Add criteria API to make it easier to set acceptance criteria for drag and drop (#9605)

Fixes #9600

5 files changed, 418 insertions, 1 deletions

diff --git a/shared/src/main/java/com/vaadin/shared/ui/dnd/DragSourceState.java b/shared/src/main/java/com/vaadin/shared/ui/dnd/DragSourceState.java
index 0fefd05665..42e3bffc07 100644
--- a/shared/src/main/java/com/vaadin/shared/ui/dnd/DragSourceState.java
+++ b/shared/src/main/java/com/vaadin/shared/ui/dnd/DragSourceState.java
@@ -21,6 +21,7 @@ import java.util.List;
 import java.util.Map;
 
 import com.vaadin.shared.communication.SharedState;
+import com.vaadin.shared.ui.dnd.criteria.Payload;
 
 /**
  * State class containing parameters for DragSourceExtension.
@@ -75,4 +76,10 @@ public class DragSourceState extends SharedState {
      * Used to store data in the {@code DataTransfer} object for the drag event.
      */
     public Map<String, String> data = new HashMap<>();
+
+    /**
+     * Payload for comparing against acceptance criteria. Transferred in the
+     * {@code DataTransfer} object as data type.
+     */
+    public Map<String, Payload> payload = new HashMap<>();
 }
diff --git a/shared/src/main/java/com/vaadin/shared/ui/dnd/DropTargetState.java b/shared/src/main/java/com/vaadin/shared/ui/dnd/DropTargetState.java
index c36d97f1dc..edd8beddbd 100644
--- a/shared/src/main/java/com/vaadin/shared/ui/dnd/DropTargetState.java
+++ b/shared/src/main/java/com/vaadin/shared/ui/dnd/DropTargetState.java
@@ -15,7 +15,11 @@
  */
 package com.vaadin.shared.ui.dnd;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import com.vaadin.shared.communication.SharedState;
+import com.vaadin.shared.ui.dnd.criteria.Criterion;
 
