From e0390f383cd2899cfbc08f36961ae0095b664698 Mon Sep 17 00:00:00 2001
From: Mark Veidemanis <m@zm.is>
Date: Thu, 21 Jul 2022 13:48:14 +0100
Subject: [PATCH] Manage Stripe customers from the User model

---
 core/lib/customers.py | 58 +++++++++++++++++++++++++++++++++++++++++++
 core/models.py        | 26 ++++++++++++++++++-
 2 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 core/lib/customers.py

diff --git a/core/lib/customers.py b/core/lib/customers.py
new file mode 100644
index 0000000..900bbda
--- /dev/null
+++ b/core/lib/customers.py
@@ -0,0 +1,58 @@
+import stripe
+
+def expand_name(first_name, last_name):
+    """
+    Convert two name variables into one.
+    Last name without a first name is ignored.
+    """
+    name = None
+    if first_name:
+        name = first_name
+        # We only want to put the last name if we have a first name
+        if last_name:
+            name += f" {last_name}"
+    return name
+
+def get_or_create(email, first_name, last_name):
+    """
+    Get a customer ID from Stripe if one with the given email exists.
+    Create a customer if one does not.
+    Raise an exception if two or more customers matching the given email exist.
+    """
+    # Let's see if we're just missing the ID
+    matching_customers = stripe.Customer.list(email=email, limit=2)
+    if len(matching_customers) == 2:
+        # Something is horribly wrong
+        print("Two customers match!")
+        raise Exception(f"Two customers found for email {email}")
+
+    elif len(matching_customers) == 1:
+        # We found a customer. Let's copy the ID
+        customer = matching_customers["data"][0]
+        customer_id = customer["id"]
+        return customer_id
+
+    else:
+        # We didn't find anything. Create the customer
+
+        # Create a name, since we have 2 variables which could be null
+        name = expand_name(first_name, last_name)
+        cast = {"email": email}
+        if name:
+            cast["name"] = name
+        customer = stripe.Customer.create(**cast)
+
+        return customer.id
+
+def update_customer_fields(stripe_id, email=None, first_name=None, last_name=None):
+    """
+    Update the customer fields in Stripe.
+    """
+    print("Update customer fields called")
+    if email:
+        print("Email modified")
+        stripe.Customer.modify(stripe_id, email=email)
+    if first_name or last_name:
+        print("Name modified")
+        name = expand_name(first_name, last_name)
+        stripe.Customer.modify(stripe_id, name=name)
\ No newline at end of file
diff --git a/core/models.py b/core/models.py
index 4de0e93..bbce63b 100644
--- a/core/models.py
+++ b/core/models.py
@@ -1,7 +1,7 @@
 from django.contrib.auth.models import AbstractUser
 from django.db import models
 
-# Create your models here.
+from core.lib.customers import get_or_create, update_customer_fields
 
 
 class Plan(models.Model):
@@ -24,6 +24,30 @@ class User(AbstractUser):
     paid = models.BooleanField(null=True, blank=True)
     plans = models.ManyToManyField(Plan, blank=True)
 
+
+def __init__(self, *args, **kwargs):
+    super().__init__(*args, **kwargs)
+    self._original = self
+
+    def save(self, *args, **kwargs):
+        """
+        Override the save function to create a Stripe customer.
+        """
+        if not self.stripe_id:  # stripe ID not stored
+            self.stripe_id = get_or_create(self.email, self.first_name, self.last_name)
+
+        to_update = {}
+        if self.email != self._original.email:
+            to_update["email"] = self.email
+        if self.first_name != self._original.first_name:
+            to_update["first_name"] = self.first_name
+        if self.last_name != self._original.last_name:
+            to_update["last_name"] = self.last_name
+
+        update_customer_fields(self.stripe_id, **to_update)
+
+        super().save(*args, **kwargs)
+
     def has_plan(self, plan):
         if not self.paid:  # We can't have any plans if we haven't paid
             return False