package org.jsoup.helper;

import org.jsoup.*;
import org.jsoup.nodes.Document;
import org.jsoup.parser.Parser;
import org.jsoup.parser.TokenQueue;

import javax.net.ssl.*;
import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.X509Certificate;
import java.util.*;
import java.util.regex.Pattern;
import java.util.zip.GZIPInputStream;

import static org.jsoup.Connection.Method.HEAD;

/**
 * Implementation of {@link Connection}.
 * @see org.jsoup.Jsoup#connect(String)
 */
public class HttpConnection implements Connection {
    public static final String  CONTENT_ENCODING = "Content-Encoding";
    private static final String CONTENT_TYPE = "Content-Type";
    private static final String MULTIPART_FORM_DATA = "multipart/form-data";
    private static final String FORM_URL_ENCODED = "application/x-www-form-urlencoded";
    private static final int HTTP_TEMP_REDIR = 307; // http/1.1 temporary redirect, not in Java's set.

    public static Connection connect(String url) {
        Connection con = new HttpConnection();
        con.url(url);
        return con;
    }

    public static Connection connect(URL url) {
        Connection con = new HttpConnection();
        con.url(url);
        return con;
    }

	private static String encodeUrl(String url) {
		if(url == null)
			return null;
    	return url.replaceAll(" ", "%20");
	}

    private static String encodeMimeName(String val) {
        if (val == null)
            return null;
        return val.replaceAll("\"", "%22");
    }

    private Connection.Request req;
    private Connection.Response res;

	private HttpConnection() {
        req = new Request();
        res = new Response();
    }

    public Connection url(URL url) {
        req.url(url);
        return this;
    }

    public Connection url(String url) {
        Validate.notEmpty(url, "Must supply a valid URL");
        try {
            req.url(new URL(encodeUrl(url)));
        } catch (MalformedURLException e) {
            throw new IllegalArgumentException("Malformed URL: " + url, e);
        }
        return this;
    }

    public Connection proxy(Proxy proxy) {
        req.proxy(proxy);
        return this;
    }

    public Connection proxy(String host, int port) {
        req.proxy(host, port);
        return this;
    }

    public Connection userAgent(String userAgent) {
        Validate.notNull(userAgent, "User agent must not be null");
        req.header("User-Agent", userAgent);
        return this;
    }

    public Connection timeout(int millis) {
        req.timeout(millis);
        return this;
    }

    public Connection maxBodySize(int bytes) {
        req.maxBodySize(bytes);
        return this;
    }

    public Connection followRedirects(boolean followRedirects) {
        req.followRedirects(followRedirects);
        return this;
    }

    public Connection referrer(String referrer) {
        Validate.notNull(referrer, "Referrer must not be null");
        req.header("Referer", referrer);
        return this;
    }

    public Connection method(Method method) {
        req.method(method);
        return this;
    }

    public Connection ignoreHttpErrors(boolean ignoreHttpErrors) {
		req.ignoreHttpErrors(ignoreHttpErrors);
		return this;
	}

    public Connection ignoreContentType(boolean ignoreContentType) {
        req.ignoreContentType(ignoreContentType);
        return this;
    }

    public Connection validateTLSCertificates(boolean value) {
        req.validateTLSCertificates(value);
        return this;
    }

    public Connection data(String key, String value) {
        req.data(KeyVal.create(key, value));
        return this;
    }

    public Connection data(String key, String filename, InputStream inputStream) {
        req.data(KeyVal.create(key, filename, inputStream));
        return this;
    }

    public Connection data(Map<String, String> data) {
        Validate.notNull(data, "Data map must not be null");
        for (Map.Entry<String, String> entry : data.entrySet()) {
            req.data(KeyVal.create(entry.getKey(), entry.getValue()));
        }
        return this;
    }

    public Connection data(String... keyvals) {
        Validate.notNull(keyvals, "Data key value pairs must not be null");
        Validate.isTrue(keyvals.length %2 == 0, "Must supply an even number of key value pairs");
        for (int i = 0; i < keyvals.length; i += 2) {
            String key = keyvals[i];
            String value = keyvals[i+1];
            Validate.notEmpty(key, "Data key must not be empty");
            Validate.notNull(value, "Data value must not be null");
            req.data(KeyVal.create(key, value));
        }
        return this;
    }

