Export retained notification images in HTML

app/src/main/java/se/ajpanton/notificationlog/SettingsFragment.kt

@@ -16,6 +16,7 @@ import se.ajpanton.notificationlog.settings.LoggingType
 import se.ajpanton.notificationlog.settings.LoggingRuleStore
 import se.ajpanton.notificationlog.settings.AppLockStore
 import se.ajpanton.notificationlog.data.EncryptedNotificationLogStore
+import se.ajpanton.notificationlog.data.EncryptedImageStore
 import se.ajpanton.notificationlog.export.LogExporter
 import java.util.zip.ZipOutputStream
 
@@ -188,8 +189,20 @@ class SettingsFragment : Fragment(R.layout.fragment_settings) {
                     ExportFormat.FORMATTED -> output.write(LogExporter.formatted(entries, settings).encodeToByteArray())
                     ExportFormat.HTML_ZIP -> ZipOutputStream(output).use { zip ->
                         zip.putNextEntry(java.util.zip.ZipEntry("notification-log.html"))
-                        zip.write(LogExporter.html(entries, settings).encodeToByteArray())
+                        val imageStore = EncryptedImageStore(context)
+                        val imageEntries = entries.filter { it.imageId != null && LogField.CONTENTS in settings.visibleFields }
+                        val exportedImages = imageEntries.mapNotNull { entry ->
+                            imageStore.read(entry.imageId!!)?.let { entry.imageId to it }
+                        }.toMap()
+                        zip.write(LogExporter.html(entries, settings) { entry ->
+                            entry.imageId?.takeIf(exportedImages::containsKey)?.let { "images/$it.png" }
+                        }.encodeToByteArray())
                         zip.closeEntry()
+                        exportedImages.forEach { (imageId, image) ->
+                            zip.putNextEntry(java.util.zip.ZipEntry("images/$imageId.png"))
+                            zip.write(image)
+                            zip.closeEntry()
+                        }
                     }
                 }
             }

app/src/main/java/se/ajpanton/notificationlog/ViewLogsFragment.kt

@@ -11,6 +11,7 @@ import android.widget.TextView
 import androidx.fragment.app.Fragment
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import se.ajpanton.notificationlog.data.EncryptedNotificationLogStore
+import se.ajpanton.notificationlog.data.EncryptedImageStore
 import se.ajpanton.notificationlog.databinding.FragmentViewLogsBinding
 import se.ajpanton.notificationlog.model.NotificationLogEntry
 import se.ajpanton.notificationlog.settings.LogField
@@ -126,8 +127,20 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
                 ExportFormat.FORMATTED -> output.write(LogExporter.formatted(entries, settings).encodeToByteArray())
                 ExportFormat.HTML_ZIP -> ZipOutputStream(output).use { zip ->
                     zip.putNextEntry(java.util.zip.ZipEntry("notification-log.html"))
-                    zip.write(LogExporter.html(entries, settings).encodeToByteArray())
+                    val imageStore = EncryptedImageStore(context)
+                    val imageEntries = entries.filter { it.imageId != null && LogField.CONTENTS in settings.visibleFields }
+                    val exportedImages = imageEntries.mapNotNull { entry ->
+                        imageStore.read(entry.imageId!!)?.let { entry.imageId to it }
+                    }.toMap()
+                    zip.write(LogExporter.html(entries, settings) { entry ->
+                        entry.imageId?.takeIf(exportedImages::containsKey)?.let { "images/$it.png" }
+                    }.encodeToByteArray())
                     zip.closeEntry()
+                    exportedImages.forEach { (imageId, image) ->
+                        zip.putNextEntry(java.util.zip.ZipEntry("images/$imageId.png"))
+                        zip.write(image)
+                        zip.closeEntry()
+                    }
                 }
             } }
         }.start()

app/src/main/java/se/ajpanton/notificationlog/capture/NotificationCaptureService.kt

