/*
 *  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.tomcat.util.http;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;

import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.CharChunk;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.buf.UDecoder;
import org.apache.tomcat.util.collections.MultiMap;

/**
 * 
 * @author Costin Manolache
 */
public final class Parameters extends MultiMap {

    
    private static org.apache.commons.logging.Log log=
        org.apache.commons.logging.LogFactory.getLog(Parameters.class );
    
    // Transition: we'll use the same Hashtable( String->String[] )
    // for the beginning. When we are sure all accesses happen through
    // this class - we can switch to MultiMap
    private Hashtable paramHashStringArray=new Hashtable();
    private boolean didQueryParameters=false;
    private boolean didMerge=false;
    
    MessageBytes queryMB;
    MimeHeaders  headers;

    UDecoder urlDec;
    MessageBytes decodedQuery=MessageBytes.newInstance();
    
    public static final int INITIAL_SIZE=4;

    // Garbage-less parameter merging.
    // In a sub-request with parameters, the new parameters
    // will be stored in child. When a getParameter happens,
    // the 2 are merged togheter. The child will be altered
    // to contain the merged values - the parent is allways the
    // original request.
    private Parameters child=null;
    private Parameters parent=null;
    private Parameters currentChild=null;

    String encoding=null;
    String queryStringEncoding=null;
    
    /**
     * 
     */
    public Parameters() {
        super( INITIAL_SIZE );
    }

    public void setQuery( MessageBytes queryMB ) {
        this.queryMB=queryMB;
    }

    public void setHeaders( MimeHeaders headers ) {
        this.headers=headers;
    }

    public void setEncoding( String s ) {
        encoding=s;
        if(debug>0) log( "Set encoding to " + s );
    }

    public void setQueryStringEncoding( String s ) {
        queryStringEncoding=s;
        if(debug>0) log( "Set query string encoding to " + s );
    }

    public void recycle() {
        super.recycle();
        paramHashStringArray.clear();
        didQueryParameters=false;
        currentChild=null;
        didMerge=false;
        encoding=null;
        decodedQuery.recycle();
    }
    
    // -------------------- Sub-request support --------------------

    public Parameters getCurrentSet() {
        if( currentChild==null )
            return this;
        return currentChild;
    }
    
    /** Create ( or reuse ) a child that will be used during a sub-request.
        All future changes ( setting query string, adding parameters )
        will affect the child ( the parent request is never changed ).
        Both setters and getters will return the data from the deepest
        child, merged with data from parents.
    */
    public void push() {
        // We maintain a linked list, that will grow to the size of the
        // longest include chain.
        // The list has 2 points of interest:
        // - request.parameters() is the original request and head,
        // - request.parameters().currentChild() is the current set.
        // The ->child and parent<- links are preserved ( currentChild is not
        // the last in the list )
        
        // create a new element in the linked list
        // note that we reuse the child, if any - pop will not
        // set child to null !
        if( currentChild==null ) {
            currentChild=new Parameters();
            currentChild.setURLDecoder( urlDec );
            currentChild.parent=this;
            return;
        }
        if( currentChild.child==null ) {
            currentChild.child=new Parameters();
            currentChild.setURLDecoder( urlDec );
            currentChild.child.parent=currentChild;
        } // it is not null if this object already had a child
        // i.e. a deeper include() ( we keep it )

        // the head will be the new element.
        currentChild=currentChild.child;
        currentChild.setEncoding( encoding );
    }

    /** Discard the last child. This happens when we return from a
        sub-request and the parameters are locally modified.
     */
    public void pop() {
        if( currentChild==null ) {
            throw new RuntimeException( "Attempt to pop without a push" );
        }
        currentChild.recycle();
        currentChild=currentChild.parent;
        // don't remove the top.
    }
    
    // -------------------- Data access --------------------
    // Access to the current name/values, no side effect ( processing ).
    // You must explicitely call handleQueryParameters and the post methods.
    
