// Durable rooms: one append-only JSONL file per room. The first line is the
// room's birth certificate; every later line is a join, a start, or a game
// command. Because the engine is deterministic, replaying a file rebuilds
// the exact game state — server restarts lose nothing.

import { appendFileSync, mkdirSync, readdirSync, readFileSync } from "node:fs";
import { join } from "node:path";

export interface RoomMetaLine {
  kind: "meta";
  id: string;
  hostId: string;
  /** sha-256 of the host's seat token. Raw tokens never touch disk. */
  hostTokenHash?: string;
  /** Legacy plaintext token (pre-hashing files only). */
  hostToken?: string;
  seed: number;
  createdAt: string;
}

export interface JoinLine {
  kind: "join";
  name: string;
  tokenHash?: string;
  /** Legacy plaintext token (pre-hashing files only). */
  token?: string;
}

export interface StartLine {
  kind: "start";
  expansion: boolean;
  /** Final wizard colors, in player join order. */
  colors?: number[];
}

export interface CommandLine {
  kind: "command";
  seq: number;
  playerId: string;
  command: unknown;
  at: string;
}

export type RoomLine = RoomMetaLine | JoinLine | StartLine | CommandLine;

const DATA_DIR = process.env.WIZWAR_DATA_DIR ?? join(process.cwd(), "data", "rooms");

function fileFor(roomId: string): string {
  return join(DATA_DIR, `${roomId}.jsonl`);
}

/** Directory holding stats.json — the parent of the rooms dir. */
export function statsDir(): string {
  return join(DATA_DIR, "..");
}

export function ensureDataDir(): void {
  mkdirSync(DATA_DIR, { recursive: true });
}

export function appendLine(roomId: string, line: RoomLine): void {
  appendFileSync(fileFor(roomId), JSON.stringify(line) + "\n", "utf8");
}

/** Read every persisted room's lines, keyed by room id. */
export function readAllRooms(): Map<string, RoomLine[]> {
  ensureDataDir();
  const rooms = new Map<string, RoomLine[]>();
  for (const file of readdirSync(DATA_DIR)) {
    if (!file.endsWith(".jsonl")) continue;
    const id = file.slice(0, -".jsonl".length);
    try {
      const lines = readFileSync(join(DATA_DIR, file), "utf8")
        .split("\n")
        .filter((l) => l.trim().length > 0)
        .map((l) => JSON.parse(l) as RoomLine);
      if (lines.length > 0 && lines[0]!.kind === "meta") rooms.set(id, lines);
    } catch (e) {
      console.error(`skipping unreadable room file ${file}:`, e);
    }
  }
  return rooms;
}