import logging
import json
from typing import Dict, Any, Optional

class SchemaProvider:
    def __init__(self, global_api_spec: Dict[str, Any]):
        self.global_api_spec = global_api_spec
        self.logger = logging.getLogger(__name__)

    def get_schema(self, endpoint_spec: Dict[str, Any], status_code: int) -> Optional[Dict]:
        """
        获取端点在特定状态码下的响应Schema。
        
        当前实现：从API规范中查找。
        未来可扩展：优先从动态映射中获取，如果失败或未配置，则回退到当前实现。
        """
        # --- 预留的动态获取逻辑扩展点 ---
        # if self._use_dynamic_provider(endpoint_spec):
        #     schema = self._fetch_dynamic_schema(endpoint_spec)
        #     if schema:
        #         return schema
        # ---------------------------------

        return self._get_schema_from_spec(endpoint_spec, status_code)

    def _get_schema_from_spec(self, endpoint_spec: Dict[str, Any], status_code: int) -> Optional[Dict]:
        """
        (私有方法) 从API规范中提取Schema，这是当前版本的主要实现。
        """
        self.logger.debug(f"尝试从API规范中为状态码 {status_code} 查找Schema。")
        
        expected_schema = None
        
        # 兼容 OpenAPI/Swagger 格式
        if 'responses' in endpoint_spec:
            responses = endpoint_spec['responses']
            # 优先匹配精确的状态码
            if str(status_code) in responses:
                response_def = responses[str(status_code)]
                if 'content' in response_def and 'application/json' in response_def['content']:
                    expected_schema = response_def['content']['application/json'].get('schema')
            # 回退到 'default'
            elif 'default' in responses:
                response_def = responses['default']
                if 'content' in response_def and 'application/json' in response_def['content']:
                    expected_schema = response_def['content']['application/json'].get('schema')

        # 兼容 YAPI 格式 (简化)
        elif 'res_body_type' in endpoint_spec and endpoint_spec['res_body_type'] == 'json':
            if endpoint_spec.get('res_body_is_json_schema') and endpoint_spec.get('res_body'):
                try:
                    expected_schema = json.loads(endpoint_spec['res_body'])
                except (json.JSONDecodeError, TypeError):
                    self.logger.error(f"从YAPI res_body解析JSON schema失败。res_body: {endpoint_spec['res_body']}")
                    return None # 解析失败

        if not expected_schema:
            self.logger.info(f"在API规范中未找到针对状态码 {status_code} 的JSON schema。")

        return expected_schema