Add flat list proof support [ECR-3608]

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/CheckedProof.java

@@ -25,6 +25,7 @@
  * If it is valid, the proof contents may be accessed. See {@link CheckedListProof}
  * and {@link CheckedMapProof} for available contents description.
  */
+// todo: Why do we need to represent invalid proofs?
 public interface CheckedProof {
 
   /**

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/CheckedListProof.java

@@ -35,6 +35,12 @@
  * }</pre>
  */
 public interface CheckedListProof<E> extends CheckedProof {
+
+  /**
+   * Returns the size of the list: the total number of elements in it.
+   */
+  long size();
+
   /**
    * Get all list proof elements. There might be several consecutive ranges.
    *

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/CheckedListProofImpl.java

@@ -58,6 +58,12 @@ public CheckedListProofImpl(HashCode calculatedIndexHash,
     this.proofStatus = checkNotNull(proofStatus);
   }
 
+  @Override
+  public long size() {
+    // todo:
+    return 0;
+  }
+
   @Override
   public NavigableMap<Long, E>  getElements() {
     checkValid();

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/FlatListProof.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * 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.exonum.binding.common.proofs.list;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.List;
+
+/**
+ * A flat list proof. It proves that certain elements are present in a proof list
+ * of a certain size.
+ */
+class FlatListProof {
+  private final List<ListProofElementEntry> elements;
+  private final List<ListProofHashedEntry> proof;
+  private final long size;
+
+  FlatListProof(List<ListProofElementEntry> elements,
+      List<ListProofHashedEntry> proof, long size) {
+    this.elements = checkNotNull(elements);
+    this.proof = checkNotNull(proof);
+    this.size = size;
+  }
+
+  CheckedListProof<byte[]> verify() {
+    return null;
+  }
+}

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/InvalidProofException.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * 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.exonum.binding.common.proofs.list;
+
+/**
+ * todo:
+ */
+public class InvalidProofException extends RuntimeException {
+
+  /**
+   * Constructs a new runtime exception with {@code null} as its detail message.  The cause is not
+   * initialized, and may subsequently be initialized by a call to {@link #initCause}.
+   */
+  public InvalidProofException() {
+    super();
+  }
+
+  /**
+   * Constructs a new runtime exception with the specified detail message. The cause is not
+   * initialized, and may subsequently be initialized by a call to {@link #initCause}.
+   *
+   * @param message the detail message. The detail message is saved for later retrieval by the
+   *                {@link #getMessage()} method.
+   */
+  public InvalidProofException(String message) {
+    super(message);
+  }
+}

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/ListProofElementEntry.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * 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.exonum.binding.common.proofs.list;
+
+import com.google.auto.value.AutoValue;
+
+/**
+ * A value stored in the Merkle tree at its bottom level (at height 0).
+ */
+@AutoValue
+abstract class ListProofElementEntry implements ListProofEntry {
+
+  /**
+   * Returns a value of the element stored at this index in the list.
+   */
+  abstract byte[] getElement();
+
+  static ListProofElementEntry newInstance(long index, byte[] element) {
+    ListProofEntry.checkIndex(index);
+    return new AutoValue_ListProofElementEntry(index, 0, element);
+  }
+}

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/ListProofEntry.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * 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.exonum.binding.common.proofs.list;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+interface ListProofEntry {
+
+  /**
+   * The maximum height of a list proof tree.
+   */
+  int MAX_HEIGHT = 56;
+
+  /**
+   * The maximum index of a list proof node: 2^56 - 1.
+   */
+  long MAX_INDEX = 0xFF_FFFF_FFFF_FFFFL;
+
+  /**
+   * Returns the index of the proof tree node at the height of its level. Indexes start
+   * from 0 for the leftmost node and up to <em>2^d - 1</em> for the rightmost node,
+   * where <em>d = ceil(log2(N)) - h</em> is the depth of the node at height <em>h</em>;
+   * <em>N</em> is the number of elements in the tree.
+   */
+  long getIndex();
+
+  /**
+   * Returns the height of the proof tree node corresponding to this entry.
+   * The height of leaf nodes is equal to 0; the height of the root, or top node:
+   * <em>ceil(log2(N))</em>.
+   */
+  int getHeight();
+
+  static void checkIndex(long index) {
+    checkArgument(0 <= index && index <= MAX_INDEX,
+        "Entry index (%s) is out of range [0; 2^56]", index);
+  }
+
+  static void checkHeight(int height) {
+    checkArgument(0 <= height && height <= MAX_HEIGHT,
+        "Entry height (%s) is out of range [0; 56]", height);
+  }
+}

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/ListProofHashedEntry.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * 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.exonum.binding.common.proofs.list;
+
+import com.exonum.binding.common.hash.HashCode;
+import com.google.auto.value.AutoValue;
+
+/**
+ * A hash of a sub-tree in a Merkle proof tree.
+ */
+@AutoValue
+abstract class ListProofHashedEntry implements ListProofEntry {
+  // todo: do we need the interface (are we going to operate on the entries using the interface?)
+  //   Do we need entries at all, or just hashes?
+
+  /**
+   * Returns the hash of the sub-tree this entry represents.
+   */
+  abstract HashCode getHash();
+
+  static ListProofHashedEntry newInstance(long index, int height, HashCode nodeHash) {
+    ListProofEntry.checkIndex(index);
+    ListProofEntry.checkHeight(height);
+    return new AutoValue_ListProofHashedEntry(index, height, nodeHash);
+  }
+}

exonum-java-binding/common/src/main/java/com/exonum/binding/common/proofs/list/UncheckedListProof.java

@@ -17,7 +17,7 @@
 package com.exonum.binding.common.proofs.list;
 
 /**
- * A proof that some elements exist in a proof list. You must
+ * A proof that some elements exist in a proof list of a certain size. You must
  * {@link #check} its structure and index hash before accessing the elements.
  */
 public interface UncheckedListProof {