@@ -77,17 +77,20 @@ class NotificationCaptureService : NotificationListenerService() {
     ) {
         if (!NotificationRuleEvaluator.allows(ruleStore.ruleFor(loggingType), snapshot.packageName)) return
         val appName = appName(snapshot.packageName)
+        val retainImage = includeContents && snapshot.imageBytes != null &&
+            NotificationRuleEvaluator.allows(ruleStore.ruleFor(LoggingType.IMAGE_CONTENT), snapshot.packageName)
         val entry = NotificationLogEntry(
             recordedAtEpochMillis = System.currentTimeMillis(),
             packageName = snapshot.packageName,
             appName = appName,
             action = action,
             contents = if (includeContents) visibleContents(snapshot) else null,
+            imageId = if (retainImage) java.util.UUID.randomUUID().toString() else null,
         )
         writeExecutor.execute {
             try {
-                if (includeContents && snapshot.imageBytes != null && NotificationRuleEvaluator.allows(ruleStore.ruleFor(LoggingType.IMAGE_CONTENT), snapshot.packageName)) {
+                if (retainImage) {
-                    imageStore.save(entry.id, snapshot.imageBytes)
+                    imageStore.save(entry.imageId!!, snapshot.imageBytes!!)
                 }
                 logStore.append(entry)
             } catch (error: Exception) {

app/src/main/java/se/ajpanton/notificationlog/data/EncryptedImageStore.kt

@@ -2,6 +2,8 @@ package se.ajpanton.notificationlog.data
 
 import android.content.Context
 import java.io.File
+import java.io.DataInputStream
+import java.io.FileNotFoundException
 
 /** Stores copied notification image bytes independently of the source app's URI lifetime. */
 class EncryptedImageStore(context: Context) {
@@ -9,6 +11,7 @@ class EncryptedImageStore(context: Context) {
     private val cipher = AesGcmCipher(LogEncryptionKeyProvider().getOrCreate())
 
     fun save(id: String, bytes: ByteArray) {
+        require(id.matches(IMAGE_ID_PATTERN)) { "Invalid notification image ID." }
         val payload = cipher.encrypt(bytes)
         File(directory, "$id.bin").outputStream().use { output ->
             output.write(payload.initializationVector.size)
@@ -16,4 +19,26 @@ class EncryptedImageStore(context: Context) {
             output.write(payload.cipherText)
         }
     }
+
+    fun read(id: String): ByteArray? {
+        require(id.matches(IMAGE_ID_PATTERN)) { "Invalid notification image ID." }
+        val file = File(directory, "$id.bin")
+        if (!file.exists()) return null
+        try {
+            DataInputStream(file.inputStream()).use { input ->
+                val ivLength = input.readUnsignedByte()
+                require(ivLength in 12..32) { "Invalid notification image IV length." }
+                val initializationVector = ByteArray(ivLength).also(input::readFully)
+                val cipherText = input.readBytes()
+                require(cipherText.isNotEmpty()) { "Empty encrypted notification image." }
+                return cipher.decrypt(EncryptedPayload(initializationVector, cipherText))
+            }
+        } catch (error: FileNotFoundException) {
+            return null
+        }
+    }
+
+    private companion object {
+        val IMAGE_ID_PATTERN = Regex("[0-9a-f-]{36}")
+    }
 }

app/src/main/java/se/ajpanton/notificationlog/data/NotificationLogEntryJson.kt

@@ -16,7 +16,8 @@ object NotificationLogEntryJson {
                     .put("packageName", entry.packageName)
                     .put("appName", entry.appName)
                     .put("action", entry.action.name)
-                    .put("contents", entry.contents),
+                    .put("contents", entry.contents)
+                    .put("imageId", entry.imageId),
             )
         }
     }.toString().encodeToByteArray()
@@ -32,6 +33,7 @@ object NotificationLogEntryJson {
                 appName = entry.getString("appName"),
                 action = NotificationAction.valueOf(entry.getString("action")),
                 contents = if (entry.isNull("contents")) null else entry.getString("contents"),
+                imageId = entry.optString("imageId").takeIf { it.isNotEmpty() },
             )
         }
     }

app/src/main/java/se/ajpanton/notificationlog/export/LogExporter.kt

@@ -18,11 +18,21 @@ object LogExporter {
         return rows.joinToString("\n") { row -> row.mapIndexed { i, value -> value.padEnd(widths[i]) }.joinToString("  ") }
     }
 
