import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import '../../services/call_session.dart';
import '../widgets/level_meter.dart';
import '../widgets/status_indicator.dart';

/// Active-call screen with push-to-talk interface.
///
/// Layout:
///   ┌─────────────────────────┐
///   │  Status indicator        │
///   │  TX / RX level meters    │
///   │  Stats (frames, errors)  │
///   │  [  PTT BUTTON  ]        │
///   │  [Listen] [End Call]     │
///   └─────────────────────────┘
class CallScreen extends StatefulWidget {
  final CallSession session;
  const CallScreen({super.key, required this.session});

  @override
  State<CallScreen> createState() => _CallScreenState();
}

class _CallScreenState extends State<CallScreen> {
  StreamSubscription<SessionState>? _stateSub;
  Timer? _statsTimer;

  SessionState _state    = SessionState.inCall;
  bool         _pttDown  = false;
  bool         _listening = false;

  // Stats (refreshed at 4 Hz).
  int    _txFrames = 0;
  int    _rxFrames = 0;
  int    _rxErrors = 0;
  double _txLevel  = 0.0;
  double _rxLevel  = 0.0;

  @override
  void initState() {
    super.initState();
    _state    = widget.session.state;
    _stateSub = widget.session.onStateChange.listen((s) {
      if (mounted) setState(() => _state = s);
    });
    // Refresh stats at 4 Hz.
    _statsTimer = Timer.periodic(const Duration(milliseconds: 250), (_) {
      if (mounted) {
        setState(() {
          _txFrames = widget.session.txFrames;
          _rxFrames = widget.session.rxFrames;
          _rxErrors = widget.session.rxErrors;
          _txLevel  = (widget.session.txRms * 4).clamp(0.0, 1.0);
          _rxLevel  = (widget.session.rxSignalRms * 4).clamp(0.0, 1.0);
        });
      }
    });
  }

  @override
  void dispose() {
    _stateSub?.cancel();
    _statsTimer?.cancel();
    super.dispose();
  }

  // ── PTT gesture handlers ───────────────────────────────────────────

  Future<void> _pttPress() async {
    if (_pttDown) return;
    HapticFeedback.heavyImpact();
    setState(() => _pttDown = true);
    if (_listening) {
      await widget.session.stopListening();
      setState(() => _listening = false);
    }
    await widget.session.pttPress();
  }

  Future<void> _pttRelease() async {
    if (!_pttDown) return;
    HapticFeedback.lightImpact();
    setState(() => _pttDown = false);
    await widget.session.pttRelease();
  }

  Future<void> _toggleListen() async {
    if (_pttDown) return;
    if (_listening) {
      await widget.session.stopListening();
      setState(() => _listening = false);
    } else {
      await widget.session.startListening();
      setState(() => _listening = true);
    }
  }

  Future<void> _endCall() async {
    await widget.session.endCall();
    if (mounted) Navigator.of(context).pop();
  }

  // ── Build ──────────────────────────────────────────────────────────

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFF0D0D1A),
      appBar: AppBar(
        backgroundColor: const Color(0xFF0D0D1A),
        title: const Text('SECURE CALL',
            style: TextStyle(color: Colors.white, letterSpacing: 2)),
        centerTitle: true,
        automaticallyImplyLeading: false,
        actions: [
          IconButton(
            icon: const Icon(Icons.call_end, color: Colors.redAccent),
            tooltip: 'End call',
            onPressed: _endCall,
          ),
        ],
      ),
      body: SafeArea(
        child: Column(
          children: [
            const SizedBox(height: 12),

            // ── Status indicator ────────────────────────────────────
            StatusIndicator(state: _state),

            const SizedBox(height: 24),

            // ── Level meters ────────────────────────────────────────
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 32),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  _meterColumn('TX', _txLevel, const Color(0xFFFF6D00)),
                  _meterColumn('RX', _rxLevel, const Color(0xFF00B0FF)),
                ],
              ),
            ),

            const SizedBox(height: 24),

            // ── Stats row ────────────────────────────────────────────
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 24),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceAround,
                children: [
                  _statChip('TX FRAMES', '$_txFrames', const Color(0xFFFF6D00)),
                  _statChip('RX FRAMES', '$_rxFrames', const Color(0xFF00B0FF)),
                  _statChip('RX ERRORS', '$_rxErrors',
                      _rxErrors > 0 ? Colors.redAccent : Colors.white38),
                ],
              ),
            ),

