/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/HttpMethod.java,v 1.41 2004/07/05 22:46:58 olegk Exp $
 * $Revision: 1.41 $
 * $Date: 2004/07/05 22:46:58 $
 *
 * ====================================================================
 *
 *  Copyright 1999-2004 The Apache Software Foundation
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.httpclient.auth.AuthState;
import org.apache.commons.httpclient.params.HttpMethodParams;

/**
 * <p>
 * HttpMethod interface represents a request to be sent via a 
 * {@link HttpConnection HTTP connection} and a corresponding response.
 * </p>
 * @author <a href="mailto:remm@apache.org">Remy Maucherat</a>
 * @author Rod Waldhoff
 * @author <a href="jsdever@apache.org">Jeff Dever</a>
 * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 *
 * @version $Revision: 1.41 $ $Date: 2004/07/05 22:46:58 $
 * 
 * @since 1.0
 */
public interface HttpMethod {

    // ------------------------------------------- Property Setters and Getters

    /**
     * Obtains the name of the HTTP method as used in the HTTP request line,
     * for example <tt>"GET"</tt> or <tt>"POST"</tt>.
     * 
     * @return the name of this method
     */
    String getName();

    /**
     * Gets the host configuration for this method.  The configuration specifies
     * the server, port, protocol, and proxy server via which this method will
     * send its HTTP request. 
     * 
     * @return the HostConfiguration or <code>null</code> if none is set
     */
    HostConfiguration getHostConfiguration();

    /**
     * Sets the path of the HTTP method.
     * It is responsibility of the caller to ensure that the path is
     * properly encoded (URL safe).
     * 
     * @param path The path of the HTTP method. The path is expected
     *             to be URL encoded.
     */
    void setPath(String path);

    /**
     * Returns the path of the HTTP method.  
     *
     * Calling this method <em>after</em> the request has been executed will 
     * return the <em>actual</em> path, following any redirects automatically
     * handled by this HTTP method.
     * 
     * @return the path of the HTTP method, in URL encoded form
     */
    String getPath();

    /**
     * Returns the URI for this method. The URI will be absolute if the host
     * configuration has been set and relative otherwise.
     * 
     * @return the URI for this method
     * 
     * @throws URIException if a URI cannot be constructed
     */
    URI getURI() throws URIException;

    /**
     * Sets the URI for this method. 
     * 
     * @param uri URI to be set 
     * 
     * @throws URIException if a URI cannot be set
     * 
     * @since 3.0
     */
    void setURI(URI uri) throws URIException;

    /**
     * Defines how strictly the method follows the HTTP protocol specification.  
     * (See RFC 2616 and other relevant RFCs.) In the strict mode the method precisely
     * implements the requirements of the specification, whereas in non-strict mode 
     * it attempts to mimic the exact behaviour of commonly used HTTP agents, 
     * which many HTTP servers expect.
     * 
     * @param strictMode <tt>true</tt> for strict mode, <tt>false</tt> otherwise
     * 
     * @deprecated Use {@link org.apache.commons.httpclient.params.HttpParams#setParameter(String, Object)} 
     * to exercise a more granular control over HTTP protocol strictness.
     * 
     * @see #isStrictMode()
     */
    void setStrictMode(boolean strictMode);

    /**
     * Returns the value of the strict mode flag.
     *
     * @return <tt>true</tt> if strict mode is enabled, <tt>false</tt> otherwise
     * 
     * @deprecated Use {@link org.apache.commons.httpclient.params.HttpParams#setParameter(String, Object)} 
     * to exercise a more granular control over HTTP protocol strictness.
     * 
     * @see #setStrictMode(boolean)
     */
    boolean isStrictMode();
     
    /**
     * Sets the specified request header, overwriting any
     * previous value.
     * Note that header-name matching is case insensitive.
     * @param headerName the header's name
     * @param headerValue the header's value
     *
     * @see #setRequestHeader(Header)
     * @see #getRequestHeader(String)
     * @see #removeRequestHeader(String)
     */
    void setRequestHeader(String headerName, String headerValue);

    /**
     * Sets the specified request header, overwriting any
     * previous value.
     * Note that header-name matching is case insensitive.
     * @param header the header to be set
     *
     * @see #setRequestHeader(String,String)
     * @see #getRequestHeader(String)
     * @see #removeRequestHeader(String)
     */
    void setRequestHeader(Header header);