-    fun html(entries: List<NotificationLogEntry>, settings: LogViewSettings): String = buildString {
+    fun html(
+        entries: List<NotificationLogEntry>,
+        settings: LogViewSettings,
+        imagePath: (NotificationLogEntry) -> String? = { null },
+    ): String = buildString {
         append("<!doctype html><meta charset=\"utf-8\"><table><thead><tr>")
         settings.order.filter { it in settings.visibleFields }.forEach { append("<th>${escape(header(it))}</th>") }
         append("</tr></thead><tbody>")
-        rows(entries, settings).forEach { row -> append("<tr>"); row.forEach { append("<td>${escape(it)}</td>") }; append("</tr>") }
+        entries.sortedByDescending { it.recordedAtEpochMillis }.forEach { entry ->
+            append("<tr>")
+            settings.order.filter { it in settings.visibleFields }.forEach { field ->
+                append("<td>${htmlValue(field, entry, settings, imagePath(entry))}</td>")
+            }
+            append("</tr>")
+        }
         append("</tbody></table>")
     }
 
@@ -37,6 +47,21 @@ object LogExporter {
         } }
     }
     private fun header(field: LogField) = field.name.lowercase().replace('_', ' ')
+    private fun htmlValue(field: LogField, entry: NotificationLogEntry, settings: LogViewSettings, imagePath: String?): String {
+        val value = when (field) {
+            LogField.TIMESTAMP -> timestamp(entry.recordedAtEpochMillis, settings.timestampZone)
+            LogField.APP_NAME -> entry.appName
+            LogField.PACKAGE_NAME -> entry.packageName
+            LogField.ACTION -> entry.action.name.lowercase().replace('_', ' ')
+            LogField.CONTENTS -> entry.contents.orEmpty()
+        }
+        val escaped = escape(value)
+        return if (field == LogField.CONTENTS && imagePath != null) {
+            escaped.replace("[image]", "<img src=\"${escape(imagePath)}\" alt=\"[image]\">")
+        } else {
+            escaped
+        }
+    }
     private fun timestamp(value: Long, zone: TimestampZone): String = DateFormat.getDateTimeInstance().apply { if (zone == TimestampZone.UTC) timeZone = TimeZone.getTimeZone("UTC") }.format(Date(value))
     private fun csvValue(value: String) = "\"${value.replace("\"", "\"\"")}\""
     private fun escape(value: String) = value.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;").replace("\"", "&quot;")

app/src/main/java/se/ajpanton/notificationlog/model/NotificationLogEntry.kt

@@ -10,6 +10,8 @@ data class NotificationLogEntry(
     val appName: String,
     val action: NotificationAction,
     val contents: String?,
+    /** ID of a private encrypted PNG copy, when this event retained a readable image. */
+    val imageId: String? = null,
 )
 
 enum class NotificationAction {

app/src/test/java/se/ajpanton/notificationlog/export/LogExporterTest.kt

@@ -0,0 +1,33 @@
+package se.ajpanton.notificationlog.export
+
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import se.ajpanton.notificationlog.model.NotificationAction
+import se.ajpanton.notificationlog.model.NotificationLogEntry
+import se.ajpanton.notificationlog.settings.LogViewSettings
+
+class LogExporterTest {
+    private val imageEntry = NotificationLogEntry(
+        recordedAtEpochMillis = 0,
+        packageName = "example.app",
+        appName = "Example",
+        action = NotificationAction.APPEARED,
+        contents = "A notification [image]",
+        imageId = "123e4567-e89b-12d3-a456-426614174000",
+    )
+
+    @Test fun `text exports retain an image placeholder`() {
+        assertTrue(LogExporter.csv(listOf(imageEntry), LogViewSettings()).contains("[image]"))
+        assertTrue(LogExporter.formatted(listOf(imageEntry), LogViewSettings()).contains("[image]"))
+    }
+
+    @Test fun `html replaces an image placeholder only when a support path exists`() {
+        val withImage = LogExporter.html(listOf(imageEntry), LogViewSettings()) { "images/${it.imageId}.png" }
+        val withoutImage = LogExporter.html(listOf(imageEntry), LogViewSettings())
+
+        assertTrue(withImage.contains("<img src=\"images/123e4567-e89b-12d3-a456-426614174000.png\""))
+        assertFalse(withoutImage.contains("<img"))
+        assertTrue(withoutImage.contains("[image]"))
+    }
+}