Add a bean validator

Added a bean validator that will validate the fields within an arbitrary
object using the annotations in the parameters package.
Also added validateMap to the bean validators.

Issue-ID: POLICY-1625
Signed-off-by: Jim Hahn <jrh3@att.com>
Change-Id: I2192f3d1ba735d3779c35711a7dba053918aa547

2 files changed, 386 insertions, 2 deletions

diff --git a/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidationResult.java b/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidationResult.java
index f8eebcf1..752e4d40 100644
--- a/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidationResult.java
+++ b/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidationResult.java
@@ -1,6 +1,6 @@
-/*
+/*-
  * ============LICENSE_START=======================================================
- *  Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ *  Copyright (C) 2019-2020 AT&T Intellectual Property. All rights reserved.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,9 @@ package org.onap.policy.common.parameters;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.function.BiConsumer;
 import java.util.function.Function;
 
 /**
@@ -129,6 +132,34 @@ public class BeanValidationResult extends ValidationResultImpl {
     }
 
     /**
+     * Validates the entries in a map.
+     *
+     * @param mapName name of the list
+     * @param map map whose entries are to be validated, or {@code null}
+     * @param entryValidator function to validate an entry in the map
+     * @return {@code true} if all entries in the map are valid, {@code false} otherwise
+     */
+    public <V> boolean validateMap(String mapName, Map<String, V> map,
+                    BiConsumer<BeanValidationResult, Entry<String, V>> entryValidator) {
+        if (map == null) {
+            return true;
+        }
+
+        BeanValidationResult result = new BeanValidationResult(mapName, null);
+        for (Entry<String, V> ent : map.entrySet()) {
+            entryValidator.accept(result, ent);
+        }
+
+        if (result.isValid()) {
+            return true;
+
+        } else {
+            addResult(result);
+            return false;
+        }
+    }
+
+    /**
      * Gets the validation result.
      *
      * @param initialIndentation the indentation to use on the main result output
diff --git a/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidator.java b/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidator.java
new file mode 100644
index 00000000..dbd3c7ce
--- /dev/null
+++ b/common-parameters/src/main/java/org/onap/policy/common/parameters/BeanValidator.java
@@ -0,0 +1,353 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.parameters;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiPredicate;
+import java.util.function.Predicate;
+import org.apache.commons.lang3.StringUtils;
+import org.onap.policy.common.parameters.annotations.Max;
+import org.onap.policy.common.parameters.annotations.Min;
+import org.onap.policy.common.parameters.annotations.NotBlank;
+import org.onap.policy.common.parameters.annotations.NotNull;
+
+/**
+ * Bean validator, supporting the parameter annotations.
+ * <p/>
+ * Note: this currently does not support Min/Max validation of "short" or "byte"; these
+ * annotations are simply ignored for these types.
+ */
+public class BeanValidator {
+
+    /**
+     * {@code True} if there is a field-level annotation, {@code false} otherwise.
+     */
+    private boolean fieldIsAnnotated;
+
+    /**
+     * Validates top level fields within an object. For each annotated field, it retrieves
+     * the value using the public "getter" method for the field. If there is no public
+     * "getter" method, then it throws an exception. Otherwise, it validates the retrieved
+     * value based on the annotations. This recurses through super classes looking for
+     * fields to be verified, but it does not examine any interfaces.
+     *
+     * @param name name of the object being validated
+     * @param object object to be validated. If {@code null}, then an empty result is
+     *        returned
+     * @return the validation result
+     */
+    public BeanValidationResult validateTop(String name, Object object) {
+        BeanValidationResult result = new BeanValidationResult(name, object);
+        if (object == null) {
+            return result;
+        }
+
+        // check class hierarchy - don't need to check interfaces
+        for (Class<?> clazz = object.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
+            validateFields(result, object, clazz);
+        }
+
+        return result;
+    }
+
+    /**
+     * Performs validation of all annotated fields found within the class.
+     *
+     * @param result validation results are added here
+     * @param object object whose fields are to be validated
+     * @param clazz class, within the object's hierarchy, to be examined for fields to be
+     *        verified
+     */
+    private void validateFields(BeanValidationResult result, Object object, Class<?> clazz) {
