/**
 *   @(#) ScriptScanner.java
 */
package edu.hust.tool;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.StringTokenizer;
import java.util.Iterator;

/**
 * ScriptScanner is a tool for escaping all the commentary in the sql script.
 * Three commentaries are supported:
 * <p>
 *  Block comment: codes in  /* and */
/* Line comment:   -- the remain of the linde  
 *                  // the remain of the line
 * </p>
 *  
 * <p>
 *  Usage:
 * <code>
 *    ScriptScanner scanner = new ScriptScanner( script ); 
 *                           // new ScriptScanner(
 *                           //            new File( scriptfile );
 *    for( Iterator iter = scanner.hasNext(); iter.hasNext(); ) {
 *         System.out.println( iter.next());
 *    }
 * </code>
 * </p> 
 */
/*
 *   @author quickpoint At HUST
 *   @version 1.0 2007-03-26  
 */
public class ScriptScanner {
	private BufferedReader reader = null;       // the reader( input stream )
	private StringBuffer buf;                   // script buffer           
	private Collection<String> statements       // sttements
	                  = new ArrayList<String>();
	private int totalStatements = 0;            // total statements count
	private boolean skipRemark = true;          // skip remark flag
	private boolean replaceQuote = true;        // replace quote flag
	
	// Constants used in the scanning
	private static final String DELIMSTATEMENT = ";"; 
	private static final char ENDLINE = '\n';
	private static final char ENDSTATEMENT = ';';
	private static final char RSPLASH = '/';
	private static final char ONE_QUOTE = '\'';
	private static final char DOUBLE_ONE_QUOTE = '"';
	private static final char STAR = '*';
	private static final char LINESIGN = '-';
	
	/**
	 *  Iterator on the statements
	 *  @return iterator on the result of statements
	 */
	public Iterator iterator() {
		return Collections.unmodifiableCollection( 
		                                     statements ).iterator();
	}
	
	/**
	 *  Total statements count 
	 *  @return total statements count
	 */
	public int totalStatements() {
		return totalStatements;
	}
	//===============================================================
	/**
	 *  Construct a scanner by the script string
	 */
	public ScriptScanner( String script ) {
		this( new StringReader( script ));
	}
	
	/**
	 *  Construct a scanner by the file
	 */  
	public ScriptScanner( File file ) {
		try {
			reader = new BufferedReader( 
			              new FileReader( file ));
			parse();
		} catch ( FileNotFoundException ex ) {
			ex.printStackTrace();
		} catch ( IOException ex ) {
			ex.printStackTrace();
		}
	}
	
	/**
	 *  Construct a scanner by the reader
	 */
	public ScriptScanner( Reader reader ) {
		try {
		    this.reader = (reader instanceof BufferedReader )?
		                      (BufferedReader)reader :
		                       new BufferedReader( reader );  
			parse();
		} catch ( IOException ex ) {
			ex.printStackTrace();
		}
	}
	
	/**
	 *   Skip remark during scanning?
	 *   @param skipRemark skip remark flag, 
	 *      if set as true, the mark will be skipped,
	 *      else the mark will not be skipped.
	 *      The default is true   
	 */
	public void skipRemark( boolean skipRemark) {
		this.skipRemark = skipRemark;
	}
	
	/**
	 *  Replace quote druing scanning?
	 *  @param replaceQuote replace quote flag.
	 *      if set as true, the quote " will be replaced as ',
	 *      else the quote will not be replaed.
	 *      The default is true
	 */
	public void replaceQuote( boolean replaceQuote ) {
		this.replaceQuote = replaceQuote;
	}
	
	// read one char
	private int read() throws IOException {
		return reader.read();
	}
	
	// do the parse	
	private void parse() throws IOException {
		int ch = read();
		buf = new StringBuffer();
		while ( true ) {
			if ( ch < 0 ) {
			    break;     // end of the file
		    }
			switch ( ch ) {
				case ONE_QUOTE:  // fall thru
				case DOUBLE_ONE_QUOTE: {
					int last = ch;
					if ( replaceQuote ) {
					  buf.append( ( char ) ONE_QUOTE );
					} else {
				      buf.append( ( char ) ch );
					}
					while ( true ) {  // read till see the last
						ch = read();
						if ( ch < 0 ) {
							break;
						}
						if ( replaceQuote && ch == last ) {
						   buf.append( ONE_QUOTE);
						} else {
						   buf.append( (char) ch );
	                    }
						if ( ch == last ) {
							break;
						}
					}
					ch = read();
					break;
				}
				
				case RSPLASH: {
					int last = ch;
					ch = read();
					if ( ch < 0 ) {
						break;
					}
					if ( ch == STAR ) {
						// block remaark
					    if ( !skipRemark ) {
						   buf.append( ( char ) last );
						   buf.append( ( char ) ch );
					    }
					    while ( true ) {  // read till see the */
 					    	ch = read();
 					    	if ( ch < 0 ) {
 					    		break;
 					    	}
 					    	if ( !skipRemark ) {
 					    		buf.append( ( char ) ch );		
 					    	}
 					    	if ( ch == STAR ) {
 					    		ch = read();
 					    		if ( ch < 0 ) {
 					    			break;
 					    		}
 					    		if ( !skipRemark ) {
 					    			buf.append( ( char ) ch );
 					    		}
 					    		if ( ch == RSPLASH ) {
 					    			break;
 					    		}
 					    	}
					    }
					    ch = read();
					} else if ( ch == RSPLASH ){
						// single line remark
						if ( !skipRemark ) {
							buf.append( ( char ) last );
							buf.append( ( char ) ch );
						}
						while ( true ) {  // read till see the \r\n
							ch = read();
							if ( ch < 0 ) {
								break;
							}
							if ( !skipRemark ) {
								buf.append( ( char ) ch );
							}
							if ( ch == ENDLINE ) {
								break;
							}
						}
						ch = read();
					} else {
						buf.append( ( char ) last );
					}
					break;
				}
				
				case LINESIGN : {
					int last = ch;
					ch = read();
					if ( ch < 0 ) {
						break;
					}
					if ( ch == LINESIGN ) {  
					     // single line remark 
						if ( !skipRemark ) {
							buf.append( ( char ) last );
							buf.append( ( char ) ch );
						}
						while ( true ) { // read till see the \r\n
						   ch = read();
						   if ( ch < 0 ) {
						   		break;
						   }
						   if ( !skipRemark ) {
						   	 buf.append( ( char ) ch );
						   }	
						   if ( ch == ENDLINE ) {
						   		break;
						   }
						}
						ch = read();
					} else {
						buf.append( (char) ch );
					}
					break;
				}
				default: {
					buf.append( ( char ) ch );
					ch = read();
					break;
				}	
			}
		} 
		// orange the results
		StringTokenizer st = new StringTokenizer( buf.toString(), DELIMSTATEMENT );
		while( st.hasMoreTokens()) {
			String statement = st.nextToken().trim();
			if ( statement.length() == 0) {  // trip out the empty string
				continue;
			}
			totalStatements++;
			statements.add( statement + ENDSTATEMENT);
		}
	}	
}