/**
 * Interface for storage operations
 */
export interface StorageWrapper {
  /**
   * Gets an item from storage
   * @param key - The key of the item to get
   * @returns The value of the item, or null if it doesn't exist
   */
  getItem(key: string): string | null;

  /**
   * Sets an item in storage
   * @param key - The key of the item to set
   * @param value - The value to set
   */
  setItem(key: string, value: string): void;

  /**
   * Removes an item from storage
   * @param key - The key of the item to remove
   */
  removeItem(key: string): void;

  /** deletes all values in storage */
  clear(): void;
}

/**
 * Implementation of StorageWrapper for testing or server environments that don't have localStorage
 */
export class MemoryStorageWrapper implements StorageWrapper {
  private storage: Record<string, string> = {};

  getItem(key: string): string | null {
    return this.storage[key] ?? null;
  }

  setItem(key: string, value: string): void {
    this.storage[key] = value;
  }

  removeItem(key: string): void {
    const { [key]: _, ...rest } = this.storage;
    this.storage = rest;
  }

  clear(): void {
    this.storage = {};
  }
}

/**
 * Declare global property for storage
 */
declare global {
  // eslint-disable-next-line no-var
  var __i18nStorage: StorageWrapper | undefined;
}

/**
 * Factory function to get the appropriate storage wrapper based on environment
 * @returns An instance of StorageWrapper appropriate for the current environment
 */
export function createStorageWrapper(): StorageWrapper {
  if (typeof globalThis.localStorage !== 'undefined') {
    return globalThis.localStorage;
  }

  if (!globalThis.__i18nStorage) {
    globalThis.__i18nStorage = new MemoryStorageWrapper();
  }

  return globalThis.__i18nStorage;
}