            const Spacer(),

            // ── Operation hint ───────────────────────────────────────
            Text(
              _pttDown
                  ? 'TRANSMITTING — release to stop'
                  : _listening
                      ? 'RECEIVING — tap Listen to stop'
                      : 'Hold PTT to speak',
              style: const TextStyle(color: Colors.white38, fontSize: 12,
                  letterSpacing: 1),
            ),

            const SizedBox(height: 28),

            // ── PTT button ──────────────────────────────────────────
            GestureDetector(
              onTapDown:   (_) => _pttPress(),
              onTapUp:     (_) => _pttRelease(),
              onTapCancel:  () => _pttRelease(),
              child: AnimatedContainer(
                duration: const Duration(milliseconds: 80),
                width:  _pttDown ? 140 : 128,
                height: _pttDown ? 140 : 128,
                decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  color: _pttDown
                      ? const Color(0xFFFF6D00)
                      : const Color(0xFF1A1A2E),
                  border: Border.all(
                    color: _pttDown
                        ? const Color(0xFFFF6D00)
                        : const Color(0xFF333355),
                    width: 3,
                  ),
                  boxShadow: _pttDown
                      ? [const BoxShadow(
                          color: Color(0x80FF6D00),
                          blurRadius: 32,
                          spreadRadius: 8,
                        )]
                      : [],
                ),
                child: Center(
                  child: Icon(
                    Icons.mic,
                    size: 52,
                    color: _pttDown ? Colors.white : Colors.white38,
                  ),
                ),
              ),
            ),

            const SizedBox(height: 8),
            const Text('PTT',
                style: TextStyle(
                    color: Colors.white38, fontSize: 12, letterSpacing: 3)),

            const SizedBox(height: 28),

            // ── Listen / End call buttons ────────────────────────────
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 32),
              child: Row(
                children: [
                  Expanded(
                    child: OutlinedButton.icon(
                      onPressed: _toggleListen,
                      icon: Icon(
                          _listening ? Icons.hearing_disabled : Icons.hearing,
                          size: 18),
                      label: Text(_listening ? 'STOP RX' : 'LISTEN',
                          style: const TextStyle(letterSpacing: 1.5)),
                      style: OutlinedButton.styleFrom(
                        foregroundColor: const Color(0xFF00B0FF),
                        side: BorderSide(
                            color: _listening
                                ? const Color(0xFF00B0FF)
                                : Colors.white24),
                        padding: const EdgeInsets.symmetric(vertical: 14),
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(10)),
                      ),
                    ),
                  ),
                  const SizedBox(width: 16),
                  Expanded(
                    child: ElevatedButton.icon(
                      onPressed: _endCall,
                      icon: const Icon(Icons.call_end, size: 18),
                      label: const Text('END CALL',
                          style: TextStyle(letterSpacing: 1.5)),
                      style: ElevatedButton.styleFrom(
                        backgroundColor: Colors.redAccent,
                        padding: const EdgeInsets.symmetric(vertical: 14),
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(10)),
                      ),
                    ),
                  ),
                ],
              ),
            ),

            const SizedBox(height: 24),

            // ── Acoustic coupling reminder ───────────────────────────
            Container(
              margin: const EdgeInsets.symmetric(horizontal: 24),
              padding: const EdgeInsets.all(10),
              decoration: BoxDecoration(
                color: const Color(0xFF1A1A2E),
                borderRadius: BorderRadius.circular(8),
                border: Border.all(color: Colors.white12),
              ),
              child: const Row(
                children: [
                  Icon(Icons.volume_up, color: Colors.white38, size: 16),
                  SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      'Keep phone in SPEAKERPHONE mode. '
                      'Hold mic close to earpiece when receiving.',
                      style: TextStyle(
                          color: Colors.white38, fontSize: 11, height: 1.4),
                    ),
                  ),
                ],
              ),
            ),

            const SizedBox(height: 16),
          ],
        ),
      ),
    );
  }

  // ── Helper widgets ─────────────────────────────────────────────────

  static Widget _meterColumn(String label, double level, Color color) => Column(
        children: [
          Text(label,
              style: TextStyle(
                  color: color, fontSize: 11, letterSpacing: 2)),
          const SizedBox(height: 6),
          LevelMeter(level: level, width: 28, height: 110),
        ],
      );

  static Widget _statChip(String label, String value, Color color) => Column(
        children: [
          Text(value,
              style: TextStyle(
                  color: color,
                  fontSize: 20,
                  fontWeight: FontWeight.bold,
                  fontFamily: 'monospace')),
          Text(label,
              style: const TextStyle(color: Colors.white38, fontSize: 10,
                  letterSpacing: 1)),
        ],
      );
}