  }

  // Populate information about the background, if it's been specified

  if (scene.content.background_id) {
    const bgImage = await state.images.findOne({ "_id": new ObjectId(scene.content.background_id) });

    if (bgImage === null) {
      throw new Error(`Database consistency failure, scene ${scene._id} missing background ${scene.content.background_id}`);
    }

    output.content.background = imageToDisplayJson(bgImage);
  }

  // All done!

  return output;
}

export function initializeSceneEndpoints(state: State) {
  // POST /handle/:handle/scene: create a new scene record

  const SceneCreation = t.type({
    place: ScenePlace,
    content: SceneContent,
    outgoing_url: t.union([t.string, t.undefined]),
    text: t.string,
    published: t.union([t.boolean, t.undefined])
  });

  type SceneCreationT = t.TypeOf<typeof SceneCreation>;

  state.app.post(
    "/handle/:handle/scene",
    async (req: JwtRequest, res: Response) => {
      const handle_name = req.params.handle;

      // Are we authorized?

      const handle = await state.handles.findOne({ "handle": handle_name });

      if (handle === null) {
        res.statusCode = 404;
        res.json({ error: true, message: "Handle not found" });
        return;
      }

      if (!handleIsAllowed(req, handle, "addScenes")) {
        res.statusCode = 403;
        res.json({ error: true, message: "Forbidden" });
        return;
      }

      // Does the input look valid?

      const maybe = SceneCreation.decode(req.body);

      if (isLeft(maybe)) {
        res.statusCode = 400;
        res.json({ error: true, message: `Submission did not match schema: ${PathReporter.report(maybe).join("\n")}` });
        return;
      }

      const input: SceneCreationT = maybe.right;

      if (input.content.image_layers !== undefined) {
        for (var layer of input.content.image_layers) {
          try {
            const result = await state.images.findOne({ "_id": layer.image_id });

            if (result === null) {
              res.statusCode = 400;
              res.json({ error: true, message: `Required image ${layer.image_id} not found` });
              return;
            }
          } catch (err) {
            res.statusCode = 500;
            res.json({ error: true, message: `Database error in ${req.path}` });
          }
        }
      } else {
        res.statusCode = 400;
        res.json({ error: true, message: "Invalid scene content: no image layers" });
        return;
      }

      // OK, looks good.

      const new_rec: MongoScene = {
        handle_id: handle._id,
        creation_date: new Date(),
        impressions: 0,
        likes: 0,
        clicks: 0,
        shares: 0,
        place: input.place,
        content: input.content,
        text: input.text,
        previews: {},
        published: input.published ?? true,
      };

      if (input.outgoing_url) {
        new_rec.outgoing_url = input.outgoing_url;
      }

      try {
        const result = await state.scenes.insertOne(new_rec);

        res.json({
          error: false,
          id: "" + result.insertedId,
          rel_url: "/scene/" + encodeURIComponent("" + result.insertedId),
        });

        requestPreviewCreation(state, result.insertedId);

      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // GET /scene/:id - Get general information about a scene

  state.app.get("/scene/:id", async (req: JwtRequest, res: Response) => {
    try {
      const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });

      if (scene === null) {
        res.statusCode = 404;
        res.json({ error: true, message: "Not found" });
        return;
      }

      const output = await sceneToJson(scene, state, req.session);
      output["error"] = false;
      res.json(output);
    } catch (err) {
      console.error(`${req.method} ${req.path} exception:`, err);
      res.statusCode = 500;
      res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
    }
  });

  // GET /scene/:id/permissions - get information about the logged-in user's
  // permissions with regards to this scene.
  //
  // This API is only informative -- of course, direct API calls are the final
  // arbiters of what is and isn't allowed. But the frontend can use this
  // information to decide what UI elements to expose to a user.
  state.app.get(
    "/scene/:id/permissions",
    async (req: JwtRequest, res: Response) => {
      try {
        const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });

        if (scene === null) {
          res.statusCode = 404;
          res.json({ error: true, message: "Not found" });
          return;
        }

        // TODO: if we end up reporting more categories, we should somehow batch
        // the checks to not look up the same handle over and over.

