package com.example.demoproject.migration;

import com.github.cloudyrock.mongock.ChangeLog; import com.github.cloudyrock.mongock.ChangeSet; import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoCursor; import com.mongodb.client.model.UpdateOneModel; import org.bson.Document; import org.bson.conversions.Bson; import org.springframework.data.mongodb.core.MongoTemplate;

import java.util.HashMap; import java.util.LinkedList; import java.util.List; import java.util.Map;

import static com.mongodb.client.model.Filters.eq; import static com.mongodb.client.model.Updates.combine; import static com.mongodb.client.model.Updates.set;

//@ChangeUnit(id="BookStoreDatabase", order = "1", author = "mongock") @ChangeLog(order = "001") public class v1_01_BookAddField {

private static final String COLLECTION = "Book";

@ChangeSet(order = "01", id = "AddNewField", author = "kmishra")
public void addNewFieldInBook(MongoTemplate template) {

// BookRepository

    MongoCollection<Document> collection = template.getCollection(COLLECTION);

    try (MongoCursor<Document> cursor = collection.find().batchSize(2).iterator()) {
        List<UpdateOneModel<Document>> bulkUpdate = new LinkedList<>();

        while (cursor.hasNext()) {
            Document book = cursor.next();
            System.out.println("Book instance ######## : " + book);

            Map<String, Object> field = new HashMap<>();

// field.put("NumberOfPages", book.get("_id").toString());

            Map<String, Object> attr = new HashMap<>();
            attr.put("number", book.getString("bookName"));
            attr.put("universalNumber", book.getString("authorName"));

            List<Bson> update = new LinkedList<>();
            update.add(set("NoOfPage", new Document(attr)));


            bulkUpdate.add(new UpdateOneModel<>(eq(book.get("_id")), combine(update)));

// bulkUpdates.add(new UpdateOneModel<>(eq(rscAttribute.getObjectId("_id")), combine(updates)));

            if (bulkUpdate.size() == 2) {
                collection.bulkWrite(bulkUpdate);
                bulkUpdate.clear();
            }
        }

        if (!bulkUpdate.isEmpty()) {
            collection.bulkWrite(bulkUpdate);
        }
    }
}

}