    public Connection data(Collection<Connection.KeyVal> data) {
        Validate.notNull(data, "Data collection must not be null");
        for (Connection.KeyVal entry: data) {
            req.data(entry);
        }
        return this;
    }

    public Connection.KeyVal data(String key) {
        Validate.notEmpty(key, "Data key must not be empty");
        for (Connection.KeyVal keyVal : request().data()) {
            if (keyVal.key().equals(key))
                return keyVal;
        }
        return null;
    }

    public Connection requestBody(String body) {
        req.requestBody(body);
        return this;
    }

    public Connection header(String name, String value) {
        req.header(name, value);
        return this;
    }

    public Connection cookie(String name, String value) {
        req.cookie(name, value);
        return this;
    }

    public Connection cookies(Map<String, String> cookies) {
        Validate.notNull(cookies, "Cookie map must not be null");
        for (Map.Entry<String, String> entry : cookies.entrySet()) {
            req.cookie(entry.getKey(), entry.getValue());
        }
        return this;
    }

    public Connection parser(Parser parser) {
        req.parser(parser);
        return this;
    }

    public Document get() throws IOException {
        req.method(Method.GET);
        execute();
        return res.parse();
    }

    public Document post() throws IOException {
        req.method(Method.POST);
        execute();
        return res.parse();
    }

    public Connection.Response execute() throws IOException {
        res = Response.execute(req);
        return res;
    }

    public Connection.Request request() {
        return req;
    }

    public Connection request(Connection.Request request) {
        req = request;
        return this;
    }

    public Connection.Response response() {
        return res;
    }

    public Connection response(Connection.Response response) {
        res = response;
        return this;
    }

    public Connection postDataCharset(String charset) {
        req.postDataCharset(charset);
        return this;
    }

    @SuppressWarnings({"unchecked"})
    private static abstract class Base<T extends Connection.Base> implements Connection.Base<T> {
        URL url;
        Method method;
        Map<String, String> headers;
        Map<String, String> cookies;

        private Base() {
            headers = new LinkedHashMap<String, String>();
            cookies = new LinkedHashMap<String, String>();
        }

        public URL url() {
            return url;
        }

        public T url(URL url) {
            Validate.notNull(url, "URL must not be null");
            this.url = url;
            return (T) this;
        }

        public Method method() {
            return method;
        }

        public T method(Method method) {
            Validate.notNull(method, "Method must not be null");
            this.method = method;
            return (T) this;
        }

        public String header(String name) {
            Validate.notNull(name, "Header name must not be null");
            return getHeaderCaseInsensitive(name);
        }

        public T header(String name, String value) {
            Validate.notEmpty(name, "Header name must not be empty");
            Validate.notNull(value, "Header value must not be null");
            removeHeader(name); // ensures we don't get an "accept-encoding" and a "Accept-Encoding"
            headers.put(name, value);
            return (T) this;
        }

        public boolean hasHeader(String name) {
            Validate.notEmpty(name, "Header name must not be empty");
            return getHeaderCaseInsensitive(name) != null;
        }

        /**
         * Test if the request has a header with this value (case insensitive).
         */
        public boolean hasHeaderWithValue(String name, String value) {
            return hasHeader(name) && header(name).equalsIgnoreCase(value);
        }

        public T removeHeader(String name) {
            Validate.notEmpty(name, "Header name must not be empty");
            Map.Entry<String, String> entry = scanHeaders(name); // remove is case insensitive too
            if (entry != null)
                headers.remove(entry.getKey()); // ensures correct case
            return (T) this;
        }

        public Map<String, String> headers() {
            return headers;
        }

        private String getHeaderCaseInsensitive(String name) {
            Validate.notNull(name, "Header name must not be null");
            // quick evals for common case of title case, lower case, then scan for mixed
            String value = headers.get(name);
            if (value == null)
                value = headers.get(name.toLowerCase());
            if (value == null) {
                Map.Entry<String, String> entry = scanHeaders(name);
                if (entry != null)
                    value = entry.getValue();
            }
            return value;
        }

        private Map.Entry<String, String> scanHeaders(String name) {
            String lc = name.toLowerCase();
            for (Map.Entry<String, String> entry : headers.entrySet()) {
                if (entry.getKey().toLowerCase().equals(lc))
                    return entry;
            }
            return null;
        }

