// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/**
 *******************************************************************************
 * Copyright (C) 2002-2010, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 */

package com.ibm.icu.dev.tool.layout;

import java.util.Vector;

import com.ibm.icu.impl.Utility;
import com.ibm.icu.lang.UCharacter;
import com.ibm.icu.lang.UScript;
import com.ibm.icu.text.CanonicalIterator;
import com.ibm.icu.text.UTF16;
import com.ibm.icu.text.UnicodeSet;

public class CanonicalCharacterData
{
    private static int THRESHOLD = 4;
    
    public class Record
    {
        // TODO: might want to save arrays of Char32's rather than UTF16 strings...
        Record(int character, int script)
        {
            String char32 = UCharacter.toString(character);
            CanonicalIterator iterator = new CanonicalIterator(char32);
            Vector equivs = new Vector();
            
            composed = character;
            
            for (String equiv = iterator.next(); equiv != null; equiv = iterator.next()) {
                // Skip all equivalents of length 1; it's either the original
                // character or something like Angstrom for A-Ring, which we don't care about
                if (UTF16.countCodePoint(equiv) > 1) {
                    equivs.add(equiv);
                }
            }
            
            int nEquivalents = equivs.size();
            
            if (nEquivalents > maxEquivalents[script]) {
                maxEquivalents[script] = nEquivalents;
            }
            
            if (nEquivalents > 0) {
                equivalents = new String[nEquivalents];
                
                if (nEquivalents > THRESHOLD) {
                    dumpEquivalents(character, equivs);
                }
                
                sortEquivalents(equivalents, equivs);
            }
        }
        
        public int getComposedCharacter()
        {
            return composed;
        }
        
        public int countEquivalents()
        {
            if (equivalents == null) {
                return 0;
            }
            
            return equivalents.length;
        }
        
        public String[] getEquivalents()
        {
            return equivalents;
        }
        
        public String getEquivalent(int index)
        {
            if (equivalents == null || index < 0 || index >= equivalents.length) {
                return null;
            }
            
            return equivalents[index];
        }
        
        private void dumpEquivalents(int character, Vector equivs)
        {
            int count = equivs.size();
            
            System.out.println(Utility.hex(character, 6) + " - " + count + ":");
            
            for (int i = 0; i < count; i += 1) {
                String equiv = (String) equivs.elementAt(i);
                int codePoints = UTF16.countCodePoint(equiv);
                
                for (int c = 0; c < codePoints; c += 1) {
                    if (c > 0) {
                        System.out.print(" ");
                    }
                    
                    System.out.print(Utility.hex(UTF16.charAt(equiv, c), 6));
                }
                
                System.out.println();
            }
            
            System.out.println();
        }
        
        private int composed;
        private String[] equivalents = null;
    }
    
    public CanonicalCharacterData()
    {
        // nothing to do...
    }
    
    public void add(int character)
    {
        int script = UScript.getScript(character);
        Vector recordVector = recordVectors[script];
        
        if (recordVector == null) {
            recordVector = recordVectors[script] = new Vector();
        }
        
        recordVector.add(new Record(character, script));
    }
    
    public int getMaxEquivalents(int script)
    {
        if (script < 0 || script >= UScript.CODE_LIMIT) {
            return 0;
        }
        
        return maxEquivalents[script];
    }
    
    public Record getRecord(int script, int index)
    {
        if (script < 0 || script >= UScript.CODE_LIMIT) {
            return null;
        }
        
        Vector recordVector = recordVectors[script];
        
        if (recordVector == null || index < 0 || index >= recordVector.size()) {
            return null;
        }
        
        return (Record) recordVector.elementAt(index);
    }
    
    public int countRecords(int script)
    {
        if (script < 0 || script >= UScript.CODE_LIMIT ||
            recordVectors[script] == null) {
            return 0;
        }
        
        return recordVectors[script].size();
    }
 
    public static CanonicalCharacterData factory(UnicodeSet characterSet)
    {
        int charCount = characterSet.size();
        CanonicalCharacterData data = new CanonicalCharacterData();
        
        System.out.println("There are " + charCount + " characters with a canonical decomposition.");
        
        for (int i = 0; i < charCount; i += 1) {
            data.add(characterSet.charAt(i));
        }
        
        return data;
    }

    private static int compareEquivalents(String a, String b)
    {
        int result = UTF16.countCodePoint(a) - UTF16.countCodePoint(b);
            
        if (result == 0) {
            return a.compareTo(b);
        }
            
        return result;
    }
        
    //
    // Straight insertion sort from Knuth vol. III, pg. 81
    //
    private static void sortEquivalents(String[] equivalents, Vector unsorted)
    {
        int nEquivalents = equivalents.length;
        
        for (int e = 0; e < nEquivalents; e += 1) {
            String v = (String) unsorted.elementAt(e);
            int i;
            
            for (i = e - 1; i >= 0; i -= 1) {
                if (compareEquivalents(v, equivalents[i]) >= 0) {
                  break;
                }

                equivalents[i + 1] = equivalents[i];
            }

            equivalents[i + 1] = v;
       }
    }
            
    private Vector recordVectors[] = new Vector[UScript.CODE_LIMIT];
    private int maxEquivalents[] = new int[UScript.CODE_LIMIT];

}