added functionality to retrieve existing longURL from shortURL (#8)

Signed-off-by: viveksahu26 <vivekkumarsahu650@gmail.com>

Signed-off-by: viveksahu26 <vivekkumarsahu650@gmail.com>

README.md

@@ -2,6 +2,16 @@
 **URL shortner endpoint - returns a short URL**
 
 It is a service which takes long URL from the user and returns Short URL. 
+It provides 3 service.
+
+1) health checks: it ensures that app is running.
+Example: `http://localhost:8080/health`
+
+2) short url : it takes long url and returns short url
+Example: `http://localhost:8080/short-url?longURL=http://google.com/1346461234567890123456789/get/viveksahu26`
+
+3) long url : it takes short url and returns long url
+Example: `http://localhost:8080/long-url?sortURL=xtNFxaBwCG`
 
 ## How URL Shortner Works !!
 It replaces long URL by randomly generated characters of size 10. 
@@ -33,7 +43,7 @@ The advantage of saving Short URL and Long URL in the file is to retrieved that
 
     http://localhost:8080/health
 
-5)  Go to browser:
+5)  Convert longURL into ShortURL:
 
     Enter your URL after *http://localhost:8080/sort-url?longURL=*
 
@@ -43,12 +53,23 @@ The advantage of saving Short URL and Long URL in the file is to retrieved that
 
     http://localhost:8080/short-url?longURL=http://google.com/1346461234567890123456789/get/viveksahu26
 
-3) You will get output
+    http://localhost:8080/long-url?sortURL=xtNFxaBwCG
+
+     You will get output
 
     ```
     {"originalURL":"http://google.com/1346461234567890123456789/get/viveksahu26","shortURL":"http://localhost:8080/xtNFxaBwCG"}
     ```
 
+6) Convert ShortURL into LongURL:
+
+    Let's say shortURL=xtNFxaBwCG
+    To get it's longURL enter below URL in the browser
+    http://localhost:8080/long-url?sortURL=xtNFxaBwCG
+
+    You will get return value as:
+    http://google.com/1346461234567890123456789/get/viveksahu26
+
 ## Steps to reproduce Using Docker Image
 ### Step:1
 Docker Image: viveksahu26/urlshortner:stable

main.go

@@ -8,6 +8,36 @@ import (
 	"github.com/viveksahu26/url_shortner/src"
 )
 
+// http://localhost:8080/long-url?sortURL=xtNFxaBwCG
+func handleLongURL(writer http.ResponseWriter, req *http.Request) {
+	// Procedure:
+	// Finally got Complete url
+	// Retrieve shortURL from it by Querying it.
+	// Once retrieve, check  check in file whether it contains short url or not.
+	// If file exist, then read that file:
+	// 1. loop over it's content.
+	// 2. Check line by line,
+	// 3. short URL is present in that line or not.
+	// 4. If present retun map and true boolean
+	// 5. Else  retuen false and empty value
+
+	if req.Method != "GET" {
+		writer.WriteHeader(http.StatusMethodNotAllowed)
+	} else {
+		// get original--> shortURL
+		originalURL := req.URL.Query().Get("sortURL")
+		fmt.Println("originalURL: ", originalURL)
+
+		longURL := src.CheckWhetherShortURLisPresentORNot(originalURL)
+		fmt.Println("longURL: ", longURL)
+
+		if longURL == "" {
+			writer.Write([]byte("<h1>HSorry, No corresponding longURL is present to the shortURL. !!</h1>"))
+		}
+		writer.Write([]byte(longURL))
+	}
+}
+
 func handleShortURL(writer http.ResponseWriter, req *http.Request) {
 	if req.Method != "GET" {
 		writer.WriteHeader(http.StatusMethodNotAllowed)
@@ -66,6 +96,9 @@ func main() {
 	// /short-url endpoint is mapped to handleShortURL
 	http.HandleFunc("/short-url", handleShortURL)
 