        public String cookie(String name) {
            Validate.notEmpty(name, "Cookie name must not be empty");
            return cookies.get(name);
        }

        public T cookie(String name, String value) {
            Validate.notEmpty(name, "Cookie name must not be empty");
            Validate.notNull(value, "Cookie value must not be null");
            cookies.put(name, value);
            return (T) this;
        }

        public boolean hasCookie(String name) {
            Validate.notEmpty(name, "Cookie name must not be empty");
            return cookies.containsKey(name);
        }

        public T removeCookie(String name) {
            Validate.notEmpty(name, "Cookie name must not be empty");
            cookies.remove(name);
            return (T) this;
        }

        public Map<String, String> cookies() {
            return cookies;
        }
    }

    public static class Request extends HttpConnection.Base<Connection.Request> implements Connection.Request {
        private Proxy proxy; // nullable
        private int timeoutMilliseconds;
        private int maxBodySizeBytes;
        private boolean followRedirects;
        private Collection<Connection.KeyVal> data;
        private String body = null;
        private boolean ignoreHttpErrors = false;
        private boolean ignoreContentType = false;
        private Parser parser;
        private boolean parserDefined = false; // called parser(...) vs initialized in ctor
        private boolean validateTSLCertificates = true;
        private String postDataCharset = DataUtil.defaultCharset;

        private Request() {
            timeoutMilliseconds = 3000;
            maxBodySizeBytes = 1024 * 1024; // 1MB
            followRedirects = true;
            data = new ArrayList<Connection.KeyVal>();
            method = Method.GET;
            headers.put("Accept-Encoding", "gzip");
            parser = Parser.htmlParser();
        }

        public Proxy proxy() {
            return proxy;
        }

        public Request proxy(Proxy proxy) {
            this.proxy = proxy;
            return this;
        }

        public Request proxy(String host, int port) {
            this.proxy = new Proxy(Proxy.Type.HTTP, InetSocketAddress.createUnresolved(host, port));
            return this;
        }

        public int timeout() {
            return timeoutMilliseconds;
        }

        public Request timeout(int millis) {
            Validate.isTrue(millis >= 0, "Timeout milliseconds must be 0 (infinite) or greater");
            timeoutMilliseconds = millis;
            return this;
        }

        public int maxBodySize() {
            return maxBodySizeBytes;
        }

        public Connection.Request maxBodySize(int bytes) {
            Validate.isTrue(bytes >= 0, "maxSize must be 0 (unlimited) or larger");
            maxBodySizeBytes = bytes;
            return this;
        }

        public boolean followRedirects() {
            return followRedirects;
        }

        public Connection.Request followRedirects(boolean followRedirects) {
            this.followRedirects = followRedirects;
            return this;
        }

        public boolean ignoreHttpErrors() {
            return ignoreHttpErrors;
        }

        public boolean validateTLSCertificates() {
            return validateTSLCertificates;
        }

        public void validateTLSCertificates(boolean value) {
            validateTSLCertificates = value;
        }

        public Connection.Request ignoreHttpErrors(boolean ignoreHttpErrors) {
            this.ignoreHttpErrors = ignoreHttpErrors;
            return this;
        }

        public boolean ignoreContentType() {
            return ignoreContentType;
        }

        public Connection.Request ignoreContentType(boolean ignoreContentType) {
            this.ignoreContentType = ignoreContentType;
            return this;
        }

        public Request data(Connection.KeyVal keyval) {
            Validate.notNull(keyval, "Key val must not be null");
            data.add(keyval);
            return this;
        }

        public Collection<Connection.KeyVal> data() {
            return data;
        }

        public Connection.Request requestBody(String body) {
            this.body = body;
            return this;
        }

        public String requestBody() {
            return body;
        }

        public Request parser(Parser parser) {
            this.parser = parser;
            parserDefined = true;
            return this;
        }

        public Parser parser() {
            return parser;
        }

        public Connection.Request postDataCharset(String charset) {
            Validate.notNull(charset, "Charset must not be null");
            if (!Charset.isSupported(charset)) throw new IllegalCharsetNameException(charset);
            this.postDataCharset = charset;
            return this;
        }

        public String postDataCharset() {
            return postDataCharset;
        }
    }

    public static class Response extends HttpConnection.Base<Connection.Response> implements Connection.Response {
        private static final int MAX_REDIRECTS = 20;
        private static SSLSocketFactory sslSocketFactory;
        private static final String LOCATION = "Location";
        private int statusCode;
        private String statusMessage;
        private ByteBuffer byteData;
        private String charset;
        private String contentType;
        private boolean executed = false;
        private int numRedirects = 0;
        private Connection.Request req;

