//
// ========================================================================
// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under
// the terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0
//
// This Source Code may also be made available under the following
// Secondary Licenses when the conditions for such availability set
// forth in the Eclipse Public License, v. 2.0 are satisfied:
// the Apache License v2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.http;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.StringUtil;

A HTTP Testing helper class.

Example usage:
       try(Socket socket = new Socket("www.google.com",80))
       {
         HttpTester.Request request = HttpTester.newRequest();
         request.setMethod("POST");
         request.setURI("/search");
         request.setVersion(HttpVersion.HTTP_1_0);
         request.put(HttpHeader.HOST,"www.google.com");
         request.put("Content-Type","application/x-www-form-urlencoded");
         request.setContent("q=jetty%20server");
         ByteBuffer output = request.generate();
         socket.getOutputStream().write(output.array(),output.arrayOffset()+output.position(),output.remaining());
         HttpTester.Input input = HttpTester.from(socket.getInputStream());
         HttpTester.Response response = HttpTester.parseResponse(input);
         System.err.printf("%s %s %s%n",response.getVersion(),response.getStatus(),response.getReason());
         for (HttpField field:response)
             System.err.printf("%s: %s%n",field.getName(),field.getValue());
         System.err.printf("%n%s%n",response.getContent());
      }

/**
 * A HTTP Testing helper class.
 * <p>
 * Example usage:
 * <pre>
 *        try(Socket socket = new Socket("www.google.com",80))
 *        {
 *          HttpTester.Request request = HttpTester.newRequest();
 *          request.setMethod("POST");
 *          request.setURI("/search");
 *          request.setVersion(HttpVersion.HTTP_1_0);
 *          request.put(HttpHeader.HOST,"www.google.com");
 *          request.put("Content-Type","application/x-www-form-urlencoded");
 *          request.setContent("q=jetty%20server");
 *          ByteBuffer output = request.generate();
 *
 *          socket.getOutputStream().write(output.array(),output.arrayOffset()+output.position(),output.remaining());
 *          HttpTester.Input input = HttpTester.from(socket.getInputStream());
 *          HttpTester.Response response = HttpTester.parseResponse(input);
 *          System.err.printf("%s %s %s%n",response.getVersion(),response.getStatus(),response.getReason());
 *          for (HttpField field:response)
 *              System.err.printf("%s: %s%n",field.getName(),field.getValue());
 *          System.err.printf("%n%s%n",response.getContent());
 *       }
 * </pre>
 */
public class HttpTester
{
    public abstract static class Input
    {
        protected final ByteBuffer _buffer;
        protected boolean _eof = false;
        protected HttpParser _parser;

        public Input()
        {
            this(BufferUtil.allocate(8192));
        }

        Input(ByteBuffer buffer)
        {
            _buffer = buffer;
        }

        public ByteBuffer getBuffer()
        {
            return _buffer;
        }

        public void setHttpParser(HttpParser parser)
        {
            _parser = parser;
        }

        public HttpParser getHttpParser()
        {
            return _parser;
        }

        public HttpParser takeHttpParser()
        {
            HttpParser p = _parser;
            _parser = null;
            return p;
        }

        public boolean isEOF()
        {
            return BufferUtil.isEmpty(_buffer) && _eof;
        }

        public abstract int fillBuffer() throws IOException;
    }

    public static Input from(final ByteBuffer data)
    {
        return new Input(data.slice())
        {
            @Override
            public int fillBuffer() throws IOException
            {
                _eof = true;
                return -1;
            }
        };
    }

    public static Input from(final InputStream in)
    {
        return new Input()
        {
            @Override
            public int fillBuffer() throws IOException
            {
                BufferUtil.compact(_buffer);
                int len = in.read(_buffer.array(), _buffer.arrayOffset() + _buffer.limit(), BufferUtil.space(_buffer));
                if (len < 0)
                    _eof = true;
                else
                    _buffer.limit(_buffer.limit() + len);
                return len;
            }
        };
    }

    public static Input from(final ReadableByteChannel in)
    {
        return new Input()
        {
            @Override
            public int fillBuffer() throws IOException
            {
                BufferUtil.compact(_buffer);
                int pos = BufferUtil.flipToFill(_buffer);
                int len = in.read(_buffer);
                if (len < 0)
                    _eof = true;
                BufferUtil.flipToFlush(_buffer, pos);
                return len;
            }
        };
    }

    private HttpTester()
    {
    }

    public static Request newRequest()
    {
        Request r = new Request();
        r.setMethod(HttpMethod.GET.asString());
        r.setURI("/");
        r.setVersion(HttpVersion.HTTP_1_1);
        return r;
    }

