/*******************************************************************************
 * Copyright (c) 2000 - 2017 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Lucas Bullen (Red Hat Inc.) - [Bug 203792] filter should support multiple keywords
 *******************************************************************************/
package org.eclipse.ui.internal.misc;

import java.util.Vector;

/**
 * A string pattern matcher, suppporting "*" and "?" wildcards.
 */
public class StringMatcher {
    protected String fPattern;

    protected int fLength; // pattern length

    protected boolean fIgnoreWildCards;

    protected boolean fIgnoreCase;

    protected boolean fHasLeadingStar;

    protected boolean fHasTrailingStar;

	protected String fSegments[]; // the given pattern is split into * separated segments

    /* boundary value beyond which we don't need to search in the text */
    protected int fBound = 0;

    protected String[] wordsSplitted;

    protected Word words[];

    protected static final char fSingleWildCard = '\u0000';

    public class Word {
        boolean hasTrailingStar = false;
        boolean hasLeadingStar = false;
        int bound = 0;
        String[] fragments = null;
        String pattern = null;
    }

    public static class Position {
        int start; //inclusive

        int end; //exclusive

        public Position(int start, int end) {
            this.start = start;
            this.end = end;
        }

        public int getStart() {
            return start;
        }

        public int getEnd() {
            return end;
        }
    }

    /**
     * StringMatcher constructor takes in a String object that is a simple
     * pattern which may contain '*' for 0 and many characters and
     * '?' for exactly one character.
     *
     * Literal '*' and '?' characters must be escaped in the pattern
     * e.g., "\*" means literal "*", etc.
     *
     * Escaping any other character (including the escape character itself),
     * just results in that character in the pattern.
     * e.g., "\a" means "a" and "\\" means "\"
     *
     * If invoking the StringMatcher with string literals in Java, don't forget
     * escape characters are represented by "\\".
     *
     * @param pattern the pattern to match text against
     * @param ignoreCase if true, case is ignored
     * @param ignoreWildCards if true, wild cards and their escape sequences are ignored
     * 		  (everything is taken literally).
     */
    public StringMatcher(String pattern, boolean ignoreCase,
            boolean ignoreWildCards) {
        if (pattern == null) {
			throw new IllegalArgumentException();
		}
        fIgnoreCase = ignoreCase;
        fIgnoreWildCards = ignoreWildCards;
        fPattern = pattern;
        fLength = pattern.length();

        parsePatternIntoWords();

        if (fIgnoreWildCards) {
            parseNoWildCards();
        } else {
            parseWildCardsForWords();
			parseWildCards();
        }
    }

    /**
     * Find the first occurrence of the pattern between <code>start</code)(inclusive)
     * and <code>end</code>(exclusive).
     * @param text the String object to search in
     * @param start the starting index of the search range, inclusive
     * @param end the ending index of the search range, exclusive
     * @return an <code>StringMatcher.Position</code> object that keeps the starting
     * (inclusive) and ending positions (exclusive) of the first occurrence of the
     * pattern in the specified range of the text; return null if not found or subtext
     * is empty (start==end). A pair of zeros is returned if pattern is empty string
     * Note that for pattern like "*abc*" with leading and trailing stars, position of "abc"
     * is returned. For a pattern like"*??*" in text "abcdf", (1,3) is returned
     */
    public StringMatcher.Position find(String text, int start, int end) {
        if (text == null) {
			throw new IllegalArgumentException();
		}

        int tlen = text.length();
        if (start < 0) {
			start = 0;
		}
        if (end > tlen) {
			end = tlen;
		}
        if (end < 0 || start >= end) {
			return null;
		}
        if (fLength == 0) {
			return new Position(start, start);
		}
        if (fIgnoreWildCards) {
            int x = posIn(text, start, end);
            if (x < 0) {
				return null;
			}
            return new Position(x, x + fLength);
        }

        int segCount = fSegments.length;
        if (segCount == 0) {
			return new Position(start, end);
		}

        int curPos = start;
        int matchStart = -1;
        int i;
        for (i = 0; i < segCount && curPos < end; ++i) {
            String current = fSegments[i];
            int nextMatch = regExpPosIn(text, curPos, end, current);
            if (nextMatch < 0) {
				return null;
			}
            if (i == 0) {
				matchStart = nextMatch;
			}
            curPos = nextMatch + current.length();
        }
        if (i < segCount) {
			return null;
		}
        return new Position(matchStart, curPos);
    }

