// Copyright 2004 Adam Megacz, see the COPYING file for licensing [GPL]
package org.xwt;

import java.io.*;
import java.net.*;
import java.util.*;
import org.xwt.js.*;
import org.xwt.util.*;
import org.bouncycastle.util.encoders.Base64;

/**
 *  An XML-RPC client implemented as a JavaScript Host Object. See the
 *  XWT spec for information on its behavior.
 *
 *  NOTE: this client is EXTREMELY lenient in the responses it will
 *  accept; there are many, many invalid responses that it will
 *  successfully parse and return. Do NOT use this to determine the
 *  validity of your server.
 *
 *  This client conforms to <a href="http://www.xmlrpc.com/spec">The
 *  XML-RPC Spec</a>, subject to these limitations:
 *  <ol>
 *    <li> XMLRPC cannot invoke methods that require a <base64/> argument
 *    <li> if a return value contains a <base64/>, it will be returned as a string
 *    <li> The decision to pass a number as <i4/> or <double/> is based
 *         entirely on whether or not the argument is fractional. Thus, it
 *         is impossible to pass a non-fractional number to an xmlrpc
 *         method that insists on being called with a <double/> element. We
 *         hope that most xml-rpc servers will be able to automatically
 *         convert.
 *  </ol>
 */
class XMLRPC extends JS {

    public XMLRPC(String url, String method) { this(url, method, new HTTP(url)); }
    public XMLRPC(String url, String method, HTTP http) { this.http = http; this.url = url; this.method = method; }
    public Object get(Object name) { return new XMLRPC(url, (method.equals("") ? "" : method + ".") + name.toString(), http); }


    /** this holds character content as we read it in -- since there is only one per instance, we don't support mixed content */
    protected AccessibleCharArrayWriter content = new AccessibleCharArrayWriter(100);
    protected String url = null;         ///< the url to connect to
    protected String method = null;      ///< the method name to invoke on the remove server
    protected HTTP http = null;          ///< the HTTP connection to use
    private Hash tracker;                ///< used to detect multi-ref data
    protected boolean fault = false;     ///< True iff the return value is a fault (and should be thrown as an exception)


    /** The object stack. As we process xml elements, pieces of the
     *  return value are pushed onto and popped off of this stack.
     *
     *  The general protocol is that any time a <value> tag is
     *  encountered, an empty String ("") is pushed onto the stack. If
     *  the <value/> node has content (either an anonymous
     *  string or some other XML node), that content replaces the
     *  empty string.
     *
     *  If an <array> tag is encountered, a null is pushed onto the
     *  stack. When a </data> is encountered, we search back on the
     *  stack to the last null, replace it with a NativeJSArray, and
     *  insert into it all elements above it on the stack.
     *
     *  If a <struct> tag is encountered, a JSect is pushed
     *  onto the stack. If a <name> tag is encountered, its CDATA is
     *  pushed onto the stack. When a </member> is encountered, the
     *  name (second element on stack) and value (top of stack) are
     *  popped off the stack and inserted into the struct (third
     *  element on stack).
     */
    protected Vec objects = null;


    // Recieve ////////////////////////////////////////////////////////////////

    private class Helper extends XML {
        public Helper() { super(BUFFER_SIZE); }

        public void startElement(XML.Element c) {
            content.reset();
            //#switch(c.getLocalName())
            case "fault": fault = true;
            case "struct": objects.setElementAt(new JS(), objects.size() - 1);
            case "array": objects.setElementAt(null, objects.size() - 1);
            case "value": objects.addElement("");
            //#end
        }
        
        public void endElement(XML.Element c) {
            //#switch(c.getLocalName())
            case "int": objects.setElementAt(new Integer(new String(content.getBuf(), 0, content.size())), objects.size() - 1);
            case "i4": objects.setElementAt(new Integer(new String(content.getBuf(), 0, content.size())), objects.size() - 1);
            case "boolean": objects.setElementAt(content.getBuf()[0] == '1' ? Boolean.TRUE : Boolean.FALSE, objects.size() - 1);
            case "string": objects.setElementAt(new String(content.getBuf(), 0, content.size()), objects.size() - 1);
            case "double": objects.setElementAt(new Double(new String(content.getBuf(), 0, content.size())), objects.size() - 1);
            case "base64":
                objects.setElementAt(new Stream.ByteArray(Base64.decode(new String(content.getBuf(), 0, content.size())),
                                                          null), objects.size() - 1);
            case "name": objects.addElement(new String(content.getBuf(), 0, content.size()));
            case "value": if ("".equals(objects.lastElement()))
                objects.setElementAt(new String(content.getBuf(), 0, content.size()), objects.size() - 1);
            case "dateTime.iso8601":
                String s = new String(content.getBuf(), 0, content.size());
                
