Generic common loader for wall types example

common_loader_example.ts

import * as assert from 'assert';
import { FSAPI, fileBaseName } from 'glov/common/fsapi';
import { DataObject } from 'glov/common/types';

type WallDesc = {
  id: string; // filled in at load
  other_id?: string; // from data
  other_desc?: WallDesc; // reference at load-time
};

let wall_descs: Partial<Record<string, WallDesc>>;

let fs: FSAPI;
function walltypeLoad(filename: string): WallDesc {
  let wall_desc = fs.getFile<WallDesc>(filename, 'jsobj');
  let id = fileBaseName(filename);
  wall_desc.id = id;
  // Do data validation and fixups here
  return wall_desc;
}

function walltypeFinalizeReferences(): void {
  // fix up any internal references between WallDescs
  for (let key in wall_descs) {
    let wall_desc = wall_descs[key]!;
    if (wall_desc.other_id) {
      wall_desc.other_desc = wall_descs[wall_desc.other_id];
    }
  }
}

function reloadInPlace(new_desc: WallDesc): void {
  let { id } = new_desc;
  let old_desc = wall_descs[id];
  if (!old_desc) {
    wall_descs[id] = new_desc;
  } else {
    for (let key in old_desc) {
      delete (old_desc as DataObject)[key];
    }
    for (let key in new_desc) {
      (old_desc as DataObject)[key] = (new_desc as DataObject)[key];
    }
    new_desc = old_desc;
  }
}

const IS_CLIENT = typeof window !== 'undefined';

function reloadWalltype(path: string): void {
  if (IS_CLIENT && path.endsWith('.json')) {
    return;
  }
  let new_desc = walltypeLoad(path);
  reloadInPlace('wall', new_desc);
  walltypeFinalizeReferences();
}

export function crawlerLoadData(fs_in: FSAPI): void {
  if (wall_descs) {
    return;
  }
  fs = fs_in;

  wall_descs = {};

  let files = fs.getFileNames('walltypes/');
  for (let ii = 0; ii < files.length; ++ii) {
    let filename = files[ii];
    let obj = walltypeLoad(filename);
    wall_descs[obj.id] = obj;
  }

  walltypeFinalizeReferences();

  fs.filewatchOn(/^walltypes\//, reloadWalltype);
}

export function crawlerGetWallDesc(id: string): WallDesc {
  let wall_desc = wall_descs[id];
  assert(wall_desc, id);
  return wall_desc;
}