#Ad REST API ##Description REST API written in Go that provides different types of clients the ability to perform CRUD operations on ads.
Ads in this case are simple (named) URLs organized into folders. Each folder can contain an arbitrary number of ads and sub-folders.

##Technology stack Written in Go.
The main reason being the simple nature of the task and Go being really good at doing simple things really fast.
For most things the standard libraries are used the few exceptions are:

• github.com/gorilla/mux - Nice router from the gorilla web toolkit: http://www.gorillatoolkit.org/pkg/mux
• github.com/go-sql-driver/mysql - A mysql driver for Go
• github.com/jmoiron/sqlx - provides a set of extensions on go's standard database/sql library. Mainly useful because it provides marshaling of rows into structs.
• github.com/asaskevich/govalidator - for validating the ad URLs

The database used is MySQL. No special reason for that... could have been any relational database. Actually changing the database would not require much work.

##Project organization
The main package is divided into two .go files. main.go and handlers.go. This code provides the backbone of the API server with all the necessary routes and handler functions to handle specific routes.
Other parts of the application are divided into 3 additional packages where the data package is the most important one. It contains code for our data models and code that communicates with the database.
The database schema for the rather simple two table database can be found in DB/dbschema.sql.

###Testing The only tests I could think of are at the model/data layer. Where tests check if the functions that check the validity of our Ad or Folder objects work for different edge type inputs.
The other thing here that should be tested are the functions that work with the database. So basically to check if adding, retrieving, updating and deleting works.
My proficiency in Go is at this point a bit limited so I have no idea how to test the handler functions that work on the http request and respond to it.

API Reference

Working with ad folders

GET /api/folders
Get a list of all folders at root level.

GET /api/folders/parent/{parentId}
Get a list of all folders inside the folder with the id {parentId}.

Request:

GET /api/folders/parent/1 HTTP/1.1
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 12:43:32 GMT
Content-Length: 79
[
{
  "id":2,
  "parentid":1,
  "name":"Subfolder",
  "lastmodified":"2017-03-01T00:39:08Z"
}
]

GET /api/folders/{folderId}/path
Gets all folders in the path from root to (and including) the folder with id {folderId}.

Request:

GET /api/folders/25/path HTTP/1.1
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Fri, 03 Mar 2017 17:09:53 GMT
Content-Length: 157
[
{
	"id": 17,
	"parentid": 0,
	"name": "Club",
	"lastmodified": "2017-03-01T14:08:30Z"
},
{
	"id": 25,
	"parentid": 17,
	"name": "Peasants",
	"lastmodified": "2017-03-03T14:03:40Z"
}
],

POST /api/folders
Add a folder at root level.

POST /api/folders/parent/{parentId}
Add a folder inside the folder with id {parentId}.

Request:

POST /api/folders/parent/1 HTTP/1.1
Accept: application/json
Content-Type: application/json
{
  "name": "New folder"
}

Response:

HTTP/1.1 201 Created
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:04:11 GMT
Content-Length: 81
{
  "status": "OK",
  "reason": "Successfully added new folder in parent: 1"
}

PUT /api/folders/{folderId}
Update the folder with id {folderId}.

Request:

PUT /api/folders/1 HTTP/1.1
Accept: application/json
Content-Type: application/json
{
  "name": "Updated folder name"
}

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:08:30 GMT
Content-Length: 77
{
  "status": "OK",
  "reason": "Successfully updated folder with id: 1"
}

DELETE /api/folders/{folderId}
Remove the folder with id {folderId}.

Request:

DELETE /api/folders/1 HTTP/1.1
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:08:30 GMT
Content-Length: 77
{
  "status": "OK",
  "reason": "Successfully removed folder with id: 1"
}

If folder has at least one subfolder the DELETE action will fail.

HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:11:03 GMT
Content-Length: 107
{
  "status": "Error",
  "reason": "This folder contains at least one other folder. Delete that first."
}

Working with ads

GET /api/ads/folder/{folderId}
Get a list of all ads inside the folder with the id {folderId}.

Request:

GET /api/ads/folder/1 HTTP/1.1
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:17:27 GMT
Content-Length: 145
[
  {
  "id": 10,
  "folderid": 1,
  "name": "Ace of hearts",
  "url": "http://cliparts.co/cliparts/8c6/oga/8c6ogaBoi.png",
  "lastmodified": "2017-03-01T01:42:50Z"
  }
]

POST /api/ads/folder/{folderId}
Add a ad inside the folder with id {folderId}.

Request:

POST /api/ads/folder/1 HTTP/1.1
Accept: application/json
Content-Type: application/json
{
  "name": "New cool ad",
  "url": "http://www.hdbloggers.net/wp-content/uploads/2016/04/Cool-Wallpapers.jpg"
}

URLs get tested for validity. URLs that are not URLs will not be accepted.

Response:

HTTP/1.1 201 Created
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:20:45 GMT
Content-Length: 77
{
  "status": "OK",
  "reason": "Successfully added new ad in folder: 1"
}

PUT /api/ads/{adId}
Update the ad with id {adId}.

Request:

PUT /api/ads/1 HTTP/1.1
Accept: application/json
Content-Type: application/json
{
  "name": "New cool ad - UPDATE",
  "url": "this is not an URL"
}

Response:

HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:25:17 GMT
Content-Length: 59
{
  "status": "Error",
  "reason": "Ad URL is invalid."
}

DELETE /api/ads/{adId}
Remove the ad with id {adId}.

Request:

DELETE /api/ads/1 HTTP/1.1
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 01 Mar 2017 13:26:44 GMT
Content-Length: 73
{
  "status": "OK"
  "reason": "Successfully removed ad with id: 1"
}