Make Sensei Compatible with all themes

[alexsanford]

This issue is a description of what it will take in order to accomplish #2125.

For more depth, see p6rkRX-HY-p2.

In summary, we need to modify the frontend displays in Sensei which use full-page templates (e.g. the /courses/<course-slug> page which uses the single-course.php template). These full-page templates do not work properly in all themes.

Instead, we will use a similar approach to what WooCommerce adopted by rendering the content of these pages within the content area provided by the theme (e.g. using the the_content filter). This way, the theme will provide the proper layout, ensuring that the site looks good, and we will be simply adding our content within that layout. Note that we will only do this for themes that do not explicitly declare support for Sensei.

For full support, we will need to implement this rendering mechanism for all of the pages listed below. These may be done in multiple PR's.

Here is the initial PR that provides the architecture to build upon, and completes the Course Page. The Module Page is a work-in-progress and should have a PR soon as well. The remaining pages can be implemented in parallel.

• Course Page
  • Path: /course/<course-slug>
  • Template: single-course.php
  • Add theme compatibility for Course Page #2155 (merged)
• Lesson Page
  • Path: /lesson/<lesson-slug>
  • Template: single-lesson.php
  • Add theme compatibility for Lesson page #2209 (merged)
• Quiz Page:
  • Path: /quiz/<quiz-slug>
  • Template: single-quiz.php
  • Add theme compatibility for Quiz page #2211 (merged)
• Message Page:
  • Path: /messages/<message-slug>
  • Template: single-message.php
  • Add theme compatibility for the Message page #2240 (merged)
• Course Archive Page:
  • Paths:
    • /courses
    • /<course-archive-page-slug> (from settings)
    • /course-category/<course-category-slug>
  • Template: archive-course.php
  • Add theme compatibility for Course Archive page #2243 (merged)
• Message Archive Page:
  • Path: /messages
  • Template: archive-message.php
  • Add theme compatibility for the Message archive page #2246 (merged)
• Lesson Tag Page:
  • Path: /lesson-tag/<lesson-tag-slug>
  • Template: archive-lesson.php
  • Add theme compatibility to the lesson tag archive page #2241 (merged)
• Learner Profile Page:
  • Path: /learner/<username>
  • Template: learner-profile.php
  • Add theme compatibility to the learner profile page #2236 (merged)
• Course Results Page:
  • Path: /course/<course-slug>/results
  • Template: course-results.php
  • Add theme compatibility to the course results page #2235 (merged)
• Teacher Archive Page:
  • Path: /author/<username>
  • Template: teacher-archive.php
  • Note: this does not seem to work for the admin user.
  • Add theme compatibility to the teacher archive page #2238 (merged)
• Course Module Page:
  • Path: modules/<module-slug>/?course_id=<course-id>
  • Template: taxonomy-module.php
  • Note: unlike the rest of these, which are handled in includes/class-sensei-templates.php, this one is handled in includes/class-sensei-modules.php
  • Add theme compatibility for Module page #2205 (merged)

[alexsanford]

Well, looks like all the templates have been taken care of, and this long-lived issue has finally run its course 😄 🎉