    /**
     * match the given <code>text</code> with the pattern
     * @return true if matched otherwise false
     * @param text a String object
     */
    public boolean match(String text) {
    	if(text == null) {
			return false;
		}
    	return match(text, 0, text.length());
    }

    /**
     * Given the starting (inclusive) and the ending (exclusive) positions in the
     * <code>text</code>, determine if the given substring matches with aPattern
     * @return true if the specified portion of the text matches the pattern
     * @param text a String object that contains the substring to match
     * @param start marks the starting position (inclusive) of the substring
     * @param end marks the ending index (exclusive) of the substring
     */
    public boolean match(String text, int start, int end) {
        boolean found = true;
        String[] segments = null;
        if (null == text) {
			throw new IllegalArgumentException();
		}

        if (start > end) {
			return false;
		}
        for (int j = 0; j < words.length; j++) {
        	if (fIgnoreWildCards) {
				if ((end - start == words[j].pattern.length())
						&& words[j].pattern.regionMatches(fIgnoreCase, 0, text, start, words[j].pattern.length()))
					return true;
				continue;
        	}
        	segments = words[j].fragments;
			fHasLeadingStar = words[j].hasLeadingStar;
			fHasTrailingStar = words[j].hasTrailingStar;
        int segCount = segments.length;
        if (segCount == 0 && (fHasLeadingStar || fHasTrailingStar)) {
			return true;
		}
        if (start == end) {
        	if (words[j].pattern.length() == 0)
				return true;
			continue;
		}
        if (words[j].pattern.length() == 0) {
			if (start == end)
				return true;
			continue;
		}

        int tlen = text.length();
        if (start < 0) {
			start = 0;
		}
        if (end > tlen) {
			end = tlen;
		}

        int tCurPos = start;
        int bound = end - words[j].bound;
        if (bound < 0) {
			continue;
		}
        int i = 0;
        String current = segments[i];
        int segLength = current.length();

        /* process first segment */
        if (!fHasLeadingStar) {
            if (!regExpRegionMatches(text, start, current, 0, segLength)) {
                continue;
            } else {
                ++i;
                tCurPos = tCurPos + segLength;
            }
        }
        if ((segments.length == 1) && (!fHasLeadingStar)
                && (!fHasTrailingStar)) {
            // only one segment to match, no wildcards specified
        	if (tCurPos == end)
				return true;
			continue;
        }
        /* process middle segments */
        while (i < segCount && found) {
            current = segments[i];
            int currentMatch;
            int k = current.indexOf(fSingleWildCard);
            if (k < 0) {
                currentMatch = textPosIn(text, tCurPos, end, current);
                if (currentMatch < 0) {
					found = false;
				}
            } else {
                currentMatch = regExpPosIn(text, tCurPos, end, current);
                if (currentMatch < 0) {
                	found = false;
				}
            }
            if(!found)
            	continue;
            tCurPos = currentMatch + current.length();
            i++;
        }

        /* process final segment */
        if (!fHasTrailingStar && tCurPos != end) {
            int clen = current.length();
            if (regExpRegionMatches(text, end - clen, current, 0, clen))
				return true;
			continue;
        }
        if (i == segCount)
			return true;
		continue;
    } //end of for loop
    return false;
    }

