Demo Mode
=========

A PlantTracer database consists of several DyanmoDB tables with a given table prefix and an S3 bucket.

When the database is created, a default course with the ID `demo_course` is created. There are two users: a default course admin and a default demo user. The demo course is then prepopulated with several demo movies from the test data.

The demo user is identified with a special API key.

Demo mode is enabled by sedding the environment variable `DEMO_COURSE_ID` to the course_id of the course that is the demo course. It need not be the demo course that is created as part of the default installation.


Demo Mode Goals
---------------

- Allows anyone on the web to anonymously and securely use some aspects of the Plant Tracer web app

- Allow the anonymous demo user to experience plant movement tracking in the app without requiring the user to create an account in a course or to be aware of the movie lifecycle of upload, track, publish, delete

- Disallow the persistence of modifications to all webapp-managed data while in demo mode

Functions
---------

Demo mode allows

- View the list of movies in a single table

- Play a movie without tracking

- Click on 'analyze' to show the user interface for playing a movie that has a stored trace

- Download a CSV representation of movie trace data

Demo mode restrictions:

  - No uploading of movies

  - No deleting of movies

  - No renaming of titles, descriptions

  - No deleting or adding trackpoints

  - No editing any text

  - No re-tracking of movies

Required in the database
------------------------

Every new database is created with a demo user and a few movies.

- The demo user has a perdefiend API key.

- When `DEMO_COURSE_ID` is set, the authentication routines always return the demo mode `api_key`. That is, there is no way to log in or log out.

To edit the movies in the demo course, just run another instance that is attached to the same database and edit the movies in the demo course.

Implementation
--------------

Demo Mode uses the following environment variables:

- `DEMO_COURSE_ID`       - The `course_id` of the demo course.  (Created as `demo` by the dbmaint.py script)
- `DEMO_DYNAMODB_PREFIX` - The table prefix. (Created as `demo-` by the `dbutil.py` script)

If we are in demo mode:

- We are always logged in, and always in Demo Mode.

- auth.get_user_api_key() always returns an API Key for demo mode.

- `demo_user` JavaScript global variable set to ``true`` (if in demo mode)

- `demo_user` Jinja2 variable will get set to ``True`` (otherwise it is ``False``)

Rendering control:

  - CSS Class ``demo`` elements display only if in demo mode
  - CSS Class ``nodemo`` elements display only if not in demo mode

To make changes to the demo course:

- Create another user who is enrolled in `DEMO_COURSE` and another login with the same `DEMO_PREFIX`

Troubleshooting/Development Note
--------------------------------

Plant-Tracer webapp creates an api_key-<database name> cookie in order to tracker
the login state of a session. Sometimes this cookie does not clear itself upon logout
and it is necessary to manually delete the cookie, especially in order to have a valid
demo mode enabled.

Here is an example of such a cookie:

.. image:: media/PlantTracerCookieExample.png