fix: stub codec2 FFI for web build using conditional exports

lib/services/voice_codec_service.dart

@@ -1,89 +1,2 @@
-import 'dart:typed_data';
+export 'voice_codec_service_stub.dart'
-import 'package:codec2_flutter/codec2_flutter.dart';
+    if (dart.library.io) 'voice_codec_service_io.dart';
-import 'package:flutter/foundation.dart';
-import '../utils/voice_message_parser.dart';
-
-export 'package:codec2_flutter/codec2_flutter.dart' show Codec2Mode;
-
-/// Maps [VoicePacketMode] to the [Codec2Mode] enum from the FFI plugin.
-Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
-  switch (pktMode) {
-    case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
-    case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
-    case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
-    case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
-    case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
-    case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
-    case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
-  }
-}
-
-/// Selects the [VoicePacketMode] best suited for a given LoRa radio bandwidth.
-///
-/// Call with [radioBandwidthHz] from the device's radio params
-/// (e.g. 125000 for 125 kHz).
-VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
-  if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
-  if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
-  return VoicePacketMode.mode1300;
-}
-
-/// High-level codec service that provides async Codec2 encode/decode
-/// executed in a background isolate so the UI thread is never blocked.
-class VoiceCodecService {
-  void _ensureCodec2Supported() {
-    if (kIsWeb ||
-        (defaultTargetPlatform != TargetPlatform.iOS &&
-            defaultTargetPlatform != TargetPlatform.android)) {
-      throw UnsupportedError('Codec2 is enabled only on iOS and Android.');
-    }
-  }
-
-  /// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
-  /// Returns the raw Codec2-encoded bytes.
-  Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
-    _ensureCodec2Supported();
-    return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
-  }
-
-  /// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
-  Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
-    _ensureCodec2Supported();
-    return Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
-  }
-
-  /// Decode and concatenate multiple [packets] into a single PCM Int16List.
-  /// Packets with null/missing entries are substituted with silence.
-  Future<Int16List> decodePackets(
-    List<VoicePacket?> packets,
-    VoicePacketMode mode,
-  ) async {
-    _ensureCodec2Supported();
-    final c2Mode = codec2ModeFor(mode);
-    final c2 = Codec2.create(c2Mode);
-    final spf = c2.samplesPerFrame;
-    c2.destroy();
-
-    // Estimate total samples (use actual data or silence per missing packet)
-    final all = <Int16List>[];
-    for (final pkt in packets) {
-      if (pkt == null || pkt.codec2Data.isEmpty) {
-        // Silence for missing packet — duration approximated by mode
-        final silenceSamples = (codec2ModeFor(mode).framesPerSecond) * spf;
-        all.add(Int16List(silenceSamples));
-      } else {
-        final decoded = await Codec2.decodeInIsolate(pkt.codec2Data, c2Mode);
-        all.add(decoded);
-      }
-    }
-
-    final total = all.fold<int>(0, (sum, l) => sum + l.length);
-    final result = Int16List(total);
-    var offset = 0;
-    for (final chunk in all) {
-      result.setRange(offset, offset + chunk.length, chunk);
-      offset += chunk.length;
-    }
-    return result;
-  }
-}

