Part five

src/flashcards/Main.java

@@ -1,7 +1,133 @@
 package flashcards;
 
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Scanner;
+
 public class Main {
-    public static void main(String[] args) {
-        System.out.print("Hello world!");
+
+  private static Map<String, String> cardToDefinition = new LinkedHashMap<>();
+  private static Map<String, String> definitionToCard = new LinkedHashMap<>();
+
+  public static void main(String[] args) {
+    try (Scanner scanner = new Scanner(System.in)) {
+      while (true) {
+        System.out.println("Input the action (add, remove, import, export, ask, exit):");
+
+        String action = scanner.nextLine();
+
+        switch (action) {
+          case "add":
+            addCard(scanner);
+            break;
+          case "remove":
+            removeCard(scanner);
+            break;
+          case "import":
+            importCard(scanner);
+            break;
+          case "export":
+            exportCard(scanner);
+            break;
+          case "ask":
+            askCard(scanner);
+            break;
+          case "exit":
+            System.out.println("Bye bye!");
+            return;
+        }
+      }
+    }
+  }
+
+  private static void askCard(Scanner scanner) {
+    System.out.println("How many times to ask?");
+    int n = Integer.parseInt(scanner.nextLine());
+    for (String card : cardToDefinition.keySet()) {
+      if (n <= 0) {
+        break;
+      }
+      System.out.printf("Print the definition of \"%s\":\n", card);
+      String guess = scanner.nextLine();
+      if (definitionToCard.containsKey(guess) && cardToDefinition.get(card).equals(guess)) {
+        System.out.printf("Correct answer.\n");
+      } else if (definitionToCard.containsKey(guess)) {
+        System.out.printf(
+            "Wrong answer (the correct one is \"%s\", you've just written a definition of \"%s\" card).\n",
+            cardToDefinition.get(card), definitionToCard.get(guess));
+      } else {
+        System.out
+            .printf("Wrong answer (the correct one is \"%s\").\n", cardToDefinition.get(card));
+      }
+      n--;
     }
+    System.out.printf("\n");
+  }
+
+  private static void exportCard(Scanner scanner) {
+    System.out.println("File name:");
+    String fileName = scanner.nextLine();
+    try (BufferedWriter writer = Files.newBufferedWriter(Paths.get(fileName));
+        PrintWriter print = new PrintWriter(writer)) {
+      for (Entry<String, String> entry : cardToDefinition.entrySet()) {
+        print.printf("%s\n%s\n", entry.getKey(), entry.getValue());
+      }
+    } catch (IOException e) {
+      System.out.printf("0 cards have been saved.\n\n");
+      return;
+    }
+    System.out.printf("%d cards have been saved.\n\n", cardToDefinition.size());
+  }
+
+  private static void importCard(Scanner scanner) {
+    System.out.println("File name:");
+    String fileName = scanner.nextLine();
+    int count = 0;
+    try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName))) {
+      String card;
+      while ((card = reader.readLine()) != null) {
+        String def = reader.readLine();
+        if (def == null) {
+          break;
+        }
+        cardToDefinition.put(card, def);
+        definitionToCard.put(def, card);
+        count++;
+      }
+    } catch (IOException e) {
+      System.out.printf("0 cards have been saved.\n\n");
+      return;
+    }
+    System.out.printf("%d cards have been saved.\n\n", count);
+  }
+
+  private static void removeCard(Scanner scanner) {
+    System.out.println("The card:");
+    String card = scanner.nextLine();
+    if (cardToDefinition.containsKey(card)) {
+      String def = cardToDefinition.get(card);
+      definitionToCard.remove(def);
+      cardToDefinition.remove(card);
+      System.out.println("The card successfully removed\n\n");
+    } else {
+      System.out.printf("Can't remove \"%s\": there is no such card.\n\n", card);
+    }
+  }
+
+  private static void addCard(Scanner scanner) {
+    System.out.println("The card:");
+    String card = scanner.nextLine();
+    System.out.println("The definition of the card:");
+    String definition = scanner.nextLine();
+    cardToDefinition.put(card, definition);
+    definitionToCard.put(definition, card);
+    System.out.printf("The pair (\"%s\":\"%s\") is added.\n\n", card, definition);
+  }
 }