    public static Request parseRequest(String request)
    {
        Request r = new Request();
        HttpParser parser = new HttpParser(r);
        parser.parseNext(BufferUtil.toBuffer(request));
        return r;
    }

    public static Request parseRequest(ByteBuffer request)
    {
        Request r = new Request();
        HttpParser parser = new HttpParser(r);
        parser.parseNext(request);
        return r;
    }

    public static Response parseResponse(String response)
    {
        Response r = new Response();
        HttpParser parser = new HttpParser(r);
        parser.parseNext(BufferUtil.toBuffer(response));
        return r;
    }

    public static Response parseResponse(ByteBuffer response)
    {
        Response r = new Response();
        HttpParser parser = new HttpParser(r);
        parser.parseNext(response);
        return r;
    }

    public static Response parseResponse(InputStream responseStream) throws IOException
    {
        Response r = new Response();
        HttpParser parser = new HttpParser(r);

        // Read and parse a character at a time so we never can read more than we should.
        byte[] array = new byte[1];
        ByteBuffer buffer = ByteBuffer.wrap(array);
        buffer.limit(1);

        while (true)
        {
            buffer.position(1);
            int l = responseStream.read(array);
            if (l < 0)
                parser.atEOF();
            else
                buffer.position(0);

            if (parser.parseNext(buffer))
                return r;
            else if (l < 0)
                return null;
        }
    }

    public static Response parseResponse(Input in) throws IOException
    {
        Response r;
        HttpParser parser = in.takeHttpParser();
        if (parser == null)
        {
            r = new Response();
            parser = new HttpParser(r);
        }
        else
            r = (Response)parser.getHandler();

        parseResponse(in, parser, r);

        if (r.isComplete())
            return r;

        in.setHttpParser(parser);
        return null;
    }

    public static void parseResponse(Input in, Response response) throws IOException
    {
        HttpParser parser = in.takeHttpParser();
        if (parser == null)
        {
            parser = new HttpParser(response);
        }
        parseResponse(in, parser, response);

        if (!response.isComplete())
            in.setHttpParser(parser);
    }

    private static void parseResponse(Input in, HttpParser parser, Response r) throws IOException
    {
        ByteBuffer buffer = in.getBuffer();

        while (true)
        {
            if (BufferUtil.hasContent(buffer))
                if (parser.parseNext(buffer))
                    break;
            int len = in.fillBuffer();
            if (len == 0)
                break;
            if (len <= 0)
            {
                parser.atEOF();
                parser.parseNext(buffer);
                break;
            }
        }
    }

    public abstract static class Message extends HttpFields.Mutable implements HttpParser.HttpHandler
    {
        boolean _earlyEOF;
        boolean _complete = false;
        ByteArrayOutputStream _content;
        HttpVersion _version = HttpVersion.HTTP_1_0;

        public boolean isComplete()
        {
            return _complete;
        }

        public HttpVersion getVersion()
        {
            return _version;
        }

        public void setVersion(String version)
        {
            setVersion(HttpVersion.CACHE.get(version));
        }

        public void setVersion(HttpVersion version)
        {
            _version = version;
        }

        public void setContent(byte[] bytes)
        {
            try
            {
                _content = new ByteArrayOutputStream();
                _content.write(bytes);
            }
            catch (IOException e)
            {
                throw new RuntimeException(e);
            }
        }

        public void setContent(String content)
        {
            try
            {
                _content = new ByteArrayOutputStream();
                _content.write(StringUtil.getBytes(content));
            }
            catch (IOException e)
            {
                throw new RuntimeException(e);
            }
        }

        public void setContent(ByteBuffer content)
        {
            try
            {
                _content = new ByteArrayOutputStream();
                _content.write(BufferUtil.toArray(content));
            }
            catch (IOException e)
            {
                throw new RuntimeException(e);
            }
        }

        public byte[] getContentBytes()
        {
            if (_content == null)
                return null;
            return _content.toByteArray();
        }

        public String getContent()
        {
            if (_content == null)
                return null;
            byte[] bytes = _content.toByteArray();

            String contentType = get(HttpHeader.CONTENT_TYPE);
            String encoding = MimeTypes.getCharsetFromContentType(contentType);
            Charset charset = encoding == null ? StandardCharsets.UTF_8 : Charset.forName(encoding);

            return new String(bytes, charset);
        }

        @Override
        public void parsedHeader(HttpField field)
        {
            add(field.getName(), field.getValue());
        }

