Salesforce APEX Trigger for Unique Identifier

Need support with a Salesforce APEX trigger that does the following:

The goal of the class is to define a unique identifier for each account record that does not have an unique identifier defined yet before create/update

-Setup a new Salesforce Developer org
-Create a text(255) custom field on Account object called Unique Account Id
-Define a custom metadata type (Prefix Settings) with the following fields:
* Label - Account
* Setting Name - Account
* Prefix - AID
* Starting Number - 1000000001
-Write a APEX trigger and methods to insert a new 'Unique Account Id' for each new or updated account record with an empty 'Unique Account Id'
- Unique Account Id should be populated based on the respective custom metadatatype record of the related object with the prefix (AID) based on the prefix field and the number based on the starting number like AID1000000001
- If there are already accounts with a 'Unique Account Id' populated it should add 1 to the highest one for new or updated records with an empty 'Unique Account Id' field like AID1000000004
- If accounts are created or updated via bulk upload the 'Unique Account Id' must be set according above requirements for all records in the bulk transaction.


Requirements:
- Test class with 100% coverage
- Unmanaged package with the created metadata deployable to other environments
- Trigger pattern according best practices, handler in apex class
- Each step in a separate method
- Class should be easy to modify for other objects, like contact