/* Copyright 2010 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS.
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License
 */

package com.google.ie.common.openid.appengine;

import com.google.appengine.api.urlfetch.HTTPHeader;
import com.google.appengine.api.urlfetch.HTTPMethod;
import com.google.appengine.api.urlfetch.HTTPRequest;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.appengine.api.urlfetch.URLFetchService;
import com.google.appengine.api.urlfetch.URLFetchServiceFactory;
import com.google.inject.Singleton;
import com.google.step2.http.FetchException;
import com.google.step2.http.FetchRequest;
import com.google.step2.http.FetchResponse;
import com.google.step2.http.HttpFetcher;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.util.List;

@Singleton
public class AppEngineHttpFetcher implements HttpFetcher {

    private final URLFetchService fetchService;

    public AppEngineHttpFetcher() {
        fetchService = URLFetchServiceFactory.getURLFetchService();
    }

    public FetchResponse fetch(FetchRequest request) throws FetchException {

        HTTPMethod method;
        switch (request.getMethod()) {
            case POST:
                method = HTTPMethod.POST;
                break;
            case HEAD:
                method = HTTPMethod.HEAD;
                break;
            default:
                method = HTTPMethod.GET;
                break;
        }

        try {

            HTTPRequest httpRequest = new HTTPRequest(request.getUri().toURL(), method);
            HTTPResponse httpResponse = fetchService.fetch(httpRequest);
            return new AppEngineFetchResponse(httpResponse);

        } catch (MalformedURLException e) {
            throw new FetchException(e);
        } catch (IOException e) {
            throw new FetchException(e);
        }
    }

    private static class AppEngineFetchResponse implements FetchResponse {

        private final HTTPResponse httpResponse;

        public AppEngineFetchResponse(HTTPResponse httpResponse) {
            this.httpResponse = httpResponse;
        }

        public byte[] getContentAsBytes() {
            return httpResponse.getContent();
        }

        public InputStream getContentAsStream() {
            return new ByteArrayInputStream(getContentAsBytes());
        }

        public String getFirstHeader(String name) {
            List<HTTPHeader> headers = httpResponse.getHeaders();
            for (HTTPHeader header : headers) {
                if (header.getName().equalsIgnoreCase(name)) {
                    return header.getValue();
                }
            }
            return null;
        }

        public int getStatusCode() {
            return httpResponse.getResponseCode();
        }
    }
}