package org.simantics.spreadsheet.graph.formula;

import org.simantics.databoard.binding.mutable.Variant;
import org.simantics.spreadsheet.graph.CellFormulaFunction;
import org.simantics.spreadsheet.graph.CellValueVisitor;
import org.simantics.spreadsheet.graph.SpreadsheetGraphUtils;
import org.simantics.spreadsheet.graph.SpreadsheetMatrix;
import org.simantics.spreadsheet.graph.parser.ast.AstArgList;

public class HlookupFormulaFunction implements CellFormulaFunction<Object> {

    @Override
    public Object evaluate(CellValueVisitor visitor, AstArgList args) {
        if (args.values.size() < 3 || args.values.size() > 4) throw new IllegalStateException();

        Object lookupValue = args.values.get(0).accept(visitor);
        boolean lookupIsString = lookupValue instanceof String;

        FormulaError2 error = FormulaError2.forObject(lookupValue);
        if(error!=null) return error.getString();
        
        if(lookupValue instanceof Variant){
        	Object varVal = ((Variant)lookupValue).getValue();
        	Double dVal = SpreadsheetGraphUtils.asDoubleWhereEmptyStringIsZero(varVal);
        	if(dVal==null) {
        		lookupValue = varVal.toString();
        		lookupIsString = true;
        	}
        	else lookupValue = dVal;
        }
        
        SpreadsheetMatrix array = (SpreadsheetMatrix) args.values.get(1).accept(visitor);
        
        boolean approximateMatch = args.values.size() == 4 ? (Boolean) args.values.get(3).accept(visitor) : true;

		if(array.values.length != 0){
			if(lookupIsString){
				Object obj = array.values[0];
				if(obj instanceof Variant)
					obj = ((Variant)obj).getValue();
				if(SpreadsheetGraphUtils.asValidNumber(obj)!=null)
					return FormulaError2.NA.getString();
				obj = obj.toString();
				String valStr = ((String)obj).toLowerCase();
				if((lookupValue.toString().toLowerCase()).compareTo(valStr)<0 )
					return FormulaError2.NA.getString();
			}
			else if(lookupValue instanceof Number){
				Double d = ((Number)lookupValue).doubleValue();
				Number d2 = SpreadsheetGraphUtils.asValidNumber(array.values[0]);
				if(d2==null || d<(d2.doubleValue()))
					return FormulaError2.NA.getString();
			}
		}

        Number rowIndexN = (Number) SpreadsheetGraphUtils.asValidNumber(args.values.get(2).accept(visitor));
        if(rowIndexN==null) return FormulaError2.REF.getString();
        int rowIndexNum = rowIndexN.intValue();
		if(rowIndexNum>array.getHeight()) return FormulaError2.REF.getString();
		
        if (approximateMatch) {
        	Integer colPosOfLargestValSmallerThanLookUp = null;
        	if(lookupIsString){
        		String largestValSmallerThanLookUp = null;
        		String ref = lookupValue.toString();
        		String previousValue = null;
        		for(int i = 0; i < array.getWidth(); i++){
        			Object val = array.get(0, i);
        			if(val instanceof Variant)
        				val = ((Variant)val).getValue();
        			String currValue = val.toString();
        			int currCompedToRef = currValue.compareTo(ref);
        			if(currCompedToRef>=0){
        				if(i==0)
        					return array.get(rowIndexNum-1, i);
        				else if(previousValue.compareTo(ref) > currCompedToRef )
        					return array.get(rowIndexNum-1, i);
        				else 
        					return array.get(rowIndexNum - 1, i - 1);
        			}
        			if(colPosOfLargestValSmallerThanLookUp==null){
        				colPosOfLargestValSmallerThanLookUp = i;
        				largestValSmallerThanLookUp = currValue;
        			} else if(largestValSmallerThanLookUp.compareTo(currValue)<0){
        				colPosOfLargestValSmallerThanLookUp = i;
        				largestValSmallerThanLookUp = currValue;
        			}
        			previousValue = currValue;
        		}
        		
        	} else {
        		double ref = SpreadsheetGraphUtils.asNumber(lookupValue);
        		double lastDiff = Double.MIN_VALUE;
        		Double largestValSmallerThanLookUp = null;
            	for (int i = 0; i < array.getWidth(); i++) {
                	Object value = array.get(0, i);
                	double n = SpreadsheetGraphUtils.asNumber(value);
                	double diff = n - ref;
                	if (diff >= 0) {
                    	if (i == 0)
                        	return array.get(rowIndexNum - 1, i);
                    	else if (diff < -lastDiff)
                        	return array.get(rowIndexNum - 1, i);
                    	else
                        	return array.get(rowIndexNum - 1, i - 1);
                	}
        			if(colPosOfLargestValSmallerThanLookUp==null){
        				colPosOfLargestValSmallerThanLookUp = i;
        				largestValSmallerThanLookUp = n;
        			} else if(largestValSmallerThanLookUp < n){
        				colPosOfLargestValSmallerThanLookUp = i;
        				largestValSmallerThanLookUp = n;
        			}
                	lastDiff = diff;
            	}
        	}
        	if(colPosOfLargestValSmallerThanLookUp!=null) return array.get(rowIndexNum - 1, colPosOfLargestValSmallerThanLookUp);
        	
        } else {

            for (int i = 0; i < array.getWidth(); i++) {
                Object value = array.get(0, i);
                if(value instanceof Variant){
                	if(lookupIsString)
                		value = ((Variant)value).getValue().toString();
                	else 
                		value = SpreadsheetGraphUtils.asNumber(value);
                }
                if (SpreadsheetGraphUtils.excelEquals(lookupValue, value)) {
                    return array.get(rowIndexNum - 1, i);
                }
            }

        }

        return FormulaError2.NA.getString();
    }

}