        /*
         * Matches XML content types (like text/xml, application/xhtml+xml;charset=UTF8, etc)
         */
        private static final Pattern xmlContentTypeRxp = Pattern.compile("(application|text)/\\w*\\+?xml.*");

        Response() {
            super();
        }

        private Response(Response previousResponse) throws IOException {
            super();
            if (previousResponse != null) {
                numRedirects = previousResponse.numRedirects + 1;
                if (numRedirects >= MAX_REDIRECTS)
                    throw new IOException(String.format("Too many redirects occurred trying to load URL %s", previousResponse.url()));
            }
        }

        static Response execute(Connection.Request req) throws IOException {
            return execute(req, null);
        }

        static Response execute(Connection.Request req, Response previousResponse) throws IOException {
            Validate.notNull(req, "Request must not be null");
            String protocol = req.url().getProtocol();
            if (!protocol.equals("http") && !protocol.equals("https"))
                throw new MalformedURLException("Only http & https protocols supported");
            final boolean methodHasBody = req.method().hasBody();
            final boolean hasRequestBody = req.requestBody() != null;
            if (!methodHasBody)
                Validate.isFalse(hasRequestBody, "Cannot set a request body for HTTP method " + req.method());

            // set up the request for execution
            String mimeBoundary = null;
            if (req.data().size() > 0 && (!methodHasBody || hasRequestBody))
                serialiseRequestUrl(req);
            else if (methodHasBody)
                mimeBoundary = setOutputContentType(req);

            HttpURLConnection conn = createConnection(req);
            Response res;
            try {
                conn.connect();
                if (conn.getDoOutput())
                    writePost(req, conn.getOutputStream(), mimeBoundary);

                int status = conn.getResponseCode();
                res = new Response(previousResponse);
                res.setupFromConnection(conn, previousResponse);
                res.req = req;

                // redirect if there's a location header (from 3xx, or 201 etc)
                if (res.hasHeader(LOCATION) && req.followRedirects()) {
                    if (status != HTTP_TEMP_REDIR) {
                        req.method(Method.GET); // always redirect with a get. any data param from original req are dropped.
                        req.data().clear();
                    }

                    String location = res.header(LOCATION);
                    if (location != null && location.startsWith("http:/") && location.charAt(6) != '/') // fix broken Location: http:/temp/AAG_New/en/index.php
                        location = location.substring(6);
                    req.url(StringUtil.resolve(req.url(), encodeUrl(location)));

                    for (Map.Entry<String, String> cookie : res.cookies.entrySet()) { // add response cookies to request (for e.g. login posts)
                        req.cookie(cookie.getKey(), cookie.getValue());
                    }
                    return execute(req, res);
                }
                if ((status < 200 || status >= 400) && !req.ignoreHttpErrors())
                        throw new HttpStatusException("HTTP error fetching URL", status, req.url().toString());

                // check that we can handle the returned content type; if not, abort before fetching it
                String contentType = res.contentType();
                if (contentType != null
                        && !req.ignoreContentType()
                        && !contentType.startsWith("text/")
                        && !xmlContentTypeRxp.matcher(contentType).matches()
                        )
                    throw new UnsupportedMimeTypeException("Unhandled content type. Must be text/*, application/xml, or application/xhtml+xml",
                            contentType, req.url().toString());

                // switch to the XML parser if content type is xml and not parser not explicitly set
                if (contentType != null && xmlContentTypeRxp.matcher(contentType).matches()) {
                    // only flip it if a HttpConnection.Request (i.e. don't presume other impls want it):
                    if (req instanceof HttpConnection.Request && !((Request) req).parserDefined) {
                        req.parser(Parser.xmlParser());
                    }
                }

                res.charset = DataUtil.getCharsetFromContentType(res.contentType); // may be null, readInputStream deals with it
                if (conn.getContentLength() != 0 && req.method() != HEAD) { // -1 means unknown, chunked. sun throws an IO exception on 500 response with no content when trying to read body
                    InputStream bodyStream = null;
                    try {
                        bodyStream = conn.getErrorStream() != null ? conn.getErrorStream() : conn.getInputStream();
                        if (res.hasHeaderWithValue(CONTENT_ENCODING, "gzip"))
                            bodyStream = new GZIPInputStream(bodyStream);