    /**
     * Adds the specified request header, <em>not</em> overwriting any previous value.
     * If the same header is added multiple times, perhaps with different values,
     * multiple instances of that header will be sent in the HTTP request.
     * Note that header-name matching is case insensitive.
     * @param headerName the header's name
     * @param headerValue the header's value
     * 
     * @see #addRequestHeader(Header)
     * @see #getRequestHeader(String)
     * @see #removeRequestHeader(String)
     */
    void addRequestHeader(String headerName, String headerValue);

    /**
     * Adds the specified request header, <em>not</em> overwriting any previous value.
     * If the same header is added multiple times, perhaps with different values,
     * multiple instances of that header will be sent in the HTTP request.
     * Note that header-name matching is case insensitive.
     * @param header the header
     * 
     * @see #addRequestHeader(String,String)
     * @see #getRequestHeader(String)
     * @see #removeRequestHeader(String)
     */
    void addRequestHeader(Header header);

    /**
     * Gets the request header with the given name.
     * If there are multiple headers with the same name,
     * there values will be combined with the ',' separator as specified by RFC2616.
     * Note that header-name matching is case insensitive.
     * @param headerName the header name
     * @return the header
     */
    Header getRequestHeader(String headerName);

    /**
     * Removes all request headers with the given name.
     * Note that header-name matching is case insensitive.
     * @param headerName the header name
     */
    void removeRequestHeader(String headerName);

    /**
     * Removes the given request header.
     * 
     * @param header the header
     * 
     * @since 3.0
     */
    void removeRequestHeader(Header header);

    /**
     * Returns <tt>true</tt> if the HTTP method should automatically follow HTTP redirects 
     * (status code 302, etc.), <tt>false</tt> otherwise.
     * 
     * @return <tt>true</tt> if the method will automatically follow HTTP redirects, 
     * <tt>false</tt> otherwise
     */
    boolean getFollowRedirects();

    /**
     * Sets whether or not the HTTP method should automatically follow HTTP redirects 
     * (status code 302, etc.)
     * 
     * @param followRedirects <tt>true</tt> if the method will automatically follow redirects,
     * <tt>false</tt> otherwise.
     */
    void setFollowRedirects(boolean followRedirects);

    /**
     * Sets the query string of the HTTP method.
     * It is responsibility of the caller to ensure that the path is
     * properly encoded (URL safe).  The string must not include an initial '?' character.
     * 
     * @param queryString the query to be used in the request, with no leading '?' character
     * 
     * @see #getQueryString()
     * @see #setQueryString(NameValuePair[])
     */
    void setQueryString(String queryString);

    /**
     * Sets the query string of this HTTP method.  The pairs are encoded as UTF-8 characters.  
     * To use a different charset the parameters can be encoded manually using EncodingUtil 
     * and set as a single String.
     *
     * @param params An array of <code>NameValuePair</code>s to use as the query string.
     *               The name/value pairs will be automatically URL encoded and should not
     *               have been encoded previously.
     * 
     * @see #getQueryString()
     * @see #setQueryString(String)
     * @see org.apache.commons.httpclient.util.EncodingUtil#formUrlEncode(NameValuePair[], String)
     */
    void setQueryString(NameValuePair[] params);

    /**
     * Returns the query string of this HTTP method.
     * 
     * @return the query string in URL encoded form, without a leading '?'.
     * 
     * @see #setQueryString(NameValuePair[]) 
     * @see #setQueryString(String)
     */
    String getQueryString();

    /**
     * Returns the current request headers for this HTTP method.  The returned headers
     * will be in the same order that they were added with <code>addRequestHeader</code>.
     * If there are multiple request headers with the same name (e.g. <code>Cookie</code>),
     * they will be returned as multiple entries in the array.
     * 
     * @return an array containing all of the request headers
     * 
     * @see #addRequestHeader(Header)
     * @see #addRequestHeader(String,String)
     */
    Header[] getRequestHeaders();

