Implement converting prices (#79)

Reviewed-on: #79

games/admin.py

@@ -1,6 +1,14 @@
 from django.contrib import admin
 
-from games.models import Device, Edition, Game, Platform, Purchase, Session
+from games.models import (
+    Device,
+    Edition,
+    ExchangeRate,
+    Game,
+    Platform,
+    Purchase,
+    Session,
+)
 
 # Register your models here.
 admin.site.register(Game)
@@ -9,3 +17,4 @@ admin.site.register(Platform)
 admin.site.register(Session)
 admin.site.register(Edition)
 admin.site.register(Device)
+admin.site.register(ExchangeRate)

games/apps.py

@@ -1,6 +1,33 @@
+from datetime import timedelta
+
 from django.apps import AppConfig
+from django.core.management import call_command
+from django.db.models.signals import post_migrate
+from django.utils.timezone import now
 
 
 class GamesConfig(AppConfig):
     default_auto_field = "django.db.models.BigAutoField"
     name = "games"
+
+    def ready(self):
+        post_migrate.connect(schedule_tasks, sender=self)
+
+
+def schedule_tasks(sender, **kwargs):
+    from django_q.models import Schedule
+    from django_q.tasks import schedule
+
+    if not Schedule.objects.filter(name="Update converted prices").exists():
+        schedule(
+            "games.tasks.convert_prices",
+            name="Update converted prices",
+            schedule_type=Schedule.MINUTES,
+            next_run=now() + timedelta(seconds=30),
+        )
+
+    from games.models import ExchangeRate
+
+    if not ExchangeRate.objects.exists():
+        print("ExchangeRate table is empty. Loading fixture...")
+        call_command("loaddata", "exchangerates.yaml")

games/fixtures/exchangerates.yaml

@@ -0,0 +1,112 @@
+- model: games.exchangerate
+  pk: 1
+  fields:
+    currency_from: USD
+    currency_to: CZK
+    year: 2024
+    rate: 23.4
+- model: games.exchangerate
+  pk: 2
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2024
+    rate: 3.267
+- model: games.exchangerate
+  pk: 3
+  fields:
+    currency_from: USD
+    currency_to: CZK
+    year: 2019
+    rate: 22.466
+- model: games.exchangerate
+  pk: 4
+  fields:
+    currency_from: USD
+    currency_to: CZK
+    year: 2023
+    rate: 22.63
+- model: games.exchangerate
+  pk: 5
+  fields:
+    currency_from: USD
+    currency_to: CZK
+    year: 2017
+    rate: 25.819
+- model: games.exchangerate
+  pk: 6
+  fields:
+    currency_from: USD
+    currency_to: CZK
+    year: 2013
+    rate: 19.023
+- model: games.exchangerate
+  pk: 7
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2019
+    rate: 3.295
+- model: games.exchangerate
+  pk: 8
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2016
+    rate: 3.795
+- model: games.exchangerate
+  pk: 9
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2015
+    rate: 3.707
+- model: games.exchangerate
+  pk: 10
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2020
+    rate: 3.26
+- model: games.exchangerate
+  pk: 11
+  fields:
+    currency_from: EUR
+    currency_to: CZK
+    year: 2012
+    rate: 25.51
+- model: games.exchangerate
+  pk: 12
+  fields:
+    currency_from: EUR
+    currency_to: CZK
+    year: 2010
+    rate: 26.465
+- model: games.exchangerate
+  pk: 13
+  fields:
+    currency_from: EUR
+    currency_to: CZK
+    year: 2014
+    rate: 27.52
+- model: games.exchangerate
+  pk: 14
+  fields:
+    currency_from: EUR
+    currency_to: CZK
+    year: 2024
+    rate: 25.21
+- model: games.exchangerate
+  pk: 15
+  fields:
+    currency_from: EUR
+    currency_to: CZK
+    year: 2022
+    rate: 24.325
+- model: games.exchangerate
+  pk: 16
+  fields:
+    currency_from: CNY
+    currency_to: CZK
+    year: 2018
+    rate: 3.268

