import 'dart:io';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../services/app_state.dart';

/// Full-screen, pinch-zoomable view of a receipt photo. Pass
/// [localImagePath] for a receipt still held locally, or [driveFileId] for
/// one already uploaded to the cloud and removed locally — in which case
/// it's downloaded on demand (no local caching afterward).
class ReceiptImageScreen extends StatefulWidget {
  final String? localImagePath;
  final String? driveFileId;

  const ReceiptImageScreen({super.key, this.localImagePath, this.driveFileId})
      : assert(localImagePath != null || driveFileId != null,
            'Must provide either a local path or a Drive file ID');

  @override
  State<ReceiptImageScreen> createState() => _ReceiptImageScreenState();
}

class _ReceiptImageScreenState extends State<ReceiptImageScreen> {
  Uint8List? _downloadedBytes;
  bool _loading = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    if (widget.driveFileId != null) {
      _download();
    }
  }

  Future<void> _download() async {
    setState(() {
      _loading = true;
      _error = null;
    });

    final provider = context.read<AppState>().activeProvider;
    if (provider == null) {
      setState(() {
        _error = 'Not connected to a cloud storage provider.';
        _loading = false;
      });
      return;
    }

    final session = provider.beginSession();
    try {
      final bytes = await session.downloadFileBytes(widget.driveFileId!);
      if (!mounted) return;
      setState(() {
        _downloadedBytes = Uint8List.fromList(bytes);
        _loading = false;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _error = 'Could not download receipt: $e';
        _loading = false;
      });
    } finally {
      session.close();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      appBar: AppBar(
        backgroundColor: Colors.black,
        foregroundColor: Colors.white,
        title: const Text('Receipt'),
      ),
      body: Center(child: _buildBody()),
    );
  }

  Widget _buildBody() {
    if (widget.localImagePath != null) {
      return InteractiveViewer(child: Image.file(File(widget.localImagePath!)));
    }
    if (_loading) {
      return const CircularProgressIndicator(color: Colors.white);
    }
    if (_error != null) {
      return Padding(
        padding: const EdgeInsets.all(24),
        child: Text(_error!, style: const TextStyle(color: Colors.white)),
      );
    }
    if (_downloadedBytes != null) {
      return InteractiveViewer(child: Image.memory(_downloadedBytes!));
    }
    return const SizedBox.shrink();
  }
}