/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.camel.component.http;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Enumeration;
import java.util.Map;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.activation.FileTypeMap;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.InvalidPayloadException;
import org.apache.camel.Message;
import org.apache.camel.StreamCache;
import org.apache.camel.component.http.helper.GZIPHelper;
import org.apache.camel.converter.stream.CachedOutputStream;
import org.apache.camel.spi.HeaderFilterStrategy;
import org.apache.camel.util.IOHelper;
import org.apache.camel.util.MessageHelper;
import org.apache.camel.util.ObjectHelper;

/**
 * Binding between {@link HttpMessage} and {@link HttpServletResponse}.
 *
 * @version $Revision$
 */
public class DefaultHttpBinding implements HttpBinding {

    private boolean useReaderForPayload;
    private HeaderFilterStrategy headerFilterStrategy = new HttpHeaderFilterStrategy();

    public DefaultHttpBinding() {
    }

    public DefaultHttpBinding(HeaderFilterStrategy headerFilterStrategy) {
        this.headerFilterStrategy = headerFilterStrategy;
    }

    public void readRequest(HttpServletRequest request, HttpMessage message) {
        
        // lets force a parse of the body and headers
        message.getBody();
        // populate the headers from the request
        Map<String, Object> headers = message.getHeaders();
        
        //apply the headerFilterStrategy
        Enumeration names = request.getHeaderNames();
        while (names.hasMoreElements()) {
            String name = (String)names.nextElement();
            Object value = request.getHeader(name);
            // mapping the content-type 
            if (name.toLowerCase().equals("content-type")) {
                name = Exchange.CONTENT_TYPE;
            }
            if (headerFilterStrategy != null
                && !headerFilterStrategy.applyFilterToExternalHeaders(name, value, message.getExchange())) {
                headers.put(name, value);
            }
        }
                
        if (request.getCharacterEncoding() != null) {
            headers.put(Exchange.HTTP_CHARACTER_ENCODING, request.getCharacterEncoding());
            message.getExchange().setProperty(Exchange.CHARSET_NAME, request.getCharacterEncoding());
        }

        popluateRequestParameters(request, message);        
        
        Object body = message.getBody();
        // reset the stream cache if the body is the instance of StreamCache
        if (body instanceof StreamCache) {
            ((StreamCache)body).reset();
        }
        
        // store the method and query and other info in headers
        headers.put(Exchange.HTTP_METHOD, request.getMethod());
        headers.put(Exchange.HTTP_QUERY, request.getQueryString());
        headers.put(Exchange.HTTP_URL, request.getRequestURL());
        headers.put(Exchange.HTTP_URI, request.getRequestURI());
        headers.put(Exchange.HTTP_PATH, request.getPathInfo());
        headers.put(Exchange.CONTENT_TYPE, request.getContentType());
        
        popluateAttachments(request, message);
    }
    
    protected void popluateRequestParameters(HttpServletRequest request, HttpMessage message) {
        //we populate the http request parameters without checking the request method
        Map<String, Object> headers = message.getHeaders();
        Enumeration names = request.getParameterNames();
        while (names.hasMoreElements()) {
            String name = (String)names.nextElement();
            Object value = request.getParameter(name);
            if (headerFilterStrategy != null
                && !headerFilterStrategy.applyFilterToExternalHeaders(name, value, message.getExchange())) {
                headers.put(name, value);
            }
        }
        
        if (request.getMethod().equals("POST") && request.getContentType() != null && request.getContentType().equals("application/x-www-form-urlencoded")) {
            String charset = request.getCharacterEncoding();
            if (charset == null) {
                charset = "UTF-8";
            }
            // Push POST form params into the headers to retain compatibility with DefaultHttpBinding
            String body = message.getBody(String.class);
            try {
                for (String param : body.split("&")) {
                    String[] pair = param.split("=", 2);
                    String name = URLDecoder.decode(pair[0], charset);
                    String value = URLDecoder.decode(pair[1], charset);
                    if (headerFilterStrategy != null
                        && !headerFilterStrategy.applyFilterToExternalHeaders(name, value, message.getExchange())) {
                        headers.put(name, value);
                    }
                }
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);
            }
        }
        
    }
    
    protected void popluateAttachments(HttpServletRequest request, HttpMessage message) {
        // check if there is multipart files, if so will put it into DataHandler
        Enumeration names = request.getAttributeNames();
        while (names.hasMoreElements()) {
            String name = (String) names.nextElement();
            Object object = request.getAttribute(name);
            if (object instanceof File) {
                String fileName = request.getParameter(name);
                message.addAttachment(fileName, new DataHandler(new FileDataSource((File)object), FileTypeMap.getDefaultFileTypeMap().getContentType(fileName)));
            }
        }
    }

    public void writeResponse(Exchange exchange, HttpServletResponse response) throws IOException {
        if (exchange.isFailed()) {
            if (exchange.getException() != null) {
                doWriteExceptionResponse(exchange.getException(), response);
            } else {
                // it must be a fault, no need to check for the fault flag on the message
                doWriteFaultResponse(exchange.getOut(), response, exchange);
            }
        } else {
            // just copy the protocol relates header
            copyProtocolHeaders(exchange.getIn(), exchange.getOut());
            Message out = exchange.getOut();            
            if (out != null) {
                doWriteResponse(out, response, exchange);
            }
        }
    }

    private void copyProtocolHeaders(Message request, Message response) {
        if (request.getHeader(Exchange.CONTENT_ENCODING) != null) {
            String contentEncoding = request.getHeader(Exchange.CONTENT_ENCODING, String.class);
            response.setHeader(Exchange.CONTENT_ENCODING, contentEncoding);
        }        
        if (checkChunked(response, response.getExchange())) {
            response.setHeader(Exchange.TRANSFER_ENCODING, "chunked");
        }
    }

    public void doWriteExceptionResponse(Throwable exception, HttpServletResponse response) throws IOException {
        response.setStatus(500); // 500 for internal server error
        response.setContentType("text/plain");

