Prompt users to update via play store, if available & necessary

This is intended for users who sideload the app (via the ADB
interceptor) and then continue to use it for a while. These users won't
receive updates at all. Not perfect, but for now we'll nudge them across
onto the play store version in that case. Later the ADB interceptor will
also update installs automatically, to handle users using ADB setup long
term.

app/build.gradle

@@ -50,6 +50,7 @@ dependencies {
     implementation 'com.beust:klaxon:5.0.1'
     implementation 'com.squareup.okhttp3:okhttp:4.3.0'
     implementation 'com.google.android.material:material:1.1.0-beta02'
+    implementation 'net.swiftzer.semver:semver:1.1.0'
     implementation 'io.sentry:sentry-android:1.7.27'
     implementation 'org.slf4j:slf4j-nop:1.7.25'
     implementation 'com.google.android.gms:play-services-analytics:10.2.4'

app/src/main/java/tech/httptoolkit/android/HttpToolkitApplication.kt

@@ -1,6 +1,7 @@
 package tech.httptoolkit.android
 
 import android.app.Application
+import android.content.Context
 import android.util.Log
 import com.android.installreferrer.api.InstallReferrerClient
 import com.android.installreferrer.api.InstallReferrerClient.InstallReferrerResponse
@@ -11,10 +12,17 @@ import com.google.android.gms.analytics.HitBuilders
 import com.google.android.gms.analytics.Tracker
 import io.sentry.Sentry
 import io.sentry.android.AndroidSentryClientFactory
+import kotlinx.coroutines.*
+import net.swiftzer.semver.SemVer
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import java.text.SimpleDateFormat
+import java.util.*
 import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.coroutines.resume
 import kotlin.coroutines.suspendCoroutine
 
+
 class HttpToolkitApplication : Application() {
 
     private val TAG = HttpToolkitApplication::class.simpleName
@@ -149,4 +157,87 @@ class HttpToolkitApplication : Application() {
         analytics?.setLocalDispatchPeriod(120) // Set dispatching back to Android default
     }
 
+    suspend fun isUpdateRequired(): Boolean {
+        return withContext(Dispatchers.IO) {
+            if (wasInstalledFromStore(this@HttpToolkitApplication)) {
+                // We only check for updates for side-loaded/ADB-loaded versions. This is useful
+                // because otherwise anything outside the play store gets no updates.
+                Log.i(TAG, "Installed from play store, no update prompting required")
+                return@withContext false
+            }
+
+            val httpClient = OkHttpClient()
+            val request = Request.Builder()
+                .url("https://api.github.com/repos/httptoolkit/httptoolkit-android/releases/latest")
+                .build()
+
+            try {
+                val response = httpClient.newCall(request).execute().use { response ->
+                    if (response.code != 200) throw RuntimeException("Failed to check for updates")
+                    response.body!!.string()
+                }
+
+                val release = Klaxon().parse<GithubRelease>(response)!!
+                val releaseVersion =
+                    tryParseSemver(release.name)
+                    ?: tryParseSemver(release.tag_name)
+                    ?: throw RuntimeException("Could not parse release version ${release.tag_name}")
+                val releaseDate = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss").parse(release.published_at)
+
+                val installedVersion = getInstalledVersion(this@HttpToolkitApplication)
+
+                val updateAvailable = releaseVersion > installedVersion
+                // We avoid immediately prompting for updates because a) there's a review delay
+                // before new updates go live, and b) it's annoying otherwise, if there's a rapid
+                // series of releases. Better to start chasing users only after a week stable.
+                val updateNotTooRecent = releaseDate.before(daysAgo(0))
+
+                Log.i(TAG,
+                    if (updateAvailable && updateNotTooRecent)
+                        "New version available, released > 1 week"
+                    else if (updateAvailable)
+                        "New version available, but still recent, released $releaseDate"
+                    else
+                        "App is up to date"
+                )
+                return@withContext updateAvailable && updateNotTooRecent
+            } catch (e: Exception) {
+                Log.w(TAG, e)
+                return@withContext false
+            }
+        }
+    }
+
+}
+
+private fun wasInstalledFromStore(context: Context): Boolean {
+    return context.packageManager.getInstallerPackageName(context.packageName) != null
+}
+
+private data class GithubRelease(
+    val tag_name: String?,
+    val name: String?,
+    val published_at: String
+)
+
+private fun tryParseSemver(version: String?): SemVer? = try {
+    if (version == null) null
+    else SemVer.parse(
+        // Strip leading 'v'
+        version.replace(Regex("^v"), "")
+    )
+} catch (e: IllegalArgumentException) {
+    null
+}
+
+private fun getInstalledVersion(context: Context): SemVer {
+    return SemVer.parse(
+        context.packageManager.getPackageInfo(context.packageName, 0).versionName
+    )
+}
+
+private fun daysAgo(days: Int): Date {
+    val calendar = Calendar.getInstance()
+    calendar.add(Calendar.DAY_OF_YEAR, -days)
+    return calendar.time
 }

app/src/main/java/tech/httptoolkit/android/MainActivity.kt

@@ -4,6 +4,7 @@ import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
+import android.content.pm.PackageManager
 import android.net.Uri
 import android.net.VpnService
 import android.os.Bundle
@@ -18,6 +19,7 @@ import android.widget.TextView
 import androidx.annotation.StringRes
 import androidx.appcompat.app.AppCompatActivity
 import androidx.localbroadcastmanager.content.LocalBroadcastManager
+import com.google.android.gms.common.GooglePlayServicesUtil
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import io.sentry.Sentry
 import kotlinx.coroutines.*
@@ -94,6 +96,13 @@ class MainActivity : AppCompatActivity(), CoroutineScope by MainScope() {
                 }
             }
         }
+
+        // Async check for updates, and maybe prompt the user if necessary (if using play store)
+        launch {
+            supervisorScope {
+                if (isStoreAvailable(this@MainActivity) && app.isUpdateRequired()) promptToUpdate()
+            }
+        }
     }
 
     override fun onResume() {
@@ -460,4 +469,31 @@ class MainActivity : AppCompatActivity(), CoroutineScope by MainScope() {
         }
     }
 
+    private suspend fun promptToUpdate() {
+        withContext(Dispatchers.Main) {
+            MaterialAlertDialogBuilder(this@MainActivity)
+                .setTitle("Updates available")
+                .setIcon(R.drawable.ic_info_circle)
+                .setMessage("An updated version of HTTP Toolkit is available")
+                .setNegativeButton("Ignore") { _, _ -> }
+                .setPositiveButton("Update now") { _, _ ->
+                    // Open the app in the market. That a release is available on github doesn't
+                    // *strictly* mean that it's available on the Android market right now, but
+                    // it is imminent, and installing from play means it'll update fully later.
+                    startActivity(
+                        Intent(Intent.ACTION_VIEW).apply {
+                            data = Uri.parse("market://details?id=tech.httptoolkit.android.v1")
+                        }
+                    )
+                }
+                .show()
+        }
+    }
+}
+
+private fun isStoreAvailable(context: Context): Boolean = try {
+    context.packageManager.getPackageInfo(GooglePlayServicesUtil.GOOGLE_PLAY_STORE_PACKAGE, 0)
+    true
+} catch (e: PackageManager.NameNotFoundException) {
+    false
 }