feat: scan book to add to sell

lib/data/repositories/bal_repository.dart

@@ -55,6 +55,13 @@ class BalRepository {
         false;
   }
 
+  Future<Bal?> ongoingBal() async {
+    if (_bals == null) {
+      await _getBalsNoCache();
+    }
+    return _bals!.where((bal) => bal.state == BalState.ongoing).firstOrNull;
+  }
+
   Future<Result<Bal>> stopBal(int id) async {
     final result = await _apiClient.stopBal(id);
     _getBalsNoCache();

lib/data/repositories/book_instance_repository.dart

@@ -11,6 +11,10 @@ class BookInstanceRepository {
 
   final ApiClient _apiClient;
 
+  Future<Result<List<BookInstance>>> getByEan(int balId, int ean) async {
+    return await _apiClient.getBookInstanceByEAN(balId, ean);
+  }
+
   Future<Result<BookInstance>> sendBook(
     Book book,
     Owner owner,

lib/data/repositories/book_repository.dart

@@ -8,6 +8,10 @@ class BookRepository {
   final ApiClient _apiClient;
 
   Future<Result<Book>> getBookByEAN(String ean) async {
-    return _apiClient.getBookByEAN(ean);
+    return await _apiClient.getBookByEAN(ean);
+  }
+
+  Future<Result<Book>> getBookById(int id) async {
+    return await _apiClient.getBookById(id);
   }
 }

lib/data/repositories/owner_repository.dart

@@ -33,6 +33,18 @@ class OwnerRepository {
     return result;
   }
 
+  Future<Result<Owner>> getOwnerById(int id) async {
+    if (_cachedOwners != null) {
+      final result1 = _cachedOwners!
+          .where((owner) => owner.id == id)
+          .firstOrNull;
+      if (result1 != null) {
+        return Result.ok(result1);
+      }
+    }
+    return await _apiClient.getOwnerById(id);
+  }
+
   /// Adds an [Owner] to the database, and gets the resulting [Owner].
   Future<Result<Owner>> addOwner(
     String firstName,

lib/data/services/api_client.dart

@@ -236,6 +236,27 @@ class ApiClient {
  * ===================
 */
 
+  Future<Result<Book>> getBookById(int id) async {
+    final client = Client();
+    try {
+      final headers = await _getHeaders();
+      final response = await client.get(
+        Uri.parse("https://$apiBasePath/book/id/${id.toString()}"),
+        headers: headers,
+      );
+      if (response.statusCode == 200) {
+        final json = jsonDecode(response.body);
+        return Result.ok(Book.fromJSON(json));
+      } else {
+        throw Exception("The book was not found");
+      }
+    } catch (e) {
+      return Result.error(Exception("API $e"));
+    } finally {
+      client.close();
+    }
+  }
+
   Future<Result<Book>> getBookByEAN(String ean) async {
     final client = Client();
     try {
@@ -263,6 +284,32 @@ class ApiClient {
  * =============================
 */
 
+  Future<Result<List<BookInstance>>> getBookInstanceByEAN(
+    int balId,
+    int ean,
+  ) async {
+    final client = Client();
+    try {
+      final headers = await _getHeaders();
+      final response = await client.get(
+        Uri.parse(
+          "https://$apiBasePath/bal/${balId.toString()}/ean/${ean.toString()}/book_instances",
+        ),
+        headers: headers,
+      );
+      if (response.statusCode == 200) {
+        final json = jsonDecode(response.body) as List<dynamic>;
+        return Result.ok(json.map((el) => BookInstance.fromJSON(el)).toList());
+      } else {
+        throw "Unknown Error";
+      }
+    } catch (e) {
+      return Result.error(Exception("API $e"));
+    } finally {
+      client.close();
+    }
+  }
+
   Future<Result<BookInstance>> sendBook(
     Book book,
     Owner owner,
@@ -304,6 +351,27 @@ class ApiClient {
  * ====================
 */
 
+  Future<Result<Owner>> getOwnerById(int id) async {
+    final client = Client();
+    try {
+      final headers = await _getHeaders();
+      final response = await client.get(
+        Uri.parse("https://$apiBasePath/owner/${id.toString()}"),
+        headers: headers,
+      );
+      if (response.statusCode == 200) {
+        final json = jsonDecode(response.body);
+        return Result.ok(Owner.fromJSON(json));
+      } else {
+        throw Exception("The owner was not found");
+      }
+    } catch (e) {
+      return Result.error(Exception("API $e"));
+    } finally {
+      client.close();
+    }
+  }
+
   Future<Result<Owner>> getSectionOwner() async {
     final client = Client();
     try {