import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:signature/signature.dart';
import '../l10n/app_localizations.dart';
import '../models/tasks/signature_task.dart';
import '../widgets/offline_banner.dart';

class SignatureCaptureScreen extends StatefulWidget {
  final SignatureTask task;
  final void Function(String svg) onSignatureCompleted;

  const SignatureCaptureScreen({
    super.key,
    required this.task,
    required this.onSignatureCompleted,
  });

  @override
  State<SignatureCaptureScreen> createState() => _SignatureCaptureScreenState();
}

class _SignatureCaptureScreenState extends State<SignatureCaptureScreen> {
  late final SignatureController _controller;
  bool _hasSignature = false;
  bool _isMobilePlatform = false;

  @override
  void initState() {
    super.initState();
    _controller = SignatureController(
      penStrokeWidth: 3,
      penColor: Colors.black,
      exportBackgroundColor: Colors.white,
    );

    // Listen to signature controller changes
    _controller.addListener(_onSignatureChanged);

    _detectPlatformAndSetOrientation();
  }

  void _onSignatureChanged() {
    final bool hasPoints = _controller.points.isNotEmpty;
    if (hasPoints != _hasSignature) {
      setState(() {
        _hasSignature = hasPoints;
      });
    }
  }

  void _detectPlatformAndSetOrientation() {
    // Check if we're on a mobile platform
    if (!kIsWeb) {
      switch (defaultTargetPlatform) {
        case TargetPlatform.android:
        case TargetPlatform.iOS:
          _isMobilePlatform = true;
          // Rotate screen 90 degrees to the right (landscape left)
          SystemChrome.setPreferredOrientations([
            DeviceOrientation.landscapeLeft,
          ]);
          break;
        default:
          _isMobilePlatform = false;
      }
    }
  }

  void _restoreOrientation() {
    // Restore original orientation when leaving the screen
    if (_isMobilePlatform) {
      SystemChrome.setPreferredOrientations([
        DeviceOrientation.portraitUp,
        DeviceOrientation.portraitDown,
        DeviceOrientation.landscapeLeft,
        DeviceOrientation.landscapeRight,
      ]);
    }
  }

  @override
  void dispose() {
    _controller.removeListener(_onSignatureChanged);
    _controller.dispose();
    _restoreOrientation();
    super.dispose();
  }

  String _buildSvgFromPoints(List<Point?> points, {double strokeWidth = 3.0, String strokeColor = '#000000'}) {
    // Convert collected signature points (with null separators for stroke breaks) into an SVG string
    // Determine bounds
    double? minX, minY, maxX, maxY;
    for (final p in points) {
      if (p == null) continue;
      final x = p.offset.dx;
      final y = p.offset.dy;
      if (minX == null || x < minX) minX = x;
      if (minY == null || y < minY) minY = y;
      if (maxX == null || x > maxX) maxX = x;
      if (maxY == null || y > maxY) maxY = y;
    }
    // Fallback bounds if empty or degenerate
    if (minX == null || minY == null || maxX == null || maxY == null) {
      minX = 0;
      minY = 0;
      maxX = 1;
      maxY = 1;
    }
    double width = (maxX - minX);
    double height = (maxY - minY);
    if (width <= 0) width = 1;
    if (height <= 0) height = 1;

    final StringBuffer d = StringBuffer();
    bool newStroke = true;
    for (final p in points) {
      if (p == null) {
        newStroke = true;
        continue;
      }
      final x = (p.offset.dx - minX);
      final y = (p.offset.dy - minY);
      if (newStroke) {
        d.write('M${x.toStringAsFixed(2)} ${y.toStringAsFixed(2)} ');
        newStroke = false;
      } else {
        d.write('L${x.toStringAsFixed(2)} ${y.toStringAsFixed(2)} ');
      }
    }

    final String svg = '<svg xmlns="http://www.w3.org/2000/svg" width="${width.toStringAsFixed(2)}" height="${height.toStringAsFixed(2)}" viewBox="0 0 ${width.toStringAsFixed(2)} ${height.toStringAsFixed(2)}"><path d="${d.toString().trim()}" fill="none" stroke="$strokeColor" stroke-width="$strokeWidth" stroke-linecap="round" stroke-linejoin="round"/></svg>';
    return svg;
  }

  Future<void> _finish() async {
    try {
      // Ensure there is at least one non-null point in the signature
      final hasAnyPoint = _controller.points.isNotEmpty;
      if (!hasAnyPoint) {
        if (!mounted) return;
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(AppLocalizations.of(context).signatureRequired)),
        );
        return;
      }

      // Build SVG from the captured signature points
      final String svg = _buildSvgFromPoints(_controller.points);

      // Close this screen first to show the updated TaskView quickly
      if (!mounted) return;
      _restoreOrientation();
      Navigator.of(context).pop();

      // Then notify the caller (SVG only)
      widget.onSignatureCompleted(svg);
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('${AppLocalizations.of(context).signatureError}: $e')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(AppLocalizations.of(context).signatureCapture),
        backgroundColor: Colors.deepPurple[100],
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () {
            _restoreOrientation();
            Navigator.of(context).pop();
          },
        ),
        actions: [
          IconButton(
            tooltip: AppLocalizations.of(context).delete,
            onPressed: () {
              _controller.clear();
              // The listener will automatically update _hasSignature when points are cleared
            },
            icon: const Icon(Icons.delete_outline),
          ),
        ],
      ),
      body: Column(
        children: [
          OfflineBanner(),
          Expanded(
            child: Padding(
              padding: const EdgeInsets.all(16.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
            Text(
              AppLocalizations.of(context).signatureInstruction,
              style: TextStyle(color: Colors.grey[700]),
            ),
            const SizedBox(height: 12),
            Expanded(
              child: Container(
                decoration: BoxDecoration(
                  color: Colors.white,
                  borderRadius: BorderRadius.circular(12),
                  border: Border.all(color: Colors.grey[400]!),
                  boxShadow: [
                    BoxShadow(
                      color: Colors.black.withValues(alpha: 0.05),
                      blurRadius: 6,
                      offset: const Offset(0, 2),
                    ),
                  ],
                ),
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(12),
                  child: Signature(
                    controller: _controller,
                    backgroundColor: Colors.white,
                  ),
                ),
              ),
            ),
            const SizedBox(height: 16),
            Row(
              children: [
                OutlinedButton.icon(
                  onPressed: () {
                    _controller.clear();
                    // The listener will automatically update _hasSignature when points are cleared
                  },
                  icon: const Icon(Icons.refresh),
                  label: Text(AppLocalizations.of(context).clear),
                ),
                const Spacer(),
                SizedBox(
                  width: 160,
                  child: ElevatedButton(
                    onPressed: _hasSignature ? _finish : null,
                    style: ElevatedButton.styleFrom(
                      padding: const EdgeInsets.symmetric(vertical: 14),
                    ),
                    child: Text(AppLocalizations.of(context).finish),
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
          ),
        ],
      ),
    );
  }
}