URL videos: Downloads video to temp file using streaming (avoids OOM), shows progress indicator, shares via Intent, cleans up after 60 seconds

Local videos: Shares directly without downloading
Video format detection: Supports MP4, WebM, MKV, AVI, MOV based on file magic numbers

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/ShareHelper.kt

@@ -33,16 +33,31 @@ import java.io.IOException
 
 object ShareHelper {
     private const val TAG = "ShareHelper"
-    private const val DEFAULT_EXTENSION = "jpg"
+    private const val DEFAULT_IMAGE_EXTENSION = "jpg"
+    private const val DEFAULT_VIDEO_EXTENSION = "mp4"
     private const val SHARED_FILE_PREFIX = "shared_media"
 
-    // Media type magic numbers
+    // Image type magic numbers
     private val JPEG_MAGIC = byteArrayOf(0xFF.toByte(), 0xD8.toByte())
     private val PNG_MAGIC = byteArrayOf(0x89.toByte(), 0x50.toByte(), 0x4E.toByte(), 0x47.toByte())
     private val WEBP_HEADER_START = "RIFF".toByteArray()
     private val WEBP_HEADER_END = "WEBP".toByteArray()
     private val GIF_MAGIC = "GIF8".toByteArray()
 
+    // Video type magic numbers
+    // Note: WebM and MKV share the same EBML header (Matroska container)
+    private val WEBM_MAGIC = byteArrayOf(0x1A, 0x45, 0xDF.toByte(), 0xA3.toByte())
+    private val AVI_HEADER_START = "RIFF".toByteArray()
+    private val AVI_HEADER_END = "AVI ".toByteArray()
+    private val MOV_FTYP = "ftyp".toByteArray()
+    private val MOV_MOOV = "moov".toByteArray()
+    private val MOV_MDAT = "mdat".toByteArray()
+    private val MOV_FREE = "free".toByteArray()
+    private val MP4_BRAND_ISOM = "isom".toByteArray()
+    private val MP4_BRAND_MP41 = "mp41".toByteArray()
+    private val MP4_BRAND_MP42 = "mp42".toByteArray()
+    private val MOV_BRAND_QT = "qt  ".toByteArray()
+
     suspend fun getSharableUriFromUrl(
         context: Context,
         imageUrl: String,
@@ -64,18 +79,26 @@ object ShareHelper {
             } ?: throw IOException("Unable to open snapshot for: $imageUrl")
         }
 
-    private fun getImageExtension(file: File): String =
+    private fun getImageExtension(file: File): String = getMediaExtension(file, isVideo = false)
-        try {
+
+    fun getVideoExtension(file: File): String = getMediaExtension(file, isVideo = true)
+
+    private fun getMediaExtension(
+        file: File,
+        isVideo: Boolean,
+    ): String {
+        val defaultExtension = if (isVideo) DEFAULT_VIDEO_EXTENSION else DEFAULT_IMAGE_EXTENSION
+        return try {
             FileInputStream(file).use { inputStream ->
-                val header = ByteArray(12)
+                val header = ByteArray(16)
                 val bytesRead = inputStream.read(header)
 
                 if (bytesRead < 4) {
-                    // If we couldn't read at least 4 bytes, default to jpg
+                    return defaultExtension
-                    return DEFAULT_EXTENSION
                 }
 
                 when {
+                    // Image formats
                     // JPEG: Check first 2 bytes
                     matchesMagicNumbers(header, 0, JPEG_MAGIC) -> "jpg"
 
@@ -90,13 +113,45 @@ object ShareHelper {
                         bytesRead >= 12 &&
                         matchesMagicNumbers(header, 8, WEBP_HEADER_END) -> "webp"
 
-                    else -> DEFAULT_EXTENSION
+                    // Video formats
+                    // WebM/MKV: Check first 4 bytes (EBML header)
+                    // Both use Matroska container; default to webm as it's more common on web
+                    matchesMagicNumbers(header, 0, WEBM_MAGIC) -> "webm"
+
+                    // AVI: Check "RIFF" (bytes 0-3) and "AVI " (bytes 8-11)
+                    matchesMagicNumbers(header, 0, AVI_HEADER_START) &&
+                        bytesRead >= 12 &&
+                        matchesMagicNumbers(header, 8, AVI_HEADER_END) -> "avi"
+
+                    // MP4/MOV: Check for ftyp box (bytes 4-7 should be "ftyp")
+                    bytesRead >= 12 && matchesMagicNumbers(header, 4, MOV_FTYP) -> detectMp4OrMov(header)
+
+                    // MP4/MOV alternative: moov, mdat, or free at offset 4
+                    bytesRead >= 8 && (
+                        matchesMagicNumbers(header, 4, MOV_MOOV) ||
+                            matchesMagicNumbers(header, 4, MOV_MDAT) ||
+                            matchesMagicNumbers(header, 4, MOV_FREE)
+                    ) -> "mp4"
+
+                    else -> defaultExtension
                 }
             }
         } catch (e: IOException) {
-            Log.w(TAG, "Could not determine image type for ${file.name}, defaulting to $DEFAULT_EXTENSION", e)
+            Log.w(TAG, "Could not determine media type for ${file.name}, defaulting to $defaultExtension", e)
-            DEFAULT_EXTENSION
+            defaultExtension
         }
+    }
+
+    private fun detectMp4OrMov(header: ByteArray): String {
+        // Check brand at bytes 8-11 to differentiate MP4 from MOV
+        return when {
+            matchesMagicNumbers(header, 8, MP4_BRAND_ISOM) -> "mp4"
+            matchesMagicNumbers(header, 8, MP4_BRAND_MP41) -> "mp4"
+            matchesMagicNumbers(header, 8, MP4_BRAND_MP42) -> "mp4"
+            matchesMagicNumbers(header, 8, MOV_BRAND_QT) -> "mov"
+            else -> "mp4" // Default to mp4 for unknown ftyp brands
+        }
+    }
 