                        res.byteData = DataUtil.readToByteBuffer(bodyStream, req.maxBodySize());
                    } finally {
                        if (bodyStream != null) bodyStream.close();
                    }
                } else {
                    res.byteData = DataUtil.emptyByteBuffer();
                }
            } finally {
                // per Java's documentation, this is not necessary, and precludes keepalives. However in practise,
                // connection errors will not be released quickly enough and can cause a too many open files error.
                conn.disconnect();
            }

            res.executed = true;
            return res;
        }

        public int statusCode() {
            return statusCode;
        }

        public String statusMessage() {
            return statusMessage;
        }

        public String charset() {
            return charset;
        }

        public String contentType() {
            return contentType;
        }

        public Document parse() throws IOException {
            Validate.isTrue(executed, "Request must be executed (with .execute(), .get(), or .post() before parsing response");
            Document doc = DataUtil.parseByteData(byteData, charset, url.toExternalForm(), req.parser());
            byteData.rewind();
            charset = doc.outputSettings().charset().name(); // update charset from meta-equiv, possibly
            return doc;
        }

        public String body() {
            Validate.isTrue(executed, "Request must be executed (with .execute(), .get(), or .post() before getting response body");
            // charset gets set from header on execute, and from meta-equiv on parse. parse may not have happened yet
            String body;
            if (charset == null)
                body = Charset.forName(DataUtil.defaultCharset).decode(byteData).toString();
            else
                body = Charset.forName(charset).decode(byteData).toString();
            byteData.rewind();
            return body;
        }

        public byte[] bodyAsBytes() {
            Validate.isTrue(executed, "Request must be executed (with .execute(), .get(), or .post() before getting response body");
            return byteData.array();
        }

        // set up connection defaults, and details from request
        private static HttpURLConnection createConnection(Connection.Request req) throws IOException {
            final HttpURLConnection conn = (HttpURLConnection) (
                req.proxy() == null ?
                req.url().openConnection() :
                req.url().openConnection(req.proxy())
            );

            conn.setRequestMethod(req.method().name());
            conn.setInstanceFollowRedirects(false); // don't rely on native redirection support
            conn.setConnectTimeout(req.timeout());
            conn.setReadTimeout(req.timeout());

            if (conn instanceof HttpsURLConnection) {
                if (!req.validateTLSCertificates()) {
                    initUnSecureTSL();
                    ((HttpsURLConnection)conn).setSSLSocketFactory(sslSocketFactory);
                    ((HttpsURLConnection)conn).setHostnameVerifier(getInsecureVerifier());
                }
            }

            if (req.method().hasBody())
                conn.setDoOutput(true);
            if (req.cookies().size() > 0)
                conn.addRequestProperty("Cookie", getRequestCookieString(req));
            for (Map.Entry<String, String> header : req.headers().entrySet()) {
                conn.addRequestProperty(header.getKey(), header.getValue());
            }
            return conn;
        }

        /**
         * Instantiate Hostname Verifier that does nothing.
         * This is used for connections with disabled SSL certificates validation.
         *
         *
         * @return Hostname Verifier that does nothing and accepts all hostnames
         */
        private static HostnameVerifier getInsecureVerifier() {
            return new HostnameVerifier() {
                public boolean verify(String urlHostName, SSLSession session) {
                    return true;
                }
            };
        }

        /**
         * Initialise Trust manager that does not validate certificate chains and
         * add it to current SSLContext.
         * <p/>
         * please not that this method will only perform action if sslSocketFactory is not yet
         * instantiated.
         *
         * @throws IOException
         */
        private static synchronized void initUnSecureTSL() throws IOException {
            if (sslSocketFactory == null) {
                // Create a trust manager that does not validate certificate chains
                final TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {

                    public void checkClientTrusted(final X509Certificate[] chain, final String authType) {
                    }

                    public void checkServerTrusted(final X509Certificate[] chain, final String authType) {
                    }

                    public X509Certificate[] getAcceptedIssuers() {
                        return null;
                    }
                }};

