feat: implement full backend API for Pantree Phase 1 MVP

src/services/pantryService.js

@@ -0,0 +1,112 @@
+'use strict';
+
+const { getDb } = require('../db/knex');
+const { AppError } = require('../utils/errors');
+
+function formatItem(row) {
+  return {
+    id: row.id,
+    item_name: row.item_name,
+    quantity: row.quantity,
+    last_modified: row.last_modified,
+    created_at: row.created_at,
+  };
+}
+
+/**
+ * Returns all pantry items for the authenticated user, ordered alphabetically.
+ */
+async function getPantryItems(userId) {
+  const db = getDb();
+  const items = await db('pantry_items')
+    .where({ user_id: userId })
+    .orderBy('item_name_lower', 'asc');
+  return items.map(formatItem);
+}
+
+/**
+ * Adds a new pantry item.
+ * Rejects with 409 if an item with the same name already exists (case-insensitive).
+ * Auto-merge is intentionally not performed — explicit > implicit.
+ */
+async function addPantryItem(userId, { item_name, quantity }) {
+  const db = getDb();
+  const trimmedName = item_name.trim();
+
+  const existing = await db('pantry_items')
+    .where({ user_id: userId })
+    .whereRaw('item_name_lower = LOWER(?)', [trimmedName])
+    .first();
+
+  if (existing) {
+    throw new AppError(
+      409,
+      'DUPLICATE_ITEM',
+      `'${existing.item_name}' already exists in your pantry.`,
+      { existing_item: formatItem(existing) }
+    );
+  }
+
+  const [item] = await db('pantry_items')
+    .insert({ user_id: userId, item_name: trimmedName, quantity })
+    .returning('*');
+
+  return formatItem(item);
+}
+
+/**
+ * Updates the quantity of an existing pantry item.
+ * Server sets last_modified = NOW() — server clock is authoritative.
+ * Verifies ownership: item must belong to the requesting user.
+ */
+async function updatePantryItem(userId, itemId, { quantity }) {
+  const db = getDb();
+
+  const existing = await db('pantry_items')
+    .where({ id: itemId, user_id: userId })
+    .first();
+
+  if (!existing) {
+    throw new AppError(404, 'NOT_FOUND', 'Pantry item not found.');
+  }
+
+  const now = new Date();
+  const [item] = await db('pantry_items')
+    .where({ id: itemId, user_id: userId })
+    .update({ quantity, last_modified: now, updated_at: now })
+    .returning('*');
+
+  return formatItem(item);
+}
+
+/**
+ * Deletes a pantry item and records a tombstone for sync.
+ * Verifies ownership before deletion.
+ */
+async function deletePantryItem(userId, itemId) {
+  const db = getDb();
+
+  const existing = await db('pantry_items')
+    .where({ id: itemId, user_id: userId })
+    .first();
+
+  if (!existing) {
+    throw new AppError(404, 'NOT_FOUND', 'Pantry item not found.');
+  }
+
+  await db.transaction(async (trx) => {
+    await trx('pantry_items').where({ id: itemId, user_id: userId }).delete();
+    await trx('deleted_records').insert({
+      user_id: userId,
+      record_type: 'pantry_item',
+      record_id: itemId,
+    });
+  });
+}
+
+module.exports = {
+  getPantryItems,
+  addPantryItem,
+  updatePantryItem,
+  deletePantryItem,
+};