     private fun matchesMagicNumbers(
         data: ByteArray,
@@ -132,4 +187,43 @@ object ShareHelper {
 
         return sharableFile
     }
+
+    suspend fun getSharableUriForLocalVideo(
+        context: Context,
+        localFile: File,
+    ): Pair<Uri, String> =
+        withContext(Dispatchers.IO) {
+            val fileExtension = getVideoExtension(localFile)
+            val sharableFile = prepareSharableFile(context, localFile, fileExtension)
+            Pair(
+                FileProvider.getUriForFile(context, "${context.packageName}.provider", sharableFile),
+                fileExtension,
+            )
+        }
+
+    fun createTempVideoFile(context: Context): File {
+        val timestamp = System.currentTimeMillis()
+        return File(context.cacheDir, "${SHARED_FILE_PREFIX}_video_$timestamp.tmp")
+    }
+
+    fun prepareTempVideoForSharing(
+        context: Context,
+        tempFile: File,
+    ): Pair<Uri, String> {
+        val extension = getVideoExtension(tempFile)
+        val timestamp = System.currentTimeMillis()
+        val sharableFile = File(context.cacheDir, "${SHARED_FILE_PREFIX}_$timestamp.$extension")
+
+        try {
+            tempFile.renameTo(sharableFile)
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to rename temp video file for sharing", e)
+            throw e
+        }
+
+        return Pair(
+            FileProvider.getUriForFile(context, "${context.packageName}.provider", sharableFile),
+            extension,
+        )
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/ZoomableContentView.kt

@@ -22,6 +22,8 @@ package com.vitorpamplona.amethyst.ui.components
 
 import android.content.Context
 import android.content.Intent
+import android.os.Handler
+import android.os.Looper
 import android.widget.Toast
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.AnimatedVisibilityScope
@@ -32,6 +34,7 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.IntrinsicSize
 import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.aspectRatio
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.size
@@ -108,10 +111,16 @@ import com.vitorpamplona.quartz.utils.Log
 import com.vitorpamplona.quartz.utils.sha256.sha256
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.coroutines.executeAsync
+import okio.sink
+import java.io.File
 import kotlin.time.Duration.Companion.seconds
 
 @Composable
@@ -765,19 +774,75 @@ fun ShareImageAction(
         }
 
         content?.let {
-            if (content is MediaUrlImage) {
+            val context = LocalContext.current
-                val context = LocalContext.current
+
-                videoUri?.let {
+            when (content) {
-                    if (videoUri.isNotEmpty()) {
+                is MediaUrlImage -> {
+                    videoUri?.let {
+                        if (videoUri.isNotEmpty()) {
+                            DropdownMenuItem(
+                                text = { Text(stringRes(R.string.share_image)) },
+                                onClick = {
+                                    scope.launch { shareImageFile(context, videoUri, mimeType) }
+                                    onDismiss()
+                                },
+                            )
+                        }
+                    }
+                }
+                is MediaUrlVideo -> {
+                    videoUri?.let {
+                        if (videoUri.isNotEmpty()) {
+                            // State is read via Compose recomposition in text{} and enabled parameter
+                            val isDownloading = remember { mutableStateOf(false) }
+
+                            DropdownMenuItem(
+                                text = {
+                                    Row(verticalAlignment = Alignment.CenterVertically) {
+                                        Text(stringRes(R.string.share_video))
+                                        if (isDownloading.value) {
+                                            Spacer(modifier = Modifier.width(8.dp))
+                                            LoadingAnimation(indicatorSize = 16.dp, circleWidth = 2.dp)
+                                        }
+                                    }
+                                },
+                                enabled = !isDownloading.value,
+                                onClick = {
+                                    isDownloading.value = true
+                                    scope.launch {
+                                        shareVideoFile(
+                                            context = context,
+                                            videoUrl = videoUri,
+                                            mimeType = mimeType,
+                                            okHttpClient = { url ->
+                                                accountViewModel.httpClientBuilder.okHttpClientForVideo(url)
+                                            },
+                                            onComplete = {
+                                                isDownloading.value = false
+                                                onDismiss()
+                                            },
+                                            onError = {
+                                                isDownloading.value = false
+                                            },
+                                        )
+                                    }
+                                },
+                            )
+                        }
+                    }
+                }
+                is MediaLocalVideo -> {
+                    content.localFile?.let { localFile ->
                         DropdownMenuItem(
-                            text = { Text(stringRes(R.string.share_image)) },
+                            text = { Text(stringRes(R.string.share_video)) },
                             onClick = {
-                                scope.launch { shareImageFile(context, videoUri, mimeType) }
+                                scope.launch { shareLocalVideoFile(context, localFile, mimeType) }
                                 onDismiss()
                             },
                         )
                     }
                 }
+                else -> { /* No share option for other types */ }
             }
         }
     }
@@ -810,6 +875,118 @@ private suspend fun shareImageFile(
     }
 }
 