    /**
     * Returns the request headers with the given name. Note that header-name matching is
     * case insensitive.
     * @param headerName the name of the headers to be returned.
     * @return an array of zero or more headers
     * 
     * @since 3.0
     */
    Header[] getRequestHeaders(String headerName);

    // ---------------------------------------------------------------- Queries

    /**
     * Returns <tt>true</tt> the method is ready to execute, <tt>false</tt> otherwise.
     * 
     * @return <tt>true</tt> if the method is ready to execute, <tt>false</tt> otherwise.
     */
    boolean validate();

    /**
     * Returns the status code associated with the latest response.
     * 
     * @return The status code from the most recent execution of this method.
     *         If the method has not yet been executed, the result is undefined.
     */
    int getStatusCode();

    /**
     * Returns the status text (or "reason phrase") associated with the latest
     * response.
     * 
     * @return The status text from the most recent execution of this method.
     *         If the method has not yet been executed, the result is undefined.
     */
    String getStatusText();

    /**
     * Returns the response headers from the most recent execution of this request.
     * 
     * @return A newly-created array containing all of the response headers, 
     *         in the order in which they appeared in the response.
     */
    Header[] getResponseHeaders();

    /**
     * Returns the specified response header. Note that header-name matching is
     * case insensitive.
     * 
     * @param headerName The name of the header to be returned.
     * 
     * @return The specified response header.  If the repsonse contained multiple
     *         instances of the header, its values will be combined using the ','
     *         separator as specified by RFC2616.
     */
    Header getResponseHeader(String headerName);

    /**
     * Returns the response headers with the given name. Note that header-name matching is
     * case insensitive.
     * @param headerName the name of the headers to be returned.
     * @return an array of zero or more headers
     * 
     * @since 3.0
     */
    Header[] getResponseHeaders(String headerName);

    /**
     * Returns the response footers from the most recent execution of this request.
     * 
     * @return an array containing the response footers in the order that they
     *         appeared in the response.  If the response had no footers,
     *         an empty array will be returned.
     */
    Header[] getResponseFooters();

    /**
     * Return the specified response footer. Note that footer-name matching is
     * case insensitive.
     * 
     * @param footerName The name of the footer.
     * @return The response footer.
     */
    Header getResponseFooter(String footerName);

    /**
     * Returns the response body of the HTTP method, if any, as an array of bytes.
     * If the method has not yet been executed or the response has no body, <code>null</code>
     * is returned.  Note that this method does not propagate I/O exceptions.
     * If an error occurs while reading the body, <code>null</code> will be returned.
     * 
     * @return The response body, or <code>null</code> if the
     *         body is not available.
     * 
     * @throws IOException if an I/O (transport) problem occurs
     */
    byte[] getResponseBody() throws IOException;

    /**
     * Returns the response body of the HTTP method, if any, as a {@link String}. 
     * If response body is not available or cannot be read, <tt>null</tt> is returned.
     * The raw bytes in the body are converted to a <code>String</code> using the
     * character encoding specified in the response's <tt>Content-Type</tt> header, or
     * ISO-8859-1 if the response did not specify a character set.
     * <p>
     * Note that this method does not propagate I/O exceptions.
     * If an error occurs while reading the body, <code>null</code> will be returned.
     *
     * @return The response body converted to a <code>String</code>, or <code>null</code>
     *         if the body is not available.
     * 
     * @throws IOException if an I/O (transport) problem occurs
     */
    String getResponseBodyAsString() throws IOException;

    /**
     * Returns the response body of the HTTP method, if any, as an InputStream.
     * If the response had no body or the method has not yet been executed,
     * <code>null</code> is returned.  Additionally, <code>null</code> may be returned
     * if {@link #releaseConnection} has been called or
     * if this method was called previously and the resulting stream was closed. 
     * 
     * @return The response body, or <code>null</code> if it is not available 
     * 
     * @throws IOException if an I/O (transport) problem occurs
     */
    InputStream getResponseBodyAsStream() throws IOException;

    /**
     * Returns <tt>true</tt> if the HTTP method has been already {@link #execute executed},
     * but not {@link #recycle recycled}.
     * 
     * @return <tt>true</tt> if the method has been executed, <tt>false</tt> otherwise
     */
    boolean hasBeenUsed();

