import base64

def decode_base64(encoded_str):
    """
    標準Base64解碼函數(shù)
    支持處理帶padding和不帶padding的字符串
    """
    try:
        # 補全可能缺失的padding
        padding = len(encoded_str) % 4
        if padding:
            encoded_str += '=' * (4 - padding)
        
        # 執(zhí)行解碼
        decoded_bytes = base64.b64decode(encoded_str)
        return decoded_bytes.decode('utf-8')
    except Exception as e:
        print(f"解碼失敗: {str(e)}")
        return None

# 示例用法
encoded_data = "SGVsbG8gV29ybGQh"  # "Hello World!"的Base64編碼
decoded_text = decode_base64(encoded_data)
print(f"解碼結(jié)果: {decoded_text}")

def base64url_decode(encoded_str):
    """
    處理URL安全的Base64編碼
    將'-'替換為'+'，'_'替換為'/'
    """
    # 替換URL安全字符
    standard_str = encoded_str.replace('-', '+').replace('_', '/')
    # 補全padding
    padding = len(standard_str) % 4
    if padding:
        standard_str += '=' * (4 - padding)
    
    return base64.b64decode(standard_str)

# 示例：解碼Base64URL
url_encoded = "SGVsbG8tV29ybGQh"
decoded_data = base64url_decode(url_encoded)
print(f"Base64URL解碼結(jié)果: {decoded_data.decode('utf-8')}")

def safe_base64_decode(encoded_str, encoding='utf-8'):
    """
    安全的Base64解碼函數(shù)
    支持多種編碼格式和錯誤處理
    """
    try:
        decoded_bytes = base64.b64decode(encoded_str)
        try:
            return decoded_bytes.decode(encoding)
        except UnicodeDecodeError:
            # 嘗試其他常見編碼
            for alt_encoding in ['gbk', 'latin-1', 'ascii']:
                try:
                    return decoded_bytes.decode(alt_encoding)
                except UnicodeDecodeError:
                    continue
            return decoded_bytes  # 返回字節(jié)數(shù)據(jù)
    except base64.binascii.Error as e:
        print(f"Base64格式錯誤: {str(e)}")
        return None

# 使用示例
result = safe_base64_decode("5L2g5aW977yM5LiW55WM")
print(f"中文解碼: {result}")