 /**
  * State class containing parameters for DropTargetExtension.
@@ -32,5 +36,16 @@ public class DropTargetState extends SharedState {
     /**
      * Criteria script to allow drop event on the element
      */
-    public String dropCriteria;
+    public String criteriaScript;
+
+    /**
+     * List of criteria to compare against the payload.
+     */
+    public List<Criterion> criteria = new ArrayList<>();
+
+    /**
+     * Declares whether any or all of the given criteria should match the
+     * payload
+     */
+    public Criterion.Match criteriaMatch = Criterion.Match.ANY;
 }
diff --git a/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/ComparisonOperator.java b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/ComparisonOperator.java
new file mode 100644
index 0000000000..d7ab6ff339
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/ComparisonOperator.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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.
+ */
+package com.vaadin.shared.ui.dnd.criteria;
+
+/**
+ * Comparison operator for drag and drop acceptance criterion.
+ *
+ * @author Vaadin Ltd.
+ * @since 8.1
+ */
+public enum ComparisonOperator {
+
+    /**
+     * Smaller than operator ("<").
+     */
+    SMALLER_THAN,
+
+    /**
+     * Smaller than or equals to operator ("<=").
+     */
+    SMALLER_THAN_OR_EQUALS,
+
+    /**
+     * Equals to operator ("==").
+     */
+    EQUALS,
+
+    /**
+     * Greater than or equals to operator (">=").
+     */
+    GREATER_THAN_OR_EQUALS,
+
+    /**
+     * Greater than operator (">").
+     */
+    GREATER_THAN,
+
+    /**
+     * Not equals operator ("!=").
+     */
+    NOT_EQUALS
+}
diff --git a/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Criterion.java b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Criterion.java
new file mode 100644
index 0000000000..c90637a6e0
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Criterion.java
@@ -0,0 +1,215 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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.
+ */
+package com.vaadin.shared.ui.dnd.criteria;
+
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.Optional;
+
+/**
+ * Stores parameters for the drag and drop acceptance criterion defined using
+ * the criteria API.
+ * <p>
+ * When data is dragged over a drop target, the value here is compared to the
+ * payload added in DropTargetExtension with same key and value type.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class Criterion implements Serializable {
+
+    /**
+     * Declares whether all or any of the given criteria should match when
+     * compared against the payload.
+     */
+    public enum Match {
+        /**
+         * When compared to the payload, the drop will be accepted if any of the
+         * criteria matches.
+         */
+        ANY,
+
+        /**
+         * When compared to the payload, the drop will be accepted only if all
+         * of the given criteria matches.
+         */
+        ALL
+    }
+
+    private String key;
+    private String value;
+    private Payload.ValueType valueType;
+    private ComparisonOperator operator;
+
+    /**
+     * Mandatory zero param constructor.
+     */
+    private Criterion() {
+
+    }
+
+    /**
+     * Creates a criterion object with the default comparison operator {@link
+     * ComparisonOperator#EQUALS}.
+     *
+     * @param key
+     *         key of the payload to be compared
+     * @param value
+     *         value of the payload to be compared
+     */
+    public Criterion(String key, String value) {
+        this(key, ComparisonOperator.EQUALS, value, Payload.ValueType.STRING);
+    }
+
+    /**
+     * Creates a criterion object.
+     *
+     * @param key
+     *         key of the payload to be compared
+     * @param operator
+     *         comparison operator
+     * @param value
+     *         value of the payload to be compared
+     */
+    public Criterion(String key, ComparisonOperator operator, int value) {
+        this(key, operator, String.valueOf(value), Payload.ValueType.INTEGER);
+    }
+
+    /**
+     * Creates a criterion object.
+     *
+     * @param key
+     *         key of the payload to be compared
+     * @param operator
+     *         comparison operator
+     * @param value
+     *         value of the payload to be compared
+     */
+    public Criterion(String key, ComparisonOperator operator, double value) {
+        this(key, operator, String.valueOf(value), Payload.ValueType.DOUBLE);
+    }
+
+    /**
+     * Creates a criterion object.
+     *
+     * @param key
+     *         key of the payload to be compared
+     * @param operator
+     *         comparison operator
+     * @param value
+     *         value of the payload to be compared
+     * @param valueType
+     *         type of the payload to be compared
+     */
+    private Criterion(String key, ComparisonOperator operator, String value,
+            Payload.ValueType valueType) {
+        this.key = key;
+        this.value = value;
+        this.valueType = valueType;
+        this.operator = operator;
+    }
+
+    /**
+     * Gets the key of the payload to be compared
+     *
+     * @return key of the payload to be compared
+     */
+    public String getKey() {
+        return key;
+    }
+
+    /**
+     * Gets the value of the payload to be compared
+     *
+     * @return value of the payload to be compared
+     */
+    public String getValue() {
+        return value;
+    }
+
+    /**
+     * Gets the type of the payload value to be compared
