/**
The contents of this file are subject to the Mozilla Public License Version 1.1 
(the "License"); you may not use this file except in compliance with the License. 
You may obtain a copy of the License at http://www.mozilla.org/MPL/ 
Software distributed under the License is distributed on an "AS IS" basis, 
WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the 
specific language governing rights and limitations under the License. 

The Original Code is "AbstractValidator.java".  Description: 
"Abstract implementation of a message validator." 

The Initial Developer of the Original Code is University Health Network. Copyright (C) 
2012.  All Rights Reserved. 

Contributor(s): ______________________________________. 

Alternatively, the contents of this file may be used under the terms of the 
GNU General Public License (the "GPL"), in which case the provisions of the GPL are 
applicable instead of those above.  If you wish to allow use of your version of this 
file only under the terms of the GPL and not to allow others to use your version 
of this file under the MPL, indicate your decision by deleting  the provisions above 
and replace  them with the notice and other provisions required by the GPL License.  
If you do not delete the provisions above, a recipient may use your version of 
this file under either the MPL or the GPL. 
 */
package ca.uhn.hl7v2.validation;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import ca.uhn.hl7v2.HL7Exception;
import ca.uhn.hl7v2.Location;
import ca.uhn.hl7v2.model.Composite;
import ca.uhn.hl7v2.model.Message;
import ca.uhn.hl7v2.model.Primitive;
import ca.uhn.hl7v2.model.Segment;
import ca.uhn.hl7v2.model.Structure;
import ca.uhn.hl7v2.model.Type;
import ca.uhn.hl7v2.model.Varies;
import ca.uhn.hl7v2.util.ReadOnlyMessageIterator;
import ca.uhn.hl7v2.util.Terser;

/**
 * Abstract implementation of a message validator.
 * 
 * @param <R> The type parameter R denotes the result type of the validation
 *            process.
 * 
 * @author Christian Ohr
 */
public abstract class AbstractValidator<R> implements Validator<R> {

        private static final Logger LOG = LoggerFactory.getLogger(AbstractValidator.class);

        private boolean validatePrimitives;

        /**
         * Turns validating primtives on and off (default). Note that primitive validation
         * will significantly slow down the validation process.
         *
         * @param validatePrimitives true if primitive fields shall be validated, false if not
         */
        public void setValidatePrimitives(boolean validatePrimitives) {
                this.validatePrimitives = validatePrimitives;
        }

        /**
         * @return true if primitive fields shall be validated, false if not
         */
        public boolean isValidatePrimitives() {
                return validatePrimitives;
        }

        /**
         * Calls {@link #initializeHandler()} to obtain a default instance of a
         * {@link ValidationExceptionHandler} before starting the validation.
         * 
         * @see ca.uhn.hl7v2.validation.Validator#validate(ca.uhn.hl7v2.model.Message)
         */
        public R validate(Message message) throws HL7Exception {
                return validate(message, initializeHandler());
        }

        /**
         * @see ca.uhn.hl7v2.validation.Validator#validate(ca.uhn.hl7v2.model.Message,
         *      ca.uhn.hl7v2.validation.ValidationExceptionHandler)
         */
        public R validate(Message message, ValidationExceptionHandler<R> handler) throws HL7Exception {
                if (message == null) {
                        throw new NullPointerException("Message may not be null");
                }
                if (handler == null) {
                        throw new NullPointerException("ValidationExceptionHandler may not be null");
                }
                handler.setValidationSubject(message);
                if (isValidatePrimitives()) testPrimitiveRules(message, handler);
                testMessageRules(message, handler);
                return handler.result();
        }

        private void testMessageRules(Message message, ValidationExceptionHandler<R> handler)
                        throws HL7Exception {
                Terser t = new Terser(message);
                String messageType = t.get("MSH-9-1");
                String triggerEvent = t.get("MSH-9-2");
                List<MessageRule> rules = new ArrayList<MessageRule>();
                if (getValidationContext() != null) {
                        rules.addAll(getValidationContext().getMessageRules(message.getVersion(), messageType,
                                        triggerEvent));
                }
                LOG.debug("Validating message against {} message rules", rules.size());
                for (MessageRule rule : rules) {
                        ValidationException[] ex = rule.apply(message);
                        if (ex != null && ex.length > 0) {
                                handler.onExceptions(ex);
                        }
                }
        }

