Merge pull request #10 from btaquee/optimizer

Optimizer

Author: XiyuanWu

cards/serializers.py

@@ -1,5 +1,6 @@
 from rest_framework import serializers
 from .models import Card, RewardRule, UserCard, CardBenefit
+from rest_framework.validators import UniqueTogetherValidator
 
 class RewardRuleSerializer(serializers.ModelSerializer):
     class Meta:
@@ -34,7 +35,22 @@ class Meta:
         fields = ("id", "issuer", "name", "annual_fee", "ftf", "reward_rules", "benefits")
 
 class UserCardSerializer(serializers.ModelSerializer):
+    user = serializers.HiddenField(default=serializers.CurrentUserDefault())
+    is_active = serializers.BooleanField(required=False, default=True)
+    card_name = serializers.SerializerMethodField(read_only=True)
+
+    def get_card_name(self, obj):
+        return f"{obj.card.name} ({obj.card.issuer})"
+    
     class Meta:
         model = UserCard
-        fields = ("id", "card", "notes", "is_active")
+        fields = ("id", "card", "card_id", "card_name", "user", "notes", "is_active")
         read_only_fields = ()
+
+        validators = [
+            UniqueTogetherValidator(
+                queryset=UserCard.objects.all(),
+                fields=("user", "card"),
+                message="You already added this card to your wallet.",
+            )
+        ]

db.sqlite3

@@ -1,3 +1,10 @@
 from django.contrib import admin
+from .models import UserCategorySelection
 
 # Register your models here.
+@admin.register(UserCategorySelection)
+class UserCategorySelectionAdmin(admin.ModelAdmin):
+    list_display = ("user", "category_tag")
+    fields = ("user", "category_tag")
+    ordering = ["user", "category_tag"]
+

optimizer/admin.py

@@ -0,0 +1,29 @@
+# Generated by Django 5.2.7 on 2025-10-24 06:08
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='UserCategorySelection',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('category_tag', models.CharField(choices=[('SELECTED_CATEGORIES', 'Selected Categories'), ('RENT', 'Rent'), ('ONLINE_SHOPPING', 'Online Shopping'), ('DINING', 'Dining'), ('GROCERIES', 'Groceries'), ('PHARMACY', 'Pharmacy'), ('GAS', 'Gas'), ('GENERAL_TRAVEL', 'General Travel'), ('AIRLINE_TRAVEL', 'Airline Travel'), ('HOTEL_TRAVEL', 'Hotel Travel'), ('TRANSIT', 'Transit'), ('ENTERTAINMENT', 'Entertainment'), ('OTHER', 'Other')], max_length=255)),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='optimizer_selections', to=settings.AUTH_USER_MODEL)),
+            ],
+            options={
+                'indexes': [models.Index(fields=['user'], name='optimizer_u_user_id_5f6de0_idx')],
+                'constraints': [models.UniqueConstraint(fields=('user', 'category_tag'), name='uniq_user_category_selection')],
+            },
+        ),
+    ]

optimizer/migrations/0001_initial.py

@@ -1,3 +1,23 @@
 from django.db import models
+from django.conf import settings
+from cards.models import RewardRule
 
 # Create your models here.
+# This function get card user have(make api call for http://127.0.0.1:8000/api/cards/user-cards/)
+class UserCategorySelection(models.Model):
+    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="optimizer_selections")
+    category_tag = models.CharField(max_length=255, choices=RewardRule.CATEGORY_CHOICES)
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["user", "category_tag"],
+                name="uniq_user_category_selection",
+            ),
+        ]
+        indexes = [
+            models.Index(fields=["user"]),
+        ]
+
+    def __str__(self):
+        return f"{self.user} · {self.category_tag}"

optimizer/models.py

@@ -0,0 +1,20 @@
+from rest_framework import serializers
+from django.db import IntegrityError
+from rest_framework.exceptions import ValidationError
+from .models import UserCategorySelection
+
+class UserCategorySelectionSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = UserCategorySelection
+        fields = ("id", "user", "category_tag")
+        read_only_fields = ("user",)
+
+    def create(self, validated_data):
+        validated_data['user'] = self.context['request'].user
+        try:
+            return super().create(validated_data)
+        except IntegrityError:
+            # Handle the case where the combination already exists
+            raise ValidationError({
+                'category_tag': 'You have already selected this category.'
+            })

