MCMapper-Backend/api/src/players.ts

import { eq } from "drizzle-orm";
import { db } from "./db/client";
import { servers } from "./db/schema";
import { redis } from "./redis";

export interface PlayerPosition {
  uuid: string;
  username: string;
  x: number;
  y: number;
  z: number;
}

export function playerChannel(serverId: string): string {
  return `mcmapper:players:${serverId}`;
}

function snapshotKey(serverId: string): string {
  return `mcmapper:players:snapshot:${serverId}`;
}

export async function arePlayerPositionsVisible(serverId: string): Promise<boolean> {
  const [row] = await db
    .select({ playerPositionsVisible: servers.playerPositionsVisible })
    .from(servers)
    .where(eq(servers.id, serverId))
    .limit(1);
  return row?.playerPositionsVisible ?? false;
}

/**
 * Fans a player roster out to every browser subscribed to this server's channel, and stashes it
 * in Redis so a browser tab that connects between mod flushes gets the current roster immediately
 * instead of waiting up to `playerPositionIntervalTicks` for the next one — see
 * players-gateway.ts's `open()`. No history/persistence beyond the latest snapshot: unlike chat,
 * player positions have no meaningful "history" to keep.
 */
export async function publishPlayerPositions(serverId: string, dimension: number, players: PlayerPosition[]) {
  const payload = JSON.stringify({ dimension, players });
  await redis.set(snapshotKey(serverId), payload);
  await redis.publish(playerChannel(serverId), payload);
}

export async function getPlayerSnapshot(serverId: string): Promise<string | null> {
  return redis.get(snapshotKey(serverId));
}