added documentation into .env.production.sample

moved max pin count into constant

.env.production.sample

@@ -156,6 +156,9 @@ STREAMING_CLUSTER_NUM=1
 # Maximum allowed character count
 # MAX_TOOT_CHARS=500
 
+# Maximum number of pinned posts
+# MAX_PINNED_TOOTS=5
+
 # LDAP authentication (optional)
 # LDAP_ENABLED=true
 # LDAP_HOST=localhost

app/validators/status_pin_validator.rb

@@ -1,10 +1,12 @@
 # frozen_string_literal: true
 
 class StatusPinValidator < ActiveModel::Validator
+  MAX_PINNED = (ENV['MAX_PINNED_TOOTS'].to_i - 1 || 4)
+  
   def validate(pin)
     pin.errors.add(:base, I18n.t('statuses.pin_errors.reblog')) if pin.status.reblog?
     pin.errors.add(:base, I18n.t('statuses.pin_errors.ownership')) if pin.account_id != pin.status.account_id
     pin.errors.add(:base, I18n.t('statuses.pin_errors.private')) unless %w(public unlisted).include?(pin.status.visibility)
-    pin.errors.add(:base, I18n.t('statuses.pin_errors.limit')) if pin.account.status_pins.count >= (ENV['MAX_PINNED_TOOTS'].to_i || 5) && pin.account.local?
+    pin.errors.add(:base, I18n.t('statuses.pin_errors.limit')) if pin.account.status_pins.count > MAX_PINNED  && pin.account.local?
   end
 end