package org.simantics.scl.compiler.parser.generator.compression;

import java.util.Arrays;

import org.simantics.scl.compiler.parser.generator.table.ParseTableBuilder;

public class GCCompress {
    
    public static final int DONT_CARE = ParseTableBuilder.ERROR_ACTION;
    
    private static int[][] compressRows(int[] colors, final int[][] table) {
        final int columns = table[0].length;
        int colorCount = GraphColoring.color(colors, new GraphColoring.ColGraph() {
            @Override
            public int size() {
                return table.length;
            }
            
            @Override
            public boolean areConnected(int a, int b) {
                int[] aRow = table[a];
                int[] bRow = table[b];
                for(int i=0;i<columns;++i) {
                    int aV = aRow[i];
                    int bV = bRow[i];
                    if(aV != DONT_CARE && bV != DONT_CARE && aV != bV)
                        return true;
                }
                return false;
            }
        });
        
        final int[][] compr = new int[colorCount][columns];
        for(int i=0;i<compr.length;++i)
            Arrays.fill(compr[i], DONT_CARE);
        
        for(int i=0;i<table.length;++i) {
            int color = colors[i];
            int[] inRow = table[i];
            int[] outRow = compr[color];
            for(int j=0;j<columns;++j) {
                int v = inRow[j];
                if(v != DONT_CARE)
                    outRow[j] = v;
            }
        }
        
        return compr;
    }
    
    private static int[][] compressColumns(int[] colors, final int[][] table) {
        final int columns = table[0].length;
        int colorCount = GraphColoring.color(colors, new GraphColoring.ColGraph() {
            @Override
            public int size() {
                return columns;
            }
            
            @Override
            public boolean areConnected(int a, int b) {
                for(int i=0;i<table.length;++i) {
                    int[] row = table[i];
                    int aV = row[a];
                    int bV = row[b];
                    if(aV != DONT_CARE && bV != DONT_CARE && aV != bV)
                        return true;
                }
                return false;
            }
        });
        
        final int[][] compr = new int[table.length][colorCount];
        for(int i=0;i<compr.length;++i) {
            Arrays.fill(compr[i], DONT_CARE);
        }
        for(int i=0;i<table.length;++i) {
            for(int j=0;j<columns;++j) {
                int v = table[i][j];
                if(v != DONT_CARE) {
                    int color = colors[j];
                    compr[i][color] = v;
                }
            }
        }
        
        return compr;
    }
    
    public static CompressedTable compress(int[][] table) {
        System.out.println("Compress:");
        System.out.println("    Rows: " + table.length);
        System.out.println("    Columns: " + table[0].length);
        
        int[] rowIndex = new int[table.length];
        int[] columnIndex = new int[table[0].length];
        
        table = compressRows(rowIndex, table);
        table = compressColumns(columnIndex, table);
        
        System.out.println("    Compressed rows: " + table.length);
        System.out.println("    Compressed columns: " + table[0].length);
        
        int columns = table[0].length;        
        
        int[] compressedTable = new int[table.length * columns];
        for(int i=0;i<table.length;++i)
            System.arraycopy(table[i], 0, compressedTable, i*columns, columns);
        for(int i=0;i<rowIndex.length;++i)
            rowIndex[i] *= columns;
        return new CompressedTable(rowIndex, columnIndex, compressedTable);
        
        //for(int[] row : table)
        //    System.out.println(Arrays.toString(row));
    }
    
}