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Core Katharsis library
There is a newer version: 2.6.3
package io.katharsis.dispatcher;

import java.util.List;

import io.katharsis.dispatcher.controller.BaseController;
import io.katharsis.dispatcher.filter.Filter;
import io.katharsis.dispatcher.filter.FilterChain;
import io.katharsis.dispatcher.filter.FilterRequestContext;
import io.katharsis.dispatcher.registry.ControllerRegistry;
import io.katharsis.errorhandling.mapper.ExceptionMapperRegistry;
import io.katharsis.errorhandling.mapper.JsonApiExceptionMapper;
import io.katharsis.module.ModuleRegistry;
import io.katharsis.queryParams.QueryParams;
import io.katharsis.repository.RepositoryMethodParameterProvider;
import io.katharsis.request.dto.RequestBody;
import io.katharsis.request.path.JsonPath;
import io.katharsis.response.BaseResponseContext;
import io.katharsis.utils.java.Optional;

/**
 * A class that can be used to integrate Katharsis with external frameworks like Jersey, Spring etc. See katharsis-rs
 * and katharsis-servlet for usage.
 */
public class RequestDispatcher {

    private final ControllerRegistry controllerRegistry;
    private final ExceptionMapperRegistry exceptionMapperRegistry;
    
	private ModuleRegistry moduleRegistry;

    public RequestDispatcher(ModuleRegistry moduleRegistry, ControllerRegistry controllerRegistry,
			ExceptionMapperRegistry exceptionMapperRegistry) {
    	this.controllerRegistry = controllerRegistry;
    	this.moduleRegistry = moduleRegistry;
    	this.exceptionMapperRegistry = exceptionMapperRegistry;
    }

    /**
     * Dispatch the request from a client
     *
     * @param jsonPath          built {@link JsonPath} instance which represents the URI sent in the request
     * @param requestType       type of the request e.g. POST, GET, PATCH
     * @param parameterProvider repository method parameter provider
     * @param queryParams       built object containing query parameters of the request
     * @param requestBody       deserialized body of the client request
     * @return the response form the Katharsis
     */
    public BaseResponseContext dispatchRequest(JsonPath jsonPath, String requestType, QueryParams queryParams,
                                                  RepositoryMethodParameterProvider parameterProvider,
                                                  @SuppressWarnings("SameParameterValue") RequestBody requestBody) {

        try {
        	BaseController controller = controllerRegistry.getController(jsonPath, requestType);

			DefaultFilterRequestContext context = new DefaultFilterRequestContext(jsonPath, queryParams,
					parameterProvider, requestBody);
			DefaultFilterChain chain = new DefaultFilterChain(controller);
			return chain.doFilter(context);
        } catch (Exception e) {
            Optional exceptionMapper = exceptionMapperRegistry.findMapperFor(e.getClass());
            if (exceptionMapper.isPresent()) {
                //noinspection unchecked
                return exceptionMapper.get()
                    .toErrorResponse(e);
            } else {
                throw new RuntimeException(e);
            }
        }
    }

    class DefaultFilterChain implements FilterChain {

		protected int filterIndex = 0;
		protected BaseController controller;

		public DefaultFilterChain(BaseController controller){
			this.controller = controller;
		}

		@Override
		public BaseResponseContext doFilter(FilterRequestContext context) {
			List filters = moduleRegistry.getFilters();
			if (filterIndex == filters.size()) {
				return controller.handle(context.getJsonPath(), context.getQueryParams(), context.getParameterProvider(), context.getRequestBody());
			} else {
				Filter filter = filters.get(filterIndex);
				filterIndex++;
				return filter.filter(context, this);
			}
		}
	}

	class DefaultFilterRequestContext implements FilterRequestContext {

		protected JsonPath jsonPath;
		protected QueryParams queryParams;
		protected RepositoryMethodParameterProvider parameterProvider;
		protected RequestBody requestBody;

		public DefaultFilterRequestContext(JsonPath jsonPath, QueryParams queryParams,
				RepositoryMethodParameterProvider parameterProvider, RequestBody requestBody) {
			this.jsonPath = jsonPath;
			this.queryParams = queryParams;
			this.parameterProvider = parameterProvider;
			this.requestBody = requestBody;
		}

		@Override
		public RequestBody getRequestBody() {
			return requestBody;
		}

		@Override
		public RepositoryMethodParameterProvider getParameterProvider() {
			return parameterProvider;
		}

		@Override
		public QueryParams getQueryParams() {
			return queryParams;
		}

		@Override
		public JsonPath getJsonPath() {
			return jsonPath;
		}
	}
}