package com.zy.acs.manager.common.interceptor;

import com.zy.acs.framework.common.Cools;
import com.zy.acs.manager.common.annotation.IntegrationAuth;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.util.ContentCachingRequestWrapper;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * Intercepts open API calls so they can be audited via IntegrationRecordAdvice.
 */
@Slf4j
@Component
public class IntegrationOpenApiInterceptor implements HandlerInterceptor {

    private static final String ATTR_APP_AUTH = "appAuth";
    private static final String ATTR_AUTH_MEMO = "integrationAuthMemo";
    private static final String ATTR_CACHE = "cache";
    private static final String ATTR_START_AT = "openApiStartTime";

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        IntegrationAuth integrationAuth = findIntegrationAuth(handlerMethod);
        if (integrationAuth == null) {
            log.debug("Skip open-api logging for {} because @IntegrationAuth is missing", handlerMethod.getMethod());
            return true;
        }

        request.setAttribute(ATTR_APP_AUTH, integrationAuth.value());
        if (!Cools.isEmpty(integrationAuth.memo())) {
            request.setAttribute(ATTR_AUTH_MEMO, integrationAuth.memo());
        }
        request.setAttribute(ATTR_START_AT, System.currentTimeMillis());
        request.setAttribute(ATTR_CACHE, buildRequestCache(request));
        return true;
    }

    private IntegrationAuth findIntegrationAuth(HandlerMethod handlerMethod) {
        IntegrationAuth annotation = AnnotatedElementUtils.findMergedAnnotation(handlerMethod.getMethod(), IntegrationAuth.class);
        if (annotation != null) {
            return annotation;
        }
        return AnnotatedElementUtils.findMergedAnnotation(handlerMethod.getBeanType(), IntegrationAuth.class);
    }

    private Map<String, Object> buildRequestCache(HttpServletRequest request) {
        Map<String, Object> cache = new LinkedHashMap<>();
        cache.put("method", request.getMethod());
        cache.put("uri", request.getRequestURI());
        cache.put("query", request.getQueryString());
        cache.put("parameters", flattenParameters(request.getParameterMap()));
        cache.put("headers", extractHeaders(request));
        String body = readBody(request);
        if (!Cools.isEmpty(body)) {
            cache.put("body", body);
        }
        return cache;
    }

    private Map<String, Object> flattenParameters(Map<String, String[]> rawParams) {
        Map<String, Object> flattened = new LinkedHashMap<>();
        if (rawParams == null) {
            return flattened;
        }
        rawParams.forEach((key, values) -> {
            if (values == null) {
                flattened.put(key, null);
            } else if (values.length == 1) {
                flattened.put(key, values[0]);
            } else {
                flattened.put(key, Arrays.asList(values));
            }
        });
        return flattened;
    }

    private Map<String, Object> extractHeaders(HttpServletRequest request) {
        Map<String, Object> headers = new LinkedHashMap<>();
        List<String> names = Collections.list(request.getHeaderNames());
        for (String name : names) {
            headers.put(name, request.getHeader(name));
        }
        return headers;
    }

    private String readBody(HttpServletRequest request) {
        if (request instanceof ContentCachingRequestWrapper) {
            ContentCachingRequestWrapper wrapper = (ContentCachingRequestWrapper) request;
            byte[] buffer = wrapper.getContentAsByteArray();
            if (buffer.length > 0) {
                Charset charset = charset(wrapper.getCharacterEncoding());
                return new String(buffer, charset);
            }
        }
        return null;
    }

    private Charset charset(String encoding) {
        if (Cools.isEmpty(encoding)) {
            return StandardCharsets.UTF_8;
        }
        try {
            return Charset.forName(encoding);
        } catch (Exception e) {
            return StandardCharsets.UTF_8;
        }
    }
}