                // strip whitespace
                int i=0;
                while(Character.isWhitespace(s.charAt(i))) i++;
                if (i > 0) s = s.substring(i);
                
                try {
                    JSDate nd = new JSDate();
                    double date = JSDate.date_msecFromDate(Double.valueOf(s.substring(0, 4)).doubleValue(),
                                                           Double.valueOf(s.substring(4, 6)).doubleValue() - 1,
                                                           Double.valueOf(s.substring(6, 8)).doubleValue(),
                                                           Double.valueOf(s.substring(9, 11)).doubleValue(),
                                                           Double.valueOf(s.substring(12, 14)).doubleValue(),
                                                           Double.valueOf(s.substring(15, 17)).doubleValue(),
                                                           (double)0
                                                           );
                    nd.setTime(JSDate.internalUTC(date));
                    objects.setElementAt(nd, objects.size() - 1);
                    
                } catch (Exception e) {
                    throw new RuntimeException("xwt.net.rpc.xml.recieve.malformedDateTag" +
                                    "the server sent a <dateTime.iso8601> tag which was malformed: " + s);
                }
            case "member":
                Object memberValue = objects.elementAt(objects.size() - 1);
                String memberName = (String)objects.elementAt(objects.size() - 2);
                JS struct = (JS)objects.elementAt(objects.size() - 3);
                try {
                    struct.put(memberName, memberValue);
                } catch (JSExn e) {
                    throw new Error("this should never happen");
                }
                objects.setSize(objects.size() - 2);
            case "data":
                int i;
                for(i=objects.size() - 1; objects.elementAt(i) != null; i--);
                JSArray arr = new JSArray();
                try {
                    for(int j = i + 1; j<objects.size(); j++) arr.put(new Integer(j - i - 1), objects.elementAt(j));
                } catch (JSExn e) {
                    throw new Error("this should never happen");
                }
                objects.setElementAt(arr, i);
                objects.setSize(i + 1);
            //#end            
            content.reset();
        }
        
        public void characters(char[] ch, int start, int length) {
            try { content.write(ch, start, length); }
            catch (Exception e) { 
                if (Log.on) Log.info(this, "Exception in XMLRPC.content() -- this should never happen");
                if (Log.on) Log.info(this, e);
            }
        }
        
        public void whitespace(char[] ch, int start, int length) {}
    }

    // Send ///////////////////////////////////////////////////////////////////////////

    protected String buildRequest(JSArray args) throws JSExn, IOException {
        StringBuffer content = new StringBuffer();
        content.append("\r\n");
        content.append("<?xml version=\"1.0\"?>\n");
        content.append("    <methodCall>\n");
        content.append("        <method>");
        content.append(method);
        content.append("</method>\n");
        content.append("        <params>\n");
        for(int i=0; i<args.length(); i++) {
            content.append("            <param>\n");
            appendObject(args.elementAt(i), content);
            content.append("            </param>\n");
        }
        content.append("        </params>\n");
        content.append("    </methodCall>");
        return content.toString();
    }

    /** Appends the XML-RPC representation of <code>o</code> to <code>sb</code> */
    void appendObject(Object o, StringBuffer sb) throws JSExn {

        if (o == null) {
            throw new JSExn("attempted to send a null value via XML-RPC");

        } else if (o instanceof Number) {
            if ((double)((Number)o).intValue() == ((Number)o).doubleValue()) {
                sb.append("                <value><i4>");
                sb.append(((Number)o).intValue());
                sb.append("</i4></value>\n");
            } else {
                sb.append("                <value><double>");
                sb.append(o);
                sb.append("</double></value>\n");
            }

        } else if (o instanceof Boolean) {
            sb.append("                <value><boolean>");
            sb.append(((Boolean)o).booleanValue() ? "1" : "0");
            sb.append("</boolean></value>\n");

        } else if (o instanceof Stream) {
            try {
                sb.append("                <value><base64>\n");
                InputStream is = ((Stream)o).getInputStream();
                byte[] buf = new byte[54];
                while(true) {
                    int numread = is.read(buf, 0, 54);
                    if (numread == -1) break;
                    byte[] writebuf = buf;
                    if (numread < buf.length) {
                        writebuf = new byte[numread];
                        System.arraycopy(buf, 0, writebuf, 0, numread);
                    }
                    sb.append("              ");
                    sb.append(new String(Base64.encode(writebuf)));
                    sb.append("\n");
                }
                sb.append("\n              </base64></value>\n");
            } catch (IOException e) {
                if (Log.on) Log.info(this, "caught IOException while attempting to send a ByteStream via XML-RPC");
                if (Log.on) Log.info(this, e);
                throw new JSExn("caught IOException while attempting to send a ByteStream via XML-RPC");
            }

