/*
 * 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.avro.io.parsing;

import java.util.HashMap;
import java.util.Map;

import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;

The class that generates a grammar suitable to parse Avro data in JSON
format.
/**
 * The class that generates a grammar suitable to parse Avro data in JSON
 * format.
 */

public class JsonGrammarGenerator extends ValidatingGrammarGenerator {
  
Returns the non-terminal that is the start symbol for the grammar for the
grammar for the given schema sc.
/**
   * Returns the non-terminal that is the start symbol for the grammar for the
   * grammar for the given schema <tt>sc</tt>.
   */
  @Override
  public Symbol generate(Schema schema) {
    return Symbol.root(generate(schema, new HashMap<>()));
  }

  
Returns the non-terminal that is the start symbol for grammar of the given
schema sc. If there is already an entry for the given schema in the
given map seen then that entry is returned. Otherwise a new symbol
is generated and an entry is inserted into the map.
Params:
sc –   The schema for which the start symbol is required
seen – A map of schema to symbol mapping done so far.
Returns:
The start symbol for the schema/**
   * Returns the non-terminal that is the start symbol for grammar of the given
   * schema <tt>sc</tt>. If there is already an entry for the given schema in the
   * given map <tt>seen</tt> then that entry is returned. Otherwise a new symbol
   * is generated and an entry is inserted into the map.
   * 
   * @param sc   The schema for which the start symbol is required
   * @param seen A map of schema to symbol mapping done so far.
   * @return The start symbol for the schema
   */
  @Override
  public Symbol generate(Schema sc, Map<LitS, Symbol> seen) {
    switch (sc.getType()) {
    case NULL:
    case BOOLEAN:
    case INT:
    case LONG:
    case FLOAT:
    case DOUBLE:
    case STRING:
    case BYTES:
    case FIXED:
    case UNION:
      return super.generate(sc, seen);
    case ENUM:
      return Symbol.seq(Symbol.enumLabelsAction(sc.getEnumSymbols()), Symbol.ENUM);
    case ARRAY:
      return Symbol.seq(Symbol.repeat(Symbol.ARRAY_END, Symbol.ITEM_END, generate(sc.getElementType(), seen)),
          Symbol.ARRAY_START);
    case MAP:
      return Symbol.seq(Symbol.repeat(Symbol.MAP_END, Symbol.ITEM_END, generate(sc.getValueType(), seen),
          Symbol.MAP_KEY_MARKER, Symbol.STRING), Symbol.MAP_START);
    case RECORD: {
      LitS wsc = new LitS(sc);
      Symbol rresult = seen.get(wsc);
      if (rresult == null) {
        Symbol[] production = new Symbol[sc.getFields().size() * 3 + 2];
        rresult = Symbol.seq(production);
        seen.put(wsc, rresult);

        int i = production.length;
        int n = 0;
        production[--i] = Symbol.RECORD_START;
        for (Field f : sc.getFields()) {
          production[--i] = Symbol.fieldAdjustAction(n, f.name(), f.aliases());
          production[--i] = generate(f.schema(), seen);
          production[--i] = Symbol.FIELD_END;
          n++;
        }
        production[--i] = Symbol.RECORD_END;
      }
      return rresult;
    }
    default:
      throw new RuntimeException("Unexpected schema type");
    }
  }
}