# Enabling Elements for Google Android

Like other platforms, Android requires the same two or three simple steps: Add a web view, handle events/messages, and, in some cases, authenticate the user.

## Step 1. Set Up a Web View

Component used: [WebView](https://developer.android.com/reference/kotlin/android/webkit/WebView)

Required Web View Configuration
- Enable JavaScript
- Enable Web Storage (DOM Storage)


#### Web View Sample

elements-in-android.kt
        // Step 1: Set Up a Web View
        webView = findViewById(R.id.webView)

        // Configure WebView settings
        val webSettings: WebSettings = webView.settings
        webSettings.javaScriptEnabled = true  // [!code highlight]
        webSettings.domStorageEnabled = true  // [!code highlight]
        webSettings.setSupportZoom(true) // Enable zoom controls
        webSettings.mixedContentMode = WebSettings.MIXED_CONTENT_ALWAYS_ALLOW // Allow mixed content (HTTP/HTTPS)

        // Set a WebViewClient to handle page navigation within the WebView itself
        webView.webViewClient = object : WebViewClient() {
            // This method is deprecated in API 24 and later, but still useful for older devices
            override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
                url?.let {
                    view?.loadUrl(it)
                }
                return true // Return true to indicate that the app handled the URL
            }

            // For API 24 and later
            override fun shouldOverrideUrlLoading(view: WebView?, request: android.webkit.WebResourceRequest?): Boolean {
                request?.url?.let { uri ->
                    view?.loadUrl(uri.toString())
                }
                return true // Return true to indicate that the app handled the URL
            }

            override fun onReceivedError(view: WebView?, request: android.webkit.WebResourceRequest?, error: android.webkit.WebResourceError?) {
                super.onReceivedError(view, request, error)
                android.util.Log.e("WebView", "Error: ${error?.description}")
            }
            override fun onReceivedHttpError(view: WebView?, request: android.webkit.WebResourceRequest?, errorResponse: android.webkit.WebResourceResponse?) {
                super.onReceivedHttpError(view, request, errorResponse)
                android.util.Log.e("WebView", "HTTP error: ${errorResponse?.statusCode}")
            }
        }
        
## Step 2. Set Up Event/Message Handling

### Sending Events

Method used: [postWebMessage](https://developer.android.com/reference/androidx/webkit/WebViewCompat#postWebMessage(android.webkit.WebView,androidx.webkit.WebMessageCompat,android.net.Uri))

#### Send Message Sample Code

elements-in-android.kt
        // Step 2: Set Up Communications: Event/Message Handling
        // Step 2a: Send Event to Elements
        //
        // Code sample coming soon
        //

        
### Listening for Events

Method used: [addJavascriptInterface](https://developer.android.com/reference/android/webkit/WebView#addJavascriptInterface(java.lang.Object,%20java.lang.String))

#### Receive Message Sample Code

elements-in-android.kt
        // Step 2b: Listen for events from Elements
  
        // Add JavaScript interface for postMessage
        webView.addJavascriptInterface(object {
            @JavascriptInterface
            fun postMessage(message: String) {
		// Interpret response and send to DailyPay using POST /accounts
        // See https://developer.dailypay.com/tag/Accounts#operation/createAccount

		// For demo - alert the response payload here.
                runOnUiThread {
                    AlertDialog.Builder(this@MainActivity)
                        .setTitle("Message from WebView")
                        .setMessage(message)
                        .setPositiveButton("OK", null)
                        .show()
                }
            }
        }, "AndroidInterface")
        
## Step 3. Set Up User Authentication (Optional)

elements-in-android.kt
        // Step 3: Setup Authentication
        //
        // Code sample coming soon
        //
        
## Full Sample Code

elements-in-android.kt
package com.example.webviewrunner

import android.os.Bundle
import android.webkit.JavascriptInterface
import android.webkit.WebSettings
import android.webkit.WebView
import android.webkit.WebViewClient
import android.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    private lateinit var webView: WebView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Step 1: Set Up a Web View
        webView = findViewById(R.id.webView)

        // Configure WebView settings
        val webSettings: WebSettings = webView.settings
        webSettings.javaScriptEnabled = true  // [!code highlight]
        webSettings.domStorageEnabled = true  // [!code highlight]
        webSettings.setSupportZoom(true) // Enable zoom controls
        webSettings.mixedContentMode = WebSettings.MIXED_CONTENT_ALWAYS_ALLOW // Allow mixed content (HTTP/HTTPS)

        // Set a WebViewClient to handle page navigation within the WebView itself
        webView.webViewClient = object : WebViewClient() {
            // This method is deprecated in API 24 and later, but still useful for older devices
            override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
                url?.let {
                    view?.loadUrl(it)
                }
                return true // Return true to indicate that the app handled the URL
            }

            // For API 24 and later
            override fun shouldOverrideUrlLoading(view: WebView?, request: android.webkit.WebResourceRequest?): Boolean {
                request?.url?.let { uri ->
                    view?.loadUrl(uri.toString())
                }
                return true // Return true to indicate that the app handled the URL
            }

            override fun onReceivedError(view: WebView?, request: android.webkit.WebResourceRequest?, error: android.webkit.WebResourceError?) {
                super.onReceivedError(view, request, error)
                android.util.Log.e("WebView", "Error: ${error?.description}")
            }
            override fun onReceivedHttpError(view: WebView?, request: android.webkit.WebResourceRequest?, errorResponse: android.webkit.WebResourceResponse?) {
                super.onReceivedHttpError(view, request, errorResponse)
                android.util.Log.e("WebView", "HTTP error: ${errorResponse?.statusCode}")
            }
        }
        // Step 1 End

        // Step 2: Set Up Communications: Event/Message Handling
        // Step 2a: Send Event to Elements
        //
        // Code sample coming soon
        //

        // Step 2b: Listen for events from Elements
  
        // Add JavaScript interface for postMessage
        webView.addJavascriptInterface(object {
            @JavascriptInterface
            fun postMessage(message: String) {
		// Interpret response and send to DailyPay using POST /accounts
        // See https://developer.dailypay.com/tag/Accounts#operation/createAccount

		// For demo - alert the response payload here.
                runOnUiThread {
                    AlertDialog.Builder(this@MainActivity)
                        .setTitle("Message from WebView")
                        .setMessage(message)
                        .setPositiveButton("OK", null)
                        .show()
                }
            }
        }, "AndroidInterface")
        // Step 2 End

        // Step 3: Setup Authentication
        //
        // Code sample coming soon
        //
        // Step 3 End

        // Replace client_id and implementation_id with values supplied by DailyPay
        // that are unique to you and your application
        webView.loadUrl("https://elements.uat.dailypay.com/v1/debit-card-tokenization?client_id=REPLACE_WITH_YOUR_CLIENT_ID&implementation_id=REPLACE_WITH_YOUR_IMPLEMENTATION_ID")
    }

    // Handle back button presses to navigate within the WebView's history
    override fun onBackPressed() {
        if (webView.canGoBack()) {
            webView.goBack()
        } else {
            super.onBackPressed()
        }
    }
}