        // append the stacktrace as response
        PrintWriter pw = response.getWriter();
        exception.printStackTrace(pw);

        pw.flush();
    }

    public void doWriteFaultResponse(Message message, HttpServletResponse response, Exchange exchange) throws IOException {
        doWriteResponse(message, response, exchange);
    }

    public void doWriteResponse(Message message, HttpServletResponse response, Exchange exchange) throws IOException {
        // set the status code in the response. Default is 200.
        if (message.getHeader(Exchange.HTTP_RESPONSE_CODE) != null) {
            int code = message.getHeader(Exchange.HTTP_RESPONSE_CODE, Integer.class);
            response.setStatus(code);
        }
        // set the content type in the response.
        String contentType = MessageHelper.getContentType(message);
        if (MessageHelper.getContentType(message) != null) {
            response.setContentType(contentType);
        }

        // append headers
        for (String key : message.getHeaders().keySet()) {
            String value = message.getHeader(key, String.class);
            if (headerFilterStrategy != null
                    && !headerFilterStrategy.applyFilterToCamelHeaders(key, value, exchange)) {
                response.setHeader(key, value);
            }
        }

        // write the body.
        if (message.getBody() != null) {
            if (GZIPHelper.isGzip(message)) {
                doWriteGZIPResponse(message, response, exchange);
            } else {
                doWriteDirectResponse(message, response, exchange);
            }
        }
    }

    protected void doWriteDirectResponse(Message message, HttpServletResponse response, Exchange exchange) throws IOException {
        InputStream is = null;
        if (checkChunked(message, exchange)) {
            is = message.getBody(InputStream.class);
        }
        if (is != null) {
            ServletOutputStream os = response.getOutputStream();
            try {
                // copy directly from input stream to output stream
                IOHelper.copy(is, os);
            } finally {
                try {
                    os.close();
                } catch (Exception e) {
                    // ignore, maybe client have disconnected or timed out
                }
                try {
                    is.close();
                } catch (Exception e) {
                    // ignore, maybe client have disconnected or timed out
                }
            }
        } else {
            // not convertable as a stream so try as a String
            String data = message.getBody(String.class);
            if (data != null) {
                // set content length before we write data
                response.setContentLength(data.length());
                response.getWriter().print(data);
                response.getWriter().flush();
            }
        }
    }

    protected boolean checkChunked(Message message, Exchange exchange) {
        boolean answer = true;
        if (message.getHeader(Exchange.HTTP_CHUNKED) == null) {
            // check the endpoint option
            Endpoint endpoint = exchange.getFromEndpoint();
            if (endpoint instanceof HttpEndpoint) {
                answer = ((HttpEndpoint)endpoint).isChunked();
            }
        } else {
            answer = message.getHeader(Exchange.HTTP_CHUNKED, boolean.class);
        }
        return answer;
    }

    protected void doWriteGZIPResponse(Message message, HttpServletResponse response, Exchange exchange) throws IOException {
        byte[] bytes;
        try {
            bytes = message.getMandatoryBody(byte[].class);
        } catch (InvalidPayloadException e) {
            throw ObjectHelper.wrapRuntimeCamelException(e);
        }

        byte[] data = GZIPHelper.compressGZIP(bytes);
        ServletOutputStream os = response.getOutputStream();
        try {
            response.setContentLength(data.length);
            os.write(data);
            os.flush();
        } finally {
            os.close();
        }
    }

    public Object parseBody(HttpMessage httpMessage) throws IOException {
        // lets assume the body is a reader
        HttpServletRequest request = httpMessage.getRequest();
        // Need to handle the GET Method which has no inputStream
        if ("GET".equals(request.getMethod())) {
            return null;
        }
        if (isUseReaderForPayload()) {
            return request.getReader();
        } else {
            // otherwise use input stream and we need to cache it first
            InputStream is = HttpConverter.toInputStream(request, httpMessage.getExchange());
            if (is == null) {
                return is;
            }
            // convert the input stream to StreamCache if the stream cache is not disabled
            if (httpMessage.getExchange().getProperty(Exchange.DISABLE_HTTP_STREAM_CACHE, Boolean.FALSE, Boolean.class)) {
                return is;
            } else {
                try {
                    CachedOutputStream cos = new CachedOutputStream(httpMessage.getExchange());
                    IOHelper.copy(is, cos);
                    return cos.getStreamCache();

                } finally {
                    is.close();
                }
            }
             
        }
    }

    public boolean isUseReaderForPayload() {
        return useReaderForPayload;
    }

    public void setUseReaderForPayload(boolean useReaderForPayload) {
        this.useReaderForPayload = useReaderForPayload;
    }

    public HeaderFilterStrategy getHeaderFilterStrategy() {
        return headerFilterStrategy;
    }

    public void setHeaderFilterStrategy(HeaderFilterStrategy headerFilterStrategy) {
        this.headerFilterStrategy = headerFilterStrategy;
    }

}