Maintenance Mode

[ferishili]

This PR
fixes #71
also fixes Opencast-Moodle/moodle-block_opencast#194

Description

Please refer to the issue.

How it works

• In admin setting a section for Maintenance for each instance is introduced!
• Admin can configure the maintenance with 3 options:
  • disable: completely off
  • Read-Only: only get requests to the opencast are possible
  • Enable: no call to opencast is allowed
• Configuring a time range is also possible.
• A HTML Editor is provided to add the maintenance message!
• Admin can also regulated the level of notification message to be shown, red: error, yellow: warning etc.

Concept

• A notification message will be printed whereever the api instance is initiated.
• Decorate Proxies are now wrapping around the opencast api services in order to check and restrict the access to the resources.
• To keep the notification message only printed once, we had to use javascript for that!
• Time ranges rules are:
  • start date can be in the past, but not equal or greater than end date if enabled
  • end date cannot be in the past, not less than or equal to start date if enabled
  • if start date is enabled but end date is disabled, that means the time range starts at the time but have no end, until admin changes it.
  • if end date is enabled but start date is disabled, that means the maintenance statrt right after saved changes until the end time reaches.

How to test

• Patch this PR
• Make sure you have course that has block opencast with an uploaded video / filter opencast is set and working / mod opencast in use and working.
• Go to admins setting of this plugin
• Locate the Maintenace Section and configure it accordingly
• save changes
• Go to the course page mentioned above.
• You need to see the Maintenance message as a notification only once with regard to the level you have set!
• Based on the maintenance mode you have configured:
  • Enabled: you should be able to access to the plugins (there are some exceptions such as studio)
  • Read-Only: you should be able to access plugins but anything other than reading videos such as update metadata, upload video should be prevented during maintenance time!