//
//  ========================================================================
//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.http;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jetty.util.QuotedStringTokenizer;

/* ------------------------------------------------------------ */
/**
 * Implements a quoted comma separated list of values
 * in accordance with RFC7230.
 * OWS is removed and quoted characters ignored for parsing.
 * @see "https://tools.ietf.org/html/rfc7230#section-3.2.6"
 * @see "https://tools.ietf.org/html/rfc7230#section-7"
 */
public class QuotedCSV implements Iterable<String>
{    
    private enum State { VALUE, PARAM_NAME, PARAM_VALUE};
    
    protected final List<String> _values = new ArrayList<>();
    protected final boolean _keepQuotes;
    
    /* ------------------------------------------------------------ */
    public QuotedCSV(String... values)
    {
        this(true,values);
    }
    
    /* ------------------------------------------------------------ */
    public QuotedCSV(boolean keepQuotes,String... values)
    {
        _keepQuotes=keepQuotes;
        for (String v:values)
            addValue(v);
    }
    
    /* ------------------------------------------------------------ */
    /** Add and parse a value string(s) 
     * @param value A value that may contain one or more Quoted CSV items.
     */
    public void addValue(String value)
    {
        StringBuffer buffer = new StringBuffer();
        
        int l=value.length();
        State state=State.VALUE;
        boolean quoted=false;
        boolean sloshed=false;
        int nws_length=0;
        int last_length=0;
        int value_length=-1;
        int param_name=-1;
        int param_value=-1;
        
        for (int i=0;i<=l;i++)
        {
            char c=i==l?0:value.charAt(i);
            
            // Handle quoting https://tools.ietf.org/html/rfc7230#section-3.2.6
            if (quoted && c!=0)
            {
                if (sloshed)
                    sloshed=false;
                else
                {
                    switch(c)
                    {
                        case '\\':
                            sloshed=true;
                            if (!_keepQuotes)
                                continue;
                            break;
                        case '"':
                            quoted=false;
                            if (!_keepQuotes)
                                continue;
                            break;
                    }
                }

                buffer.append(c);
                nws_length=buffer.length();
                continue;
            }
            
            // Handle common cases
            switch(c)
            {
                case ' ':
                case '\t':
                    if (buffer.length()>last_length) // not leading OWS
                        buffer.append(c);
                    continue;

                case '"':
                    quoted=true;
                    if (_keepQuotes)
                    {
                        if (state==State.PARAM_VALUE && param_value<0)
                            param_value=nws_length;
                        buffer.append(c);
                    }
                    else if (state==State.PARAM_VALUE && param_value<0)
                        param_value=nws_length;
                    nws_length=buffer.length();
                    continue;
                    
                case ';':                    
                    buffer.setLength(nws_length); // trim following OWS
                    if (state==State.VALUE)
                    {
                        parsedValue(buffer);
                        value_length=buffer.length();
                    }
                    else
                        parsedParam(buffer,value_length,param_name,param_value);
                    nws_length=buffer.length();
                    param_name=param_value=-1;
                    buffer.append(c);
                    last_length=++nws_length;
                    state=State.PARAM_NAME;
                    continue;
                    
                case ',':
                case 0:
                    if (nws_length>0)
                    {
                        buffer.setLength(nws_length); // trim following OWS
                        switch(state)
                        {
                            case VALUE:
                                parsedValue(buffer);
                                value_length=buffer.length();
                                break;
                            case PARAM_NAME:
                            case PARAM_VALUE:
                                parsedParam(buffer,value_length,param_name,param_value);
                                break;
                        }
                        _values.add(buffer.toString());
                    }
                    buffer.setLength(0);
                    last_length=0;
                    nws_length=0;
                    value_length=param_name=param_value=-1;
                    state=State.VALUE;
                    continue;

                case '=':
                    switch (state)
                    {
                        case VALUE:
                            // It wasn't really a value, it was a param name
                            value_length=param_name=0;
                            buffer.setLength(nws_length); // trim following OWS
                            buffer.append(c);
                            last_length=++nws_length;
                            state=State.PARAM_VALUE;
                            continue;

                        case PARAM_NAME:
                            buffer.setLength(nws_length); // trim following OWS
                            buffer.append(c);
                            last_length=++nws_length;
                            state=State.PARAM_VALUE;
                            continue;

                        case PARAM_VALUE:
                            if (param_value<0)
                                param_value=nws_length;
                            buffer.append(c);
                            nws_length=buffer.length();
                            continue;
                    }
                    continue;
                    
                default:
                {
                    switch (state)
                    {
                        case VALUE:
                        {
                            buffer.append(c);
                            nws_length=buffer.length();
                            continue;
                        }

                        case PARAM_NAME:
                        {
                            if (param_name<0)
                                param_name=nws_length;
                            buffer.append(c);
                            nws_length=buffer.length();
                            continue;
                        }

                        case PARAM_VALUE:
                        {
                            if (param_value<0)
                                param_value=nws_length;
                            buffer.append(c);
                            nws_length=buffer.length();
                            continue;
                        }
                    }
                }
            }  
        }
    }

    /**
     * Called when a value has been parsed
     * @param buffer Containing the trimmed value, which may be mutated
     */
    protected void parsedValue(StringBuffer buffer)
    {
    }

    /**
     * Called when a parameter has been parsed
     * @param buffer Containing the trimmed value and all parameters, which may be mutated
     * @param valueLength The length of the value
     * @param paramName The index of the start of the parameter just parsed
     * @param paramValue The index of the start of the parameter value just parsed, or -1
     */
    protected void parsedParam(StringBuffer buffer, int valueLength, int paramName, int paramValue)
    {
    }

    public int size()
    {
        return _values.size();
    }

    public boolean isEmpty()
    {
        return _values.isEmpty();
    }

    public List<String> getValues()
    {
        return _values;
    }
    
    @Override
    public Iterator<String> iterator()
    {
        return _values.iterator();
    }
    
    public static String unquote(String s)
    {
        // handle trivial cases
        int l=s.length();
        if (s==null || l==0)
            return s;
        
        // Look for any quotes
        int i=0;
        for (;i<l;i++)
        {
            char c=s.charAt(i);
            if (c=='"')
                break;
        }
        if (i==l)
            return s;

        boolean quoted=true;
        boolean sloshed=false;
        StringBuffer buffer = new StringBuffer();
        buffer.append(s,0,i);
        i++;
        for (;i<l;i++)
        {
            char c=s.charAt(i);
            if (quoted)
            {
                if (sloshed)
                {
                    buffer.append(c);
                    sloshed=false;
                }
                else if (c=='"')
                    quoted=false;
                else if (c=='\\')
                    sloshed=true;
                else
                    buffer.append(c);
            }
            else if (c=='"')
                quoted=true;
            else
                buffer.append(c);
        }
        return buffer.toString();
    }
}
