// see http://www.apache.org/licenses/LICENSE-2.0

/*
 * $Id: JSONParser.java,v 1.1 2006/04/15 14:10:48 platform Exp $
 * Created on 2006-4-15
 */
package org.teiid.json.simple;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.util.LinkedList;


/**
 * Parser for JSON text. Please note that JSONParser is NOT thread-safe.
 * 
 * @author FangYidong<fangyidong@yahoo.com.cn>
 */
public class JSONParser {
	
    /**
     * Modified from JSONValue 
     * @param s - Must not be null.
     * @param sb
     * @throws IOException 
     */
    public static void escape(CharSequence s, Writer sb) throws IOException {
                for(int i=0;i<s.length();i++){
                        char ch=s.charAt(i);
                        switch(ch){
                        case '"':
                                sb.append("\\\"");  //$NON-NLS-1$
                                break;
                        case '\\':
                                sb.append("\\\\"); //$NON-NLS-1$
                                break;
                        case '\b':
                                sb.append("\\b"); //$NON-NLS-1$
                                break;
                        case '\f':
                                sb.append("\\f"); //$NON-NLS-1$
                                break;
                        case '\n':
                                sb.append("\\n"); //$NON-NLS-1$
                                break;
                        case '\r':
                                sb.append("\\r"); //$NON-NLS-1$
                                break;
                        case '\t':
                                sb.append("\\t"); //$NON-NLS-1$
                                break;
                        case '/':
                                sb.append("\\/"); //$NON-NLS-1$
                                break;
                        default:
                //Reference: http://www.unicode.org/versions/Unicode5.1.0/
                                if((ch>='\u0000' && ch<='\u001F') || (ch>='\u007F' && ch<='\u009F') || (ch>='\u2000' && ch<='\u20FF')){
                                        String ss=Integer.toHexString(ch);
                                        sb.append("\\u");
                                        for(int k=0;k<4-ss.length();k++){
                                                sb.append('0');
                                        }
                                        sb.append(ss.toUpperCase());
                                }
                                else{
                                        sb.append(ch);
                                }
                        }
                }//for
        }
	
	public static final int S_INIT=0;
	public static final int S_IN_FINISHED_VALUE=1;//string,number,boolean,null,object,array
	public static final int S_IN_OBJECT=2;
	public static final int S_IN_ARRAY=3;
	public static final int S_PASSED_PAIR_KEY=4;
	public static final int S_IN_PAIR_VALUE=5;
	public static final int S_END=6;
	public static final int S_IN_ERROR=-1;
	
	private LinkedList handlerStatusStack;
	private Yylex lexer = new Yylex((Reader)null);
	private Yytoken token = null;
	private int status = S_INIT;
	
	private int peekStatus(LinkedList statusStack){
		if(statusStack.size()==0)
			return -1;
		Integer status=(Integer)statusStack.getFirst();
		return status.intValue();
	}
	
    /**
     *  Reset the parser to the initial state without resetting the underlying reader.
     *
     */
    public void reset(){
        token = null;
        status = S_INIT;
        handlerStatusStack = null;
    }
    
    /**
     * Reset the parser to the initial state with a new character reader.
     * 
     * @param in - The new character reader.
     * @throws IOException
     * @throws ParseException
     */
	public void reset(Reader in){
		lexer.yyreset(in);
		reset();
	}
	
	/**
	 * @return The position of the beginning of the current token.
	 */
	public int getPosition(){
		return lexer.getPosition();
	}
	
	private void nextToken() throws ParseException, IOException{
		token = lexer.yylex();
		if(token == null)
			token = new Yytoken(Yytoken.TYPE_EOF, null);
	}
	
	public void parse(String s, ContentHandler contentHandler) throws ParseException{
		parse(s, contentHandler, false);
	}
	
	public void parse(String s, ContentHandler contentHandler, boolean isResume) throws ParseException{
		StringReader in=new StringReader(s);
		try{
			parse(in, contentHandler, isResume);
		}
		catch(IOException ie){
			/*
			 * Actually it will never happen.
			 */
			throw new ParseException(-1, ParseException.ERROR_UNEXPECTED_EXCEPTION, ie);
		}
	}
	
	public void parse(Reader in, ContentHandler contentHandler) throws IOException, ParseException{
		parse(in, contentHandler, false);
	}
	
	/**
	 * Stream processing of JSON text.
	 * 
	 * @see ContentHandler
	 * 
	 * @param in
	 * @param contentHandler
	 * @param isResume - Indicates if it continues previous parsing operation.
     *                   If set to true, resume parsing the old stream, and parameter 'in' will be ignored. 
	 *                   If this method is called for the first time in this instance, isResume will be ignored.
	 * 
	 * @throws IOException
	 * @throws ParseException
	 */
	public void parse(Reader in, ContentHandler contentHandler, boolean isResume) throws IOException, ParseException{
		if(!isResume){
			reset(in);
			handlerStatusStack = new LinkedList();
		}
		else{
			if(handlerStatusStack == null){
				isResume = false;
				reset(in);
				handlerStatusStack = new LinkedList();
			}
		}
		
