/**
    * Copyright 2005-2016 The Kuali Foundation
    *
    * Licensed under the Educational Community License, Version 2.0 (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.opensource.org/licenses/ecl2.php
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.kuali.rice.krms.framework;
  
  import static junit.framework.Assert.assertEquals;
  import static junit.framework.Assert.assertTrue;
  import static junit.framework.Assert.fail;
  
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.commons.lang.StringUtils;
  import org.junit.Before;
  import org.junit.Test;
  import org.kuali.rice.krms.api.engine.Term;
  import org.kuali.rice.krms.api.engine.TermResolutionEngine;
  import org.kuali.rice.krms.api.engine.TermResolutionException;
  import org.kuali.rice.krms.api.engine.TermResolver;
  import org.kuali.rice.krms.framework.engine.TermResolutionEngineImpl;
  import org.springframework.util.CollectionUtils;
  
  
  public class TermResolutionEngineTest {
  	
  	private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(TermResolutionEngineTest.class);
  
  	private TermResolutionEngine termResolutionEngine = null;
  	
  	@Before
  	public void setUp() {
  		termResolutionEngine = new TermResolutionEngineImpl();
  	}
  	
  	@Test
  	public void testNoResolution() {
  		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
  		
  		// GIVENS:
  		testHelper.addGivens("A");
  
  		testHelper.logScenarioDescription();
  		
  		testHelper.assertSuccess("A");
  	}
  	
  	@Test
  	public void testSimpleResolution() {
  		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
  		
  		// GIVENS:
  		testHelper.addGivens("A");
  		
  		// RESOLVERS:
  		testHelper.addResolver("B", /* <-- */ "A");
  		
  		testHelper.logScenarioDescription();
  		
  		testHelper.assertSuccess("B");
  	}
  	
  	@Test
  	public void testTwoStepResolution() {
  		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
  		
  		// GIVENS:
  		testHelper.addGivens("A");
  		
  		// RESOLVERS:
  		testHelper.addResolver("B", /* <-- */ "A");
  		testHelper.addResolver("C", /* <-- */ "B");
  		
  		testHelper.logScenarioDescription();
  		
  		testHelper.assertSuccess("C");
  	}
  
  	@Test
  	public void testForkingResolution() {
  		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
  
 		// GIVENS:
 		testHelper.addGivens("A", "Z");
 		
 		// RESOLVERS:
 		testHelper.addResolver("D", /* <-- */ "B","C");
 		testHelper.addResolver("C", /* <-- */ "Z");
 		testHelper.addResolver("B", /* <-- */ "A");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertSuccess("D");
 	}
 	
 	@Test
 	public void testMultipleValidPaths() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 		
 		// GIVENS:
 		testHelper.addGivens("A", "Z");
 		
 		// RESOLVERS:
 		testHelper.addResolver("D", /* <-- */ "B","C");
 		testHelper.addResolver("C", /* <-- */ "Z");
 		testHelper.addResolver("B", /* <-- */ "A");
 		testHelper.addResolver("D", /* <-- */ "A");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertSuccess("D");
 	}
 	
 	@Test
 	public void testDiamond() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("A");
 		
 		// RESOLVERS:
 		testHelper.addResolver("D", /* <-- */ "B","C");
 		testHelper.addResolver("C", /* <-- */ "A");
 		testHelper.addResolver("B", /* <-- */ "A");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertSuccess("D");
 		
 	}
 
 	@Test
 	public void testComplexPath() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("Q","R","S");
 		
 		// RESOLVERS:
 		testHelper.addResolver("A", /* <-- */ "B","F");
 		testHelper.addResolver("A", /* <-- */ "Z");
 		testHelper.addResolver("B", /* <-- */ "D");
 		testHelper.addResolver("B", /* <-- */ "C");
 		testHelper.addResolver("C", /* <-- */ "S");
 		testHelper.addResolver("D", /* <-- */ "E");
 		testHelper.addResolver("E", /* <-- */ "S");
 		testHelper.addResolver("F", /* <-- */ "G","Q");
 		testHelper.addResolver("G", /* <-- */ "R");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertSuccess("A");
 		
 	}
 
 	@Test
 	public void testCycle() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		// none
 		
 		// RESOLVERS:
 		testHelper.addResolver("D", /* <-- */ "C");
 		testHelper.addResolver("C", /* <-- */ "D");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertException("D");
 		
 	}
 	
 
 	@Test
 	public void testUnreachableTerm() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		// none
 		
 		// RESOLVERS:
 		testHelper.addResolver("D", /* <-- */ "C");
 		testHelper.addResolver("C", /* <-- */ "B");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertException("D");
 		
 	}
 	
 	@Test
 	public void testRedHerringPath() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("Q");
 		