lib/services/voice_codec_service_io.dart

@@ -0,0 +1,89 @@
+import 'dart:typed_data';
+import 'package:codec2_flutter/codec2_flutter.dart';
+import 'package:flutter/foundation.dart';
+import '../utils/voice_message_parser.dart';
+
+export 'package:codec2_flutter/codec2_flutter.dart' show Codec2Mode;
+
+/// Maps [VoicePacketMode] to the [Codec2Mode] enum from the FFI plugin.
+Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
+  switch (pktMode) {
+    case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
+    case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
+    case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
+    case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
+    case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
+    case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
+  }
+}
+
+/// Selects the [VoicePacketMode] best suited for a given LoRa radio bandwidth.
+///
+/// Call with [radioBandwidthHz] from the device's radio params
+/// (e.g. 125000 for 125 kHz).
+VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
+  if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
+  if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
+  return VoicePacketMode.mode1300;
+}
+
+/// High-level codec service that provides async Codec2 encode/decode
+/// executed in a background isolate so the UI thread is never blocked.
+class VoiceCodecService {
+  void _ensureCodec2Supported() {
+    if (kIsWeb ||
+        (defaultTargetPlatform != TargetPlatform.iOS &&
+            defaultTargetPlatform != TargetPlatform.android)) {
+      throw UnsupportedError('Codec2 is enabled only on iOS and Android.');
+    }
+  }
+
+  /// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
+  /// Returns the raw Codec2-encoded bytes.
+  Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
+    _ensureCodec2Supported();
+    return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
+  }
+
+  /// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
+  Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
+    _ensureCodec2Supported();
+    return Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
+  }
+
+  /// Decode and concatenate multiple [packets] into a single PCM Int16List.
+  /// Packets with null/missing entries are substituted with silence.
+  Future<Int16List> decodePackets(
+    List<VoicePacket?> packets,
+    VoicePacketMode mode,
+  ) async {
+    _ensureCodec2Supported();
+    final c2Mode = codec2ModeFor(mode);
+    final c2 = Codec2.create(c2Mode);
+    final spf = c2.samplesPerFrame;
+    c2.destroy();
+
+    // Estimate total samples (use actual data or silence per missing packet)
+    final all = <Int16List>[];
+    for (final pkt in packets) {
+      if (pkt == null || pkt.codec2Data.isEmpty) {
+        // Silence for missing packet — duration approximated by mode
+        final silenceSamples = (codec2ModeFor(mode).framesPerSecond) * spf;
+        all.add(Int16List(silenceSamples));
+      } else {
+        final decoded = await Codec2.decodeInIsolate(pkt.codec2Data, c2Mode);
+        all.add(decoded);
+      }
+    }
+
+    final total = all.fold<int>(0, (sum, l) => sum + l.length);
+    final result = Int16List(total);
+    var offset = 0;
+    for (final chunk in all) {
+      result.setRange(offset, offset + chunk.length, chunk);
+      offset += chunk.length;
+    }
+    return result;
+  }
+}

lib/services/voice_codec_service_stub.dart

@@ -0,0 +1,71 @@
+import 'dart:typed_data';
+import '../utils/voice_message_parser.dart';
+
+/// Web/unsupported platform stub — Codec2 FFI is not available.
+enum Codec2Mode {
+  mode3200(0),
+  mode2400(1),
+  mode1600(2),
+  mode1400(3),
+  mode1300(4),
+  mode1200(5),
+  mode700c(8);
+
+  const Codec2Mode(this.c2ModeId);
+  final int c2ModeId;
+
+  int get framesPerSecond => (this == mode3200 || this == mode2400) ? 50 : 25;
+  int get samplesPerFrame => 8000 ~/ framesPerSecond;
+
+  int get bytesPerSecond {
+    switch (this) {
+      case mode3200: return 400;
+      case mode700c: return 100;
+      case mode1200: return 150;
+      case mode1300: return 175;
+      case mode1400: return 175;
+      case mode1600: return 200;
+      case mode2400: return 300;
+    }
+  }
+
+  static const int _maxBytesPerPacket = 160;
+
+  int get packetDurationMs {
+    final bytesPerFrame = bytesPerSecond / framesPerSecond;
+    final framesPerPacket = (_maxBytesPerPacket / bytesPerFrame).floor();
+    return (framesPerPacket * 1000 ~/ framesPerSecond);
+  }
+}
+
+Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
+  switch (pktMode) {
+    case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
+    case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
+    case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
+    case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
+    case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
+    case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
+  }
+}
+
+VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
+  if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
+  if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
+  return VoicePacketMode.mode1300;
+}
+
+class VoiceCodecService {
+  Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) =>
+      Future.error(UnsupportedError('Voice not supported on web'));
+
+  Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) =>
+      Future.error(UnsupportedError('Voice not supported on web'));
+
+  Future<Int16List> decodePackets(
+    List<VoicePacket?> packets,
+    VoicePacketMode mode,
+  ) =>
+      Future.error(UnsupportedError('Voice not supported on web'));
+}