content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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
   *
   *     https://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 org.apache.trevni.avro;
  
  import java.util.List;
  import java.util.ArrayList;
  import java.util.Map;
  import java.util.IdentityHashMap;
  
  import org.apache.trevni.ColumnMetaData;
  import org.apache.trevni.ValueType;
  import org.apache.trevni.TrevniRuntimeException;
  
  import org.apache.avro.Schema;
  import org.apache.avro.Schema.Field;
  
  /** Utility that computes the column layout of a schema. */
  class AvroColumnator {
  
    private List<ColumnMetaData> columns = new ArrayList<>();
    private List<Integer> arrayWidths = new ArrayList<>();
  
    public AvroColumnator(Schema schema) {
      Schema schema1 = schema;
      columnize(null, schema, null, false);
    }
  
    /** Return columns for the schema. */
    public ColumnMetaData[] getColumns() {
      return columns.toArray(new ColumnMetaData[0]);
    }
  
    /**
     * Return array giving the number of columns immediately following each column
     * that are descendents of that column.
     */
    public int[] getArrayWidths() {
      int[] result = new int[arrayWidths.size()];
      int i = 0;
      for (Integer width : arrayWidths)
        result[i++] = width;
      return result;
    }
  
    private Map<Schema, Schema> seen = new IdentityHashMap<>();
  
    private void columnize(String path, Schema s, ColumnMetaData parent, boolean isArray) {
  
      if (isSimple(s)) {
        if (path == null)
          path = s.getFullName();
        addColumn(path, simpleValueType(s), parent, isArray);
        return;
      }
  
      if (seen.containsKey(s)) // catch recursion
        throw new TrevniRuntimeException("Cannot shred recursive schemas: " + s);
      seen.put(s, s);
  
      switch (s.getType()) {
      case MAP:
        path = path == null ? ">" : path + ">";
        int start = columns.size();
        ColumnMetaData p = addColumn(path, ValueType.NULL, parent, true);
        addColumn(p(path, "key", ""), ValueType.STRING, p, false);
        columnize(p(path, "value", ""), s.getValueType(), p, false);
        arrayWidths.set(start, columns.size() - start); // fixup with actual width
        break;
      case RECORD:
        for (Field field : s.getFields()) // flatten fields to columns
          columnize(p(path, field.name(), "#"), field.schema(), parent, isArray);
        break;
      case ARRAY:
        path = path == null ? "[]" : path + "[]";
        addArrayColumn(path, s.getElementType(), parent);
        break;
      case UNION:
        for (Schema branch : s.getTypes()) // array per non-null branch
          if (branch.getType() != Schema.Type.NULL)
            addArrayColumn(p(path, branch, "/"), branch, parent);
        break;
      default:
        throw new TrevniRuntimeException("Unknown schema: " + s);
      }
      seen.remove(s);
    }
  
    private String p(String parent, Schema child, String sep) {
      if (child.getType() == Schema.Type.UNION)
        return parent;
      return p(parent, child.getFullName(), sep);
    }
  
    private String p(String parent, String child, String sep) {
      return parent == null ? child : parent + sep + child;
    }
  
    private ColumnMetaData addColumn(String path, ValueType type, ColumnMetaData parent, boolean isArray) {
      ColumnMetaData column = new ColumnMetaData(path, type);
      if (parent != null)
        column.setParent(parent);
      column.isArray(isArray);
      columns.add(column);
      arrayWidths.add(1); // placeholder
      return column;
    }
  
    private void addArrayColumn(String path, Schema element, ColumnMetaData parent) {
      if (path == null)
        path = element.getFullName();
      if (isSimple(element)) { // optimize simple arrays
        addColumn(path, simpleValueType(element), parent, true);
        return;
      }
      // complex array: insert a parent column with lengths
      int start = columns.size();
      ColumnMetaData array = addColumn(path, ValueType.NULL, parent, true);
      columnize(path, element, array, false);
      arrayWidths.set(start, columns.size() - start); // fixup with actual width
    }
  
    static boolean isSimple(Schema s) {
      switch (s.getType()) {
      case NULL:
      case BOOLEAN:
      case INT:
      case LONG:
      case FLOAT:
      case DOUBLE:
      case BYTES:
      case STRING:
      case ENUM:
      case FIXED:
        return true;
      default:
        return false;
      }
    }
  
    private ValueType simpleValueType(Schema s) {
      switch (s.getType()) {
      case NULL:
        return ValueType.NULL;
      case BOOLEAN:
        return ValueType.BOOLEAN;
      case INT:
        return ValueType.INT;
      case LONG:
        return ValueType.LONG;
      case FLOAT:
        return ValueType.FLOAT;
      case DOUBLE:
        return ValueType.DOUBLE;
      case BYTES:
        return ValueType.BYTES;
      case STRING:
        return ValueType.STRING;
      case ENUM:
        return ValueType.INT;
      case FIXED:
        return ValueType.BYTES;
      default:
        throw new TrevniRuntimeException("Unknown schema: " + s);
      }
    }
  
  }
  