add db initialization with sample data (#20)

* add db initialization with sample data

* fix according to comments

* fix ExampleDataInitializer description

server/src/main/java/org/hyperskill/community/flashcards/card/ExampleDataInitializer.java

@@ -1,83 +1,110 @@
 package org.hyperskill.community.flashcards.card;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import jakarta.annotation.PostConstruct;
+import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.hyperskill.community.flashcards.card.model.Card;
 import org.hyperskill.community.flashcards.card.model.MultipleChoiceQuiz;
 import org.hyperskill.community.flashcards.card.model.QuestionAndAnswerCard;
 import org.hyperskill.community.flashcards.card.model.SingleChoiceQuiz;
 import org.hyperskill.community.flashcards.category.model.Category;
 import org.hyperskill.community.flashcards.category.model.CategoryAccess;
-import org.springframework.beans.factory.annotation.Qualifier;
+import org.hyperskill.community.flashcards.registration.User;
+import org.hyperskill.community.flashcards.registration.UserDto;
+import org.hyperskill.community.flashcards.registration.UserMapper;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
 import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.stereotype.Component;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 
 /**
- * Initializes the 'example' database with sample cards.
+ * Initializes the 'cards' database with sample cards.
  */
 @Component
+@RequiredArgsConstructor
 @Slf4j
 public class ExampleDataInitializer {
+    private static final String exampleCollection = "example";
+    private static final String userCollection = "user";
+    private static final String categoryCollection = "category";
+    private static final String userJsonPath = "/json/users.json";
+    private static final String flashcardsJsonPath = "/json/flashcards.json";
+    private final ObjectMapper objectMapper = new ObjectMapper();
+    private final UserMapper userMapper;
     private final MongoTemplate mongoTemplate;
 
-    public ExampleDataInitializer(@Qualifier("example") MongoTemplate mongoTemplate) {
-        this.mongoTemplate = mongoTemplate;
-    }
-
+    /**
+     * This method checks if collections to be initialized are empty, and if yes
+     * it reads data from <code>/resources/json</code> folder and insert it
+     * in the said collections. This ensures that empty database is initialized
+     * with the same data, while non-empty database state remains unchanged.
+     */
     @PostConstruct
     public void init() {
-        List<Card> mathCards = List.of(
-                QuestionAndAnswerCard.builder()
-                        .title("card 1")
-                        .question("Calculate 2 + 2 = ?")
-                        .answer("4")
-                        .tags(Set.of("equations"))
-                        .build(),
-                SingleChoiceQuiz.builder()
-                        .title("card 2")
-                        .question("Solve the equation: 2x + 3 = 9")
-                        .options(List.of("2", "5", "6", "3"))
-                        .correctOption(3)
-                        .build(),
-                MultipleChoiceQuiz.builder()
-                        .title("card 3")
-                        .question("Select all correct statements about the equation: 2x + 3 = 9")
-                        .options(List.of("It's a square equation", "It's a linear equation", "It doesn't have a root", "It's root is 3"))
-                        .correctOptions(List.of(1, 3))
-                        .build()
-        );
-        var geographyCards = List.of(
-                QuestionAndAnswerCard.builder()
-                        .title("card 4")
-                        .question("Capital of Spain")
-                        .answer("Madrid")
-                        .tags(Set.of("Europe", "cities"))
-                        .build()
-        );
-        var chemistryCards = List.of(
-                SingleChoiceQuiz.builder()
-                        .title("card 5")
-                        .question("Which of the elements has the lowest atomic weight?")
-                        .options(List.of("Au", "Fe", "Li", "Pt"))
-                        .correctOption(2)
-                        .tags(Set.of("elements", "atoms"))
-                        .build()
-        );
+        if (isCollectionNotEmpty(userCollection)) {
+            log.warn("Collection {} is not empty, aborting database initialization", userCollection);
+            return;
+        }
+        if (isCollectionNotEmpty(categoryCollection)) {
+            log.warn("Collection {} is not empty, aborting database initialization", categoryCollection);
+            return;
+        }
+        if (isCollectionNotEmpty(exampleCollection)) {
+            log.warn("Collection {} is not empty, aborting database initialization", exampleCollection);
+            return;
+        }
+
+        Resource usersJson = new ClassPathResource(userJsonPath);
+        Resource flashcardsJson = new ClassPathResource(flashcardsJsonPath);
+
+        try {
+            List<UserDto> userDTOs = objectMapper.readValue(usersJson.getFile(), new TypeReference<>() {});
+            List<User> users = userDTOs.stream().map(userMapper::toDocument).toList();
+            if (users.size() == 0) {
+                throw new IllegalStateException("No users to insert");
+            }
+            mongoTemplate.insertAll(users);
+
+            var categoryAccess = new CategoryAccess(users.get(0).getUsername(), "rwd");
+            mongoTemplate.insert(new Category(null, exampleCollection, Set.of(categoryAccess)));
 