    // --------------------------------------------------------- Action Methods

    /**
     * Executes this method using the specified <code>HttpConnection</code> and
     * <code>HttpState</code>. 
     *
     * @param state the {@link HttpState state} information to associate with this method
     * @param connection the {@link HttpConnection connection} used to execute
     *        this HTTP method
     *
     * @throws IOException If an I/O (transport) error occurs. Some transport exceptions
     *                     can be recovered from.
     * @throws HttpException  If a protocol exception occurs. Usually protocol exceptions 
     *                    cannot be recovered from.
     *
     * @return the integer status code if one was obtained, or <tt>-1</tt>
     */
    int execute(HttpState state, HttpConnection connection) 
        throws HttpException, IOException;

    /**
     * Aborts the execution of the HTTP method.
     * 
     * @see #execute(HttpState, HttpConnection)
     * 
     * @since 3.0
     */
    void abort();

    /**
     * Recycles the HTTP method so that it can be used again.
     * Note that all of the instance variables will be reset
     * once this method has been called. This method will also
     * release the connection being used by this HTTP method.
     * 
     * @see #releaseConnection()
     * 
     * @deprecated no longer supported and will be removed in the future
     *             version of HttpClient
     */
    void recycle();

    /**
     * Releases the connection being used by this HTTP method. In particular the
     * connection is used to read the response (if there is one) and will be held
     * until the response has been read. If the connection can be reused by other 
     * HTTP methods it is NOT closed at this point.
     * <p>
     * After this method is called, {@link #getResponseBodyAsStream} will return
     * <code>null</code>, and {@link #getResponseBody} and {@link #getResponseBodyAsString}
     * <em>may</em> return <code>null</code>. 
     */
    void releaseConnection();

    /**
     * Add a footer to this method's response.
     * <p>
     * <b>Note:</b> This method is for
     * internal use only and should not be called by external clients.
     * 
     * @param footer the footer to add
     * 
     * @since 2.0
     */
    void addResponseFooter(Header footer);

    /** 
     * Returns the Status-Line from the most recent response for this method,
     * or <code>null</code> if the method has not been executed.
     * 
     * @return the status line, or <code>null</code> if the method has not been executed
     * 
     * @since 2.0
     */
    StatusLine getStatusLine();

    /**
     * Returns <tt>true</tt> if the HTTP method should automatically handle HTTP 
     * authentication challenges (status code 401, etc.), <tt>false</tt> otherwise
     *
     * @return <tt>true</tt> if authentication challenges will be processed 
     * automatically, <tt>false</tt> otherwise.
     * 
     * @since 2.0
     * 
     * @see #setDoAuthentication(boolean)
     */
    boolean getDoAuthentication();

    /**
     * Sets whether or not the HTTP method should automatically handle HTTP 
     * authentication challenges (status code 401, etc.)
     *
     * @param doAuthentication <tt>true</tt> to process authentication challenges
     * automatically, <tt>false</tt> otherwise.
     * 
     * @since 2.0
     * 
     * @see #getDoAuthentication()
     */
    void setDoAuthentication(boolean doAuthentication);


    /**
     * Returns {@link HttpMethodParams HTTP protocol parameters} associated with this method.
     * 
     * @since 3.0
     * 
     * @see HttpMethodParams
     */
    public HttpMethodParams getParams();

    /**
     * Assigns {@link HttpMethodParams HTTP protocol parameters} for this method.
     * 
     * @since 3.0
     * 
     * @see HttpMethodParams
     */
    public void setParams(final HttpMethodParams params);

    /**
     * Returns the target host {@link AuthState authentication state}
     * 
     * @return host authentication state
     * 
     * @since 3.0
     */
    public AuthState getHostAuthState();

    /**
     * Returns the proxy {@link AuthState authentication state}
     * 
     * @return host authentication state
     * 
     * @since 3.0
     */
    public AuthState getProxyAuthState();

    /**
     * Returns <tt>true</tt> if the HTTP has been transmitted to the target
     * server in its entirety, <tt>false</tt> otherwise. This flag can be useful 
     * for recovery logic. If the request has not been transmitted in its entirety,
     * it is safe to retry the failed method.
     * 
     * @return <tt>true</tt> if the request has been sent, <tt>false</tt> otherwise
     */
    boolean isRequestSent();

}