 		// RESOLVERS:
 		testHelper.addResolver("A", /* <-- */ "B");
 		// this is the shortest path, but C can't be resolved
 		testHelper.addResolver("B", /* <-- */ "C");
 		
 		testHelper.addResolver("B", /* <-- */ "D");
 		testHelper.addResolver("D", /* <-- */ "Q");
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertSuccess("A");
 	}
 	
 	@Test
 	public void testResolveParamaterizedTerm() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("Q");
 		
 		// RESOLVERS:
 		testHelper.addResolver(1, "A", new String[] {"param"}, /* <-- */ "B");
 		testHelper.addResolver("B", /* <-- */ "Q");
 		
 		testHelper.logScenarioDescription();
 		
 		Map<String,String> params = new HashMap();
 		params.put("param", "value");
 		testHelper.assertSuccess(testHelper.getTerm("A", params));
 
 		// termName A needs parameters, so this shouldn't work
 		testHelper.assertException(new Term("A"));
 
 	}
 	
 	@Test
 	public void testIntermediateParamaterizedTerm() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("Q");
 		
 		// RESOLVERS:
 		testHelper.addResolver(1, "A", new String[] {"foo"}, /* <-- */ "B");
 		testHelper.addResolver(1, "B", new String[] {"bar"},  /* <-- */ "Q");
 		
 		testHelper.logScenarioDescription();
 		
 		Map<String,String> params = new HashMap();
 		params.put("foo", "foovalue");
 
 		// Resolver for termName b requires parameters, so this shouldn't work
 		testHelper.assertException(testHelper.getTerm("A", params));
 	}
 	
 	private static class WhiteBoxTermResolutionEngineImpl extends TermResolutionEngineImpl {
 		
 		// expose this for testing purposes
 		@Override
 		public List<TermResolverKey> buildTermResolutionPlan(String termName) {
 			return super.buildTermResolutionPlan(termName);
 		}
 	}
 	
 	
 	@Test
 	public void testShortestPath() {
 		
 		WhiteBoxTermResolutionEngineImpl whiteBoxTermResolutionService = new WhiteBoxTermResolutionEngineImpl();
 		TestScenarioHelper testHelper = new TestScenarioHelper(whiteBoxTermResolutionService);
 
 		// GIVENS:
 		testHelper.addGivens("Q");
 		
 		// RESOLVERS:
 		// this one costs 3 (instead of default cost of 1)
 		testHelper.addResolver(3, "A", /* <-- */ "Q");
 
 		// the steps for the alternate path each cost 1, but total length is 4
 		testHelper.addResolver("A", /* <-- */ "B");
 		testHelper.addResolver("B", /* <-- */ "C");
 		testHelper.addResolver("C", /* <-- */ "D");
 		testHelper.addResolver("D", /* <-- */ "Q");
 		
 		testHelper.logScenarioDescription();
 		
 		List<?> plan = whiteBoxTermResolutionService.buildTermResolutionPlan("A");
 		LOG.info("resolutionPlan: " + StringUtils.join(plan, ", ") + " <-- should be length 1!");
 		assertTrue("didn't choose the shortest resolution path (of length 1)", plan.size() == 1);
 	}
 	
 	/*
 	 *  TODO: test exception variants:
 	 *  - TermResolver throws TermResolutionException
 	 *  - TermResolutionEngine is passed a null termName
 	 */
 	
 	// TODO: what should the TermResolutionEngine do if a resolver throws a RuntimeException?
 	/*
 	@Test
 	public void testExplodingResolver() {
 		TestScenarioHelper testHelper = new TestScenarioHelper(termResolutionEngine);
 
 		// GIVENS:
 		testHelper.addGivens("Q");
 		
 		// RESOLVERS:
 		TermResolverMock exploder = new TermResolverMock(testHelper.getTerm("A"), testHelper.getResult("A"), testHelper.getTerm("Q"));
 		exploder.setIsExploder(true);
 		termResolutionEngine.addTermResolver(exploder);
 		
 		testHelper.logScenarioDescription();
 		
 		testHelper.assertException("A");
 	}
 	*/
 	
 	
 	private static class TermResolverMock<T> implements TermResolver<T> {
 		private String output;
 		private Set<String> params;
 		private T result;
 		private Set<String> prereqs;
 		private int cost;
 		private boolean isExploder = false;
 
 		public TermResolverMock(String output, T result, int cost, String ... prereqs) {
 			this(output, null, result, cost, prereqs);
 		}
 		
 		public TermResolverMock(String output, Set<String> params, T result, int cost, String ... prereqs) {
 			this.output = output;
 			this.params = Collections.unmodifiableSet(params);
 			this.result = result;
 			this.prereqs = new HashSet<String>(Arrays.asList(prereqs));
 			this.cost = cost;
 		}
 		
