Privilege
---

Privilege::list_of_privileges( privilege_id )

Privilege::privileges_tree()





User
---

User::get_privileges


User::has_privilege( privilege_id )


User::reset_password()
    -> create otp
    -> send email


User::set_privilege( privilege_id )


User::track_action()
    -> user_id
    -> action : Contoller::method(args)
    -> timestamp



Lesson:
---

Lesson::create_lesson( POST )

Lesson::get_lesson( lesson_id )



Course
---

Course::create_course( POST )

Course::courses_tree()



Upgrades (??)
---


A1

A2 : includes A1

A3 : includes A1, A2

A4 : includes A1, A2, A3


A1  100
A2  200
A3  350
A4  500

B1  100
B2  200
B3  400
B4  800


:1 -> 0%
:2 -> 15%
:3 -> 20%




A1 -> A2
A1 -> A3
A1 -> A4

A2 -> A3
A2 -> A4

A3 -> A4

A1 < A2 < A3 < A4



B1 -> B2
B1 -> B3
B1 -> B4

B2 -> B3
B2 -> B4

B3 -> B4


A1+B1

A2+B2

A3+B3


A1+B1 -> A2+B2
A1+B1 -> A3+B3
A1+B1 -> A4+B4

A2+B2 -> A3+B3
A2+B2 -> A4+B4

A3+B3 -> A4+B4



UPGRADE PRICE = upper_priv_price - own_priv_price

buy 1 item : -0%
buy 2 items : -10%
buy 3 items : -15%