frontend/src/components/ui/select.tsx

import * as React from 'react';

// 创建Select上下文
const SelectContext = React.createContext<{
  value: string;
  setValue: (value: string) => void;
  open: boolean;
  setOpen: (open: boolean) => void;
} | null>(null);

// Select组件接口
export interface SelectProps {
  defaultValue?: string;
  value?: string;
  onValueChange?: (value: string) => void;
  children: React.ReactNode;
  className?: string;
}

// SelectTrigger组件接口
export interface SelectTriggerProps {
  children: React.ReactNode;
  className?: string;
}

// SelectValue组件接口
export interface SelectValueProps {
  placeholder?: string;
  children?: React.ReactNode;
}

// SelectContent组件接口
export interface SelectContentProps {
  children: React.ReactNode;
  className?: string;
}

// SelectItem组件接口
export interface SelectItemProps {
  value: string;
  children: React.ReactNode;
  className?: string;
}

/**
 * Select组件 - 管理选择器的状态
 */
export const Select: React.FC<SelectProps> = ({ 
  defaultValue = '', 
  value: valueProp, 
  onValueChange, 
  children, 
  className = '' 
}) => {
  const [valueState, setValueState] = React.useState(defaultValue);
  const [open, setOpen] = React.useState(false);
  
  const value = valueProp !== undefined ? valueProp : valueState;
  const setValue = valueProp !== undefined && onValueChange 
    ? onValueChange 
    : setValueState;

  // 点击外部关闭下拉菜单
  React.useEffect(() => {
    if (open) {
      const handleClickOutside = (event: MouseEvent) => {
        const target = event.target as HTMLElement;
        if (!target.closest(`.${className}`) && !target.closest('.select-trigger')) {
          setOpen(false);
        }
      };

      document.addEventListener('mousedown', handleClickOutside);
      return () => {
        document.removeEventListener('mousedown', handleClickOutside);
      };
    }
  }, [open, className]);

  return (
    <SelectContext.Provider value={{ value, setValue, open, setOpen }}>
      <div className={className}>{children}</div>
    </SelectContext.Provider>
  );
};

/**
 * SelectTrigger组件 - 选择器的触发器按钮
 */
export const SelectTrigger: React.FC<SelectTriggerProps> = ({ children, className = '' }) => {
  const context = React.useContext(SelectContext);
  
  if (!context) {
    throw new Error('SelectTrigger must be used within a Select component');
  }
  
  const handleClick = () => {
    context.setOpen(!context.open);
  };
  
  return (
    <button
      type="button"
      onClick={handleClick}
      className={`px-4 py-2 border rounded-md flex items-center justify-between w-full select-trigger ${className}`}
    >
      {children}
      <span className="ml-2">▼</span>
    </button>
  );
};

/**
 * SelectValue组件 - 显示当前选中的值或占位符
 */
export const SelectValue: React.FC<SelectValueProps> = ({ placeholder, children }) => {
  const context = React.useContext(SelectContext);
  
  if (!context) {
    throw new Error('SelectValue must be used within a Select component');
  }
  
  if (context.value && children) {
    return <span>{children}</span>;
  }
  
  return placeholder ? (
    <span className="text-gray-500">{placeholder}</span>
  ) : null;
};

/**
 * SelectContent组件 - 包含选项的下拉菜单
 */
export const SelectContent: React.FC<SelectContentProps> = ({ children, className = '' }) => {
  const context = React.useContext(SelectContext);
  
  if (!context) {
    throw new Error('SelectContent must be used within a Select component');
  }
  
  if (!context.open) {
    return null;
  }
  
  return (
    <div className={`absolute mt-1 border rounded-md bg-white shadow-lg z-10 max-h-60 overflow-auto ${className}`}>
      {children}
    </div>
  );
};

/**
 * SelectItem组件 - 选择器中的单个选项
 */
export const SelectItem: React.FC<SelectItemProps> = ({ 
  value, 
  children, 
  className = '' 
}) => {
  const context = React.useContext(SelectContext);
  
  if (!context) {
    throw new Error('SelectItem must be used within a Select component');
  }
  
  const isSelected = context.value === value;
  
  const handleClick = () => {
    context.setValue(value);
    context.setOpen(false);
  };
  
  return (
    <button
      type="button"
      onClick={handleClick}
      className={`block w-full text-left px-4 py-2 hover:bg-gray-100 ${isSelected ? 'bg-blue-50 text-blue-500' : ''} ${className}`}
    >
      {children}
    </button>
  );
};

export default Select;