        private void testPrimitiveRules(Message message, ValidationExceptionHandler<R> handler)
                        throws HL7Exception {
                LOG.debug("Validating message against primitive type rules");
                for (Iterator<Structure> iter = ReadOnlyMessageIterator
                                .createPopulatedSegmentIterator(message); iter.hasNext();) {
                        Segment s = (Segment) iter.next();
                        for (int field = 1; field <= s.numFields(); field++) {
                                Type[] t = s.getField(field);
                                for (int rep = 0; rep < t.length; rep++) {
                                        Location location = new Location();
                                        location
                                            .withSegmentName(s.getName())
                                            .withField(field)
                                            .withFieldRepetition(rep);
                                        testType(t[rep], handler, location);
                                }
                        }
                }
        }

        private void testType(Type type, ValidationExceptionHandler<R> handler, Location l) {
                if (type instanceof Composite) {
                        Type[] components = ((Composite) type).getComponents();
                        for (int comp = 0; comp < components.length; comp++) {
                                Location location = new Location(l).withComponent(comp + 1);
                                testComponent(components[comp], handler, location);
                        }
                } else if (type instanceof Varies) {
                        testType(((Varies) type).getData(), handler, l);
                } else {
                        testPrimitive((Primitive) type, handler, l);
                }
        }

        private void testComponent(Type type, ValidationExceptionHandler<R> handler, Location l) {
                if (type instanceof Composite) {
                        Type[] component = ((Composite) type).getComponents();
                        for (int sub = 0; sub < component.length; sub++) {
                                Location location = new Location(l).withSubcomponent(sub + 1);
                                testSubComponent(component[sub], handler, location);
                        }
                } else if (type instanceof Varies) {
                        testComponent(((Varies) type).getData(), handler, l);
                } else {
                        testPrimitive((Primitive) type, handler, l);
                }
        }

        private void testSubComponent(Type type, ValidationExceptionHandler<R> handler, Location l) {
                if (type instanceof Primitive) {
                        testPrimitive((Primitive) type, handler, l);
                } else if (type instanceof Varies) {
                        testSubComponent(((Varies) type).getData(), handler, l);
                }
        }

        private void testPrimitive(Primitive p, ValidationExceptionHandler<R> handler, Location l) {
                List<PrimitiveTypeRule> rules = new ArrayList<PrimitiveTypeRule>();
                Message m = p.getMessage();
                if (getValidationContext() != null) {
                        rules.addAll(getValidationContext().getPrimitiveRules(m.getVersion(), p.getName(), p));
                }
                for (PrimitiveTypeRule rule : rules) {
                        ValidationException[] exceptions = rule.apply(p.getValue());
                        for (ValidationException ve : exceptions) {
                ve.setLocation(l);
                        }
                        if (exceptions.length > 0) {
                                handler.onExceptions(exceptions);
                        }
                }
        }

        /**
         * Calls {@link #initializeHandler()} to obtain a default instance of a
         * {@link ValidationExceptionHandler} before starting the validation.
         * 
         * @see ca.uhn.hl7v2.validation.Validator#validate(Message,
         *      ValidationExceptionHandler)
         */
        public R validate(String message, boolean isXML, String version) throws HL7Exception {
                return validate(message, isXML, version, initializeHandler());
        }

        /**
         * @see ca.uhn.hl7v2.validation.Validator#validate(java.lang.String,
         *      boolean, java.lang.String,
         *      ca.uhn.hl7v2.validation.ValidationExceptionHandler)
         */
        public R validate(String message, boolean isXML, String version,
                        ValidationExceptionHandler<R> handler) throws HL7Exception {
                if (message == null) {
                        throw new NullPointerException("Message may not be null");
                }
                if (handler == null) {
                        throw new NullPointerException("ValidationExceptionHandler may not be null");
                }
                handler.setValidationSubject(message);
                List<EncodingRule> rules = new ArrayList<EncodingRule>();
                if (getValidationContext() != null) {
                        rules.addAll(getValidationContext().getEncodingRules(version, isXML ? "XML" : "ER7"));
                }
                LOG.debug("Validating message against {} encoding rules", rules.size());
                for (EncodingRule rule : rules) {
                        ValidationException[] ex = rule.apply(message);
                        if (ex != null && ex.length > 0) {
                                handler.onExceptions(ex);
                        }
                }
                return handler.result();
        }

        protected abstract ValidationContext getValidationContext();

        protected abstract ValidationExceptionHandler<R> initializeHandler();

}