suggest recipes based on cook history

src/main/java/com/brennaswitzer/cookbook/graphql/LibraryQuery.java

@@ -3,11 +3,11 @@
 import com.brennaswitzer.cookbook.domain.Recipe;
 import com.brennaswitzer.cookbook.graphql.model.OffsetConnection;
 import com.brennaswitzer.cookbook.graphql.model.OffsetConnectionCursor;
+import com.brennaswitzer.cookbook.graphql.model.SuggestionRequest;
 import com.brennaswitzer.cookbook.payload.RecognizedItem;
 import com.brennaswitzer.cookbook.repositories.SearchResponse;
 import com.brennaswitzer.cookbook.repositories.impl.LibrarySearchScope;
 import com.brennaswitzer.cookbook.services.ItemService;
-import com.brennaswitzer.cookbook.services.PantryItemService;
 import com.brennaswitzer.cookbook.services.RecipeService;
 import graphql.relay.Connection;
 import jakarta.persistence.NoResultException;
@@ -22,9 +22,6 @@ public class LibraryQuery extends PagingQuery {
     @Autowired
     private RecipeService recipeService;
 
-    @Autowired
-    private PantryItemService pantryItemService;
-
     @Autowired
     private ItemService itemService;
 
@@ -52,4 +49,11 @@ public RecognizedItem recognizeItem(String raw, Integer cursor) {
                 false);
     }
 
+    public Connection<Recipe> suggestRecipesToCook(SuggestionRequest req) {
+        if (req == null) req = new SuggestionRequest();
+        SearchResponse<Recipe> rs = recipeService.suggestRecipes(getOffset(req.getAfter()),
+                                                                 req.getFirst());
+        return new OffsetConnection<>(rs);
+    }
+
 }

src/main/java/com/brennaswitzer/cookbook/graphql/model/OffsetConnectionCursor.java

@@ -30,18 +30,33 @@ static String encode(int offset) {
 
     String value;
 
+    // for Jackson conversion
+    @SuppressWarnings("unused")
+    private OffsetConnectionCursor(int offset, String value) {
+        this.offset = offset;
+        this.value = value;
+        if (decode(value) != offset) {
+            throw new IllegalArgumentException(String.format(
+                    "Inconsistent %d and '%s' cursor values",
+                    offset,
+                    value));
+        }
+    }
+
     public OffsetConnectionCursor(String value) {
         this(decode(value));
         if (!Objects.equals(value, this.value)) {
-            throw new IllegalArgumentException(String.format("Invalid '%s' cursor value",
-                                                             value));
+            throw new IllegalArgumentException(String.format(
+                    "Invalid '%s' cursor value",
+                    value));
         }
     }
 
     public OffsetConnectionCursor(int offset) {
         if (offset < 0) {
-            throw new IllegalArgumentException(String.format("Offsets cannot be negative, but '%d' is",
-                                                             offset));
+            throw new IllegalArgumentException(String.format(
+                    "Offsets cannot be negative, but '%d' is",
+                    offset));
         }
         this.offset = offset;
         this.value = encode(offset);

src/main/java/com/brennaswitzer/cookbook/graphql/model/SuggestionRequest.java

@@ -0,0 +1,12 @@
+package com.brennaswitzer.cookbook.graphql.model;
+
+import lombok.Data;
+
+@Data
+public class SuggestionRequest {
+
+    int first;
+
+    OffsetConnectionCursor after;
+
+}

src/main/java/com/brennaswitzer/cookbook/repositories/PlannedRecipeHistoryRepository.java

@@ -1,6 +1,35 @@
 package com.brennaswitzer.cookbook.repositories;
 
 import com.brennaswitzer.cookbook.domain.PlannedRecipeHistory;
+import org.springframework.data.jpa.repository.Query;
+
+import java.util.List;
 