-        log.info("Dropping any existing collections in 'example' database...");
-        mongoTemplate.getDb().listCollectionNames().forEach(mongoTemplate::dropCollection);
+            JsonNode jsonNode = objectMapper.readTree(flashcardsJson.getFile());
+            List<SingleChoiceQuiz> scqCards = parseCards(jsonNode.get("scq_cards"), SingleChoiceQuiz.class);
+            List<MultipleChoiceQuiz> mcqCards = parseCards(jsonNode.get("mcq_cards"), MultipleChoiceQuiz.class);
+            List<QuestionAndAnswerCard> qnaCards = parseCards(jsonNode.get("qna_cards"), QuestionAndAnswerCard.class);
+
+            mongoTemplate.insert(scqCards, exampleCollection);
+            mongoTemplate.insert(mcqCards, exampleCollection);
+            mongoTemplate.insert(qnaCards, exampleCollection);
+
+        } catch (Exception e) {
+            log.error("Error updating database", e);
+            mongoTemplate.getDb().drop();
+        }
+    }
+
+    private <T extends Card> List<T> parseCards(JsonNode jsonNode, Class<T> clazz) throws JsonProcessingException {
+        List<T> list = new ArrayList<>();
+        for (JsonNode node : jsonNode) {
+            T card = objectMapper.treeToValue(node, clazz);
+            list.add(card);
+        }
+        return list;
+    }
 
-        log.info("Inserting sample data to 'example' database...");
-        var categoryAccess = new CategoryAccess("[email protected]", "rwd");
-        mongoTemplate.insert(new Category(null, "math", Set.of(categoryAccess)));
-        mongoTemplate.insert(new Category(null, "geography", Set.of(categoryAccess)));
-        mongoTemplate.insert(new Category(null, "chemistry", Set.of(categoryAccess)));
+    private boolean isCollectionNotEmpty(String collection) {
+        var collectionExists = mongoTemplate.getDb().listCollectionNames()
+                .into(new ArrayList<>())
+                .contains(collection);
 
-        mathCards.forEach(card -> mongoTemplate.insert(card, "math"));
-        geographyCards.forEach(card -> mongoTemplate.insert(card, "geography"));
-        chemistryCards.forEach(card -> mongoTemplate.insert(card, "chemistry"));
+        return collectionExists && mongoTemplate.getDb().getCollection(collection).countDocuments() > 0;
     }
 }

server/src/main/java/org/hyperskill/community/flashcards/card/model/MultipleChoiceQuiz.java

@@ -22,6 +22,10 @@ public final class MultipleChoiceQuiz extends Card {
     private List<String> options;
     private List<Integer> correctOptions;
 
+    public MultipleChoiceQuiz() {
+        super(null, null, null);
+    }
+
     @Builder
     public MultipleChoiceQuiz(String title, Set<String> tags, String question,
                               List<String> options, List<Integer> correctOptions) {

server/src/main/java/org/hyperskill/community/flashcards/card/model/QuestionAndAnswerCard.java

@@ -15,6 +15,10 @@
 public final class QuestionAndAnswerCard extends Card {
     private String answer;
 
+    public QuestionAndAnswerCard() {
+        super(null, null, null);
+    }
+
     @Builder
     public QuestionAndAnswerCard(String title, Set<String> tags, String question, String answer) {
         super(title, tags, question);

server/src/main/java/org/hyperskill/community/flashcards/card/model/SingleChoiceQuiz.java

@@ -22,6 +22,10 @@ public final class SingleChoiceQuiz extends Card {
     private List<String> options;
     private Integer correctOption;
 