+	// /long-url endpoint is mapped to handleLongURL
+	http.HandleFunc("/long-url", handleLongURL)
+
 	// Server Listening on localhost:8080
 	err := http.ListenAndServe(":"+port, nil)
 	if err != nil {

src/saveInfile.go

@@ -42,27 +42,53 @@ func IsFileExist(fileName string) (bool, error) {
 	return true, nil
 }
 
-func IsLongURLPresentInFile(fileName, longURL string) (map[string]string, string, bool) {
+// It can check whether LongURL is present in the file or not.
+// As well as also it can check whether shortURL is present in the file or not.
+func IsLongURLPresentInFile(fileName, url string) (map[string]string, string, bool) {
 	fileBytes, err := ioutil.ReadFile(fileName)
 	if err != nil {
 		log.Fatalln(err)
 	}
 	fileContent := strings.Split(string(fileBytes), "\n")
 
+	incommingLongURLisShortURL := false
+	if len(url) == 10 {
+		// way  of differentialting bewtween URL: whether the argument url
+		// is actual longURL or shortURL
+		// ShortURL is of length 10
+
+		// yes, it's a shortURL
+		incommingLongURLisShortURL = true
+	}
+	fmt.Println("incommingLongURLisShortURL: ", incommingLongURLisShortURL)
+
 	fileContainLongURL := false
 	var message string
 	ShortAndLongURLValue := make(map[string]string)
+
 	for _, line := range fileContent {
 		totalURL := strings.Split(line, "=")
 		if len(totalURL) == 2 {
+			// if Long URL, then store key as LongURL and value as ShortURL in map
 			ShortAndLongURLValue[totalURL[1]] = totalURL[0]
+
+			// if short URL, then store key as shortURL and value as LongURL in map
+			if incommingLongURLisShortURL {
+				fmt.Println("storing map values for shortURL as key and longURL as value")
+				ShortAndLongURLValue[totalURL[0]] = totalURL[1]
+			}
 		}
 
-		if strings.HasSuffix(line, longURL) {
+		if strings.HasSuffix(line, url) && !incommingLongURLisShortURL {
+			message = fmt.Sprintln("Yes, URL is already present in the file")
+			fileContainLongURL = true
+			return ShortAndLongURLValue, message, fileContainLongURL
+		} else if strings.HasPrefix(line, url) && incommingLongURLisShortURL {
 			message = fmt.Sprintln("Yes, URL is already present in the file")
 			fileContainLongURL = true
 			return ShortAndLongURLValue, message, fileContainLongURL
 		}
+
 		message = fmt.Sprintln("URL is not present in the file.")
 	}
 	fmt.Println("\n", message)

src/shortURLGenerator.go

@@ -1,6 +1,7 @@
 package src
 
 import (
+	"fmt"
 	"math/rand"
 )
 
@@ -33,3 +34,30 @@ func GenerateShortURL(longURL string) string {
 	}
 	return string(randomChar)
 }
+
+// If file exist, then read that file, otherwise return empty:
+// 1. loop over it's content.
+// 2. Check line by line,
+// 3. that short URL is present in that line or not.
+// 4. retun.
+
+// Check whether Short URL is present or not.
+// If present returns shorturl, else empty string
+func CheckWhetherShortURLisPresentORNot(shorturl string) string {
+	fmt.Println("Yes, you are inside CheckWhetherShortURLisPresentORNot")
+
+	fileName := "url.properties"
+	isFilePresent, _ := IsFileExist(fileName)
+
+	if isFilePresent {
+		shortAndLongURLKeyValuePair, _, fileContainShortURL := IsLongURLPresentInFile(fileName, shorturl)
+		if fileContainShortURL {
+			// then retrieve ShortURL from there.
+			if longurl, ok := shortAndLongURLKeyValuePair[shorturl]; ok {
+				return longurl
+			}
+		}
+	}
+
+	return ""
+}