feat: Implement REST API endpoints for Library Management System

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

@@ -4,12 +4,18 @@
 import com.codedifferently.lesson23.library.Library;
 import com.codedifferently.lesson23.library.MediaItem;
 import com.codedifferently.lesson23.library.search.SearchCriteria;
+import jakarta.validation.Valid;
 import java.io.IOException;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 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.RestController;
 
 @RestController
@@ -24,11 +30,67 @@ public MediaItemsController(Library library) throws IOException {
     this.librarian = library.getLibrarians().stream().findFirst().orElseThrow();
   }
 
+  @GetMapping("/")
+  public ResponseEntity<Map<String, Object>> welcome() {
+    Map<String, Object> response =
+        Map.of(
+            "message", "Welcome to the Library Management API!",
+            "version", "1.0.0",
+            "endpoints",
+                Map.of(
+                    "DELETE /items/{id}", "Delete a media item",
+                    "POST /items", "Create a new media item",
+                    "GET /items", "Get all media items",
+                    "GET /items/{id}", "Get a specific media item"),
+            "documentation",
+                Map.of(
+                    "note", "Built-in Swagger/OpenAPI documentation available if configured"),
+            "statistics",
+                Map.of(
+                    "totalItems", library.search(SearchCriteria.builder().build()).size(),
+                    "totalLibrarians", library.getLibrarians().size()));
+    return ResponseEntity.ok(response);
+  }
+
   @GetMapping("/items")
   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);
   }
+
+  @GetMapping("/items/{id}")
+  public ResponseEntity<MediaItemResponse> getItem(@PathVariable String id) {
+    Set<MediaItem> items = library.search(SearchCriteria.builder().id(id).build());
+    if (items.isEmpty()) {
+      return ResponseEntity.notFound().build();
+    }
+    MediaItem item = items.iterator().next();
+    MediaItemResponse response = MediaItemResponse.from(item);
+    return ResponseEntity.ok(response);
+  }
+
+  @PostMapping("/items")
+  public ResponseEntity<CreateMediaItemResponse> createItem(
+      @Valid @RequestBody CreateMediaItemRequest request) {
+    MediaItem mediaItem = MediaItemRequest.asMediaItem(request.getItem());
+    library.addMediaItem(mediaItem, librarian);
+    MediaItemResponse responseItem = MediaItemResponse.from(mediaItem);
+    var response = CreateMediaItemResponse.builder().item(responseItem).build();
+    return ResponseEntity.ok(response);
+  }
+
+
+
+  @DeleteMapping("/items/{id}")
+  public ResponseEntity<Void> deleteItem(@PathVariable String id) {
+    Set<MediaItem> items = library.search(SearchCriteria.builder().id(id).build());
+    if (items.isEmpty()) {
+      return ResponseEntity.notFound().build();
+    }
+    MediaItem item = items.iterator().next();
+    library.removeMediaItem(item, librarian);
+    return ResponseEntity.noContent().build();
+  }
 }