@startuml
start
note left: Operational Mode 'onedrive -sync -local-first'
:Performing a database consistency and\nintegrity check on locally stored data;
note left: This data is considered the 'source-of-truth'\nOnline data should be a 'replica' of this data
repeat
  :Process each DB record;
  if (Is the DB record is in sync with local file) then (yes)
  
  else (no)
  
    :Log reason for discrepancy;
    :Flag item to be processed as a modified local file;
  
  endif
repeat while

:Process modified items to upload;

if (Does local file DB record match current latest online JSON data) then (yes)

else (no)

  :Log that the local file was modified locally since last sync;
  :Renaming local file to avoid potential local data loss;
  note left: Local data loss prevention\nRenamed file will be uploaded as new file
  :Upload renamed local file as new file;

endif

:Upload modified file;

:Scan file system for any new data to upload;

:Query OneDrive /delta API for online changes;

:Process received JSON data;
if (JSON item is a file) then (yes)
  if (Does the file exist locally) then (yes)
    :Compute relevant file hashes;
    :Check DB for file record;
    if (DB record found) then (yes)
      :Compare file hash with DB hash;
      if (Is the hash different) then (yes)
        :Log that the local file was modified locally since last sync;
        :Renaming local file to avoid potential local data loss;
        note left: Local data loss prevention\nRenamed file will be uploaded as new file
      else (no)
      endif
    else (no)
    
    endif
  else (no)
  endif

  :Download file (as per online JSON item) as required;
  
else (no)
  :Other handling for directories | root objects | deleted items;
endif
stop
@enduml