feat(projects): add project-specific member rates

apps/projects/services/rates.py

@@ -0,0 +1,63 @@
+from django.utils import timezone
+
+from apps.projects.models import ProjectUserRate
+
+
+def get_current_project_user_rate(*, project, user):
+    return (
+        ProjectUserRate.objects.filter(
+            project=project,
+            user=user,
+            is_active=True,
+            is_deleted=False,
+        )
+        .order_by("-effective_from", "-updated_at")
+        .first()
+    )
+
+
+def upsert_project_user_rate(*, project, user, hourly_rate, currency="USD"):
+    currency = currency.upper()
+    rate = (
+        ProjectUserRate.all_objects.filter(
+            project=project,
+            user=user,
+        )
+        .order_by("-updated_at", "-created_at")
+        .first()
+    )
+
+    if rate:
+        update_fields = []
+        if rate.is_deleted:
+            rate.restore()
+        if rate.hourly_rate != hourly_rate:
+            rate.hourly_rate = hourly_rate
+            update_fields.append("hourly_rate")
+        if rate.currency != currency:
+            rate.currency = currency
+            update_fields.append("currency")
+        if not rate.is_active:
+            rate.is_active = True
+            update_fields.append("is_active")
+        if update_fields:
+            update_fields.append("updated_at")
+            rate.save(update_fields=update_fields)
+        return rate
+
+    return ProjectUserRate.objects.create(
+        project=project,
+        user=user,
+        hourly_rate=hourly_rate,
+        currency=currency,
+        effective_from=timezone.now(),
+        is_active=True,
+    )
+
+
+def remove_project_user_rate(*, project, user):
+    rate = get_current_project_user_rate(project=project, user=user)
+    if not rate:
+        return False
+    rate.delete()
+    return True