/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
package net.sourceforge.phpdt.internal.corext.util;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DefaultLineTracker;
import org.eclipse.jface.text.ILineTracker;
import org.eclipse.jface.text.IRegion;

//import org.eclipse.jdt.internal.corext.Assert;

/**
 * Helper class to provide String manipulation functions not available in standard JDK.
 */
public class Strings {

	public static String removeNewLine(String message) {
		StringBuffer result= new StringBuffer();
		int current= 0;
		int index= message.indexOf('\n', 0);
		while (index != -1) {
			result.append(message.substring(current, index));
			if (current < index && index != 0)
				result.append(' ');
			current= index + 1;
			index= message.indexOf('\n', current);
		}
		result.append(message.substring(current));
		return result.toString();
	}

	/**
	 * Converts the given string into an array of lines. The lines 
	 * don't contain any line delimiter characters.
	 *
	 * @return the string converted into an array of strings. Returns <code>
	 * 	null</code> if the input string can't be converted in an array of lines.
	 */
	public static String[] convertIntoLines(String input) {
		try {
			ILineTracker tracker= new DefaultLineTracker();
			tracker.set(input);
			int size= tracker.getNumberOfLines();
			String result[]= new String[size];
			for (int i= 0; i < size; i++) {
				IRegion region= tracker.getLineInformation(i);
				int offset= region.getOffset();
				result[i]= input.substring(offset, offset + region.getLength());
			}
			return result;
		} catch (BadLocationException e) {
			return null;
		}
	}

	/**
	 * Returns <code>true</code> if the given string only consists of
	 * white spaces according to Java. If the string is empty, <code>true
	 * </code> is returned.
	 * 
	 * @return <code>true</code> if the string only consists of white
	 * 	spaces; otherwise <code>false</code> is returned
	 * 
	 * @see java.lang.Character#isWhitespace(char)
	 */
	public static boolean containsOnlyWhitespaces(String s) {
		int size= s.length();
		for (int i= 0; i < size; i++) {
			if (!Character.isWhitespace(s.charAt(i)))
				return false;
		}
		return true;
	}
	
	/**
	 * Removes leading tabs and spaces from the given string. If the string
	 * doesn't contain any leading tabs or spaces then the string itself is 
	 * returned.
	 */
	public static String trimLeadingTabsAndSpaces(String line) {
		int size= line.length();
		int start= size;
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c != '\t' && !Character.isSpaceChar(c)) {
				start= i;
				break;
			}
		}
		if (start == 0)
			return line;
		else if (start == size)
			return ""; //$NON-NLS-1$
		else
			return line.substring(start);
	}
	
	public static String trimTrailingTabsAndSpaces(String line) {
		int size= line.length();
		int end= size;
		for (int i= size - 1; i >= 0; i--) {
			char c= line.charAt(i);
			if (c == '\t' || Character.isSpaceChar(c)) {
				end= i;
			} else {
				break;
			}
		}
		if (end == size)
			return line;
		else if (end == 0)
			return ""; //$NON-NLS-1$
		else
			return line.substring(0, end);
	}
	
	/**
	 * Returns the indent of the given string.
	 * 
	 * @param line the text line
	 * @param tabWidth the width of the '\t' character.
	 */
	public static int computeIndent(String line, int tabWidth) {
		int result= 0;
		int blanks= 0;
		int size= line.length();
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c == '\t') {
				result++;
				blanks= 0;
			} else if (Character.isSpaceChar(c)) {
				blanks++;
				if (blanks == tabWidth) {
					result++;
					blanks= 0;
				}
			} else {
				return result;
			}
		}
		return result;
	}
	
	/**
	 * Removes the given number of idents from the line. Asserts that the given line 
	 * has the requested number of indents. If <code>indentsToRemove <= 0</code>
	 * the line is returned.
	 */
	public static String trimIndent(String line, int indentsToRemove, int tabWidth) {
		if (line == null || indentsToRemove <= 0)
			return line;
			
		int start= 0;
		int indents= 0;
		int blanks= 0;
		int size= line.length();
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c == '\t') {
				indents++;
				blanks= 0;
			} else if (Character.isSpaceChar(c)) {
					blanks++;
					if (blanks == tabWidth) {
						indents++;
						blanks= 0;
					}
			} else {
//				Assert.isTrue(false, "Line does not have requested number of indents"); //$NON-NLS-1$
			}
			if (indents == indentsToRemove) {
				start= i + 1;
				break;
			}	
		}
		if (start == size)
			return ""; //$NON-NLS-1$
		else
			return line.substring(start);
	}
	
	/**
	 * Removes all leading indents from the given line. If the line doesn't contain
	 * any indents the line itself is returned.
	 */
	public static String trimIndents(String s, int tabWidth) {
		int indent= computeIndent(s, tabWidth);
		if (indent == 0)
			return s;
		return trimIndent(s, indent, tabWidth);
	}
	
	/**
	 * Removes the common number of indents from all lines. If a line
	 * only consists out of white space it is ignored.
	 */
	public static void trimIndentation(String[] lines, int tabWidth) {
		String[] toDo= new String[lines.length];
		// find indentation common to all lines
		int minIndent= Integer.MAX_VALUE; // very large
		for (int i= 0; i < lines.length; i++) {
			String line= lines[i];
			if (containsOnlyWhitespaces(line))
				continue;
			toDo[i]= line;
			int indent= computeIndent(line, tabWidth);
			if (indent < minIndent) {
				minIndent= indent;
			}
		}
		
		if (minIndent > 0) {
			// remove this indent from all lines
			for (int i= 0; i < toDo.length; i++) {
				String s= toDo[i];
				if (s != null)
					lines[i]= trimIndent(s, minIndent, tabWidth);
				else {
					String line= lines[i];
					int indent= computeIndent(line, tabWidth);
					if (indent > minIndent)
						lines[i]= trimIndent(line, minIndent, tabWidth);
					else
						lines[i]= trimLeadingTabsAndSpaces(line);
				}
			}
		}
	}
	
	public static String getIndentString(String line, int tabWidth) {
		int size= line.length();
		int end= 0;
		int blanks= 0;
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c == '\t') {
				end= i;
				blanks= 0;
			} else if (Character.isSpaceChar(c)) {
				blanks++;
				if (blanks == tabWidth) {
					end= i;
					blanks= 0;
				}
			} else {
				break;
			}
		}
		if (end == 0)
			return ""; //$NON-NLS-1$
		else if (end == size)
			return line;
		else
			return line.substring(0, end + 1);
	}
}