feat: add ability to quickly read game winners

src/SlippiGame.ts

@@ -22,6 +22,7 @@ import type {
 } from "./types";
 import { SlpParser, SlpParserEvent } from "./utils/slpParser";
 import type { SlpReadInput } from "./utils/slpReader";
+import { getGameEnd } from "./utils/slpReader";
 import { closeSlpFile, getMetadata, iterateEvents, openSlpFile, SlpInputSource } from "./utils/slpReader";
 
 /**
@@ -205,9 +206,7 @@ export class SlippiGame {
   }
 
   public getWinners(): PlacementType[] {
-    this._process();
-
-    const gameEnd = this.getGameEnd();
+    const gameEnd = getGameEnd(this.input);
     if (!gameEnd) {
       return [];
     }

src/utils/slpReader.ts

@@ -6,6 +6,7 @@ import { mapValues } from "lodash";
 import type {
   EventCallbackFunc,
   EventPayloadTypes,
+  GameEndType,
   GameInfoType,
   GeckoCodeType,
   MetadataType,
@@ -14,6 +15,7 @@ import type {
   SelfInducedSpeedsType,
 } from "../types";
 import { Command } from "../types";
+import { exists } from "./exists";
 import { toHalfwidth } from "./fullwidth";
 
 export enum SlpInputSource {
@@ -642,3 +644,38 @@ export function getMetadata(slpFile: SlpFileType): MetadataType | null {
   // $FlowFixMe
   return metadata;
 }
+
+export function getGameEnd(input: SlpReadInput): GameEndType | null {
+  let slpFile: SlpFileType | undefined;
+
+  try {
+    slpFile = openSlpFile(input);
+    const { rawDataPosition, rawDataLength, messageSizes } = slpFile;
+    const gameEndSize = messageSizes[Command.GAME_END];
+    if (!exists(gameEndSize)) {
+      return null;
+    }
+
+    // Subtract one to account for command byte
+    const gameEndPosition = rawDataPosition + rawDataLength - gameEndSize - 1;
+
+    // Add one to include command byte in payload
+    const buffer = new Uint8Array(gameEndSize + 1);
+    readRef(slpFile.ref, buffer, 0, buffer.length, gameEndPosition);
+    if (buffer[0] !== Command.GAME_END) {
+      // This isn't even a game end payload
+      return null;
+    }
+
+    const gameEndMessage = parseMessage(Command.GAME_END, buffer);
+    if (!gameEndMessage) {
+      return null;
+    }
+
+    return gameEndMessage as GameEndType;
+  } catch (err) {
+    return null;
+  } finally {
+    slpFile && closeSlpFile(slpFile);
+  }
+}

test/slpReader.spec.ts

@@ -0,0 +1,63 @@
+import _ from "lodash";
+
+import { SlippiGame } from "../src";
+import { getGameEnd, SlpInputSource } from "../src/utils/slpReader";
+
+describe("when reading game end directly", () => {
+  it("should return the same game end object", () => {
+    const game = new SlippiGame("slp/test.slp");
+    const gameEnd = game.getGameEnd()!;
+
+    const manualGameEnd = getManualGameEnd("slp/test.slp")!;
+    expect(gameEnd.gameEndMethod).toEqual(manualGameEnd.gameEndMethod);
+    expect(gameEnd.lrasInitiatorIndex).toEqual(manualGameEnd.lrasInitiatorIndex);
+    expect(gameEnd.placements.length).toEqual(manualGameEnd.placements.length);
+  });
+
+  it("should return the correct placings for 2 player games", () => {
+    const manualGameEnd = getManualGameEnd("slp/placementsTest/ffa_1p2p_winner_2p.slp")!;
+    const placements = manualGameEnd.placements!;
+    expect(placements).toHaveLength(4);
+    console.log(JSON.stringify(placements));
+    expect(placements[0].position).toBe(1); // player in port 1 is on second place
+    expect(placements[0].playerIndex).toBe(0);
+    expect(placements[1].position).toBe(0); // player in port 2 is on first place
+    expect(placements[1].playerIndex).toBe(1);
+  });
+
+  it("should return placings for 3 player games", () => {
+    let manualGameEnd = getManualGameEnd("slp/placementsTest/ffa_1p2p3p_winner_3p.slp")!;
+    let placements = manualGameEnd.placements!;
+    expect(placements).toBeDefined();
+    expect(placements).toHaveLength(4);
+
+    expect(placements[0].playerIndex).toBe(0);
+    expect(placements[1].playerIndex).toBe(1);
+    expect(placements[2].playerIndex).toBe(2);
+    expect(placements[3].playerIndex).toBe(3);
+
+    expect(placements[0].position).toBe(1); // Expect player 1 to be on second place
+    expect(placements[1].position).toBe(2); // Expect player 2 to be on third place
+    expect(placements[2].position).toBe(0); // Expect player 3 to be first place
+    expect(placements[3].position).toBe(-1); // Expect player 4 to not be present
+
+    manualGameEnd = getManualGameEnd("slp/placementsTest/ffa_1p2p4p_winner_4p.slp")!;
+    placements = manualGameEnd.placements!;
+    expect(placements).toBeDefined();
+    expect(placements).toHaveLength(4);
+
+    expect(placements[0].playerIndex).toBe(0);
+    expect(placements[1].playerIndex).toBe(1);
+    expect(placements[2].playerIndex).toBe(2);
+    expect(placements[3].playerIndex).toBe(3);
+
+    expect(placements[0].position).toBe(1); // Expect player 1 to be on second place
+    expect(placements[1].position).toBe(2); // Expect player 2 to be on third place
+    expect(placements[2].position).toBe(-1); // Expect player 3 to not be present
+    expect(placements[3].position).toBe(0); // Expect player 4 to be first place
+  });
+});
+
+function getManualGameEnd(filePath: string) {
+  return getGameEnd({ source: SlpInputSource.FILE, filePath });
+}