package com.metaweb.gridworks.operations;

import java.util.List;
import java.util.Properties;

import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONWriter;

import com.metaweb.gridworks.browsing.RowVisitor;
import com.metaweb.gridworks.expr.Evaluable;
import com.metaweb.gridworks.expr.ExpressionUtils;
import com.metaweb.gridworks.expr.MetaParser;
import com.metaweb.gridworks.model.AbstractOperation;
import com.metaweb.gridworks.model.Cell;
import com.metaweb.gridworks.model.Column;
import com.metaweb.gridworks.model.Project;
import com.metaweb.gridworks.model.Row;
import com.metaweb.gridworks.model.changes.CellChange;

public class TextTransformOperation extends EngineDependentMassCellOperation {
    private static final long serialVersionUID = -7698202759999537298L;
    
    static public enum OnError {
    	KeepOriginal,
    	SetToBlank,
    	StoreError
    }

    final protected String _expression;
    final protected OnError _onError;
    
    static public AbstractOperation reconstruct(Project project, JSONObject obj) throws Exception {
        JSONObject engineConfig = obj.getJSONObject("engineConfig");
        
        return new TextTransformOperation(
            engineConfig,
            obj.getString("columnName"),
            obj.getString("expression"),
            stringToOnError(obj.getString("onError"))
        );
    }
    
    static public OnError stringToOnError(String s) {
    	if ("set-to-blank".equalsIgnoreCase(s)) {
    		return OnError.SetToBlank;
    	} else if ("store-error".equalsIgnoreCase(s)) {
    		return OnError.StoreError;
    	} else {
    		return OnError.KeepOriginal;
    	}
    }
    static public String onErrorToString(OnError onError) {
    	if (onError == OnError.SetToBlank) {
    		return "set-to-blank";
    	} else if (onError == OnError.StoreError) {
    		return "store-error";
    	} else {
    		return "keep-original";
    	}
    }
    
    public TextTransformOperation(JSONObject engineConfig, String columnName, String expression, OnError onError) {
        super(engineConfig, columnName, true);
        _expression = expression;
        _onError = onError;
    }

    public void write(JSONWriter writer, Properties options)
            throws JSONException {
        
        writer.object();
        writer.key("op"); writer.value(OperationRegistry.s_opClassToName.get(this.getClass()));
        writer.key("description"); writer.value(getBriefDescription(null));
        writer.key("engineConfig"); writer.value(getEngineConfig());
        writer.key("columnName"); writer.value(_columnName);
        writer.key("expression"); writer.value(_expression);
        writer.key("onError"); writer.value(onErrorToString(_onError));
        writer.endObject();
    }

    protected String getBriefDescription(Project project) {
        return "Text transform on cells in column " + _columnName + " using expression " + _expression;
    }

    protected String createDescription(Column column,
            List<CellChange> cellChanges) {
        
        return "Text transform on " + cellChanges.size() + 
            " cells in column " + column.getHeaderLabel() + ": " + _expression;
    }

    protected RowVisitor createRowVisitor(Project project, List<CellChange> cellChanges) throws Exception {
        Column column = project.columnModel.getColumnByName(_columnName);
        
        Evaluable eval = MetaParser.parse(_expression);
        Properties bindings = ExpressionUtils.createBindings(project);
        
        return new RowVisitor() {
            int                 cellIndex;
            Properties             bindings;
            List<CellChange>     cellChanges;
            Evaluable             eval;
            
            public RowVisitor init(int cellIndex, Properties bindings, List<CellChange> cellChanges, Evaluable eval) {
                this.cellIndex = cellIndex;
                this.bindings = bindings;
                this.cellChanges = cellChanges;
                this.eval = eval;
                return this;
            }
            
            public boolean visit(Project project, int rowIndex, Row row, boolean contextual) {
                Cell cell = row.getCell(cellIndex);
                Object oldValue = cell != null ? cell.value : null;

                ExpressionUtils.bind(bindings, row, rowIndex, cell);
                
                Object newValue = eval.evaluate(bindings);
                if (ExpressionUtils.isError(newValue)) {
                	if (_onError == OnError.KeepOriginal) {
                		return false;
                	} else if (_onError == OnError.SetToBlank) {
                		newValue = null;
                	}
                }
                
                if (!ExpressionUtils.sameValue(oldValue, newValue)) {
                    Cell newCell = new Cell(newValue, (cell != null) ? cell.recon : null);
                
                    CellChange cellChange = new CellChange(rowIndex, cellIndex, cell, newCell);
                    cellChanges.add(cellChange);
                }
                
                return false;
            }
        }.init(column.getCellIndex(), bindings, cellChanges, eval);
    }
}