feat(mobile): day dividers, video upload, emoji picker & UX polish

mobile/android/app/src/main/kotlin/com/sprout/sprout_mobile/MainActivity.kt

@@ -3,12 +3,16 @@ package com.sprout.sprout_mobile
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.graphics.ImageDecoder
+import android.media.MediaExtractor
+import android.media.MediaMuxer
 import android.os.Build
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.plugin.common.MethodChannel
 import java.io.ByteArrayOutputStream
+import java.io.File
 import java.nio.ByteBuffer
+import java.util.UUID
 
 class MainActivity : FlutterActivity() {
     private var mediaUploadChannel: MethodChannel? = null
@@ -28,6 +32,9 @@ class MainActivity : FlutterActivity() {
                     TRANSCODE_IMAGE_TO_JPEG_METHOD -> {
                         handleTranscodeImageToJpeg(call.arguments, result)
                     }
+                    TRANSCODE_VIDEO_TO_MP4_METHOD -> {
+                        handleTranscodeVideoToMp4(call.arguments, result)
+                    }
                     else -> result.notImplemented()
                 }
             }
@@ -150,6 +157,63 @@ class MainActivity : FlutterActivity() {
         result.success(transformedBytes)
     }
 
+    private fun handleTranscodeVideoToMp4(
+        arguments: Any?,
+        result: MethodChannel.Result,
+    ) {
+        val sourcePath = arguments as? String ?: run {
+            invalidArguments(result, "Expected source file path as String.")
+            return
+        }
+
+        Thread {
+            val outputFile = File(cacheDir, "${UUID.randomUUID()}.mp4")
+            var muxer: MediaMuxer? = null
+            val extractor = MediaExtractor()
+            try {
+                extractor.setDataSource(sourcePath)
+                muxer = MediaMuxer(outputFile.absolutePath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4)
+
+                val trackIndices = mutableMapOf<Int, Int>()
+                for (i in 0 until extractor.trackCount) {
+                    val format = extractor.getTrackFormat(i)
+                    val newIndex = muxer.addTrack(format)
+                    trackIndices[i] = newIndex
+                    extractor.selectTrack(i)
+                }
+
+                muxer.start()
+                val buffer = ByteBuffer.allocate(1024 * 1024) // 1MB buffer
+                val bufferInfo = android.media.MediaCodec.BufferInfo()
+
+                while (true) {
+                    val sampleSize = extractor.readSampleData(buffer, 0)
+                    if (sampleSize < 0) break
+                    val muxerTrack = trackIndices[extractor.sampleTrackIndex]!!
+                    bufferInfo.offset = 0
+                    bufferInfo.size = sampleSize
+                    bufferInfo.presentationTimeUs = extractor.sampleTime
+                    bufferInfo.flags = extractor.sampleFlags
+                    muxer.writeSampleData(muxerTrack, buffer, bufferInfo)
+                    extractor.advance()
+                }
+
+                muxer.stop()
+                result.success(outputFile.absolutePath)
+            } catch (e: Exception) {
+                outputFile.delete()
+                result.error(
+                    "transcode_failed",
+                    e.message ?: "Video transcoding failed.",
+                    null,
+                )
+            } finally {
+                try { muxer?.release() } catch (_: Exception) {}
+                extractor.release()
+            }
+        }.start()
+    }
+
     private fun invalidArguments(
         result: MethodChannel.Result,
         message: String,
@@ -161,5 +225,6 @@ class MainActivity : FlutterActivity() {
         private const val MEDIA_UPLOAD_CHANNEL = "sprout/media_upload"
         private const val SANITIZE_IMAGE_FOR_UPLOAD_METHOD = "sanitizeImageForUpload"
         private const val TRANSCODE_IMAGE_TO_JPEG_METHOD = "transcodeImageToJpeg"
+        private const val TRANSCODE_VIDEO_TO_MP4_METHOD = "transcodeVideoToMp4"
     }
 }

mobile/ios/Runner/AppDelegate.swift

@@ -1,3 +1,4 @@
+import AVFoundation
 import Flutter
 import UIKit
 
@@ -103,8 +104,69 @@ import UIKit
       }
 
       result(FlutterStandardTypedData(bytes: jpegData))
+    case "transcodeVideoToMp4":
+      guard let sourcePath = call.arguments as? String else {
+        result(
+          FlutterError(
+            code: "invalid_arguments",
+            message: "Expected source file path as String.",
+            details: nil
+          )
+        )
+        return
+      }
+      transcodeVideoToMp4(sourcePath: sourcePath, result: result)
     default:
       result(FlutterMethodNotImplemented)
     }
   }
+
+  private func transcodeVideoToMp4(
+    sourcePath: String,
+    result: @escaping FlutterResult
+  ) {
+    let sourceURL = URL(fileURLWithPath: sourcePath)
+    let asset = AVURLAsset(url: sourceURL)
+
+    guard let exportSession = AVAssetExportSession(
+      asset: asset,
+      presetName: AVAssetExportPresetPassthrough
+    ) else {
+      result(
+        FlutterError(
+          code: "transcode_failed",
+          message: "Unable to create export session.",
+          details: nil
+        )
+      )
+      return
+    }
+
+    let outputURL = FileManager.default.temporaryDirectory
+      .appendingPathComponent(UUID().uuidString)
+      .appendingPathExtension("mp4")
+
+    exportSession.outputURL = outputURL
+    exportSession.outputFileType = .mp4
+    exportSession.shouldOptimizeForNetworkUse = true
+
+    exportSession.exportAsynchronously {
+      switch exportSession.status {
+      case .completed:
+        result(outputURL.path)
+      default:
+        let errorMessage = exportSession.error?.localizedDescription
+          ?? "Video transcoding failed with status \(exportSession.status.rawValue)."
+        result(
+          FlutterError(
+            code: "transcode_failed",
+            message: errorMessage,
+            details: nil
+          )
+        )
+        // Clean up partial output on failure.
+        try? FileManager.default.removeItem(at: outputURL)
+      }
+    }
+  }
 }