+private suspend fun shareVideoFile(
+    context: Context,
+    videoUrl: String,
+    mimeType: String?,
+    okHttpClient: (String) -> OkHttpClient,
+    onComplete: () -> Unit,
+    onError: () -> Unit,
+) {
+    val tempFile = ShareHelper.createTempVideoFile(context)
+    try {
+        withContext(Dispatchers.IO) {
+            // Download video using streaming
+            val client = okHttpClient(videoUrl)
+            val request =
+                Request
+                    .Builder()
+                    .get()
+                    .url(videoUrl)
+                    .build()
+
+            client.newCall(request).executeAsync().use { response ->
+                check(response.isSuccessful) { "Download failed: ${response.code}" }
+
+                // Stream the response to the temp file
+                tempFile.outputStream().use { outputStream ->
+                    response.body.source().readAll(outputStream.sink())
+                }
+            }
+
+            // Prepare the temp file for sharing (determines extension and creates sharable URI)
+            val (uri, extension) = ShareHelper.prepareTempVideoForSharing(context, tempFile)
+
+            // Determine mime type
+            val determinedMimeType = mimeType ?: "video/$extension"
+
+            // Create share intent
+            val shareIntent =
+                Intent(Intent.ACTION_SEND).apply {
+                    type = determinedMimeType
+                    putExtra(Intent.EXTRA_STREAM, uri)
+                    addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+                }
+
+            withContext(Dispatchers.Main) {
+                context.startActivity(Intent.createChooser(shareIntent, null))
+            }
+
+            // Schedule cleanup after 60 seconds to allow the receiving app time to copy the file
+            Handler(Looper.getMainLooper()).postDelayed({
+                tempFile.delete()
+            }, 60_000)
+        }
+
+        withContext(Dispatchers.Main) {
+            onComplete()
+        }
+    } catch (e: Exception) {
+        if (e is CancellationException) throw e
+        Log.w("ZoomableContentView", "Failed to share video: $videoUrl", e)
+
+        // Clean up temp file on error
+        tempFile.delete()
+
+        withContext(Dispatchers.Main) {
+            Toast
+                .makeText(
+                    context,
+                    context.getString(R.string.unable_to_share_video),
+                    Toast.LENGTH_SHORT,
+                ).show()
+            onError()
+        }
+    }
+}
+
+private suspend fun shareLocalVideoFile(
+    context: Context,
+    localFile: File,
+    mimeType: String?,
+) {
+    try {
+        withContext(Dispatchers.IO) {
+            // Get sharable URI for the local file
+            val (uri, extension) = ShareHelper.getSharableUriForLocalVideo(context, localFile)
+
+            // Determine mime type
+            val determinedMimeType = mimeType ?: "video/$extension"
+
+            // Create share intent
+            val shareIntent =
+                Intent(Intent.ACTION_SEND).apply {
+                    type = determinedMimeType
+                    putExtra(Intent.EXTRA_STREAM, uri)
+                    addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+                }
+
+            withContext(Dispatchers.Main) {
+                context.startActivity(Intent.createChooser(shareIntent, null))
+            }
+        }
+    } catch (e: Exception) {
+        if (e is CancellationException) throw e
+        Log.w("ZoomableContentView", "Failed to share local video: ${localFile.path}", e)
+        Toast
+            .makeText(
+                context,
+                context.getString(R.string.unable_to_share_video),
+                Toast.LENGTH_SHORT,
+            ).show()
+    }
+}
+
 private fun verifyHash(content: MediaUrlContent): Boolean? {
     if (content.hash == null) return null
 

amethyst/src/main/res/values/strings.xml

@@ -1426,6 +1426,9 @@
     <string name="group_relay_explanation">The relay that all users of this chat connect to</string>
     <string name="share_image">Share image…</string>
     <string name="unable_to_share_image">Unable to share image, please try again later…</string>
+    <string name="share_video">Share video…</string>
+    <string name="unable_to_share_video">Unable to share video, please try again later…</string>
+    <string name="downloading_video_for_sharing">Downloading video…</string>
 
     <string name="search_by_hashtag">Search hashtag: #%1$s</string>