feat: add reauth flow for wa embedded signup (#11940)

# Pull Request Template

## Description

Please include a summary of the change and issue(s) fixed. Also, mention
relevant motivation, context, and any dependencies that this change
requires.
Fixes # (issue)

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration.


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/services/whatsapp/embedded_signup_service.rb

@@ -1,10 +1,11 @@
 class Whatsapp::EmbeddedSignupService
-  def initialize(account:, code:, business_id:, waba_id:, phone_number_id:)
+  def initialize(account:, params:, inbox_id: nil)
     @account = account
-    @code = code
-    @business_id = business_id
-    @waba_id = waba_id
-    @phone_number_id = phone_number_id
+    @code = params[:code]
+    @business_id = params[:business_id]
+    @waba_id = params[:waba_id]
+    @phone_number_id = params[:phone_number_id]
+    @inbox_id = inbox_id
   end
 
   def perform
@@ -19,11 +20,19 @@ class Whatsapp::EmbeddedSignupService
     # Validate token has access to the WABA
     Whatsapp::TokenValidationService.new(access_token, @waba_id).perform
 
-    # Create channel
-    waba_info = { waba_id: @waba_id, business_name: phone_info[:business_name] }
-
-    # Webhook setup is now handled in the channel after_create_commit callback
-    Whatsapp::ChannelCreationService.new(@account, waba_info, phone_info, access_token).perform
+    # Reauthorization flow if inbox_id is present
+    if @inbox_id.present?
+      Whatsapp::ReauthorizationService.new(
+        account: @account,
+        inbox_id: @inbox_id,
+        phone_number_id: @phone_number_id,
+        business_id: @business_id
+      ).perform(access_token, phone_info)
+    else
+      # Create channel for new authorization
+      waba_info = { waba_id: @waba_id, business_name: phone_info[:business_name] }
+      Whatsapp::ChannelCreationService.new(@account, waba_info, phone_info, access_token).perform
+    end
   rescue StandardError => e
     Rails.logger.error("[WHATSAPP] Embedded signup failed: #{e.message}")
     raise e

app/services/whatsapp/reauthorization_service.rb

@@ -0,0 +1,42 @@
+class Whatsapp::ReauthorizationService
+  def initialize(account:, inbox_id:, phone_number_id:, business_id:)
+    @account = account
+    @inbox_id = inbox_id
+    @phone_number_id = phone_number_id
+    @business_id = business_id
+  end
+
+  def perform(access_token, phone_info)
+    inbox = @account.inboxes.find(@inbox_id)
+    channel = inbox.channel
+
+    # Validate phone number matches for reauthorization
+    if phone_info[:phone_number] != channel.phone_number
+      raise StandardError, "Phone number mismatch. Expected #{channel.phone_number}, got #{phone_info[:phone_number]}"
+    end
+
+    # Update channel configuration
+    update_channel_config(channel, access_token, phone_info)
+    # Mark as reauthorized
+    channel.reauthorized! if channel.respond_to?(:reauthorized!)
+
+    channel
+  end
+
+  private
+
+  def update_channel_config(channel, access_token, phone_info)
+    current_config = channel.provider_config || {}
+    channel.provider_config = current_config.merge(
+      'api_key' => access_token,
+      'phone_number_id' => @phone_number_id,
+      'business_account_id' => @business_id,
+      'source' => 'embedded_signup'
+    )
+    channel.save!
+
+    # Update inbox name if business name changed
+    business_name = phone_info[:business_name] || phone_info[:verified_name]
+    channel.inbox.update!(name: business_name) if business_name.present?
+  end
+end