Add Support for ordering and limiting results in CLI show commands

hoodie-cli/src/main/java/com/uber/hoodie/cli/Table.java

@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2016 Uber Technologies, Inc. (hoodie-dev-group@uber.com)
+ *
+ * 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.uber.hoodie.cli;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+/**
+ * Table to be rendered. This class takes care of ordering
+ * rows and limiting before renderer renders it.
+ */
+public class Table implements Iterable<List<String>> {
+
+  // Header for this table
+  private final TableHeader rowHeader;
+  // User-specified conversions before rendering
+  private final Map<String, Function<Object, String>> fieldNameToConverterMap;
+  // Optional attribute to track sorting field
+  private final Optional<String> orderingFieldNameOptional;
+  // Whether sorting has to be in descending order (by default : optional)
+  private final Optional<Boolean> isDescendingOptional;
+  // Limit the number of entries rendered
+  private final Optional<Integer> limitOptional;
+  // Raw list of rows
+  private final List<List<Comparable>> rawRows;
+  // Flag to determine if all the rows have been added
+  private boolean finishedAdding = false;
+  // Rows ready for Rendering
+  private List<List<String>> renderRows;
+
+  public Table(TableHeader rowHeader,
+      Map<String, Function<Object, String>> fieldNameToConverterMap,
+      Optional<String> orderingFieldNameOptional,
+      Optional<Boolean> isDescendingOptional,
+      Optional<Integer> limitOptional) {
+    this.rowHeader = rowHeader;
+    this.fieldNameToConverterMap = fieldNameToConverterMap;
+    this.orderingFieldNameOptional = orderingFieldNameOptional;
+    this.isDescendingOptional = isDescendingOptional;
+    this.limitOptional = limitOptional;
+    this.rawRows = new ArrayList<>();
+  }
+
+  /**
+   * Main API to add row to the table
+   * @param row Row
+   */
+  public Table add(List<Comparable> row) {
+    if (finishedAdding) {
+      throw new IllegalStateException("Container already marked done for adding. No more entries can be added.");
+    }
+
+    if (rowHeader.getFieldNames().size() != row.size()) {
+      throw new IllegalArgumentException("Incorrect number of fields in row. Expected: "
+          + rowHeader.getFieldNames().size() + ", Got: " + row.size() + ", Row: " + row);
+    }
+
+    this.rawRows.add(new ArrayList<>(row));
+    return this;
+  }
+
+  /**
+   * Add all rows
+   * @param rows Rows to be aded
+   * @return
+   */
+  public Table addAll(List<List<Comparable>> rows) {
+    rows.forEach(r -> add(r));
+    return this;
+  }
+
+  /**
+   * Add all rows
+   * @param rows Rows to be added
+   * @return
+   */
+  public Table addAllRows(List<Comparable[]> rows) {
+    rows.forEach(r -> add(Arrays.asList(r)));
+    return this;
+  }
+
+  /**
+   * API to let the table know writing is over and reading is going to start
+   */
+  public Table flip() {
+    this.finishedAdding = true;
+    sortAndLimit();
+    return this;
+  }
+
+  /**
+   * Sorting of rows by a specified field
+   * @return
+   */
+  private List<List<Comparable>> orderRows() {
+    return orderingFieldNameOptional.map(orderingColumnName -> {
+      return rawRows.stream().sorted(new Comparator<List<Comparable>>() {
+        @Override
+        public int compare(List<Comparable> row1, List<Comparable> row2) {
+          Comparable fieldForRow1 = row1.get(rowHeader.indexOf(orderingColumnName));
+          Comparable fieldForRow2 = row2.get(rowHeader.indexOf(orderingColumnName));
+          int cmpRawResult = fieldForRow1.compareTo(fieldForRow2);
+          return isDescendingOptional.map(isDescending -> {
+            return isDescending ? -1 * cmpRawResult : cmpRawResult;
+          }).orElse(cmpRawResult);
+        }
+      }).collect(Collectors.toList());
+    }).orElse(rawRows);
+  }
+
+  /**
+   * Prepares for rendering. Rows are sorted and limited
+   */
+  private void sortAndLimit() {
+    this.renderRows = new ArrayList<>();
+    final int limit = this.limitOptional.orElse(rawRows.size());
+    final List<List<Comparable>> orderedRows = orderRows();
+    renderRows = orderedRows.stream().limit(limit).map(row -> {
+      return IntStream.range(0, rowHeader.getNumFields()).mapToObj(idx -> {
+        String fieldName = rowHeader.get(idx);
+        if (fieldNameToConverterMap.containsKey(fieldName)) {
+          return fieldNameToConverterMap.get(fieldName).apply(row.get(idx));
+        }
+        return row.get(idx).toString();
+      }).collect(Collectors.toList());
+    }).collect(Collectors.toList());
+  }
+
+  @Override
+  public Iterator<List<String>> iterator() {
+    if (!finishedAdding) {
+      throw new IllegalStateException("Container must be flipped before reading the data");
+    }
+    return renderRows.iterator();
+  }
+
+  @Override
+  public void forEach(Consumer<? super List<String>> action) {
+    if (!finishedAdding) {
+      throw new IllegalStateException("Container must be flipped before reading the data");
+    }
+    renderRows.forEach(action);
+  }
+
+  public List<String> getFieldNames() {
+    return rowHeader.getFieldNames();
+  }
+
+  public List<List<String>> getRenderRows() {
+    return renderRows;
+  }
+}