    // This is the original data representation ( hash of String->String[])

    public void addParameterValues( String key, String[] newValues) {
        if ( key==null ) return;
        String values[];
        if (paramHashStringArray.containsKey(key)) {
            String oldValues[] = (String[])paramHashStringArray.get(key);
            values = new String[oldValues.length + newValues.length];
            for (int i = 0; i < oldValues.length; i++) {
                values[i] = oldValues[i];
            }
            for (int i = 0; i < newValues.length; i++) {
                values[i+ oldValues.length] = newValues[i];
            }
        } else {
            values = newValues;
        }

        paramHashStringArray.put(key, values);
    }

    public String[] getParameterValues(String name) {
        handleQueryParameters();
        // sub-request
        if( currentChild!=null ) {
            currentChild.merge();
            return (String[])currentChild.paramHashStringArray.get(name);
        }

        // no "facade"
        String values[]=(String[])paramHashStringArray.get(name);
        return values;
    }
 
    public Enumeration getParameterNames() {
        handleQueryParameters();
        // Slow - the original code
        if( currentChild!=null ) {
            currentChild.merge();
            return currentChild.paramHashStringArray.keys();
        }

        // merge in child
        return paramHashStringArray.keys();
    }

    /** Combine the parameters from parent with our local ones
     */
    private void merge() {
        // recursive
        if( debug > 0 ) {
            log("Before merging " + this + " " + parent + " " + didMerge );
            log(  paramsAsString());
        }
        // Local parameters first - they take precedence as in spec.
        handleQueryParameters();

        // we already merged with the parent
        if( didMerge ) return;

        // we are the top level
        if( parent==null ) return;

        // Add the parent props to the child ( lower precedence )
        parent.merge();
        Hashtable parentProps=parent.paramHashStringArray;
        merge2( paramHashStringArray , parentProps);
        didMerge=true;
        if(debug > 0 )
            log("After " + paramsAsString());
    }


    // Shortcut.
    public String getParameter(String name ) {
        String[] values = getParameterValues(name);
        if (values != null) {
            if( values.length==0 ) return "";
            return values[0];
        } else {
            return null;
        }
    }
    // -------------------- Processing --------------------
    /** Process the query string into parameters
     */
    public void handleQueryParameters() {
        if( didQueryParameters ) return;

        didQueryParameters=true;

        if( queryMB==null || queryMB.isNull() )
            return;
        
        if( debug > 0  )
            log( "Decoding query " + decodedQuery + " " + queryStringEncoding);

        try {
            decodedQuery.duplicate( queryMB );
        } catch (IOException e) {
            // Can't happen, as decodedQuery can't overflow
            e.printStackTrace();
        }
        processParameters( decodedQuery, queryStringEncoding );
    }

    // --------------------
    
    /** Combine 2 hashtables into a new one.
     *  ( two will be added to one ).
     *  Used to combine child parameters ( RequestDispatcher's query )
     *  with parent parameters ( original query or parent dispatcher )
     */
    private static void merge2(Hashtable one, Hashtable two ) {
        Enumeration e = two.keys();

        while (e.hasMoreElements()) {
            String name = (String) e.nextElement();
            String[] oneValue = (String[]) one.get(name);
            String[] twoValue = (String[]) two.get(name);
            String[] combinedValue;

            if (twoValue == null) {
                continue;
            } else {
                if( oneValue==null ) {
                    combinedValue = new String[twoValue.length];
                    System.arraycopy(twoValue, 0, combinedValue,
                                     0, twoValue.length);
                } else {
                    combinedValue = new String[oneValue.length +
                                               twoValue.length];
                    System.arraycopy(oneValue, 0, combinedValue, 0,
                                     oneValue.length);
                    System.arraycopy(twoValue, 0, combinedValue,
                                     oneValue.length, twoValue.length);
                }
                one.put(name, combinedValue);
            }
        }
    }

    // incredibly inefficient data representation for parameters,
    // until we test the new one
    private void addParam( String key, String value ) {
        if( key==null ) return;
        String values[];
        if (paramHashStringArray.containsKey(key)) {
            String oldValues[] = (String[])paramHashStringArray.
                get(key);
            values = new String[oldValues.length + 1];
            for (int i = 0; i < oldValues.length; i++) {
                values[i] = oldValues[i];
            }
            values[oldValues.length] = value;
        } else {
            values = new String[1];
            values[0] = value;
        }
        
        
        paramHashStringArray.put(key, values);
    }

    public void setURLDecoder( UDecoder u ) {
        urlDec=u;
    }

    // -------------------- Parameter parsing --------------------

    // This code is not used right now - it's the optimized version
    // of the above.