	/**
	 * This method parses the given pattern into words separated by spaces
	 * characters. Since wildcards are not being used in this case, the pattern
	 * consists of a single segment.
	 */
	private void parsePatternIntoWords() {
		String trimedPattern = fPattern.trim();
		wordsSplitted = trimedPattern.split("\\s+"); //$NON-NLS-1$
		int wordsIndex = 0;
		if (!trimedPattern.isEmpty()) {
			words = new Word[wordsSplitted.length + 1];
			words[wordsIndex] = new Word();
			words[wordsIndex].pattern = trimedPattern;
			wordsIndex = 1;
		} else {
			words = new Word[wordsSplitted.length];
		}
		for (int i = 0; i < wordsSplitted.length; i++) {
			words[wordsIndex] = new Word();
			words[wordsIndex].pattern = wordsSplitted[i];
			wordsIndex++;
		}
	}

    /**
     * This method parses the given pattern into segments seperated by wildcard '*' characters.
     * Since wildcards are not being used in this case, the pattern consists of a single segment.
     */
    private void parseNoWildCards() {
        fSegments = new String[1];
        fSegments[0] = fPattern;
        fBound = fLength;
        words = new Word[1];
        words[0].pattern = fPattern;
        words[0].bound = fLength;
        words[0].fragments = wordsSplitted;
    }

    /**
     * Parses the given pattern into segments seperated by wildcard '*' characters.
     * @param p, a String object that is a simple regular expression with '*' and/or '?'
     */
    private void parseWildCards() {
        if (fPattern.startsWith("*")) { //$NON-NLS-1$
			fHasLeadingStar = true;
		}
        if (fPattern.endsWith("*")) {//$NON-NLS-1$
            /* make sure it's not an escaped wildcard */
            if (fLength > 1 && fPattern.charAt(fLength - 2) != '\\') {
                fHasTrailingStar = true;
            }
        }

        Vector temp = new Vector();

        int pos = 0;
        StringBuilder buf = new StringBuilder();
        while (pos < fLength) {
            char c = fPattern.charAt(pos++);
            switch (c) {
            case '\\':
                if (pos >= fLength) {
                    buf.append(c);
                } else {
                    char next = fPattern.charAt(pos++);
                    /* if it's an escape sequence */
                    if (next == '*' || next == '?' || next == '\\') {
                        buf.append(next);
                    } else {
                        /* not an escape sequence, just insert literally */
                        buf.append(c);
                        buf.append(next);
                    }
                }
                break;
            case '*':
                if (buf.length() > 0) {
                    /* new segment */
                    temp.addElement(buf.toString());
                    fBound += buf.length();
                    buf.setLength(0);
                }
                break;
            case '?':
                /* append special character representing single match wildcard */
                buf.append(fSingleWildCard);
                break;
            default:
                buf.append(c);
            }
        }

        /* add last buffer to segment list */
        if (buf.length() > 0) {
            temp.addElement(buf.toString());
            fBound += buf.length();
        }

        fSegments = new String[temp.size()];
        temp.copyInto(fSegments);
    }

    /**
	 * Parses the given words into segments separated by wildcard '*'
	 */
	private void parseWildCardsForWords() {
		for (int i = 0; i < words.length; i++) {

			if (words[i].pattern.startsWith("*")) { //$NON-NLS-1$
				words[i].hasLeadingStar = true;
			}
			if (words[i].pattern.endsWith("*")) {//$NON-NLS-1$
				/* make sure it's not an escaped wildcard */
				if (words[i].pattern.length() > 1 && words[i].pattern.charAt(words[i].pattern.length() - 2) != '\\') {
					words[i].hasTrailingStar = true;
				}
			}