		LinkedList statusStack = handlerStatusStack;	
		
		try{
			do{
				switch(status){
				case S_INIT:
					contentHandler.startJSON();
					nextToken();
					switch(token.type){
					case Yytoken.TYPE_VALUE:
						status=S_IN_FINISHED_VALUE;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.primitive(token.value))
							return;
						break;
					case Yytoken.TYPE_LEFT_BRACE:
						status=S_IN_OBJECT;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startObject())
							return;
						break;
					case Yytoken.TYPE_LEFT_SQUARE:
						status=S_IN_ARRAY;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startArray())
							return;
						break;
					default:
						status=S_IN_ERROR;
					}//inner switch
					break;
					
				case S_IN_FINISHED_VALUE:
					nextToken();
					if(token.type==Yytoken.TYPE_EOF){
						contentHandler.endJSON();
						status = S_END;
						return;
					}
					else{
						status = S_IN_ERROR;
						throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
					}
			
				case S_IN_OBJECT:
					nextToken();
					switch(token.type){
					case Yytoken.TYPE_COMMA:
						break;
					case Yytoken.TYPE_VALUE:
						if(token.value instanceof String){
							String key=(String)token.value;
							status=S_PASSED_PAIR_KEY;
							statusStack.addFirst(new Integer(status));
							if(!contentHandler.startObjectEntry(key))
								return;
						}
						else{
							status=S_IN_ERROR;
						}
						break;
					case Yytoken.TYPE_RIGHT_BRACE:
						if(statusStack.size()>1){
							statusStack.removeFirst();
							status=peekStatus(statusStack);
						}
						else{
							status=S_IN_FINISHED_VALUE;
						}
						if(!contentHandler.endObject())
							return;
						break;
					default:
						status=S_IN_ERROR;
						break;
					}//inner switch
					break;
					
				case S_PASSED_PAIR_KEY:
					nextToken();
					switch(token.type){
					case Yytoken.TYPE_COLON:
						break;
					case Yytoken.TYPE_VALUE:
						statusStack.removeFirst();
						status=peekStatus(statusStack);
						if(!contentHandler.primitive(token.value))
							return;
						if(!contentHandler.endObjectEntry())
							return;
						break;
					case Yytoken.TYPE_LEFT_SQUARE:
						statusStack.removeFirst();
						statusStack.addFirst(new Integer(S_IN_PAIR_VALUE));
						status=S_IN_ARRAY;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startArray())
							return;
						break;
					case Yytoken.TYPE_LEFT_BRACE:
						statusStack.removeFirst();
						statusStack.addFirst(new Integer(S_IN_PAIR_VALUE));
						status=S_IN_OBJECT;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startObject())
							return;
						break;
					default:
						status=S_IN_ERROR;
					}
					break;
				
				case S_IN_PAIR_VALUE:
					/*
					 * S_IN_PAIR_VALUE is just a marker to indicate the end of an object entry, it doesn't proccess any token,
					 * therefore delay consuming token until next round.
					 */
					statusStack.removeFirst();
					status = peekStatus(statusStack);
					if(!contentHandler.endObjectEntry())
						return;
					break;
					
				case S_IN_ARRAY:
					nextToken();
					switch(token.type){
					case Yytoken.TYPE_COMMA:
						break;
					case Yytoken.TYPE_VALUE:
						if(!contentHandler.primitive(token.value))
							return;
						break;
					case Yytoken.TYPE_RIGHT_SQUARE:
						if(statusStack.size()>1){
							statusStack.removeFirst();
							status=peekStatus(statusStack);
						}
						else{
							status=S_IN_FINISHED_VALUE;
						}
						if(!contentHandler.endArray())
							return;
						break;
					case Yytoken.TYPE_LEFT_BRACE:
						status=S_IN_OBJECT;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startObject())
							return;
						break;
					case Yytoken.TYPE_LEFT_SQUARE:
						status=S_IN_ARRAY;
						statusStack.addFirst(new Integer(status));
						if(!contentHandler.startArray())
							return;
						break;
					default:
						status=S_IN_ERROR;
					}//inner switch
					break;
					
				case S_END:
					return;
					
				case S_IN_ERROR:
					throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
				}//switch
				if(status==S_IN_ERROR){
					throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
				}
			}while(token.type!=Yytoken.TYPE_EOF);
		}
		catch(IOException ie){
			status = S_IN_ERROR;
			throw ie;
		}
		catch(ParseException pe){
			status = S_IN_ERROR;
			throw pe;
		}
		catch(RuntimeException re){
			status = S_IN_ERROR;
			throw re;
		}
		catch(Error e){
			status = S_IN_ERROR;
			throw e;
		}
		
		status = S_IN_ERROR;
		throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
	}
}