                // Install the all-trusting trust manager
                final SSLContext sslContext;
                try {
                    sslContext = SSLContext.getInstance("SSL");
                    sslContext.init(null, trustAllCerts, new java.security.SecureRandom());
                    // Create an ssl socket factory with our all-trusting manager
                    sslSocketFactory = sslContext.getSocketFactory();
                } catch (NoSuchAlgorithmException e) {
                    throw new IOException("Can't create unsecure trust manager");
                } catch (KeyManagementException e) {
                    throw new IOException("Can't create unsecure trust manager");
                }
            }

        }

        // set up url, method, header, cookies
        private void setupFromConnection(HttpURLConnection conn, Connection.Response previousResponse) throws IOException {
            method = Method.valueOf(conn.getRequestMethod());
            url = conn.getURL();
            statusCode = conn.getResponseCode();
            statusMessage = conn.getResponseMessage();
            contentType = conn.getContentType();

            Map<String, List<String>> resHeaders = createHeaderMap(conn);
            processResponseHeaders(resHeaders);

            // if from a redirect, map previous response cookies into this response
            if (previousResponse != null) {
                for (Map.Entry<String, String> prevCookie : previousResponse.cookies().entrySet()) {
                    if (!hasCookie(prevCookie.getKey()))
                        cookie(prevCookie.getKey(), prevCookie.getValue());
                }
            }
        }

        private static LinkedHashMap<String, List<String>> createHeaderMap(HttpURLConnection conn) {
            // the default sun impl of conn.getHeaderFields() returns header values out of order
            final LinkedHashMap<String, List<String>> headers = new LinkedHashMap<String, List<String>>();
            int i = 0;
            while (true) {
                final String key = conn.getHeaderFieldKey(i);
                final String val = conn.getHeaderField(i);
                if (key == null && val == null)
                    break;
                i++;
                if (key == null || val == null)
                    continue; // skip http1.1 line

                if (headers.containsKey(key))
                    headers.get(key).add(val);
                else {
                    final ArrayList<String> vals = new ArrayList<String>();
                    vals.add(val);
                    headers.put(key, vals);
                }
            }
            return headers;
        }

        void processResponseHeaders(Map<String, List<String>> resHeaders) {
            for (Map.Entry<String, List<String>> entry : resHeaders.entrySet()) {
                String name = entry.getKey();
                if (name == null)
                    continue; // http/1.1 line

                List<String> values = entry.getValue();
                if (name.equalsIgnoreCase("Set-Cookie")) {
                    for (String value : values) {
                        if (value == null)
                            continue;
                        TokenQueue cd = new TokenQueue(value);
                        String cookieName = cd.chompTo("=").trim();
                        String cookieVal = cd.consumeTo(";").trim();
                        // ignores path, date, domain, validateTLSCertificates et al. req'd?
                        // name not blank, value not null
                        if (cookieName.length() > 0)
                            cookie(cookieName, cookieVal);
                    }
                } else { // combine same header names with comma: http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
                    if (values.size() == 1)
                        header(name, values.get(0));
                    else if (values.size() > 1) {
                        StringBuilder accum = new StringBuilder();
                        for (int i = 0; i < values.size(); i++) {
                            final String val = values.get(i);
                            if (i != 0)
                                accum.append(", ");
                            accum.append(val);
                        }
                        header(name, accum.toString());
                    }
                }
            }
        }

        private static String setOutputContentType(final Connection.Request req) {
            String bound = null;
            if (needsMultipart(req)) {
                bound = DataUtil.mimeBoundary();
                req.header(CONTENT_TYPE, MULTIPART_FORM_DATA + "; boundary=" + bound);
            } else {
                req.header(CONTENT_TYPE, FORM_URL_ENCODED + "; charset=" + req.postDataCharset());
            }
            return bound;
        }

        private static void writePost(final Connection.Request req, final OutputStream outputStream, final String bound) throws IOException {
            final Collection<Connection.KeyVal> data = req.data();
            final BufferedWriter w = new BufferedWriter(new OutputStreamWriter(outputStream, req.postDataCharset()));

