In-app-uppdatering: koll mot version.json, nedladdning och installation

- CI publicerar version.json (versionCode/versionName ur APK:n, sha256,
  apkUrl) som release-asset
- Appen jämför versionCode vid start; banner på hemskärmen med
  nedladdningsprogress; sha256-verifiering; Androids installationsdialog
  via FileProvider (samma signatur -> uppdaterar rakt över)
- REQUEST_INSTALL_PACKAGES + FileProvider i manifestet

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kf4MAbZ3c3B4Xy5XfuGsCP

app/src/main/java/eu/brassepc/fitnessdroid/data/UpdateChecker.kt

@@ -0,0 +1,109 @@
+package eu.brassepc.fitnessdroid.data
+
+import android.content.Context
+import android.content.Intent
+import androidx.core.content.FileProvider
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.intOrNull
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import java.io.File
+import java.security.MessageDigest
+import java.util.concurrent.TimeUnit
+
+data class UpdateInfo(
+    val versionCode: Long,
+    val versionName: String,
+    val apkUrl: String,
+    val sha256: String?,
+)
+
+/**
+ * Uppdateringskoll mot släppsidans version.json (skrivs av CI:t).
+ * Nedladdning till appens cache + verifiering, sedan Androids
+ * installationsdialog — samma signeringsnyckel gör att den uppdaterar
+ * rakt över befintlig installation.
+ */
+class UpdateChecker(private val context: Context) {
+
+    private val http = OkHttpClient.Builder()
+        .connectTimeout(10, TimeUnit.SECONDS)
+        .readTimeout(120, TimeUnit.SECONDS)
+        .build()
+
+    private fun installedVersionCode(): Long =
+        context.packageManager.getPackageInfo(context.packageName, 0).longVersionCode
+
+    /** null = uppdaterad, nätfel eller trasig manifest — stör aldrig användaren. */
+    suspend fun check(): UpdateInfo? = withContext(Dispatchers.IO) {
+        runCatching {
+            val request = Request.Builder().url(VERSION_URL).build()
+            http.newCall(request).execute().use { response ->
+                if (!response.isSuccessful) return@withContext null
+                val o = Json.parseToJsonElement(response.body!!.string()).jsonObject
+                val info = UpdateInfo(
+                    versionCode = (o["versionCode"]?.jsonPrimitive?.intOrNull ?: 0).toLong(),
+                    versionName = o["versionName"]?.jsonPrimitive?.content ?: "?",
+                    apkUrl = o["apkUrl"]?.jsonPrimitive?.content ?: return@withContext null,
+                    sha256 = o["sha256"]?.jsonPrimitive?.content,
+                )
+                if (info.versionCode > installedVersionCode()) info else null
+            }
+        }.getOrNull()
+    }
+
+    /** Laddar ner APK:n till cachen, verifierar sha256, returnerar filen. */
+    suspend fun download(info: UpdateInfo, onProgress: (Float) -> Unit): File =
+        withContext(Dispatchers.IO) {
+            val dir = File(context.cacheDir, "updates").apply { mkdirs() }
+            val file = File(dir, "FitnessDroid-${info.versionCode}.apk")
+            val request = Request.Builder().url(info.apkUrl).build()
+            http.newCall(request).execute().use { response ->
+                if (!response.isSuccessful) error("HTTP ${response.code}")
+                val body = response.body!!
+                val total = body.contentLength().takeIf { it > 0 }
+                val digest = MessageDigest.getInstance("SHA-256")
+                body.byteStream().use { input ->
+                    file.outputStream().use { output ->
+                        val buffer = ByteArray(64 * 1024)
+                        var read: Int
+                        var done = 0L
+                        while (input.read(buffer).also { read = it } != -1) {
+                            output.write(buffer, 0, read)
+                            digest.update(buffer, 0, read)
+                            done += read
+                            total?.let { onProgress(done.toFloat() / it) }
+                        }
+                    }
+                }
+                val actual = digest.digest().joinToString("") { "%02x".format(it) }
+                if (info.sha256 != null && !actual.equals(info.sha256, ignoreCase = true)) {
+                    file.delete()
+                    error("sha256 stämmer inte — avbryter")
+                }
+            }
+            file
+        }
+
+    /** Öppnar Androids installationsdialog för den nedladdade APK:n. */
+    fun install(file: File) {
+        val uri = FileProvider.getUriForFile(
+            context, "${context.packageName}.fileprovider", file,
+        )
+        context.startActivity(
+            Intent(Intent.ACTION_VIEW).apply {
+                setDataAndType(uri, "application/vnd.android.package-archive")
+                addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_ACTIVITY_NEW_TASK)
+            }
+        )
+    }
+
+    companion object {
+        private const val VERSION_URL =
+            "https://gitea.brasse-pc.eu/brasse/FitnessDroid/releases/download/latest/version.json"
+    }
+}