4192 - Write a generateShortUrl() Function using Kotlin

Update README.md

kotlin/generateShortUrl/README.md

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+# generateShortUrl() - Kotlin
+
+## ⚡ Function Details
+
+Generate a short URL.
+Introduce support for bitly and tinyurl APIs.
+
+If necessary, introduce their secret keys as function variables. URL and provider to use must be provided as payload, and shortened URL should be returned.
+
+## Example input:
+
+```json
+{ 
+ "provider":"bitly",
+ "url":"https://google.com/",
+ "provider_api_key": "--the api key from the provider--"
+}
+```
+
+## Example output:
+
+Successful response:
+
+```json
+{
+ "success":true,
+ "url":"https://bit.ly/3y3HDkC"
+}
+```
+
+Error response:
+
+```json
+{
+ "success":false,
+ "message":"Payload does not contain 'provider'"
+}
+```
+
+```json
+{
+ "success":false,
+ "message":"Payload does not contain 'url'"
+}
+```
+
+```json
+{
+ "success":false,
+ "message":"Payload doesn't contain valid provider - 'random'"
+}
+```
+
+## 🚀 Deployment
+
+1. Clone this repository, and enter this function folder:
+
+```
+$ git clone https://github.com/open-runtimes/examples.git && cd examples
+$ cd kotlin/generateShortUrl
+```
+
+2. Build the code:
+
+```bash
+docker run -e INTERNAL_RUNTIME_ENTRYPOINT=src/Index.kt --rm --interactive --tty --volume $PWD:/usr/code openruntimes/kotlin:v2-1.6 sh /usr/local/src/build.sh
+```
+
+3. Spin-up open-runtime:
+
+```bash
+docker run -p 3001:3000 -e INTERNAL_RUNTIME_KEY=secret-key --rm --interactive --tty --volume $PWD/code.tar.gz:/tmp/code.tar.gz:ro openruntimes/kotlin:v2-1.6 sh /usr/local/src/start.sh
+```
+
+Your function is now listening on port `3000`, and you can execute it by sending `POST` request with appropriate authorization headers. To learn more about runtime, you can visit Kotlin runtime [README](https://github.com/open-runtimes/open-runtimes/tree/main/runtimes/kotlin-1.6).
+
+4. Execute command:
+```bash
+curl -X 'POST' \
+'http:https://localhost:3000/' \
+-H 'Accept: application/json' \
+-H 'Content-Type: application/json' \
+-H 'X-Internal-Challenge: secret-key' \
+-d '{
+"payload": "{\"url\":\"https://facebook.com/test\",\"provider\":\"bitly\",\"provider_api_key\":\"to-be-created\"}"
+}'
+```
+The provider_api_key should be created 
+
+
+## 📝 Notes
+
+- This function is designed for use with Appwrite Cloud Functions. You can learn more about it in [Appwrite docs](https://appwrite.io/docs/functions).

kotlin/generateShortUrl/deps.gradle

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+dependencies {
+ implementation 'com.google.code.gson:gson:2.9.0'
+}

kotlin/generateShortUrl/src/Index.kt

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+import com.google.gson.Gson
+import com.google.gson.JsonParser
+import com.google.gson.JsonSyntaxException
+import io.openruntimes.kotlin.RuntimeRequest
+import io.openruntimes.kotlin.RuntimeResponse
+import java.io.BufferedReader
+import java.io.IOException
+import java.io.InputStreamReader
+import java.io.OutputStream
+import java.net.HttpURLConnection
+import java.net.URL
+
+
+val PROVIDER_API_MAP = mapOf("bitly" to "https://api-ssl.bitly.com/v4/shorten",
+ "tinyurl" to "https://api.tinyurl.com/create")
+
+val PROVIDER_API_URL_KEY = mapOf("bitly" to "long_url","tinyurl" to "url")
+
+val gson = Gson()
+
+fun getErrorResponseWithMessage(res: RuntimeResponse, message: String? = "Some error occurred"): RuntimeResponse {
+ return res.json(
+ data = mapOf(
+ "success" to false,
+ "message" to message
+ ),
+ statusCode = 400
+ )
+}
+
+@Throws(Exception::class)
+suspend fun main(req: RuntimeRequest, res: RuntimeResponse): RuntimeResponse {
+
+ val payloadMap = Gson().fromJson<Map<String, String>>(
+ req.payload.ifBlank { "{}" },
+ Map::class.java
+ )
+
+ val provider = payloadMap["provider"]?:""
+ val longUrl = payloadMap["url"] ?: ""
+ val providerApiKey = payloadMap["provider_api_key"]?:""
+ var providerResponse="";
+
+ try{
+
+ if (provider.isEmpty() || provider.trim().isEmpty()) {
+ return getErrorResponseWithMessage(res, "Payload doesn't contain 'provider'")
+ }
+ if (longUrl.isEmpty() || longUrl.trim().isEmpty()) {
+ return getErrorResponseWithMessage(res, "Payload doesn't contain 'url'")
+ }
+
+ if(!PROVIDER_API_MAP.contains(provider)){
+ return getErrorResponseWithMessage(res, "Payload doesn't contain valid provider - '$provider'.")
+ }
+
+ val providerUrl = URL(PROVIDER_API_MAP.get(provider))
+
+ val connection = createConnection(providerUrl,providerApiKey)
+
+ val requestBody ="{\"${PROVIDER_API_URL_KEY.get(provider)}\":\"$longUrl\"}"
+
+ providerResponse= parseResponse(connection,requestBody,provider)
+ }
+ catch (e: Exception){
+ return getErrorResponseWithMessage(res, e.message)
+ }
+
+ return res.json(
+ data = mapOf(
+ "success" to true,
+ "url" to providerResponse
+ ),
+ statusCode = 200
+ )
+}
+
+fun createConnection(providerUrl:URL,providerApiKey:String): HttpURLConnection {
+ val connection: HttpURLConnection = providerUrl.openConnection() as HttpURLConnection
+ connection.requestMethod = "POST"
+ connection.addRequestProperty("Content-Type", "application/json")
+ connection.addRequestProperty("Authorization", "Bearer $providerApiKey")
+ connection.setRequestProperty("accept", "application/json")
+ connection.doOutput = true
+ return connection
+}
+
+fun parseResponse(connection:HttpURLConnection,requestBody:String,provider:String): String {
+ val response = StringBuilder()
+ val os: OutputStream = connection.getOutputStream()
+ val input: ByteArray = requestBody.toByteArray(Charsets.UTF_8)
+ os.write(input, 0, input.size)
+
+ val br = BufferedReader(InputStreamReader(connection.getInputStream(), Charsets.UTF_8))
+
+ var responseLine: String? = null
+
+ while (br.readLine().also { responseLine = it } != null) {
+ response.append(responseLine!!.trim { it <= ' ' })
+ }
+
+ br.close()
+ connection.disconnect()
+
+ val jsonObject = JsonParser().parse(response.toString()).getAsJsonObject()
+
+ return when {
+ provider == "bitly" -> jsonObject.get("link").getAsString()
+ else -> jsonObject.getAsJsonObject("data").get("tiny_url").getAsString()
+ }
+
+}
+