+    public SingleChoiceQuiz() {
+        super(null, null, null);
+    }
+
     @Builder
     public SingleChoiceQuiz(String title, Set<String> tags, String question,
                             List<String> options, Integer correctOption) {

server/src/main/java/org/hyperskill/community/flashcards/config/MongoConfiguration.java

@@ -1,7 +1,6 @@
 package org.hyperskill.community.flashcards.config;
 
 import com.mongodb.client.MongoClients;
-import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.mongodb.config.EnableMongoAuditing;
@@ -15,10 +14,4 @@ public class MongoConfiguration {
     public MongoTemplate mongoTemplate() {
         return new MongoTemplate(MongoClients.create(), "cards");
     }
-
-    @Bean
-    @Qualifier("example")
-    public MongoTemplate exampleMongoTemplate() {
-        return new MongoTemplate(MongoClients.create(), "example");
-    }
 }

server/src/main/resources/json/flashcards.json

@@ -0,0 +1,94 @@
+{
+  "qna_cards": [
+    {
+      "title": "card 1",
+      "question": "Capital of Brazil",
+      "answer": "Brasilia",
+      "tags": [
+        "america", "cities"
+      ]
+    },
+    {
+      "title": "card 2",
+      "question": "Capital of Spain",
+      "answer": "Madrid",
+      "tags": [
+        "europe", "cities"
+      ]
+    },
+    {
+      "title": "card 3",
+      "question": "Name this chemical element: Tl",
+      "answer": "Thallium",
+      "tags": [
+        "elements", "symbols"
+      ]
+    },
+    {
+      "title": "card 4",
+      "question": "What is the square root of 144",
+      "answer": "12",
+      "tags": []
+    }
+  ],
+  "scq_cards": [
+    {
+      "title": "card 5",
+      "question": "What is the root of this equation: 3x + 2 = 14",
+      "options": ["5", "9", "3", "4"],
+      "correctOption": 3,
+      "tags": ["equations"]
+    },
+    {
+      "title": "card 6",
+      "question": "Name the largest country among the following:",
+      "options": ["Portugal", "Sweden", "Australia", "Japan"],
+      "correctOption": 2,
+      "tags": ["countries"]
+    },
+    {
+      "title": "card 7",
+      "question": "What is the type of this reaction: NaOH + HCl = NaCl + H2O",
+      "options": ["Oxidation", "Reduction", "Neutralization", "Neither"],
+      "correctOption": 3,
+      "tags": ["reactions"]
+    },
+    {
+      "title": "card 8",
+      "question": "Name the capital of Luxembourg",
+      "options": ["Luxembourg", "Strasbourg", "Andorra la Vella", "London"],
+      "correctOption": 3,
+      "tags": ["europe", "cities"]
+    }
+  ],
+  "mcq_cards": [
+    {
+      "title": "card 9",
+      "question": "Select all correct statements about this equation: ax + by = c",
+      "options": ["It's a quadratic equation", "It's a linear equation", "It describes a line", "It describes a curve"],
+      "correctOptions": [1, 2],
+      "tags": ["geometry", "equations"]
+    },
+    {
+      "title": "card 10",
+      "question": "Which of the following is true about DNA?",
+      "options": ["DNA is a double-stranded molecule", "DNA contains genetic information", "DNA stands for Deoxyribonucleic acid", "DNA is found only in animals"],
+      "correctOptions": [0, 1, 2],
+      "tags": ["genetics"]
+    },
+    {
+      "title": "card 11",
+      "question": "Which of the following elements is a noble gas?",
+      "options": ["Oxygen", "Helium", "Carbon", "Nitrogen"],
+      "correctOptions": [1],
+      "tags": ["elements"]
+    },
+    {
+      "title": "card 12",
+      "question": "Which of the following is a fundamental force in nature?",
+      "options": ["Gravity", "Friction", "Light", "Heat"],
+      "correctOptions": [0],
+      "tags": ["forces"]
+    }
+  ]
+}

server/src/main/resources/json/users.json

@@ -0,0 +1,10 @@
+[
+  {
+    "email": "[email protected]",
+    "password": "12345678"
+  },
+  {
+    "email": "[email protected]",
+    "password": "12345678"
+  }
+]