package org.alfresco.util.schemacomp;

import org.alfresco.util.schemacomp.model.Schema;
import org.apache.xml.serialize.LineSeparator;
import org.hibernate.dialect.Dialect;

/**
 * Compares two abstract database schemas, a reference schema and a target schema (the schema to check for validity).
 * The reference schema is the primary schema and all objects in the right schema are judged relative to it.
 * 
 * @author Matt Ward
 */
public class SchemaComparator
{
    public static final String CHAR_SET = "UTF-8";
    public static final String LINE_SEPARATOR = LineSeparator.Windows;  
    private final Schema referenceSchema;
    private final Schema targetSchema;
    private final DiffContext ctx;
    
    /**
     * Construct a comparator to compare a target schema against a reference schema. Validators supplied
     * by the reference schema will be used to validate the target schema.
     * 
     * @param referenceSchema Schema
     * @param targetSchema Schema
     * @param dialect Dialect
     */
    public SchemaComparator(Schema referenceSchema, Schema targetSchema, Dialect dialect)
    {
        this.referenceSchema = referenceSchema;
        this.targetSchema = targetSchema;
        this.ctx = new DiffContext(dialect, referenceSchema, targetSchema);
    }
    
    
    public void validateAndCompare()
    {
        validateTargetSchema();
        compare();
    }


    /**
     * Check the left schema against the right schema and record any differences.
     */
    private void compare()
    {
        referenceSchema.diff(targetSchema, ctx);
    }


    /**
     * Validate the target schema against the reference schema using the reference schema's validators.
     */
    private void validateTargetSchema()
    {
        ValidatingVisitor validatingVisitor = new ValidatingVisitor(ctx);
        referenceSchema.accept(validatingVisitor);
    }


    /**
     * @return the schema comparison results.
     */
    public Results getComparisonResults()
    {
        return ctx.getComparisonResults();
    }    
}