 		@Override
 		public int getCost() {
 			return cost;
 		}
 		
 		@Override
 		public String getOutput() {
 			return output;
 		}
 		
 		@Override
 		public Set<String> getPrerequisites() {
 			return prereqs;
 		}
 		
 		@Override
 		public Set<String> getParameterNames() {
 			return params;
 		}
 		
 		public void setIsExploder(boolean isExploder) {
 			this.isExploder = isExploder;
 		}
 		
 		@Override
 		public T resolve(Map<String, Object> resolvedPrereqs, Map<String, String> parameters) {
 			
 			if (isExploder) {
 				throw new RuntimeException("I'm the exploder, coo coo catchoo");
 			}
 			
 			// get all prereqs first
 			for (String prereq : prereqs) {
 				Object result = resolvedPrereqs.get(prereq);
 				if (result == null) fail("got back null for prereq " + prereq);
 			}
 
 			LOG.info("resolving " + output);
 			return result;
 		}
 		
 		@Override
 		public String toString() {
 			String paramStr = "";
 			if (!CollectionUtils.isEmpty(params)) {
 				paramStr = "+(" + StringUtils.join(params, ",") + ")";
 			}
 			return getClass().getSimpleName()+"[ "+output+paramStr+ " <- " + StringUtils.join(prereqs.iterator(), ",") + " ]";
 		}
 
 	}
 	
 
 	private static class TestScenarioHelper {
 		
 		private final TermResolutionEngine ars;
 		
 		private List<String> givens = new LinkedList<String>();
 		private List<String> resolvers = new LinkedList<String>();
 
 		public TestScenarioHelper(TermResolutionEngine tre) {
 			this.ars = tre;
 		}
 		
 		public void addGivens(String ... names) {
 			for (String name : names) {
 				ars.addTermValue(new Term(name, null), getResult(name));
 				givens.add(name);
 			}
 		}
 		
 		public String getResult(String name) {
 			return getResult(new Term(name, null));
 		}
 		
 		public String getResult(Term term) {
 			return term.getName()  +"-result";
 		}
 		
 		public Term getTerm(String name, Map<String,String> params) {
 			return new Term(name, params);
 		}
 		
 		public void addResolver(String out, String ... prereqs) {
 			addResolver(1, out, prereqs);
 		}
 
 		public void addResolver(int cost, String out, String ... prereqs) {
 			addResolver(1, out, null, prereqs);
 		}
 		
 		public void addResolver(int cost, String out, String[] params, String ... prereqs) {
 			String [] prereqTerms = new String [prereqs.length];
 			
 			for (int i=0; i<prereqs.length; i++) prereqTerms[i] = prereqs[i];
 			
 			Set<String> paramSet = Collections.emptySet();
 			if (params != null) paramSet = new HashSet<String>(Arrays.asList(params));
 			
 			ars.addTermResolver(new TermResolverMock<Object>(out, paramSet, getResult(out), cost, prereqTerms));
 			resolvers.add("(" + out + " <- " + StringUtils.join(prereqs, ",") + ")");
 		}
 		
 		public void logScenarioDescription() {
 			StringBuilder sb = new StringBuilder();
 			
 			sb.append("givens: " + StringUtils.join(givens.iterator(), ", ") + "\n\n");
 			sb.append("resolvers:\n----------------------\n");
 			if (resolvers == null || resolvers.size() == 0) {
 				sb.append("none");
 			} else { 
 				sb.append(StringUtils.join(resolvers.iterator(), "\n"));
 			}
 			sb.append("\n");
 
 			LOG.info("Test Scenario:\n\n" + sb.toString());
 		}
 		
 		public void assertSuccess(String toResolve) {
 			assertSuccess(new Term(toResolve, null));
 		}
 		
 		public void assertSuccess(Term toResolve) {
 			LOG.info("Testing resolution of " + toResolve);
 			try {
 				assertEquals(getResult(toResolve), ars.resolveTerm(toResolve));
 				LOG.info("Success!");
 			} catch (TermResolutionException e) {
 				fail("Should resolve the termName w/o exceptions");
 			}
 		}
 
 		public void assertException(String toResolve) {
 			assertException(new Term(toResolve, null));
 		}
 			
 		public void assertException(Term toResolve) {
 			LOG.info("Testing resolution of " + toResolve);
 			try {
 				ars.resolveTerm(toResolve);
 				fail("Should throw TermResolutionException");
 			} catch (TermResolutionException e) {
 				LOG.info("Success! threw " + e);
 				// Good, this is what we expect
 			}
 		}
 	}
 	
 }