Add code_structure & database_design doc

Signed-off-by: Arnob kumar saha <arnob@appscode.com>

README.md

@@ -1 +1,14 @@
-# praromvik
+# praromvik
+
+The staring point, that will define your path on the DevOps journey !
+
+## Contribution guidelines
+
+Want to help improve praromvik? Please read the design docs [here](https://github.com/Praromvik/praromvik/tree/master/docs).
+
+## Support
+
+To speak with us, please leave a message on our email `praromvik.hq@gmail.com`. 
+To receive product announcements, follow us on [Twitter](https://twitter.com/PraromvikHq), [LinkedIn](https://www.linkedin.com/company/praromvik/), [Facebook](https://www.facebook.com/profile.php?id=61557462003505).
+
+If you have found a bug with Praromvik or want to request for new features, please [file an issue](https://github.com/praromvik/praromvik/issues/new).

docs/architecture.md

@@ -0,0 +1,77 @@
+Description on each of the packages
+
+# cmd
+Under the root command, there is only one subcommand named start_server. We use the routers package from it & start the server.
+
+# routes
+We have these types of routes: 
+
+`user_auth`: signUp, signIn, signOut
+
+`course`: 
+i) get/list -> general authenticated users can do it.
+ii) create/update -> admin or moderators can do.
+iii) delete -> only admin can do it.
+
+For get,update & delete calls(those work on a specific course uid), we utilize a context middleware for injecting context data.
+
+There is one special route for providing role to a user. It requires the admin access.
+
+# pkg
+-`pkg.auth`:
+
+We store these fields in the redis session:
+i) authenticated, ii) role, iii) userName, iv) userIP, v) user_agent
+There are some getters implemented in the session.go file.
+
+
+
+-`pkg.error`
+
+-`pkg.middleware`:
+
+There are 4 types of middlewares in this package.
+i) global middleware: For example logger, urlFormatter etc.
+
+ii) common security middleware: To check if a session is valid & authenticated.
+
+iii) access related middleware: To check if the role(in session) is matched.
+
+iv) context middleware: To append additional info to the context.
+
+
+# handlers
+`routes -> handlers -> models`
+
+Routes package will call functions from handlers package. And handlers package will call functions from models package.
+We should be strict to this design principle to avoid implementation complexity & circular dependencies.
+
+In general, the handlers are pretty straight-forward. They contain functions like Create, Get, List, Update, Delete etc.
+
+# models
+This is the actual working unit. The API & common constants are declared here. Also, it is responsible for all the database calls.
+
+
+1) `models.db.client`:
+A special package only to initialize the db clients thorough init().
+
+2) `models.db`:
+DB calls are implemented here. No one calls the DB directly except this package.
+
+3) `models.course`:
+Dedicated package for course related methods. Intended to only be called from `handlers/course`.
+
+4) `models.user`:
+   Dedicated package for user related methods. Intended to only be called from `handlers/user`.
+
+
+---
+There are some other non-code packages/files worth mentioning.
+
+`docs`: Holds the documentation files.
+
+`hack`: Holds the utility script files.
+
+`.env` file: Export the required ENVs to run this backend server.
+
+`req.http` file: Holds the curl request-response examples for the implemented http routes.

docs/database_design.md

@@ -0,0 +1,124 @@
+## API
+```
+type Course struct {
+    CourseId           string    `json:"_id" bson:"_id"`
+    Title              string    `json:"title" bson:"title"`
+    Description        string    `json:"description" bson:"description"`
+    Instructors        []string  `json:"instructors" bson:"instructors"`
+    Moderators         []string  `json:"moderators" bson:"moderators"`
+    StartDate          date.Date `json:"startDate" bson:"startDate"`
+    EndDate            date.Date `json:"endDate" bson:"endDate"`
+    Duration           int       `json:"duration" bson:"duration"` // Duration in week
+    Capacity           int       `json:"capacity" bson:"capacity"`
+    Students           []string  `json:"students" bson:"students"`
+    Price              int       `json:"price" bson:"price"`
+    Image              []byte    `json:"image" bson:"-"`
+}
+```
+
+```
+type Lesson struct {
+    LessonID     string       `json:"_id" bson:"_id"`
+    Title        string       `json:"title" bson:"title"`
+    Contents     []ContentRef `json:"contents" bson:"contents"`
+}
+
+type ContentRef struct {
+    ID      string `json:"id" bson:"id"`
+    Title   string `json:"title" bson:"title"`
+}
+
+type Content struct {
+    ContentID    string `json:"_id" bson:"_id"`
+    Title        string `json:"title" bson:"title"`
+    Type         string `json:"type" bson:"type"` // video, resource, quiz, lab
+    Data         []byte `json:"data" bson:"data"`
+    LessonRef    UUID   `json:"lessonRef" bson:"lessonRef"`
+}
+```
+
+
+## A concrete Example
+```
+Course name: Mastering golang
+<Lessons>:
+Introduction:
+    Why Go?
+    Installation
+    <resources>
+    <quiz>
+Concurrency in Go:
+    channels
+    mutex
+    <lab1>
+    <resources>
+    go routines
+    <lab2>
+Conclusion
+    thank you
+```
+
+For the `lab1` under 'Concurrency in Go', url will be like:
+http://praromvik.com/course/mastering_golang/concurrency_lab_1/
+Intentionally cutting off the lesson id part to keep the url shorter.
+
+---
+
+We have divided a single course into 2 different databases. One for holding the metadata, & one for holding the actual information.
+Again the actual information is divided into two collections. One will be called once, & the other one will be called several times (with specific contentID) from the frontend.
+### `praromvik.courses` collection
+This will hold the metadata information only.
+```
+{
+    "_id": "mastering_golang",
+    "title": "Mastering Golang",
+    "instructors": []string{<some_user_ids>},
+    "students": []string{<some_user_ids>}
+}
+```
+Removed the lessons slice above to avoid multiple reference update on create/delete calls.
+
+### `mastering_golang.lessons` collection
+The _id format is `<4_digit_serial_number>_<epoch_time>`
+```
+{
+    "_id": "<0001_1715524983>",
+    "title": "Introduction",
+    "contents": []string{<_ids>}
+},
+{
+    "_id": "<0002_1715527643>",
+    "title": "Concurrency in Go",
+    "contents": []string{"channel", "concurrency_lab_1", "resouce_from_doc"}
+}
+```
+
+### `mastering_golang.contents` collection
+```
+{
+    "_id": "channel",
+    "title": "Channel",
+    "type": "Video",
+    "lessonRef": "0002_1715527643"
+},
+{
+    "_id": "concurrency_lab_1",
+    "title": "Hands-on the Go channel",
+    "type": "Lab",
+    "lessonRef": "0002_1715527643"
+},
+{
+    "_id": "resouce_from_doc",
+    "title": "Additional learing resouces",
+    "type": "Written",
+    "lessonRef": "0002_1715527643"
+},
+```
+
+So the `RESTRICTIONS` are:
+
+i) course ids have to be unique.
+
+ii) content ids within a course have to be unique.
+
+iii) both course & content ids have to be <= 24 characters, as they will be used as _id in mongodb.