Update readme

README.md

@@ -4,8 +4,9 @@
 [![Software License][ico-license]](LICENSE)
 [![Build Status][ico-github-actions]][link-github-actions]
 
-This plugin adds Google Analytics tracking to your store. It injects the tags directly
-and hence does not depend on third party tools like Google Tag Manager.
+This plugin adds Google Analytics tracking to your store. You can choose between a gtag and tag manager integration.
+The gtag integration will output the traditional `gtag()` functions when tracking events, while the tag manager integration
+will populate the `dataLayer` with event data.
 
 ## Installation
 
@@ -36,9 +37,12 @@ $bundles = [
 ```yaml
 # config/packages/setono_sylius_analytics.yaml
 imports:
-    # ...
     - { resource: "@SetonoSyliusAnalyticsPlugin/Resources/config/app/config.yaml" }
-    # ...
+
+setono_google_analytics:
+    gtag: ~
+    # If you want to use tag manager instead of gtag, just comment the line above and remove the comment below
+    # tag_manager: ~
 ```
 
 ### Step 4: Import routing
@@ -56,19 +60,99 @@ php bin/console doctrine:migrations:diff
 php bin/console doctrine:migrations:migrate
 ```
 
-### Step 6: Create a property
-When you create a property in Google Analytics you receive a measurement id which looks something like G-12345678.
-
-Now create a new property in your Sylius shop by navigating to `/admin/google-analytics/properties/new`.
-Remember to enable the property and enable the channels you want to track. 
+### Step 6: Create a property / container
+Click the Google Analytics link in your backend and create a new property/container.
 
 ### Step 7: You're ready!
+Your Sylius store will start tracking now!
+
 The events that are tracked are located in the [EventSubscriber folder](src/EventSubscriber).
 
+Read on if you want to enrich events with more data.
+
+## Enrich events with more data
+When we want to track an event inside the Sylius application the `Setono\GoogleAnalyticsBundle\Event\ClientSideEvent` is fired.
+
+That event holds the actual Google Analytics event, e.g. `Setono\GoogleAnalyticsMeasurementProtocol\Request\Body\Event\PurchaseEvent`.
+This way, if you subscribe to the `ClientSideEvent`, you can manipulate everything about the event before it's rendered (and sent to Google).
+
+But there are other ways to change the data enrichment. This can be done via resolvers. The plugin uses resolvers to
+resolve a brand from a product, a category from a product etc. Read on to figure out how to use this functionality.
+
+### Brand resolver
+An item has a brand property (`item_brand`), but the plugin doesn't know how you have chosen to
+add brand data in your application. Therefore, you need to implement your own `BrandResolver`. Here is an example:
+
+```php
+<?php
+use Setono\SyliusAnalyticsPlugin\Resolver\Brand\BrandResolverInterface;
+use Sylius\Component\Core\Model\ProductInterface;
+use Sylius\Component\Core\Model\ProductVariantInterface;
+
+final class BrandResolver implements BrandResolverInterface
+{
+    public function resolveFromProduct(ProductInterface $product): ?string
+    {
+        return $product->getBrand(); // here we assume the getBrand() method will return a brand name or null (if not set)
+    }
+
+    public function resolveFromProductVariant(ProductVariantInterface $productVariant): ?string
+    {
+        return $this->resolveFromProduct($productVariant->getProduct());
+    }
+}
+```
+
+When you implement the [`BrandResolverInterface`](src/Resolver/Brand/BrandResolverInterface.php) and register your class as a service it will automatically
+be tagged with `setono_sylius_analytics.brand_resolver` and used when tracking.
+
+### Category resolver
+An item has category properties (`item_category`, `item_category2`, etc.) and by default the plugin will resolve these
+properties based on either a product's main taxon or (if no main taxon is set) the first taxon in the collection of taxons.
+
+You can see the implementation inside the
+[`Setono\SyliusAnalyticsPlugin\Resolver\Category\CategoryResolver`](src/Resolver/Category/CategoryResolver.php) class.
+
+### Item resolver
+The job of the item resolver is to return an `Setono\GoogleAnalyticsMeasurementProtocol\Request\Body\Event\Item\Item`
+either from an order item or a product. This resolver also has a default implementation which you can see in the class
+[`Setono\SyliusAnalyticsPlugin\Resolver\Item\ItemResolver`](src/Resolver/Item/ItemResolver.php).
+
+### Items resolver
+The items resolver must return an array of items given an order as input. The default implementation is found in the class
+[`Setono\SyliusAnalyticsPlugin\Resolver\Items\ItemsResolver`](src/Resolver/Items/ItemsResolver.php).
+
+### Variant resolver
+An item has a variant property (`item_variant`). How you want to view your variant data inside the Analytics
+user interface is up to you, however, the plugin provides two default resolvers, namely the
+[`Setono\SyliusAnalyticsPlugin\Resolver\Variant\NameBasedVariantResolver`](src/Resolver/Variant/NameBasedVariantResolver.php)
+and the [`Setono\SyliusAnalyticsPlugin\Resolver\Variant\OptionBasedVariantResolver`](src/Resolver/Variant/OptionBasedVariantResolver.php).
+
+The option based version has the highest priority of the two and will therefore be tried first. It tries to create a
+variant string based on the options on the variant (if any).
+
+The name based version returns the `\Sylius\Component\Product\Model\ProductVariantInterface::getName()`.
+
+To implement your own resolver just implement the `Setono\SyliusAnalyticsPlugin\Resolver\Variant\VariantResolverInterface`.
+Here is an example:
+
+```php
+<?php
+use Setono\SyliusAnalyticsPlugin\Resolver\Variant\VariantResolverInterface;
+use Sylius\Component\Core\Model\ProductVariantInterface;
+
+final class ProductNameBasedVariantResolver implements VariantResolverInterface
+{
+    public function resolve(ProductVariantInterface $productVariant): ?string
+    {
+        return $productVariant->getProduct()->getName();
+    }
+}
+```
+
 ## Contribute
 Ways you can contribute:
 * Translate [messages](src/Resources/translations/messages.en.yaml) and [validators](src/Resources/translations/validators.en.yaml) into your mother tongue
-* Create Behat tests that verifies the scripts are outputted on the respective pages
 * Create new event subscribers that handle Analytics events which are not implemented
 
 Thank you!