/**
 * 节流函数
 * @param func 要节流的函数
 * @param wait 等待时间（毫秒）
 * @param options 选项
 */
export function throttle<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number,
  options: { leading?: boolean; trailing?: boolean } = {}
): (...args: Parameters<T>) => void {
  let timeout: ReturnType<typeof setTimeout> | null = null;
  let previous = 0;

  const { leading = true, trailing = true } = options;

  return function(this: unknown, ...args: Parameters<T>) {
    const now = Date.now();

    if (!previous && !leading) previous = now;

    const remaining = wait - (now - previous);

    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout);
        timeout = null;
      }
      previous = now;
      func.apply(this, args);
    } else if (!timeout && trailing) {
      timeout = setTimeout(() => {
        previous = leading ? Date.now() : 0;
        timeout = null;
        func.apply(this, args);
      }, remaining);
    }
  };
}

/**
 * 深拷贝函数
 * @param obj 要拷贝的对象
 * @returns 深拷贝后的对象
 */
export const deepClone = <T>(obj: T): T => {
  if (obj === null || typeof obj !== 'object') {
    return obj;
  }

  // 处理日期对象
  if (obj instanceof Date) {
    return new Date(obj.getTime()) as unknown as T;
  }

  // 处理数组
  if (Array.isArray(obj)) {
    return obj.map(item => deepClone(item)) as unknown as T;
  }

  // 处理普通对象
  const clonedObj = {} as T;
  for (const key in obj) {
    if (Object.prototype.hasOwnProperty.call(obj, key)) {
      clonedObj[key] = deepClone(obj[key]);
    }
  }

  return clonedObj;
};

/**
 * 深度比较两个值是否相等
 * @param a 第一个值
 * @param b 第二个值
 * @returns 是否相等
 */
export function deepEqual(a: unknown, b: unknown): boolean {
  if (a === b) return true;

  if (typeof a !== 'object' || a === null || typeof b !== 'object' || b === null) {
    return false;
  }

  const keysA = Object.keys(a as Record<string, unknown>);
  const keysB = Object.keys(b as Record<string, unknown>);

  if (keysA.length !== keysB.length) return false;

  for (const key of keysA) {
    if (!keysB.includes(key) || !deepEqual((a as Record<string, unknown>)[key], (b as Record<string, unknown>)[key])) {
      return false;
    }
  }

  return true;
}

/**
 * 从对象中选取指定的属性
 * @param obj 源对象
 * @param keys 要选取的属性键数组
 * @returns 包含指定属性的新对象
 */
export function pick<T extends Record<string, unknown>, K extends keyof T>(
  obj: T,
  keys: K[]
): Pick<T, K> {
  const result = {} as Pick<T, K>;
  for (const key of keys) {
    if (key in obj) {
      result[key] = obj[key];
    }
  }
  return result;
}

/**
 * 从对象中排除指定的属性
 * @param obj 源对象
 * @param keys 要排除的属性键数组
 * @returns 排除指定属性后的新对象
 */
export function omit<T extends Record<string, unknown>, K extends keyof T>(
  obj: T,
  keys: K[]
): Omit<T, K> {
  const result = { ...obj } as T;
  for (const key of keys) {
    delete result[key];
  }
  return result as Omit<T, K>;
}

/**
 * 合并多个对象
 * @param objects 要合并的对象数组
 * @returns 合并后的新对象
 */
export function merge<T extends Record<string, unknown>>(...objects: Partial<T>[]): T {
  const result = {} as T;

  for (const obj of objects) {
    if (obj && typeof obj === 'object') {
      Object.assign(result, obj);
    }
  }

  return result;
}

/**
 * 将对象转换为查询字符串
 * @param obj 要转换的对象
 * @returns 查询字符串
 */
export const toQueryString = (obj: Record<string, unknown>): string => {
  const params = new URLSearchParams();

  for (const key in obj) {
    if (Object.prototype.hasOwnProperty.call(obj, key)) {
      const value = obj[key];
      if (value !== null && value !== undefined) {
        params.append(key, String(value));
      }
    }
  }

  return params.toString();
};

/**
 * 将查询字符串转换为对象
 * @param queryString 查询字符串
 * @returns 转换后的对象
 */
export const fromQueryString = (queryString: string): Record<string, string> => {
  const params = new URLSearchParams(queryString);
  const result: Record<string, string> = {};

  for (const [key, value] of params.entries()) {
    result[key] = value;
  }

  return result;
};

/**
 * 数组去重
 * @param array 要去重的数组
 * @param keyFn 可选的键函数，用于复杂对象去重
 * @returns 去重后的数组
 */
export const unique = <T, K = unknown>(
  array: T[],
  keyFn?: (item: T) => K
): T[] => {
  if (!keyFn) {
    return [...new Set(array)];
  }

  const seen = new Set<K>();
  return array.filter(item => {
    const key = keyFn(item);
    if (seen.has(key)) {
      return false;
    }
    seen.add(key);
    return true;
  });
};

/**
 * 数组分组
 * @param array 要分组的数组
 * @param keyFn 分组键函数
 * @returns 分组后的对象
 */
export const groupBy = <T, K extends string | number | symbol>(
  array: T[],
  keyFn: (item: T) => K
): Record<K, T[]> => {
  return array.reduce((groups, item) => {
    const key = keyFn(item);
    if (!groups[key]) {
      groups[key] = [];
    }
    groups[key].push(item);
    return groups;
  }, {} as Record<K, T[]>);
};

/**
 * 数组排序
 * @param array 要排序的数组
 * @param compareFn 比较函数
 * @returns 排序后的新数组
 */
export const sortBy = <T>(
  array: T[],
  compareFn?: (a: T, b: T) => number
): T[] => {
  return [...array].sort(compareFn);
};

/**
 * 防抖函数
 * @param func 要防抖的函数
 * @param wait 等待时间（毫秒）
 * @param immediate 是否立即执行
 */
export function debounce<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number,
  immediate = false
): (...args: Parameters<T>) => void {
  let timeout: ReturnType<typeof setTimeout> | null = null;

  return function(this: unknown, ...args: Parameters<T>) {
    const later = () => {
      timeout = null;
      if (!immediate) func.apply(this, args);
    };

    const callNow = immediate && !timeout;

    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(later, wait);

    if (callNow) func.apply(this, args);
  };
}