    // we are called from a single thread - we can do it the hard way
    // if needed
    ByteChunk tmpName=new ByteChunk();
    ByteChunk tmpValue=new ByteChunk();
    CharChunk tmpNameC=new CharChunk(1024);
    CharChunk tmpValueC=new CharChunk(1024);
    
    public void processParameters( byte bytes[], int start, int len ) {
        processParameters(bytes, start, len, encoding);
    }

    public void processParameters( byte bytes[], int start, int len, 
                                   String enc ) {
        int end=start+len;
        int pos=start;
        
        if( debug>0 ) 
            log( "Bytes: " + new String( bytes, start, len ));

        do {
            boolean noEq=false;
            int valStart=-1;
            int valEnd=-1;
            
            int nameStart=pos;
            int nameEnd=ByteChunk.indexOf(bytes, nameStart, end, '=' );
            // Workaround for a&b&c encoding
            int nameEnd2=ByteChunk.indexOf(bytes, nameStart, end, '&' );
            if( (nameEnd2!=-1 ) &&
                ( nameEnd==-1 || nameEnd > nameEnd2) ) {
                nameEnd=nameEnd2;
                noEq=true;
                valStart=nameEnd;
                valEnd=nameEnd;
                if(debug>0) log("no equal " + nameStart + " " + nameEnd + " " +
                        new String(bytes, nameStart, nameEnd-nameStart) );
            }
            if( nameEnd== -1 ) 
                nameEnd=end;

            if( ! noEq ) {
                valStart= (nameEnd < end) ? nameEnd+1 : end;
                valEnd=ByteChunk.indexOf(bytes, valStart, end, '&');
                if( valEnd== -1 ) valEnd = (valStart < end) ? end : valStart;
            }
            
            pos=valEnd+1;
            
            if( nameEnd<=nameStart ) {
                log.warn("Parameters: Invalid chunk ignored.");
                continue;
                // invalid chunk - it's better to ignore
            }
            tmpName.setBytes( bytes, nameStart, nameEnd-nameStart );
            tmpValue.setBytes( bytes, valStart, valEnd-valStart );

            try {
                addParam( urlDecode(tmpName, enc), urlDecode(tmpValue, enc) );
            } catch (IOException e) {
                // Exception during character decoding: skip parameter
                log.warn("Parameters: Character decoding failed. " + 
                        "Parameter skipped.", e);
            }

            tmpName.recycle();
            tmpValue.recycle();

        } while( pos<end );
    }

    private String urlDecode(ByteChunk bc, String enc)
        throws IOException {
        if( urlDec==null ) {
            urlDec=new UDecoder();   
        }
        urlDec.convert(bc);
        String result = null;
        if (enc != null) {
            bc.setEncoding(enc);
            result = bc.toString();
        } else {
            CharChunk cc = tmpNameC;
            cc.allocate(bc.getLength(), -1);
            // Default encoding: fast conversion
            byte[] bbuf = bc.getBuffer();
            char[] cbuf = cc.getBuffer();
            int start = bc.getStart();
            for (int i = 0; i < bc.getLength(); i++) {
                cbuf[i] = (char) (bbuf[i + start] & 0xff);
            }
            cc.setChars(cbuf, 0, bc.getLength());
            result = cc.toString();
            cc.recycle();
        }
        return result;
    }

    public void processParameters( char chars[], int start, int len ) {
        int end=start+len;
        int pos=start;
        
        if( debug>0 ) 
            log( "Chars: " + new String( chars, start, len ));
        do {
            boolean noEq=false;
            int nameStart=pos;
            int valStart=-1;
            int valEnd=-1;
            
            int nameEnd=CharChunk.indexOf(chars, nameStart, end, '=' );
            int nameEnd2=CharChunk.indexOf(chars, nameStart, end, '&' );
            if( (nameEnd2!=-1 ) &&
                ( nameEnd==-1 || nameEnd > nameEnd2) ) {
                nameEnd=nameEnd2;
                noEq=true;
                valStart=nameEnd;
                valEnd=nameEnd;
                if(debug>0) log("no equal " + nameStart + " " + nameEnd + " " +
                        new String(chars, nameStart, nameEnd-nameStart) );
            }
            if( nameEnd== -1 ) nameEnd=end;
            
            if( ! noEq ) {
                valStart= (nameEnd < end) ? nameEnd+1 : end;
                valEnd=CharChunk.indexOf(chars, valStart, end, '&');
                if( valEnd== -1 ) valEnd = (valStart < end) ? end : valStart;
            }
            
            pos=valEnd+1;
            
