@startuml

participant "OneDrive Client\nfor Linux" as Client
participant "Microsoft OneDrive\nAPI" as API

== Access Token Validation ==
Client -> Client: Validate access and\nexisting access token\nRefresh if needed

== Query Microsoft OneDrive /delta API ==
Client -> API: Query /delta API
API -> Client: JSON responses

== Process JSON Responses ==
loop for each JSON response
    Client -> Client: Determine if JSON is 'root'\nor 'deleted' item\nElse, push into temporary array for further processing
    alt if 'root' or 'deleted'
        Client -> Client: Process 'root' or 'deleted' items
    else
        Client -> Client: Evaluate against 'Client Side Filtering' rules
        alt if unwanted
            Client -> Client: Discard JSON
        else
            Client -> Client: Process JSON (create dir/download file)
            Client -> Client: Save in local database cache
        end
    end
end

== Local Cache Database Processing for Data Integrity ==
Client -> Client: Process local cache database\nto check local data integrity and for differences
alt if difference found
    Client -> API: Upload file/folder change including deletion
    API -> Client: Response with item metadata
    Client -> Client: Save response to local cache database
end

== Local Filesystem Scanning ==
Client -> Client: Scan local filesystem\nfor new files/folders

loop for each new item
    Client -> Client: Check item against 'Client Side Filtering' rules
    alt if item passes filtering
        Client -> API: Upload new file/folder change including deletion
        API -> Client: Response with item metadata
        Client -> Client: Save response in local\ncache database
    else
        Client -> Client: Discard item\n(Does not meet filtering criteria)
    end
end

== Final Data True-Up ==
Client -> API: Query /delta link for true-up
API -> Client: Process further online JSON changes if required

@enduml