Snakes-And-Ladders/src/logging/games_log.ts

import { GamesLogError } from "./errors/games_log_error.js";
import { GamesLogParser, LogData } from "./games_log_parser.js";

import { GameEvent } from "../game/events/game_event.js";
import { GameStartedEvent } from "../game/events/game_started_event.js";
import { PlayerJoinedEvent } from "../game/events/player_joined_event.js";
import { PlayerRolledEvent } from "../game/events/player_rolled_event.js";

export class GamesLog {
  private logData: LogData = [];
  private gamesLogParser = new GamesLogParser();

  async loadFile(filename: string, encoding?: BufferEncoding) {
    this.logData = await this.gamesLogParser.parseFile(filename, encoding);
  }

  async readEvents() {
    return this.logData.map((row, rowNumber) => {
      const payload = row.eventPayload;
      const requireProperties = this.requirePropertiesFor(payload, rowNumber);

      let gameEvent: GameEvent;
      switch (row.eventType) {
        case "player_rolls_dice":
          requireProperties("gameId", "playerId", "roll");
          gameEvent = new PlayerRolledEvent(
            payload.gameId,
            payload.playerId,
            payload.roll
          );
          break;
        case "player_joins_game":
          requireProperties("gameId", "playerId");
          gameEvent = new PlayerJoinedEvent(payload.gameId, payload.playerId);
          break;
        case "game_started":
          requireProperties("gameId");
          gameEvent = new GameStartedEvent(payload.gameId);
          break;
        default:
          throw new Error(
            `Unknown event type: "${payload.eventType}" on row ${rowNumber}`
          );
      }

      return gameEvent;
    });
  }

  private requirePropertiesFor(
    payload: { [key: string]: any },
    rowNumber: number
  ) {
    return (...props: string[]) =>
      props.forEach((name) => {
        if (!(name in payload)) {
          throw new GamesLogError(
            `Missing property: ${name} for event on row ${rowNumber}`
          );
        }
        if (!Number.isInteger(payload[name])) {
          throw new GamesLogError(
            `Invalid value for: ${name} on row ${rowNumber}`
          );
        }
      });
  }
}