            if( nameEnd<=nameStart ) {
                continue;
                // invalid chunk - no name, it's better to ignore
                // XXX log it ?
            }
            
            try {
                tmpNameC.append( chars, nameStart, nameEnd-nameStart );
                tmpValueC.append( chars, valStart, valEnd-valStart );

                if( debug > 0 )
                    log( tmpNameC + "= " + tmpValueC);

                if( urlDec==null ) {
                    urlDec=new UDecoder();   
                }

                urlDec.convert( tmpNameC );
                urlDec.convert( tmpValueC );

                if( debug > 0 )
                    log( tmpNameC + "= " + tmpValueC);
                
                addParam( tmpNameC.toString(), tmpValueC.toString() );
            } catch( IOException ex ) {
                ex.printStackTrace();
            }

            tmpNameC.recycle();
            tmpValueC.recycle();

        } while( pos<end );
    }
    
    public void processParameters( MessageBytes data ) {
        processParameters(data, encoding);
    }

    public void processParameters( MessageBytes data, String encoding ) {
        if( data==null || data.isNull() || data.getLength() <= 0 ) return;

        if( data.getType() == MessageBytes.T_BYTES ) {
            ByteChunk bc=data.getByteChunk();
            processParameters( bc.getBytes(), bc.getOffset(),
                               bc.getLength(), encoding);
        } else {
            if (data.getType()!= MessageBytes.T_CHARS ) 
                data.toChars();
            CharChunk cc=data.getCharChunk();
            processParameters( cc.getChars(), cc.getOffset(),
                               cc.getLength());
        }
    }

    /** Debug purpose
     */
    public String paramsAsString() {
        StringBuffer sb=new StringBuffer();
        Enumeration en= paramHashStringArray.keys();
        while( en.hasMoreElements() ) {
            String k=(String)en.nextElement();
            sb.append( k ).append("=");
            String v[]=(String[])paramHashStringArray.get( k );
            for( int i=0; i<v.length; i++ )
                sb.append( v[i] ).append(",");
            sb.append("\n");
        }
        return sb.toString();
    }

    private static int debug=0;
    private void log(String s ) {
        if (log.isDebugEnabled())
            log.debug("Parameters: " + s );
    }
   
    // -------------------- Old code, needs rewrite --------------------
    
    /** Used by RequestDispatcher
     */
    public void processParameters( String str ) {
        int end=str.length();
        int pos=0;
        if( debug > 0)
            log("String: " + str );
        
        do {
            boolean noEq=false;
            int valStart=-1;
            int valEnd=-1;
            
            int nameStart=pos;
            int nameEnd=str.indexOf('=', nameStart );
            int nameEnd2=str.indexOf('&', nameStart );
            if( nameEnd2== -1 ) nameEnd2=end;
            if( (nameEnd2!=-1 ) &&
                ( nameEnd==-1 || nameEnd > nameEnd2) ) {
                nameEnd=nameEnd2;
                noEq=true;
                valStart=nameEnd;
                valEnd=nameEnd;
                if(debug>0) log("no equal " + nameStart + " " + nameEnd + " " +
                        str.substring(nameStart, nameEnd));
            }

            if( nameEnd== -1 ) nameEnd=end;

            if( ! noEq ) {
                valStart=nameEnd+1;
                valEnd=str.indexOf('&', valStart);
                if( valEnd== -1 ) valEnd = (valStart < end) ? end : valStart;
            }
            
            pos=valEnd+1;
            
            if( nameEnd<=nameStart ) {
                continue;
            }
            if( debug>0)
                log( "XXX " + nameStart + " " + nameEnd + " "
                     + valStart + " " + valEnd );
            
            try {
                tmpNameC.append(str, nameStart, nameEnd-nameStart );
                tmpValueC.append(str, valStart, valEnd-valStart );
            
                if( debug > 0 )
                    log( tmpNameC + "= " + tmpValueC);

                if( urlDec==null ) {
                    urlDec=new UDecoder();   
                }

                urlDec.convert( tmpNameC );
                urlDec.convert( tmpValueC );

                if( debug > 0 )
                    log( tmpNameC + "= " + tmpValueC);
                
                addParam( tmpNameC.toString(), tmpValueC.toString() );
            } catch( IOException ex ) {
                ex.printStackTrace();
            }

            tmpNameC.recycle();
            tmpValueC.recycle();

        } while( pos<end );
    }


}