            if (bound != null) {
                // boundary will be set if we're in multipart mode
                for (Connection.KeyVal keyVal : data) {
                    w.write("--");
                    w.write(bound);
                    w.write("\r\n");
                    w.write("Content-Disposition: form-data; name=\"");
                    w.write(encodeMimeName(keyVal.key())); // encodes " to %22
                    w.write("\"");
                    if (keyVal.hasInputStream()) {
                        w.write("; filename=\"");
                        w.write(encodeMimeName(keyVal.value()));
                        w.write("\"\r\nContent-Type: application/octet-stream\r\n\r\n");
                        w.flush(); // flush
                        DataUtil.crossStreams(keyVal.inputStream(), outputStream);
                        outputStream.flush();
                    } else {
                        w.write("\r\n\r\n");
                        w.write(keyVal.value());
                    }
                    w.write("\r\n");
                }
                w.write("--");
                w.write(bound);
                w.write("--");
            } else if (req.requestBody() != null) {
                // data will be in query string, we're sending a plaintext body
                w.write(req.requestBody());
            }
            else {
                // regular form data (application/x-www-form-urlencoded)
                boolean first = true;
                for (Connection.KeyVal keyVal : data) {
                    if (!first)
                        w.append('&');
                    else
                        first = false;

                    w.write(URLEncoder.encode(keyVal.key(), req.postDataCharset()));
                    w.write('=');
                    w.write(URLEncoder.encode(keyVal.value(), req.postDataCharset()));
                }
            }
            w.close();
        }

        private static String getRequestCookieString(Connection.Request req) {
            StringBuilder sb = new StringBuilder();
            boolean first = true;
            for (Map.Entry<String, String> cookie : req.cookies().entrySet()) {
                if (!first)
                    sb.append("; ");
                else
                    first = false;
                sb.append(cookie.getKey()).append('=').append(cookie.getValue());
                // todo: spec says only ascii, no escaping / encoding defined. validate on set? or escape somehow here?
            }
            return sb.toString();
        }

        // for get url reqs, serialise the data map into the url
        private static void serialiseRequestUrl(Connection.Request req) throws IOException {
            URL in = req.url();
            StringBuilder url = new StringBuilder();
            boolean first = true;
            // reconstitute the query, ready for appends
            url
                .append(in.getProtocol())
                .append("://")
                .append(in.getAuthority()) // includes host, port
                .append(in.getPath())
                .append("?");
            if (in.getQuery() != null) {
                url.append(in.getQuery());
                first = false;
            }
            for (Connection.KeyVal keyVal : req.data()) {
                Validate.isFalse(keyVal.hasInputStream(), "InputStream data not supported in URL query string.");
                if (!first)
                    url.append('&');
                else
                    first = false;
                url
                    .append(URLEncoder.encode(keyVal.key(), DataUtil.defaultCharset))
                    .append('=')
                    .append(URLEncoder.encode(keyVal.value(), DataUtil.defaultCharset));
            }
            req.url(new URL(url.toString()));
            req.data().clear(); // moved into url as get params
        }
    }

    private static boolean needsMultipart(Connection.Request req) {
        // multipart mode, for files. add the header if we see something with an inputstream, and return a non-null boundary
        boolean needsMulti = false;
        for (Connection.KeyVal keyVal : req.data()) {
            if (keyVal.hasInputStream()) {
                needsMulti = true;
                break;
            }
        }
        return needsMulti;
    }

    public static class KeyVal implements Connection.KeyVal {
        private String key;
        private String value;
        private InputStream stream;

        public static KeyVal create(String key, String value) {
            return new KeyVal().key(key).value(value);
        }

        public static KeyVal create(String key, String filename, InputStream stream) {
            return new KeyVal().key(key).value(filename).inputStream(stream);
        }

        private KeyVal() {}

        public KeyVal key(String key) {
            Validate.notEmpty(key, "Data key must not be empty");
            this.key = key;
            return this;
        }

        public String key() {
            return key;
        }

        public KeyVal value(String value) {
            Validate.notNull(value, "Data value must not be null");
            this.value = value;
            return this;
        }

        public String value() {
            return value;
        }

        public KeyVal inputStream(InputStream inputStream) {
            Validate.notNull(value, "Data input stream must not be null");
            this.stream = inputStream;
            return this;
        }

        public InputStream inputStream() {
            return stream;
        }

        public boolean hasInputStream() {
            return stream != null;
        }

        @Override
        public String toString() {
            return key + "=" + value;
        }
    }
}
