Enhance MediaItemsController with CRUD operations and error handling

lesson_23/api/java/api_app/src/main/java/com/codedifferently/lesson23/web/MediaItemsController.java

@@ -1,34 +1,102 @@
 package com.codedifferently.lesson23.web;
 
-import com.codedifferently.lesson23.library.Librarian;
-import com.codedifferently.lesson23.library.Library;
-import com.codedifferently.lesson23.library.MediaItem;
-import com.codedifferently.lesson23.library.search.SearchCriteria;
 import java.io.IOException;
 import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
+import java.util.UUID;
+
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.CrossOrigin;
+import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+
+import com.codedifferently.lesson23.library.Librarian;
+import com.codedifferently.lesson23.library.Library;
+import com.codedifferently.lesson23.library.MediaItem;
+import com.codedifferently.lesson23.library.exceptions.MediaItemCheckedOutException;
+import com.codedifferently.lesson23.library.search.SearchCriteria;
+
+import jakarta.validation.Valid;
 
 @RestController
 @CrossOrigin
+@RequestMapping("/items") 
 public class MediaItemsController {
 
   private final Library library;
   private final Librarian librarian;
 
   public MediaItemsController(Library library) throws IOException {
-    this.library = library;
-    this.librarian = library.getLibrarians().stream().findFirst().orElseThrow();
+    this.library = Objects.requireNonNull(library, "Library cannot be null");
+    this.librarian = library.getLibrarians().stream().findFirst()
+        .orElseThrow(() -> new IllegalStateException("No librarians available"));
   }
 
-  @GetMapping("/items")
+  @GetMapping
   public ResponseEntity<GetMediaItemsResponse> getItems() {
     Set<MediaItem> items = library.search(SearchCriteria.builder().build());
     List<MediaItemResponse> responseItems = items.stream().map(MediaItemResponse::from).toList();
     var response = GetMediaItemsResponse.builder().items(responseItems).build();
     return ResponseEntity.ok(response);
   }
+
+  @PostMapping
+  public CreateMediaItemResponse createItem(@Valid @RequestBody CreateMediaItemRequest request) {
+    MediaItem newItem = MediaItemRequest.asMediaItem(request.getItem());
+    library.addMediaItem(newItem, librarian);
+    return CreateMediaItemResponse.builder()
+        .item(MediaItemResponse.from(newItem))
+        .build();
+  }
+
+  @GetMapping("/{id}")
+  public MediaItemResponse getItemById(@PathVariable UUID id) {
+    Set<MediaItem> allItems = library.search(SearchCriteria.builder().build());
+    Optional<MediaItem> foundItem = allItems.stream()
+        .filter(item -> item.getId().equals(id))
+        .findFirst();
+
+    if (foundItem.isEmpty()) {
+      throw new ResponseStatusException(
+        HttpStatus.NOT_FOUND,
+        "Media item with ID " + id + " not found."
+      );
+    }
+
+    return MediaItemResponse.from(foundItem.get());
+  }
+
+  @DeleteMapping("/{id}")
+  public ResponseEntity<Void> deleteItemById(@PathVariable UUID id) {
+    Set<MediaItem> allItems = library.search(SearchCriteria.builder().build());
+    Optional<MediaItem> foundItem = allItems.stream()
+        .filter(item -> item.getId().equals(id))
+        .findFirst();
+
+    if (foundItem.isEmpty()) {
+      throw new ResponseStatusException(
+        HttpStatus.NOT_FOUND,
+        "Media item with ID " + id + " not found."
+      );
+    }
+
+    try {
+      library.removeMediaItem(id, librarian);
+      return ResponseEntity.noContent().build();
+    } catch (MediaItemCheckedOutException e) {
+      throw new ResponseStatusException(
+        HttpStatus.CONFLICT,
+        "Cannot delete item: " + e.getMessage()
+      );
+    }
+  }
 }