        const edit = await isAllowed(state, req, scene, "edit");

        const output = {
          error: false,
          id: scene._id,
          edit: edit,
        };

        res.json(output);
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // GET /scene/:id/place.wtml - (try to) get WTML expressing this scene as a WWT Place.
  state.app.get(
    "/scene/:id/place.wtml",
    async (req: JwtRequest, res: Response) => {
      try {
        const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });

        if (scene === null) {
          res.statusCode = 404;
          res.json({ error: true, message: "Not found" });
          return;
        }

        const desc = `Scene ${req.params.id}`;

        const root = create().ele("Folder");
        root.att("Browseable", "True");
        root.att("Group", "Explorer");
        root.att("Name", desc);
        root.att("Searchable", "True");
        root.att("Type", "Sky");

        try {
          await sceneToPlace(scene, desc, root, state);
        } catch (err) {
          // I think a 404 is the most appropriate response here? Not sure.
          res.statusCode = 404;
          res.json({ error: true, message: `scene ${req.params.id} cannot be represented as a WWT Place` });
        }

        root.end({ prettyPrint: true });
        res.type("application/xml")
        res.send(root.toString());
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // GET /scene/:id/click - register a click on a scene's outgoing link
  //
  // The response is a redirect to the outgoing link, so that we can
  // transparently send the user on their way.
  state.app.get(
    "/scene/:id/click",
    async (req: JwtRequest, res: Response) => {
      try {
        const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });

        if (scene === null || scene.outgoing_url === undefined) {
          res.statusCode = 404;
          res.json({ error: true, message: "Not found" });
          return;
        }

        await logClickEvent(state, req, scene._id);
        res.redirect(302, scene.outgoing_url);
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // POST /scene/:id/impressions - record an impression of a scene.
  state.app.post("/scene/:id/impressions", async (req: JwtRequest, res: Response) => {
    try {
      const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });
      if (scene) {
        let success: boolean;

        if (success = tryAddImpressionToSession(req.session, req.params.id)) {
          await logImpressionEvent(state, req, scene._id);
        };

        res.statusCode = 200;
        res.json({ error: false, id: req.params.id, success: success });
      } else {
        console.error(`${req.method} ${req.path} scene does not exist`);
        res.statusCode = 404;
        res.json({ error: true, message: `scene ${req.params.id} does not exist` });
      }
    } catch (err) {
      console.error(`${req.method} ${req.path} exception:`, err);
      res.statusCode = 500;
      res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
    }

  });

  // POST /scene/:id/likes - record a like of a scene.
  state.app.post("/scene/:id/likes", async (req: JwtRequest, res: Response) => {
    try {
      const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });
      if (scene) {
        let success: boolean;

        if (success = tryAddLikeToSession(req.session, req.params.id)) {
          await logLikeEvent(state, req, scene._id, 1);
        };

        res.statusCode = 200;
        res.json({ error: false, id: req.params.id, success: success });
      } else {
        console.error(`${req.method} ${req.path} scene does not exist`);
        res.statusCode = 404;
        res.json({ error: true, message: `scene ${req.params.id} does not exist` });
      }
    } catch (err) {
      console.error(`${req.method} ${req.path} exception:`, err);
      res.statusCode = 500;
      res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
    }

  });

  // POST /scene/:id/shares/:type - record a share of a scene
  state.app.post("/scene/:id/shares/:type", async (req: JwtRequest, res: Response) => {

    const type = req.params.type;
    if (!isSceneShareType(type)) {
      res.statusCode = 400;
      res.json({ error: true, message: `${type} is not a valid scene sharing type` });
      return;
    }

    try {
      const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });
      if (scene) {
        let success: boolean;

        if (success = isValidSession(req.session)) {
          await logShareEvent(state, req, scene._id, type);
        }
        res.statusCode = 200;
        res.json({ error: false, id: req.params.id, success: true });
      } else {
        console.error(`${req.method} ${req.path} scene does not exist`);
        res.statusCode = 404;
        res.json({ error: true, message: `scene ${req.params.id} does not exist` });
      }
    } catch (err) {
      console.error(`${req.method} ${req.path} exception:`, err);
      res.statusCode = 500;
      res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
    }

  });

