import { vi } from "vitest";

export function createDeterministicClock(start = 0) {
  let current = start;
  return Object.freeze({
    now: () => current,
    sleep: async (milliseconds: number, signal?: AbortSignal) => {
      if (signal?.aborted) throw new DOMException("aborted", "AbortError");
      current += Math.max(0, milliseconds);
    },
    advance(milliseconds: number) {
      current += Math.max(0, milliseconds);
    },
  });
}

export function createSeededRandom(seed = 1) {
  let state = seed >>> 0;
  return () => {
    state = (state * 1_664_525 + 1_013_904_223) >>> 0;
    return state / 0x1_0000_0000;
  };
}

export function createControlledScheduler() {
  const callbacks: Array<() => void> = [];
  return Object.freeze({
    callbacks,
    setTimeout: vi.fn((callback: () => void) => {
      callbacks.push(callback);
      return callbacks.length - 1;
    }),
    clearTimeout: vi.fn(),
    runNext() {
      callbacks.shift()?.();
    },
  });
}

export function createRecordingStorage() {
  const values = new Map<string, string>();
  const operations: Array<
    Readonly<{ operation: "get" | "set" | "remove"; key: string }>
  > = [];
  const storage: Storage = {
    getItem(key) {
      operations.push({ operation: "get", key });
      return values.get(key) ?? null;
    },
    setItem(key, value) {
      operations.push({ operation: "set", key });
      values.set(key, value);
    },
    removeItem(key) {
      operations.push({ operation: "remove", key });
      values.delete(key);
    },
    clear() {
      values.clear();
    },
    key(index) {
      return [...values.keys()][index] ?? null;
    },
    get length() {
      return values.size;
    },
  };
  return Object.freeze({ storage, operations, values });
}