optimizer/serializers.py

@@ -0,0 +1,121 @@
+from decimal import Decimal
+from cards.models import RewardRule, UserCard, Card
+
+
+# Most of code logic are generated by AI, but with human fix the code and correct logic.
+# eg, at first the code is calculate the best card for a category from card database,
+# but it should be calculate the best card for a category from user's cards.
+
+SELECTED = "SELECTED_CATEGORIES"
+BASE_ANYWHERE = "OTHER"
+BIG = Decimal("1000000000")  # treat None cap as "very large"
+
+def _rank(items):
+    # items: list of (card, multiplier_float, cap_or_BIG)
+    # Sort by: higher multiplier → higher cap → lower annual fee → issuer/name
+    items.sort(
+        key=lambda t: (t[1], t[2], -float(t[0].annual_fee or 0), t[0].issuer, t[0].name),
+        reverse=True,
+    )
+
+    # Best card = first after sort
+    best_card, best_mult, _ = items[0]
+
+    # Collect other cards that tie with the best multiplier (exclude best itself)
+    ties = [
+        (c, m, cap)
+        for (c, m, cap) in items[1:]  # skip the best one
+        if m == best_mult
+    ][:2]  # +2 because we already have one best → total 3 max
+
+    # Prepare top3 list = alternatives (no duplication of the best card)
+    top3 = [
+        {"card_id": c.id, "card_name": f"{c.issuer} {c.name}", "multiplier": m}
+        for (c, m, _cap) in ties
+    ]
+
+    return best_card, best_mult, top3
+
+
+def best_cards_for_category(category_tag: str, user) -> dict:
+    # 0) user's active cards
+    my_card_ids = list(
+        UserCard.objects.filter(user=user, is_active=True).values_list("card_id", flat=True)
+    )
+    if not my_card_ids:
+        return {
+            "best_card": None,
+            "multiplier": 1.0,
+            "rationale": "You have no active cards. Showing baseline 1.0× recommendation.",
+            "top3": [],
+        }
+
+    # 1) exact category among user's cards
+    qs = (
+        RewardRule.objects
+        .exclude(category__contains=SELECTED)
+        .filter(category__contains=category_tag, card_id__in=my_card_ids)
+        .select_related("card")
+    )
+    primary = []
+    for r in qs:
+        m = float(r.multiplier or 0)
+        cap = r.cap_amount if r.cap_amount is not None else BIG
+        primary.append((r.card, m, cap))
+
+    if primary:
+        best_card, best_mult, top3 = _rank(primary)
+        return {
+            "best_card": {"card_id": best_card.id, "card_name": f"{best_card.issuer} {best_card.name}"},
+            "multiplier": best_mult,
+            "rationale": f"{best_mult}× on {category_tag} (from your wallet).",
+            "top3": top3,
+        }
+
+    # 2) fallback: use only each card's base/anywhere rate (OTHER)
+    alt_qs = (
+        RewardRule.objects
+        .exclude(category__contains=SELECTED)
+        .filter(card_id__in=my_card_ids, category__contains=BASE_ANYWHERE)
+        .select_related("card")
+    )
+
+    # pick the best OTHER rule per card (dedupe by card)
+    by_card = {}
+    for r in alt_qs:
+        c = r.card
+        m = float(r.multiplier or 0)
+        cap = r.cap_amount if r.cap_amount is not None else BIG
+        cur = by_card.get(c.id)
+        if cur is None or (m, cap) > (cur[1], cur[2]):
+            by_card[c.id] = (c, m, cap)
+
+    if by_card:
+        items = list(by_card.values())
+        best_card, best_mult, top3 = _rank(items)
+        return {
+            "best_card": {"card_id": best_card.id, "card_name": f"{best_card.issuer} {best_card.name}"},
+            "multiplier": best_mult,
+            "rationale": (
+                f"No {category_tag} bonus among your cards. "
+                f"Showing your best base rate (OTHER): {best_mult}×."
+            ),
+            "top3": top3,
+        }
+
+    # 3) final fallback: baseline 1.0× on lowest-AF card
+    any_card = (
+        Card.objects.filter(id__in=my_card_ids).order_by("annual_fee", "issuer", "name").first()
+    )
+    return {
+        "best_card": (
+            {"card_id": any_card.id, "card_name": f"{any_card.issuer} {any_card.name}"}
+            if any_card else None
+        ),
+        "multiplier": 1.0,
+        "rationale": (
+            f"No base (OTHER) rates found for your cards. Showing baseline 1.0×"
+            f"{' on ' + any_card.name if any_card else ''}."
+        ),
+        "top3": [],
+    }

optimizer/services.py

@@ -1,6 +1,13 @@
-from django.urls import path
+from django.urls import path, include
 from . import views
+from rest_framework.routers import DefaultRouter
+from .views import UserCategorySelectionViewSet, MyOptimizerDashboardView, HealthCheckView
+
+router = DefaultRouter()
+router.register(r'user-category-selections', UserCategorySelectionViewSet, basename='user-category-selections')
 
 urlpatterns = [
-    path('health/', views.HealthCheckView.as_view(), name='health'),
+    path('', include(router.urls)),
+    path('health/', HealthCheckView.as_view(), name='health'),
+    path('my-optimizer-dashboard/', MyOptimizerDashboardView.as_view(), name='my-optimizer-dashboard'),
 ]

optimizer/urls.py

@@ -1,10 +1,39 @@
 from django.shortcuts import render
 from rest_framework.views import APIView
 from rest_framework.response import Response
-from rest_framework import status
+from rest_framework import status, viewsets, permissions
+from .models import UserCategorySelection
+from .serializers import UserCategorySelectionSerializer
+from .services import best_cards_for_category
 
 # Create your views here.
 # Check API health
 class HealthCheckView(APIView):
     def get(self, request):
-        return Response({"status": "ok"}, status=status.HTTP_200_OK)
+        return Response({"status": "ok"}, status=status.HTTP_200_OK)
+
+# AI generated code
+class UserCategorySelectionViewSet(viewsets.ModelViewSet):
+    queryset = UserCategorySelection.objects.all()
+    serializer_class = UserCategorySelectionSerializer
+    permission_classes = [permissions.IsAuthenticated]
+    def get_queryset(self):
+        return UserCategorySelection.objects.filter(user=self.request.user)
+    def perform_create(self, serializer):
+        serializer.save(user=self.request.user)
+
+class MyOptimizerDashboardView(APIView):
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get(self, request):
+        tags = (UserCategorySelection.objects
+                .filter(user=request.user)
+                .values_list("category_tag", flat=True))
+
+        results = []
+        for tag in tags:
+            results.append({
+                "category_tag": tag,
+                **best_cards_for_category(tag, request.user)  # ← pass user here
+            })
+        return Response(results)