  // DELETE /scene/:id/likes - remove a like of a scene.
  state.app.delete("/scene/:id/likes", async (req: JwtRequest, res: Response) => {
    try {
      const scene = await state.scenes.findOne({ "_id": new ObjectId(req.params.id) });
      if (scene) {
        let success: boolean;

        if (success = tryRemoveLikeFromSession(req.session, req.params.id)) {
          await logLikeEvent(state, req, scene._id, -1);
        };

        res.statusCode = 200;
        res.json({ error: false, id: req.params.id, success: success });
      } else {
        console.error(`${req.method} ${req.path} scene does not exist`);
        res.statusCode = 404;
        res.json({ error: true, message: `scene ${req.params.id} does not exist` });
      }
    } catch (err) {
      console.error(`${req.method} ${req.path} exception:`, err);
      res.statusCode = 500;
      res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
    }

  });

  // PATCH /scene/:id - update scene properties

  const SceneContentPatch = t.partial({
    background_id: t.string,
  });

  const ScenePatch = t.partial({
    text: t.string,
    outgoing_url: t.string,
    place: ScenePlace,
    content: SceneContentPatch,
    published: t.boolean,
  });

  type ScenePatchT = t.TypeOf<typeof ScenePatch>;

  state.app.patch(
    "/scene/:id",
    async (req: JwtRequest, res: Response) => {
      try {
        // Validate inputs

        const thisScene = { "_id": new ObjectId(req.params.id) };
        const scene = await state.scenes.findOne(thisScene);

        if (scene === null) {
          res.statusCode = 404;
          res.json({ error: true, message: "Not found" });
          return;
        }

        const maybe = ScenePatch.decode(req.body);

        if (isLeft(maybe)) {
          res.statusCode = 400;
          res.json({ error: true, message: `Submission did not match schema: ${PathReporter.report(maybe).join("\n")}` });
          return;
        }

        const input: ScenePatchT = maybe.right;

        // For this operation, we might require different permissions depending
        // on what changes are exactly being requested. Note that patch
        // operations should either fully succeed or fully fail -- no partial
        // applications. Here we cache the `canEdit` permission since everything
        // uses it.

        let allowed = true;
        const canEdit = await isAllowed(state, req, scene, "edit");

        // Depending on what changes, we might need to update the preview.
        let update_preview = false;

        // For convenience, this value should be pre-filled with whatever
        // operations we might use below. We have to hack around the typing
        // below, though, because TypeScript takes some elements here to be
        // read-only.
        let operation: UpdateFilter<MongoScene> = { "$set": {} };

        if (input.text) {
          allowed = allowed && canEdit;

          // Validate this particular input. (TODO: I think io-ts could do this?)
          if (input.text.length > 5000) {
            res.statusCode = 400;
            res.json({ error: true, message: "Invalid input `text`: too long" });
            return;
          }

          (operation as any)["$set"]["text"] = input.text;
        }

        if (input.outgoing_url) {
          allowed = allowed && canEdit;

          // Validate.
          if (input.outgoing_url.length > 5000) {
            res.statusCode = 400;
            res.json({ error: true, message: "Invalid input `outgoing_url`: too long" });
            return;
          }

          (operation as any)["$set"]["outgoing_url"] = input.outgoing_url;
        }

        if (input.place) {
          allowed = allowed && canEdit;

          // Validate.
          var valid = true;
          valid = valid && input.place.ra_rad >= 0 && input.place.ra_rad <= 2 * Math.PI;
          valid = valid && input.place.dec_rad >= -0.5 * Math.PI && input.place.dec_rad <= 0.5 * Math.PI;
          valid = valid && input.place.roi_height_deg >= 0 && input.place.roi_height_deg <= 360;
          valid = valid && input.place.roi_aspect_ratio >= 0.1 && input.place.roi_aspect_ratio <= 10;
          valid = valid && input.place.roll_rad >= -Math.PI && valid && input.place.roll_rad <= Math.PI;

          if (!valid) {
            res.statusCode = 400;
            res.json({ error: true, message: "Invalid input `place`" });
            return;
          }

          (operation as any)["$set"]["place"] = input.place;
          update_preview = true;
        }

        if (input.content) {
          if (input.content.background_id) {
            allowed = allowed && canEdit;

            // Validate.

            const image = await state.images.findOne({ "_id": new ObjectId(input.content.background_id) });

            if (image === null) {
              res.statusCode = 400;
              res.json({ error: true, message: "Invalid input `content.background_id`: not an image ID" });
              return;
            }

            (operation as any)["$set"]["content.background_id"] = input.content.background_id;
            update_preview = true;
          }
        }

        if (input.published !== undefined) {
          allowed = allowed && canEdit;
          (operation as any)["$set"]["published"] = input.published;
        }