games/management/commands/schedule_convert_prices.py

@@ -0,0 +1,24 @@
+from datetime import timedelta
+
+from django.core.management.base import BaseCommand
+from django.utils.timezone import now
+from django_q.models import Schedule
+from django_q.tasks import schedule
+
+
+class Command(BaseCommand):
+    help = "Manually schedule the next update_converted_prices task"
+
+    def handle(self, *args, **kwargs):
+        if not Schedule.objects.filter(name="Update converted prices").exists():
+            schedule(
+                "games.tasks.convert_prices",
+                name="Update converted prices",
+                schedule_type=Schedule.MINUTES,
+                next_run=now() + timedelta(seconds=30),
+            )
+            self.stdout.write(
+                self.style.SUCCESS("Scheduled the update_converted_prices task.")
+            )
+        else:
+            self.stdout.write(self.style.WARNING("Task is already scheduled."))

games/migrations/0041_purchase_converted_currency_purchase_converted_price_and_more.py

@@ -0,0 +1,36 @@
+# Generated by Django 5.1.3 on 2024-11-10 15:14
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('games', '0040_migrate_device_types'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='purchase',
+            name='converted_currency',
+            field=models.CharField(max_length=3, null=True),
+        ),
+        migrations.AddField(
+            model_name='purchase',
+            name='converted_price',
+            field=models.FloatField(null=True),
+        ),
+        migrations.CreateModel(
+            name='ExchangeRate',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('currency_from', models.CharField(max_length=255)),
+                ('currency_to', models.CharField(max_length=255)),
+                ('year', models.PositiveIntegerField()),
+                ('rate', models.FloatField()),
+            ],
+            options={
+                'unique_together': {('currency_from', 'currency_to', 'year')},
+            },
+        ),
+    ]

games/models.py

@@ -124,6 +124,8 @@ class Purchase(models.Model):
     infinite = models.BooleanField(default=False)
     price = models.FloatField(default=0)
     price_currency = models.CharField(max_length=3, default="USD")
+    converted_price = models.FloatField(null=True)
+    converted_currency = models.CharField(max_length=3, null=True)
     ownership_type = models.CharField(
         max_length=2, choices=OWNERSHIP_TYPES, default=DIGITAL
     )
@@ -162,6 +164,16 @@ class Purchase(models.Model):
             raise ValidationError(
                 f"{self.get_type_display()} must have a related purchase."
             )
+        if self.pk is not None:
+            # Retrieve the existing instance from the database
+            existing_purchase = Purchase.objects.get(pk=self.pk)
+            # If price has changed, reset converted fields
+            if (
+                existing_purchase.price != self.price
+                or existing_purchase.price_currency != self.price_currency
+            ):
+                self.converted_price = None
+                self.converted_currency = None
         super().save(*args, **kwargs)
 
 
@@ -279,3 +291,16 @@ class Device(models.Model):
 
     def __str__(self):
         return f"{self.name} ({self.type})"
+
+
+class ExchangeRate(models.Model):
+    currency_from = models.CharField(max_length=255)
+    currency_to = models.CharField(max_length=255)
+    year = models.PositiveIntegerField()
+    rate = models.FloatField()
+
+    class Meta:
+        unique_together = ("currency_from", "currency_to", "year")
+
+    def __str__(self):
+        return f"{self.currency_from}/{self.currency_to} - {self.rate} ({self.year})"