        @Override
        public boolean contentComplete()
        {
            return false;
        }

        @Override
        public boolean messageComplete()
        {
            _complete = true;
            return true;
        }

        @Override
        public boolean headerComplete()
        {
            _content = new ByteArrayOutputStream();
            return false;
        }

        @Override
        public void earlyEOF()
        {
            _earlyEOF = true;
        }

        public boolean isEarlyEOF()
        {
            return _earlyEOF;
        }

        @Override
        public boolean content(ByteBuffer ref)
        {
            try
            {
                _content.write(BufferUtil.toArray(ref));
            }
            catch (IOException e)
            {
                throw new RuntimeException(e);
            }
            return false;
        }

        @Override
        public void badMessage(BadMessageException failure)
        {
            throw failure;
        }

        public ByteBuffer generate()
        {
            try
            {
                HttpGenerator generator = new HttpGenerator();
                MetaData info = getInfo();
                // System.err.println(info.getClass());
                // System.err.println(info);

                ByteArrayOutputStream out = new ByteArrayOutputStream();
                ByteBuffer header = null;
                ByteBuffer chunk = null;
                ByteBuffer content = _content == null ? null : ByteBuffer.wrap(_content.toByteArray());

                loop:
                while (!generator.isEnd())
                {
                    HttpGenerator.Result result = info instanceof MetaData.Request
                        ? generator.generateRequest((MetaData.Request)info, header, chunk, content, true)
                        : generator.generateResponse((MetaData.Response)info, false, header, chunk, content, true);
                    switch (result)
                    {
                        case NEED_HEADER:
                            header = BufferUtil.allocate(8192);
                            continue;

                        case HEADER_OVERFLOW:
                            if (header.capacity() >= 32 * 1024)
                                throw new BadMessageException(500, "Header too large");
                            header = BufferUtil.allocate(32 * 1024);
                            continue;

                        case NEED_CHUNK:
                            chunk = BufferUtil.allocate(HttpGenerator.CHUNK_SIZE);
                            continue;

                        case NEED_CHUNK_TRAILER:
                            chunk = BufferUtil.allocate(8192);
                            continue;

                        case NEED_INFO:
                            throw new IllegalStateException();

                        case FLUSH:
                            if (BufferUtil.hasContent(header))
                            {
                                out.write(BufferUtil.toArray(header));
                                BufferUtil.clear(header);
                            }
                            if (BufferUtil.hasContent(chunk))
                            {
                                out.write(BufferUtil.toArray(chunk));
                                BufferUtil.clear(chunk);
                            }
                            if (BufferUtil.hasContent(content))
                            {
                                out.write(BufferUtil.toArray(content));
                                BufferUtil.clear(content);
                            }
                            break;

                        case SHUTDOWN_OUT:
                            break loop;

                        default:
                            break; // TODO verify if this should be ISE
                    }
                }

                return ByteBuffer.wrap(out.toByteArray());
            }
            catch (IOException e)
            {
                throw new RuntimeException(e);
            }
        }

        public abstract MetaData getInfo();
    }

    public static class Request extends Message implements HttpParser.RequestHandler
    {
        private String _method;
        private String _uri;

        @Override
        public void startRequest(String method, String uri, HttpVersion version)
        {
            _method = method;
            _uri = uri;
            _version = version;
        }

        public String getMethod()
        {
            return _method;
        }

        public String getUri()
        {
            return _uri;
        }

        public void setMethod(String method)
        {
            _method = method;
        }

        public void setURI(String uri)
        {
            _uri = uri;
        }

        @Override
        public MetaData.Request getInfo()
        {
            return new MetaData.Request(_method, HttpURI.from(_uri), _version, this, _content == null ? 0 : _content.size());
        }

        @Override
        public String toString()
        {
            return String.format("%s %s %s\n%s\n", _method, _uri, _version, super.toString());
        }

        public void setHeader(String name, String value)
        {
            put(name, value);
        }
    }

    public static class Response extends Message implements HttpParser.ResponseHandler
    {
        private int _status;
        private String _reason;

        @Override
        public void startResponse(HttpVersion version, int status, String reason)
        {
            _version = version;
            _status = status;
            _reason = reason;
        }

        public int getStatus()
        {
            return _status;
        }

        public String getReason()
        {
            return _reason;
        }

        @Override
        public MetaData.Response getInfo()
        {
            return new MetaData.Response(_version, _status, _reason, this, _content == null ? -1 : _content.size());
        }

        @Override
        public String toString()
        {
            return String.format("%s %s %s\n%s\n", _version, _status, _reason, super.toString());
        }
    }
}