// Copyright 2020 Google LLC. All Rights Reserved.
//
// 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 vocabulary

import (
	metrics "github.com/google/gnostic/metrics"
)

// Union implements the union operation between multiple Vocabularies.
// The function accepts a slice of Vocabularies and returns a single Vocabulary
// struct which contains all of the data from the Vocabularies.
func Union(vocabularies []*metrics.Vocabulary) *metrics.Vocabulary {
	var vocab Vocabulary
	vocab.schemas = make(map[string]int)
	vocab.operationID = make(map[string]int)
	vocab.parameters = make(map[string]int)
	vocab.properties = make(map[string]int)

	for _, v := range vocabularies {
		vocab.unpackageVocabulary(v)
	}

	combinedVocab := &metrics.Vocabulary{
		Properties: fillProtoStructure(vocab.properties),
		Schemas:    fillProtoStructure(vocab.schemas),
		Operations: fillProtoStructure(vocab.operationID),
		Parameters: fillProtoStructure(vocab.parameters),
	}

	return combinedVocab
}