+     *
+     * @return type of the payload value to be compared
+     */
+    public Payload.ValueType getValueType() {
+        return valueType;
+    }
+
+    /**
+     * Gets the comparison operator.
+     *
+     * @return operator to be used when comparing payload value with criterion
+     */
+    public ComparisonOperator getOperator() {
+        return operator;
+    }
+
+    /**
+     * Compares this criterion's value to the given payload's value and returns
+     * whether the result matches the criterion's operator. The comparison is
+     * done with the payload whose key and value type match the criterion's key
+     * and value type.
+     *
+     * @param payloadCollection
+     *         collection of payloads to compare the criterion against
+     * @return {@code false} if there exists a payload in the collection with
+     * the same key and value type and it doesn't match the criterion, {@code
+     * true} otherwise
+     */
+    public boolean resolve(Collection<Payload> payloadCollection) {
+        Optional<Payload> payload = payloadCollection.stream()
+                .filter(p -> p.getKey().equals(key) && p.getValueType()
+                        .equals(valueType)).findAny();
+
+        return payload.map(this::compareCriterionValue).orElse(true);
+    }
+
+    private boolean compareCriterionValue(Payload payload) {
+        int result;
+
+        switch (valueType) {
+        case STRING:
+        default:
+            result = value.compareTo(payload.getValue());
+            break;
+        case INTEGER:
+            result = Integer.valueOf(value)
+                    .compareTo(Integer.valueOf(payload.getValue()));
+            break;
+        case DOUBLE:
+            result = Double.valueOf(value)
+                    .compareTo(Double.valueOf(payload.getValue()));
+            break;
+        }
+
+        switch (operator) {
+        case SMALLER_THAN:
+            return result < 0;
+        case SMALLER_THAN_OR_EQUALS:
+            return result <= 0;
+        case EQUALS:
+        default:
+            return result == 0;
+        case GREATER_THAN_OR_EQUALS:
+            return result >= 0;
+        case GREATER_THAN:
+            return result > 0;
+        case NOT_EQUALS:
+            return result != 0;
+        }
+    }
+}
diff --git a/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Payload.java b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Payload.java
new file mode 100644
index 0000000000..ffa3d0a1e6
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/dnd/criteria/Payload.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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.
+ */
+package com.vaadin.shared.ui.dnd.criteria;
+
+import java.io.Serializable;
+
+/**
+ * Stores key/value pairs and the value type. Payload is set in
+ * DragSourceExtension and is transferred during drag operation. It is used for
+ * comparing values to acceptance criteria.
+ */
+public class Payload implements Serializable {
+
+    /**
+     * Type of the payload's value.
+     */
+    public enum ValueType {
+        STRING, INTEGER, DOUBLE;
+    }
+
+    /**
+     * Prefix of the payload data type.
+     */
+    public static final String ITEM_PREFIX = "v-item";
+
+    private String key;
+    private String value;
+    private ValueType valueType;
+
+    /**
+     * Mandatory zero arg constructor.
+     */
+    private Payload() {
+
+    }
+
+    /**
+     * Creates a payload object.
+     *
+     * @param key
+     *         key of the payload
+     * @param value
+     *         value of the payload
+     * @param valueType
+     *         type of the payload value
+     */
+    public Payload(String key, String value, ValueType valueType) {
+        this.key = key;
+        this.value = value;
+        this.valueType = valueType;
+    }
+
+    /**
+     * Gets the key of this payload.
+     *
+     * @return key identifying this payload
+     */
+    public String getKey() {
+        return key;
+    }
+
+    /**
+     * Gets the value of this payload.
+     *
+     * @return value of this payload
+     */
+    public String getValue() {
+        return value;
+    }
+
+    /**
+     * Gets the value type of this payload.
+     *
+     * @return the type of the value of this payload
+     */
+    public ValueType getValueType() {
+        return valueType;
+    }
+
+    /**
+     * Returns the string representation of this payload. It is used as the data
+     * type in the {@code DataTransfer} object.
+     *
+     * @return the string representation of this payload
+     */
+    public String getPayloadString() {
+        return ITEM_PREFIX + ":" + valueType.name().toLowerCase() + ":" + key
+                + ":" + value;
+    }
+
+    /**
+     * Parses a payload string and returns a payload object represented by that
+     * string.
+     *
+     * @param payloadString
+     *         string that represents a payload object
+     * @return a payload object represented by the given string
+     */
+    public static Payload parse(String payloadString) {
+        String[] parts = payloadString.split(":");
+
+        if (parts.length != 4 || !ITEM_PREFIX.equals(parts[0])) {
+            throw new IllegalArgumentException(
+                    "Data type does not have a valid payload format");
+        }
+
+        // Create payload object of the given parts. Value type is converted to
+        // upper case to match the enum's case.
+        return new Payload(parts[2], parts[3],
+                ValueType.valueOf(parts[1].toUpperCase()));
+    }
+}