Added Static File Handler

docs/advanced-guide/serving-static-files/page.md

@@ -0,0 +1,76 @@
+# Serving Static Files using GoFr
+
+Often, we require to serve static content be it a default profile image or a static website. We want to have a mechanism to serve those content without having a hassel of implementing it from scratch.
+
+GoFr provides a default mechanism where if a public folder is available in the directory of the application, it automatically provides an endpoint with `/public/<filename>`, here filename refers to the file we want to get static content to be served. 
+
+Example Project folder utilizing public endpoint:
+
+```
+project_folder
+|
+|---config
+|       .env
+|---public
+|       <img1>.jpeg
+|       <img2>.png
+|       <img3>.jpeg
+|   main.go
+|   main_test.go
+```
+
+main.go code:
+
+```go
+package main
+
+import "gofr.dev/pkg/gofr"
+
+func main(){
+    app := gofr.New()
+    app.Run()
+}
+
+```
+
+Additionally, if we want to serve more static endpoints, we have a dedicated function called `AddStaticFiles()` which takes 2 parameters endpoint and the filepath of the static folder which we want to serve.
+
+Providing an example below along with File System Example:
+
+```
+project_folder
+|
+|---config
+|       .env
+|---public
+|       <img1>.jpeg
+|       <img2>.png
+|       <img3>.jpeg
+|---static
+|       |---css
+|       |       main.css
+|       |---js
+|       |       main.js
+|       |   index.html
+|   main.go
+|   main_test.go
+```
+
+
+main.go file:
+
+```go
+
+package main
+
+import "gofr.dev/pkg/gofr"
+
+func main(){
+    app := gofr.New()
+    app.AddStaticFiles("static","./static")
+    app.Run()
+}
+
+```
+
+In the above example, both endpoints `/public` and `/static` are available for the app to render the static content.

pkg/gofr/gofr.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"sync"
@@ -94,9 +95,36 @@ func New() *App {
 
 	app.subscriptionManager = newSubscriptionManager(app.container)
 
+	// static fileserver
+	currentWd, _ := os.Getwd()
+	checkDirectory := filepath.Join(currentWd, "public")
+
+	if _, err := os.Stat(checkDirectory); !os.IsNotExist(err) {
+		app.AddStaticFiles("public", checkDirectory)
+	}
+
 	return app
 }
 
+func (a *App) AddStaticFiles(endpoint, filePath string) {
+	a.httpRegistered = true
+	dupFilePath := ""
+	if strings.HasPrefix(filePath, "./") {
+		dupFilePath, _ = os.Getwd()
+		dupFilePath = filepath.Join(dupFilePath, filePath)
+	} else {
+		dupFilePath = filePath
+	}
+
+	endpoint = "/" + strings.TrimPrefix(endpoint, "/")
+
+	if _, err := os.Stat(dupFilePath); err != nil {
+		a.container.Logger.Errorf("Couldn't register %s static endpoint", endpoint)
+		return
+	}
+	a.httpServer.router.AddStaticFiles(endpoint, dupFilePath)
+}
+
 // NewCMD creates a command-line application.
 func NewCMD() *App {
 	app := &App{}