[WordService] Refactor RestoreFrontierWords (#4161)

Author: imnasnainaec

Backend.Tests/Mocks/WordRepositoryMock.cs

@@ -35,15 +35,20 @@ public Task<List<Word>> GetAllWords(string projectId)
         {
             try
             {
-                var foundWord = _words.Single(word => word.Id == wordId);
-                return Task.FromResult<Word?>(foundWord.Clone());
+                return Task.FromResult<Word?>(_words.Single(w => w.ProjectId == projectId && w.Id == wordId).Clone());
             }
             catch (InvalidOperationException)
             {
                 return Task.FromResult<Word?>(null);
             }
         }
 
+        public Task<List<Word>> GetWords(string projectId, List<string> wordIds)
+        {
+            return Task.FromResult(
+                _words.Where(w => w.ProjectId == projectId && wordIds.Contains(w.Id)).Select(w => w.Clone()).ToList());
+        }
+
         public Task<Word> Create(Word word)
         {
             word.Id = Guid.NewGuid().ToString();

Backend/Interfaces/IWordRepository.cs

@@ -8,6 +8,7 @@ public interface IWordRepository
     {
         Task<List<Word>> GetAllWords(string projectId);
         Task<Word?> GetWord(string projectId, string wordId);
+        Task<List<Word>> GetWords(string projectId, List<string> wordIds);
         Task<Word> Create(Word word);
         Task<List<Word>> Create(List<Word> words);
         Task<Word> Add(Word word);

Backend/Repositories/WordRepository.cs

@@ -80,8 +80,17 @@ public async Task<List<Word>> GetAllWords(string projectId)
             }
         }
 
-        /// <summary> Removes all <see cref="Word"/>s from the WordsCollection and Frontier for specified
-        /// <see cref="Project"/> </summary>
+        /// <summary> Finds project <see cref="Word"/>s with specified ids </summary>
+        public async Task<List<Word>> GetWords(string projectId, List<string> wordIds)
+        {
+            using var activity = OtelService.StartActivityWithTag(otelTagName, "getting words");
+
+            return await _words.Find(GetProjectWordsFilter(projectId, wordIds)).ToListAsync();
+        }
+
+        /// <summary>
+        /// Removes all <see cref="Word"/>s from the WordsCollection and Frontier for specified <see cref="Project"/>
+        /// </summary>
         /// <returns> A bool: success of operation </returns>
         public async Task<bool> DeleteAllWords(string projectId)
         {
@@ -130,7 +139,6 @@ private static void PopulateBlankWordTimes(Word word)
         /// If the Created or Modified time fields are blank, they will automatically calculated using the current
         /// time. This allows services to set or clear the values before creation to control these fields.
         /// </remarks>
-        /// <param name="word"></param>
         /// <returns> The word created </returns>
         public async Task<Word> Create(Word word)
         {
@@ -148,7 +156,6 @@ public async Task<Word> Create(Word word)
         /// If the Created or Modified time fields are blank, they will automatically calculated using the current
         /// time. This allows services to set or clear the values before creation to control these fields.
         /// </remarks>
-        /// <param name="words"></param>
         /// <returns> The words created </returns>
         public async Task<List<Word>> Create(List<Word> words)
         {

Backend/Services/WordService.cs

@@ -93,23 +93,44 @@ private async Task<Word> Add(string userId, Word word)
             return deletedWord.Id;
         }
 
-        /// <summary> Restores words to the Frontier </summary>
-        /// <returns> A bool: true if successful, false if any don't exist or are already in the Frontier. </returns>
+        /// <summary> Restores words to the Frontier that aren't in the Frontier </summary>
+        /// <remarks>
+        /// Aborts if any word can't be restored for any of the following reasons:
+        /// doesn't exist; has Status.Deleted; or is already in the Frontier
+        /// </remarks>
+        /// <returns> A bool: true if all successfully restored; false if none restored. </returns>
         public async Task<bool> RestoreFrontierWords(string projectId, List<string> wordIds)
         {
             using var activity = OtelService.StartActivityWithTag(otelTagName, "restoring words to Frontier");
 
-            var words = new List<Word>();
-            foreach (var id in wordIds)
+            // Allow calls that don't specify any wordIds, but don't do any work.
+            if (wordIds.Count == 0)
             {
-                var word = await _wordRepo.GetWord(projectId, id);
-                if (word is null || await _wordRepo.IsInFrontier(projectId, id))
-                {
-                    return false;
-                }
-                words.Add(word);
+                return true;
             }
-            await _wordRepo.AddFrontier(words);
+
+            wordIds = wordIds.Distinct().ToList();
+
+            // Make sure none of the words are in the Frontier.
+            if (await _wordRepo.AreInFrontier(projectId, wordIds, 1))
+            {
+                return false;
+            }
+
+            // Make sure all the words exist and are valid.
+            var wordsToRestore = await _wordRepo.GetWords(projectId, wordIds);
+            if (wordsToRestore.Count != wordIds.Count)
+            {
+                return false;
+            }
+            if (wordsToRestore.Any(w => w.Accessibility == Status.Deleted))
+            {
+                // We should be restoring words that were removed from the Frontier,
+                // and not their "Deleted" copies in the words collection.
+                return false;
+            }
+
+            await _wordRepo.AddFrontier(wordsToRestore);
             return true;
         }