			Vector temp = new Vector();

			int pos = 0;
			StringBuilder buf = new StringBuilder();
			while (pos < words[i].pattern.length()) {
				char c = words[i].pattern.charAt(pos++);
				switch (c) {
				case '\\':
					if (pos >= words[i].pattern.length()) {
						buf.append(c);
					} else {
						char next = words[i].pattern.charAt(pos++);
						/* if it's an escape sequence */
						if (next == '*' || next == '?' || next == '\\') {
							buf.append(next);
						} else {
							/* not an escape sequence, just insert literally */
							buf.append(c);
							buf.append(next);
						}
					}
					break;
				case '*':
					if (buf.length() > 0) {
						/* new segment */
						temp.addElement(buf.toString());
						words[i].bound += buf.length();
						buf.setLength(0);
					}
					break;
				case '?':
					/* append special character representing single match wildcard */
					buf.append(fSingleWildCard);
					break;
				default:
					buf.append(c);
				}
			}

			/* add last buffer to segment list */
			if (buf.length() > 0) {
				temp.addElement(buf.toString());
				words[i].bound += buf.length();
			}

			words[i].fragments = new String[temp.size()];
			temp.copyInto(words[i].fragments);
		} // end of for loop
	}

    /**
     * @param text a string which contains no wildcard
     * @param start the starting index in the text for search, inclusive
     * @param end the stopping point of search, exclusive
     * @return the starting index in the text of the pattern , or -1 if not found
     */
    protected int posIn(String text, int start, int end) {//no wild card in pattern
        int max = end - fLength;

        if (!fIgnoreCase) {
            int i = text.indexOf(fPattern, start);
            if (i == -1 || i > max) {
				return -1;
			}
            return i;
        }

        for (int i = start; i <= max; ++i) {
            if (text.regionMatches(true, i, fPattern, 0, fLength)) {
				return i;
			}
        }

        return -1;
    }

    /**
     * @param text a simple regular expression that may only contain '?'(s)
     * @param start the starting index in the text for search, inclusive
     * @param end the stopping point of search, exclusive
     * @param p a simple regular expression that may contains '?'
     * @return the starting index in the text of the pattern , or -1 if not found
     */
    protected int regExpPosIn(String text, int start, int end, String p) {
        int plen = p.length();

        int max = end - plen;
        for (int i = start; i <= max; ++i) {
            if (regExpRegionMatches(text, i, p, 0, plen)) {
				return i;
			}
        }
        return -1;
    }

    /**
     *
     * @return boolean
     * @param text a String to match
     * @param start int that indicates the starting index of match, inclusive
     * @param end</code> int that indicates the ending index of match, exclusive
     * @param p String,  String, a simple regular expression that may contain '?'
     * @param ignoreCase boolean indicating wether code>p</code> is case sensitive
     */
    protected boolean regExpRegionMatches(String text, int tStart, String p,
            int pStart, int plen) {
        while (plen-- > 0) {
            char tchar = text.charAt(tStart++);
            char pchar = p.charAt(pStart++);

            /* process wild cards */
            if (!fIgnoreWildCards) {
                /* skip single wild cards */
                if (pchar == fSingleWildCard) {
                    continue;
                }
            }
            if (pchar == tchar) {
				continue;
			}
            if (fIgnoreCase) {
                if (Character.toUpperCase(tchar) == Character
                        .toUpperCase(pchar)) {
					continue;
				}
                // comparing after converting to upper case doesn't handle all cases;
                // also compare after converting to lower case
                if (Character.toLowerCase(tchar) == Character
                        .toLowerCase(pchar)) {
					continue;
				}
            }
            return false;
        }
        return true;
    }

    /**
     * @param text the string to match
     * @param start the starting index in the text for search, inclusive
     * @param end the stopping point of search, exclusive
     * @param p a pattern string that has no wildcard
     * @return the starting index in the text of the pattern , or -1 if not found
     */
    protected int textPosIn(String text, int start, int end, String p) {

        int plen = p.length();
        int max = end - plen;

        if (!fIgnoreCase) {
            int i = text.indexOf(p, start);
            if (i == -1 || i > max) {
				return -1;
			}
            return i;
        }

        for (int i = start; i <= max; ++i) {
            if (text.regionMatches(true, i, p, 0, plen)) {
				return i;
			}
        }

        return -1;
    }
}