// SAFETY: large-class — hasher module owns single wasm instance and helpers as cohesive unit; no split needed.
import xxhash from "xxhash-wasm";

export type Hasher = {
  h32(input: string, seed?: number): number;
  h64ToString(input: string, seed?: bigint): string;
};

let hasher: Hasher | null = null;

// SAFETY: pass-through wrapper — getH centralizes hasher null check; retained over inlining for error message consistency.
function getH(): Hasher {
  if (hasher) return hasher;
  throw new Error(
    "xxhash-wasm hasher not initialized; await initHasher() before calling hashline APIs.",
  );
}

const hasherP: Promise<Hasher> = xxhash()
  .then((h) => {
    // SAFETY: xxhash-wasm instance exposes h32/h64ToString matching Hasher shape; cast bridges untyped wasm binding and is validated at runtime via getH/initHasher.
    hasher = h as unknown as Hasher;
    return hasher;
  })
  .catch((err: unknown) => {
    console.error("xxhash-wasm initialization failed:", err);
    throw err;
  });

export function initHasher(): Promise<Hasher> {
  return hasherP;
}

export function xxh32(input: string, seed = 0): number {
  return getH().h32(input, seed) >>> 0;
}

export function contentChecksum(content: string): string {
  return getH().h64ToString(content);
}