Refactoring module

[tbembersimeao]

Improvements:

• Reduced number of triggered logs
• Added more information to logs (fixes issue #7)
• Split existing export page into 5 files: export.php, progress_bar.php (template), download.php, css/batch.css, js/batch.js
• Removed redirect loop
• Added more error handlers
• Moved CSS styles to separated files
• Moved progress bar JS to a separated file
• Moved settings from Control Center scope to Project level
• Replaced max time limit with max time limit per batch
• UI changes:
  • Added progress percent
  • Changed progress bar color to blue
  • Replaced the concept of batch with items, which is more readable by the end user

Review steps:

• [x] Enable the module on a project
• [x] Test the normal use case: go to "Data Exports, Reports, and Stats", then click on "Export Large Projects", and make sure everything goes well, and you are able to download the export file
• [x] Make sure the file is correct (i.e. contains all fields and records)
• [x] Go to Logs page and make sure you see 3 logged events: export request, export finished and file downloaded
• [x] Still on Logs page, make sure you can see useful information like the list of exported fields, export time duration, file name, etc
• [x] If you want to simulate a big export without having a big project, you may insert a sleep(5); in /plugins/ajax/batch.php, then reduce the number of fields per batch, and then run export process again
• [x] Try any possible boundary cases such as timeout, empty project, missing parameters, etc - and make sure error handling works well (obs.: PHP ignores sleep() when calculating timeouts)

[123andy]

FWIW - Haven't looked at the code, but the rationale for 'fields per batch' instead of 'records per batch' was to handle cases in testing that had thousands of fields per record where batching by record in a reasonable number could easily overwhelm the memory limits...

[tbembersimeao]

@123andy that makes sense, I confess I didn't get it at first glance. I just committed "fields per batch" option back. Thank you!