games/tasks.py

@@ -0,0 +1,57 @@
+import requests
+
+from games.models import ExchangeRate, Purchase
+
+# fixme: save preferred currency in user model
+currency_to = "CZK"
+currency_to = currency_to.upper()
+
+
+def save_converted_info(purchase, converted_price, converted_currency):
+    print(
+        f"Changing converted price of {purchase} to {converted_price} {converted_currency} "
+    )
+    purchase.converted_price = converted_price
+    purchase.converted_currency = converted_currency
+    purchase.save()
+
+
+def convert_prices():
+    purchases = Purchase.objects.filter(
+        converted_price__isnull=True, converted_currency__isnull=True
+    )
+
+    for purchase in purchases:
+        if purchase.price_currency.upper() == currency_to or purchase.price == 0:
+            save_converted_info(purchase, purchase.price, currency_to)
+            continue
+        year = purchase.date_purchased.year
+        currency_from = purchase.price_currency.upper()
+        exchange_rate = ExchangeRate.objects.filter(
+            currency_from=currency_from, currency_to=currency_to, year=year
+        ).first()
+
+        if not exchange_rate:
+            try:
+                response = requests.get(
+                    f"https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@{year}-01-01/v1/currencies/{currency_from}.json"
+                )
+                response.raise_for_status()
+                data = response.json()
+                rate = data[currency_from].get(currency_to)
+
+                if rate:
+                    exchange_rate = ExchangeRate.objects.create(
+                        currency_from=currency_from,
+                        currency_to=currency_to,
+                        year=year,
+                        rate=rate,
+                    )
+            except requests.RequestException as e:
+                print(
+                    f"Failed to fetch exchange rate for {currency_from}->{currency_to} in {year}: {e}"
+                )
+        if exchange_rate:
+            save_converted_info(
+                purchase, purchase.price * exchange_rate.rate, currency_to
+            )

games/templates/stats.html

@@ -253,7 +253,7 @@
                 {% for purchase in purchased_unfinished %}
                     <tr>
                         <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{% partial purchase-name %}</td>
-                        <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.price }}</td>
+                        <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.converted_price }}</td>
                         <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.date_purchased | date:"d/m/Y" }}</td>
                     </tr>
                 {% endfor %}
@@ -274,7 +274,7 @@
                 {% for purchase in all_purchased_this_year %}
                     <tr>
                         <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{% partial purchase-name %}</td>
-                        <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.price }}</td>
+                        <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.converted_price }}</td>
                         <td class="px-2 sm:px-4 md:px-6 md:py-2 font-mono">{{ purchase.date_purchased | date:"d/m/Y" }}</td>
                     </tr>
                 {% endfor %}

games/views/general.py

@@ -78,9 +78,7 @@ def stats_alltime(request: HttpRequest) -> HttpResponse:
     ).distinct()
 
     this_year_purchases = Purchase.objects.all()
-    this_year_purchases_with_currency = this_year_purchases.select_related(
-        "edition"
-    ).filter(price_currency__exact=selected_currency)
+    this_year_purchases_with_currency = this_year_purchases.select_related("edition")
     this_year_purchases_without_refunded = this_year_purchases_with_currency.filter(
         date_refunded=None
     )
@@ -124,7 +122,7 @@ def stats_alltime(request: HttpRequest) -> HttpResponse:
     ).order_by("date_finished")
 
     this_year_spendings = this_year_purchases_without_refunded.aggregate(
-        total_spent=Sum(F("price"))
+        total_spent=Sum(F("converted_price"))
     )
     total_spent = this_year_spendings["total_spent"] or 0
 
@@ -300,12 +298,10 @@ def stats(request: HttpRequest, year: int = 0) -> HttpResponse:
     ).distinct()
 
     this_year_purchases = Purchase.objects.filter(date_purchased__year=year)
-    this_year_purchases_with_currency = this_year_purchases.select_related(
-        "edition"
-    ).filter(price_currency__exact=selected_currency)
+    this_year_purchases_with_currency = this_year_purchases.select_related("edition")
     this_year_purchases_without_refunded = this_year_purchases_with_currency.filter(
         date_refunded=None
-    )
+    ).exclude(ownership_type=Purchase.DEMO)
     this_year_purchases_refunded = this_year_purchases_with_currency.refunded()
 
     this_year_purchases_unfinished_dropped_nondropped = (
@@ -348,7 +344,7 @@ def stats(request: HttpRequest, year: int = 0) -> HttpResponse:
     ).order_by("date_finished")
 
     this_year_spendings = this_year_purchases_without_refunded.aggregate(
-        total_spent=Sum(F("price"))
+        total_spent=Sum(F("converted_price"))
     )
     total_spent = this_year_spendings["total_spent"] or 0