+        for (Field field : clazz.getDeclaredFields()) {
+            validateField(result, object, clazz, field);
+        }
+    }
+
+    /**
+     * Performs validation of a single field.
+     *
+     * @param result validation results are added here
+     * @param object object whose fields are to be validated
+     * @param clazz class, within the object's hierarchy, containing the field
+     * @param field field whose value is to be validated
+     */
+    private void validateField(BeanValidationResult result, Object object, Class<?> clazz, Field field) {
+        final String fieldName = field.getName();
+        if (fieldName.contains("$")) {
+            return;
+        }
+
+        /*
+         * Identify the annotations. NotNull MUST be first so the check is run before the
+         * others.
+         */
+        fieldIsAnnotated = false;
+        List<Predicate<Object>> checkers = new ArrayList<>(10);
+        addAnnotation(clazz, field, checkers, NotNull.class, (annot, value) -> verNotNull(result, fieldName, value));
+        addAnnotation(clazz, field, checkers, NotBlank.class, (annot, value) -> verNotBlank(result, fieldName, value));
+        addAnnotation(clazz, field, checkers, Max.class, (annot, value) -> verMax(result, fieldName, annot, value));
+        addAnnotation(clazz, field, checkers, Min.class, (annot, value) -> verMin(result, fieldName, annot, value));
+
+        if (checkers.isEmpty()) {
+            // has no annotations - nothing to check
+            return;
+        }
+
+        // verify the field type is of interest
+        int mod = field.getModifiers();
+        if (Modifier.isStatic(mod)) {
+            classOnly(clazz.getName() + "." + fieldName + " is annotated but the field is static");
+            return;
+        }
+
+        // get the field's "getter" method
+        Method accessor = getAccessor(object.getClass(), fieldName);
+        if (accessor == null) {
+            classOnly(clazz.getName() + "." + fieldName + " is annotated but has no \"get\" method");
+            return;
+        }
+
+        // get the value
+        Object value = getValue(object, clazz, fieldName, accessor);
+
+        // perform the checks
+        if (value == null && field.getAnnotation(NotNull.class) == null && clazz.getAnnotation(NotNull.class) == null) {
+            // value is null and there's no null check - just return
+            return;
+        }
+
+        for (Predicate<Object> checker : checkers) {
+            if (!checker.test(value)) {
+                // invalid - don't bother with additional checks
+                return;
+            }
+        }
+    }
+
+    /**
+     * Gets the value from the object using the accessor function.
+     *
+     * @param object object whose value is to be retrieved
+     * @param clazz class containing the field
+     * @param fieldName name of the field
+     * @param accessor "getter" method
+     * @return the object's value
+     */
+    private Object getValue(Object object, Class<?> clazz, final String fieldName, Method accessor) {
+        try {
+            return accessor.invoke(object);
+
+        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
+            throw new IllegalArgumentException(clazz.getName() + "." + fieldName + " accessor threw an exception", e);
+        }
+    }
+
+    /**
+     * Throws an exception if there are field-level annotations.
+     *
+     * @param exceptionMessage exception message
+     */
+    private void classOnly(String exceptionMessage) {
+        if (fieldIsAnnotated) {
+            throw new IllegalArgumentException(exceptionMessage);
+        }
+    }
+
+    /**
+     * Looks for an annotation at the class or field level. If an annotation is found at
+     * either the field or class level, then it adds a verifier to the list of checkers.
+     *
+     * @param clazz class to be searched
+     * @param field field to be searched
+     * @param checkers where to place the new field verifier
+     * @param annotClass class of annotation to find
+     * @param check verification function to be added to the list, if the annotation is
+     *        found
+     */
+    private <T extends Annotation> void addAnnotation(Class<?> clazz, Field field, List<Predicate<Object>> checkers,
+                    Class<T> annotClass, BiPredicate<T, Object> check) {
+
+        // field annotation takes precedence over class annotation
+        T annot = field.getAnnotation(annotClass);
+        if (annot != null) {
+            fieldIsAnnotated = true;
+
+        } else if ((annot = clazz.getAnnotation(annotClass)) == null) {
+            return;
+        }
+
+        T annot2 = annot;
+        checkers.add(value -> check.test(annot2, value));
+    }
+
+    /**
+     * Verifies that the value is not null.
+     *
+     * @param result where to add the validation result
+     * @param fieldName field whose value is being verified
+     * @param value value to be verified, assumed to be non-null
+     * @return {@code true} if the value is valid, {@code false} otherwise
