/*******************************************************************************
 * Copyright (c) 2010-2014, Abel Hegedus, Istvan Rath and Daniel Varro
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *   Abel Hegedus - initial API and implementation
 *******************************************************************************/
package org.eclipse.viatra.modelobfuscator.emf.simple

import com.google.common.base.Preconditions
import java.util.Map
import org.eclipse.emf.ecore.resource.ResourceSet
import org.eclipse.viatra.modelobfuscator.util.ObfuscatorUtil
import org.eclipse.viatra.modelobfuscator.util.StringObfuscator
import java.math.BigInteger

/**
 * Builder API for setting up an EMF obfuscator. Currently the only implementation that can
 * be built is {@link SimpleEMFModelObfuscator}. the input for the obfuscator is a ResourceSet, and
 * it is possible to provide a {@link ResourceFilter} as well.
 * 
 * <p/>The builder allows setting a seed and a salt for the obfuscator, which is used when initializing
 * the {@link StringObfuscator}, thus supporting reproducibility and restoration.
 * 
 * <p/>The default value of the seed is a random, 32 character long, base36 string created by
 * {@link ObfuscatorUtil#generateBase36RandomString}. The default value of the salt is a random, 4 character long, base36 string.
 * 
 * @author Abel Hegedus
 * 
 */
class EMFModelObfuscatorBuilder {

    private ResourceSet inputRS
    private ResourceFilter filter
    private String saltString = ObfuscatorUtil.generateBase36RandomString(4)
    private BigInteger seedNumber = new BigInteger(ObfuscatorUtil.generateBase36RandomString(32), 36)
    private String prefix = "oC"
    private Map<String, String> obfuscationMap = null

    /**
     * Hiding constructor of builder
     */
    protected new() {
    }

    /**
     * Creates a new, unconfigured builder for EMF model obfuscators.
     */
    def static create() {
        new EMFModelObfuscatorBuilder
    }

    /**
     * Sets the input of the built obfuscator
     */
    def setInput(ResourceSet inputResourceSet) {
        inputRS = inputResourceSet
        return this
    }

    /**
     * Sets the filter used in the built obfuscator.
     * See {@link ResourceFilter} for details.
     */
    def setFilter(ResourceFilter filter) {
        this.filter = filter
        return this
    }

    /**
     * Sets the salt used for obfuscating String values.
     * See {@link StringObfuscator} for details.
     * 
     */
    def setSalt(String salt) {
        saltString = salt
        return this
    }

    def setTraceMap(Map<String, String> obfuscationMap) {
        this.obfuscationMap = obfuscationMap
        return this
    }

    def getSeed() {
        return seedNumber.toString(36)
    }

    def getSalt() {
        return saltString
    }

    /**
     * Sets the seed used for obfuscating String values.
     * See {@link StringObfuscator} for details.
     * <p>
     * Must be a base 36 number!
     * 
     * @throw NumberFormatException if seed is not base 36
     */
    @Deprecated
    def setSeed(String seed) {
        seedNumber = new BigInteger(seed, 36)
        return this
    }

    /**
     * Sets the seed used for obfuscating String values.
     * See {@link StringObfuscator} for details.
     */
    def setSeed(BigInteger seed) {
        seedNumber = seed
        return this
    }

    /**
     * Sets the prefix used for obfuscating String values.
     * See {@link StringObfuscator} for details.
     */
    def setPrefix(String prefix) {
        this.prefix = prefix
        return this
    }

    /**
     * Returns the {@link SimpleEMFModelObfuscator} instance built using the current configuration of the builder. 
     */
    def AbstractModelObfuscator build() {
        Preconditions.checkState(inputRS != null, "Input resource set cannot be null")
        Preconditions.checkState(seedNumber != null, "Seed cannot be null")
        Preconditions.checkState(prefix != null, "Prefix cannot be null (empty string allowed)")
        Preconditions.checkState(saltString != null, "Salt cannot be null (empty string allowed)")
        val obfuscator = createObfuscator()
        obfuscator.inputResourceSet = inputRS
        obfuscator.filter = filter
        obfuscator.stringObfuscator = new StringObfuscator(seedNumber, saltString, prefix)
        if (obfuscationMap != null) {
            obfuscator.obfuscationMap = obfuscationMap
            obfuscator.trace = true
        }
        return obfuscator
    }

    protected def AbstractModelObfuscator createObfuscator() {
        return new SimpleEMFModelObfuscator()
    }

}