        // How did we do?

        if (!allowed) {
          res.statusCode = 403;
          res.json({ error: true, message: "Forbidden" });
          return;
        }

        await state.scenes.findOneAndUpdate(
          thisScene,
          operation
        );

        if (update_preview) {
          requestPreviewCreation(state, req.params.id);
        }

        res.json({
          error: false,
        });
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // GET /scenes/home-timeline?page=$int - get scenes for the homepage timeline

  const page_size = 8;

  state.app.get(
    "/scenes/home-timeline",
    async (req: JwtRequest, res: Response) => {
      try {
        var page_num = 0;

        try {
          const qpage = parseInt(req.query.page as string, 10);

          if (qpage >= 0) {
            page_num = qpage;
          }
        } catch {
          res.statusCode = 400;
          res.json({ error: true, message: `invalid page number` });
        }

        const docs = await state.scenes.find({
          home_timeline_sort_key: { $gte: 0 },
          published: true,
        })
          .sort({ home_timeline_sort_key: 1 })
          .skip(page_num * page_size)
          .limit(page_size)
          .toArray();
        const scenes = [];

        for (var doc of docs) {
          scenes.push(await sceneToJson(doc, state, req.session));
        }

        res.json({
          error: false,
          results: scenes,
        });
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  // GET /handle/:handle/sceneinfo?page=$int&pagesize=$int - get admin
  // information about scenes
  //
  // This endpoint is for the handle dashboard showing summary information about
  // the handle's scenes.

  state.app.get(
    "/handle/:handle/sceneinfo",
    async (req: JwtRequest, res: Response) => {
      try {
        // Validate input(s)

        const handle = await state.handles.findOne({ "handle": req.params.handle });

        if (handle === null) {
          res.statusCode = 404;
          res.json({ error: true, message: "Not found" });
          return;
        }

        var page_num = 0;

        try {
          const qpage = parseInt(req.query.page as string, 10);

          if (qpage >= 0) {
            page_num = qpage;
          }
        } catch {
          res.statusCode = 400;
          res.json({ error: true, message: `invalid page number` });
        }

        var page_size = 10;

        try {
          const qps = parseInt(req.query.pagesize as string, 10);

          if (qps > 0 && qps <= 100) {
            page_size = qps;
          }
        } catch {
          res.statusCode = 400;
          res.json({ error: true, message: `invalid page size` });
        }

        // Check authorization

        if (!handleIsAllowed(req, handle, "viewDashboard")) {
          res.statusCode = 403;
          res.json({ error: true, message: "Forbidden" });
          return;
        }

        // OK to proceed

        const filter = { "handle_id": handle._id };
        const count = await state.scenes.countDocuments(filter);
        const infos = await state.scenes.find(filter)
          .sort({ creation_date: -1 })
          .skip(page_num * page_size)
          .limit(page_size)
          .project({
            "_id": 1,
            "creation_date": 1,
            "impressions": 1,
            "likes": 1,
            "clicks": 1,
            "shares": 1,
            "text": 1,
            "published": 1
          })
          .toArray();

        res.json({
          error: false,
          total_count: count,
          results: infos,
        });
      } catch (err) {
        console.error(`${req.method} ${req.path} exception:`, err);
        res.statusCode = 500;
        res.json({ error: true, message: `error serving ${req.method} ${req.path}` });
      }
    }
  );

  state.app.get(
    "/scene/:id/nearby-global",
    async (req: JwtRequest, res: Response) => {
      const tessellation = await state.tessellations.findOne({ name: "global" });
      if (tessellation === null) {
        res.statusCode = 500;
        res.json({ error: true, message: "error finding global tessellation" });
        return;
      }

      if (req.query.size === undefined) {
        res.statusCode = 400;
        res.json({ error: true, message: "invalid size" });
        return;
      }
      const size = parseInt(req.query.size as string, 10);
      const sceneID = new ObjectId(req.params.id as string);
      const nearbyIDs = nearbySceneIDs(sceneID, tessellation, size);
      const docs = state.scenes.find({ _id: { "$in": nearbyIDs } });

      const scenes = [];
      for await (const doc of docs) {
        scenes.push(await sceneToJson(doc, state, req.session));
      }

      res.json({
        error: false,
        results: scenes
      });
    });

}