 public interface PlannedRecipeHistoryRepository extends BaseEntityRepository<PlannedRecipeHistory> {
+
+    /**
+     * I return a list of recipe ids based on how likely the user is to want to
+     * cook them, most likely first. The specific algorithm (and its parameters)
+     * are subject to change.
+     *
+     * <p>Currently, recipes are ranked based on the user's (not other users')
+     * ratings, decayed over time. If a recipe was cooked but not rated, a
+     * 3-star rating is assumed. If a recipe was cooked two months ago, it will
+     * contribute half the weight it would if it were cooked today. Four months
+     * ago will contribute a quarter as much as today.
+     */
+    @Query(value = """
+                   SELECT recipe_id
+                     FROM planned_recipe_history
+                    WHERE owner_id = :userId
+                      AND status_id = 100 -- completed
+                    GROUP BY recipe_id
+                    ORDER BY SUM(EXP(LN(0.5) / 60 * (CURRENT_DATE - CAST(done_at AS DATE))) * COALESCE(rating, 3)) DESC
+                           , 1
+                    LIMIT :limit
+                   OFFSET :offset
+                   """,
+            nativeQuery = true)
+    List<Long> getRecipeSuggestions(Long userId, int offset, int limit);
+
 }

src/main/java/com/brennaswitzer/cookbook/repositories/RecipeRepository.java

@@ -4,6 +4,7 @@
 import com.brennaswitzer.cookbook.domain.User;
 import org.springframework.stereotype.Repository;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 
@@ -17,6 +18,8 @@ public interface RecipeRepository extends BaseEntityRepository<Recipe>, RecipeSe
 
     List<Recipe> findAllByOwnerAndNameIgnoreCaseContainingOrderById(User owner, String name);
 
+    List<Recipe> findByIdIn(Collection<Long> ids);
+
     @Override
     Optional<Recipe> findById(Long aLong);
 

src/main/java/com/brennaswitzer/cookbook/services/RecipeService.java

@@ -4,6 +4,7 @@
 import com.brennaswitzer.cookbook.domain.Recipe;
 import com.brennaswitzer.cookbook.domain.S3File;
 import com.brennaswitzer.cookbook.domain.Upload;
+import com.brennaswitzer.cookbook.repositories.PlannedRecipeHistoryRepository;
 import com.brennaswitzer.cookbook.repositories.RecipeRepository;
 import com.brennaswitzer.cookbook.repositories.SearchResponse;
 import com.brennaswitzer.cookbook.repositories.impl.LibrarySearchRequest;
@@ -15,8 +16,11 @@
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.util.List;
 import java.util.Optional;
 import java.util.Set;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 @Service
 @Transactional
@@ -37,6 +41,9 @@ public class RecipeService {
     @Autowired
     private StorageService storageService;
 
+    @Autowired
+    private PlannedRecipeHistoryRepository historyRepository;
+
     public Recipe createNewRecipe(Recipe recipe) {
         return createNewRecipe(recipe, null);
     }
@@ -162,4 +169,24 @@ public SearchResponse<Recipe> searchRecipes(LibrarySearchScope scope,
                         .build());
     }
 
+    public SearchResponse<Recipe> suggestRecipes(int offset, int limit) {
+        LibrarySearchRequest req = LibrarySearchRequest.builder()
+                .user(principalAccess.getUser())
+                .offset(offset)
+                .limit(limit)
+                .build();
+        List<Long> ids = historyRepository.getRecipeSuggestions(
+                req.getUser().getId(),
+                req.getOffset(),
+                req.getLimit() + 1); // one extra (for SearchResponse)
+        var byId = recipeRepository.findByIdIn(ids).stream()
+                .collect(Collectors.toMap(
+                        Recipe::getId,
+                        Function.identity()));
+        List<Recipe> recipes = ids.stream()
+                .map(byId::get)
+                .toList();
+        return SearchResponse.of(req, recipes);
+    }
+
 }

src/main/resources/db/changelog/gobrennas-2024.sql

@@ -457,3 +457,7 @@ where exists (select *
               from ingredient
               where id = s.pantry_item_id
                 and name = s.synonym);
+
+--changeset barneyb:index-cook-history-owner-status
+CREATE INDEX idx_planned_recipe_history_owner_status
+    ON planned_recipe_history (owner_id, status_id);

src/main/resources/graphqls/library.graphqls

@@ -31,6 +31,8 @@ type LibraryQuery {
         after: Cursor = null
     ): RecipeConnection!
 
+    suggestRecipesToCook(req: SuggestionRequest): RecipeConnection!
+
     getRecipeById(id: ID!): Recipe
 
     """Recognize quantity, unit, and/or ingredient in a raw ingredient ref (aka
@@ -48,6 +50,11 @@ type LibraryQuery {
     ): RecognizedItem
 }
 
+input SuggestionRequest {
+    first: NonNegativeInt! = 5
+    after: Cursor = null
+}
+
 """The result of recognizing a raw ingredient ref item.
 """
 type RecognizedItem {