        } else if (o instanceof String) {
            sb.append("                <value><string>");
            String s = (String)o;
            if (s.indexOf('<') == -1 && s.indexOf('&') == -1) {
                sb.append(s);
            } else {
                char[] cbuf = s.toCharArray();
                int oldi = 0, i=0;
                while(true) {
                    while(i < cbuf.length && cbuf[i] != '<' && cbuf[i] != '&') i++;
                    sb.append(cbuf, oldi, i - oldi);
                    if (i >= cbuf.length) break;
                    if (cbuf[i] == '<') sb.append("<");
                    else if (cbuf[i] == '&') sb.append("&");
                    i = oldi = i + 1;
                    if (i >= cbuf.length) break;
                }
            }
            sb.append("</string></value>\n");

        } else if (o instanceof JSDate) {
            sb.append("                <value><dateTime.iso8601>");
            java.util.Date d = new java.util.Date(((JSDate)o).getRawTime());
            sb.append(d.getYear() + 1900);
            if (d.getMonth() + 1 < 10) sb.append('0');
            sb.append(d.getMonth() + 1);
            if (d.getDate() < 10) sb.append('0');
            sb.append(d.getDate());
            sb.append('T');
            if (d.getHours() < 10) sb.append('0');
            sb.append(d.getHours());
            sb.append(':');
            if (d.getMinutes() < 10) sb.append('0');
            sb.append(d.getMinutes());
            sb.append(':');
            if (d.getSeconds() < 10) sb.append('0');
            sb.append(d.getSeconds());
            sb.append("</dateTime.iso8601></value>\n");

        } else if (o instanceof JSArray) {
            if (tracker.get(o) != null) throw new JSExn("attempted to send multi-ref data structure via XML-RPC");
            tracker.put(o, Boolean.TRUE);
            sb.append("                <value><array><data>\n");
            JSArray a = (JSArray)o;
            for(int i=0; i<a.length(); i++) appendObject(a.elementAt(i), sb);
            sb.append("                </data></array></value>\n");

        } else if (o instanceof JS) {
            if (tracker.get(o) != null) throw new JSExn("attempted to send multi-ref data structure via XML-RPC");
            tracker.put(o, Boolean.TRUE);
            JS j = (JS)o;
            sb.append("                <value><struct>\n");
            Enumeration e = j.keys();
            while(e.hasMoreElements()) {
                Object key = e.nextElement();
                sb.append("                <member><name>" + key + "</name>\n");
                appendObject(j.get(key), sb);
                sb.append("                </member>\n");
            }
            sb.append("                </struct></value>\n");

        } else {
            throw new JSExn("attempt to send object of type " + o.getClass().getName() + " via XML-RPC");

        }
    }


    // Call Sequence //////////////////////////////////////////////////////////////////////////

    public final Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
        JSArray args = new JSArray();
        for(int i=0; i<nargs; i++) args.addElement(i==0?a0:i==1?a1:i==2?a2:rest[i-3]);
        return call(args);
    }

    public final Object call(final JSArray args) throws JSExn {
        try {
            final JS.UnpauseCallback callback = JS.pause();
            new java.lang.Thread() { public void run() { call(callback, args); }  }.start();
            return null; // doesn't matter since we paused
        } catch (NotPauseableException npe) {
            throw new JSExn("cannot invoke an XML-RPC call in the foreground thread");
        }
    }

    final void call(final JS.UnpauseCallback callback, final JSArray args) {
        try {
            if (Log.verbose) Log.info(this, "call to " + url + " : " + method);
            String request = buildRequest(args);
            if (Log.verbose) Log.info(this, "send:\n" + request);
            InputStream is = http.POST("text/xml", request);
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            if (tracker == null) tracker = new Hash();
            if (objects == null) objects = new Vec();
            try {
                new Helper().parse(br);
                final Object result = fault ? new JSExn(objects.elementAt(0)) : objects.size() == 0 ? null : objects.elementAt(0);
                Scheduler.add(new Scheduler.Task() { public void perform() throws Exception { callback.unpause(result); }});
            } finally {
                tracker.clear();
                objects.setSize(0);
            }
        } catch (final JSExn e) {
            final Exception e2 = e;
            Scheduler.add(new Scheduler.Task() { public void perform() throws Exception { callback.unpause(e2); }});
        } catch (final IOException e) {
            final Exception e2 = e;
            Scheduler.add(new Scheduler.Task() { public void perform() throws Exception { callback.unpause(new JSExn(e2)); }});
        } catch (final XML.Exn e) {
            final Exception e2 = e;
            Scheduler.add(new Scheduler.Task() { public void perform() throws Exception { callback.unpause(new JSExn(e2)); }});
        }
    }
}