+     */
+    private boolean verNotNull(BeanValidationResult result, String fieldName, Object value) {
+        return result.validateNotNull(fieldName, value);
+    }
+
+    /**
+     * Verifies that the value is not blank.
+     *
+     * @param result where to add the validation result
+     * @param fieldName field whose value is being verified
+     * @param value value to be verified, assumed to be non-null
+     * @return {@code true} if the value is valid, {@code false} otherwise
+     */
+    private boolean verNotBlank(BeanValidationResult result, String fieldName, Object value) {
+        if (value instanceof String && StringUtils.isBlank(value.toString())) {
+            ObjectValidationResult fieldResult =
+                            new ObjectValidationResult(fieldName, value, ValidationStatus.INVALID, "is blank");
+            result.addResult(fieldResult);
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Verifies that the value is <= the minimum value.
+     *
+     * @param result where to add the validation result
+     * @param fieldName field whose value is being verified
+     * @param annot annotation against which the value is being verified
+     * @param value value to be verified, assumed to be non-null
+     * @return {@code true} if the value is valid, {@code false} otherwise
+     */
+    private boolean verMax(BeanValidationResult result, String fieldName, Max annot, Object value) {
+        if (!(value instanceof Number)) {
+            return true;
+        }
+
+        Number num = (Number) value;
+        if (num instanceof Integer || num instanceof Long) {
+            if (num.longValue() <= annot.value()) {
+                return true;
+            }
+
+        } else if (num instanceof Float || num instanceof Double) {
+            if (num.doubleValue() <= annot.value()) {
+                return true;
+            }
+
+        } else {
+            return true;
+        }
+
+        ObjectValidationResult fieldResult = new ObjectValidationResult(fieldName, value, ValidationStatus.INVALID,
+                        "exceeds the maximum value: " + annot.value());
+        result.addResult(fieldResult);
+        return false;
+    }
+
+    /**
+     * Verifies that the value is >= the minimum value.
+     *
+     * @param result where to add the validation result
+     * @param fieldName field whose value is being verified
+     * @param annot annotation against which the value is being verified
+     * @param value value to be verified, assumed to be non-null
+     * @return {@code true} if the value is valid, {@code false} otherwise
+     */
+    private boolean verMin(BeanValidationResult result, String fieldName, Min annot, Object value) {
+        if (!(value instanceof Number)) {
+            return true;
+        }
+
+        Number num = (Number) value;
+        if (num instanceof Integer || num instanceof Long) {
+            if (num.longValue() >= annot.value()) {
+                return true;
+            }
+
+        } else if (num instanceof Float || num instanceof Double) {
+            if (num.doubleValue() >= annot.value()) {
+                return true;
+            }
+
+        } else {
+            return true;
+        }
+
+        ObjectValidationResult fieldResult = new ObjectValidationResult(fieldName, value, ValidationStatus.INVALID,
+                        "is below the minimum value: " + annot.value());
+        result.addResult(fieldResult);
+        return false;
+    }
+
+    /**
+     * Gets an accessor method for the given field.
+     *
+     * @param clazz class whose methods are to be searched
+     * @param fieldName field whose "getter" is to be identified
+     * @return the field's "getter" method, or {@code null} if it is not found
+     */
+    private Method getAccessor(Class<?> clazz, String fieldName) {
+        String capname = StringUtils.capitalize(fieldName);
+        Method accessor = getMethod(clazz, "get" + capname);
+        if (accessor != null) {
+            return accessor;
+        }
+
+        return getMethod(clazz, "is" + capname);
+    }
+
+    /**
+     * Gets the "getter" method having the specified name.
+     *
+     * @param clazz class whose methods are to be searched
+     * @param methodName name of the method of interest
+     * @return the method, or {@code null} if it is not found
+     */
+    private Method getMethod(Class<?> clazz, String methodName) {
+        for (Method method : clazz.getMethods()) {
+            if (methodName.equals(method.getName()) && validMethod(method)) {
+                return method;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Determines if a method is a valid "getter".
+     *
+     * @param method method to be checked
+     * @return {@code true} if the method is a valid "getter", {@code false} otherwise
+     */
+    private boolean validMethod(Method method) {
+        int mod = method.getModifiers();
+        return !(Modifier.isStatic(mod) || method.getReturnType() == void.class || method.getParameterCount() != 0);
+    }
+}