import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:file_picker/file_picker.dart';
import 'package:intl/intl.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/loading_button.dart';
import '../../core/api/api_client.dart';
import '../../shared/models/contract.dart';
import '../../shared/providers/lookup_providers.dart';
import 'contracts_provider.dart';

class ContractUploadScreen extends ConsumerStatefulWidget {
  const ContractUploadScreen({super.key});

  @override
  ConsumerState<ContractUploadScreen> createState() => _ContractUploadScreenState();
}

class _ContractUploadScreenState extends ConsumerState<ContractUploadScreen> {
  int _step = 0; // 0: upload, 1: analyzing, 2: fill form
  File? _file;
  ContractAnalysis? _analysis;
  bool _saving = false;

  final _titleCtrl = TextEditingController();
  DateTime? _periodStart;
  DateTime? _periodEnd;
  int? _companyId;
  int? _vendorId;
  final _formKey = GlobalKey<FormState>();

  @override
  void dispose() {
    _titleCtrl.dispose();
    super.dispose();
  }

  Future<void> _pickFile() async {
    final result = await FilePicker.platform.pickFiles(
      type: FileType.custom,
      allowedExtensions: ['pdf'],
    );
    if (result != null && result.files.single.path != null) {
      setState(() { _file = File(result.files.single.path!); });
    }
  }

  Future<void> _analyze() async {
    if (_file == null) return;
    setState(() => _step = 1);
    try {
      final analysis = await analyzePdf(_file!.path, _file!.path.split('/').last);
      _titleCtrl.text = analysis.title;
      if (analysis.periodStart != null) _periodStart = DateTime.tryParse(analysis.periodStart!);
      if (analysis.periodEnd != null)   _periodEnd   = DateTime.tryParse(analysis.periodEnd!);
      setState(() { _analysis = analysis; _step = 2; });
    } on ApiException catch (e) {
      setState(() => _step = 0);
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message), backgroundColor: AppColors.danger));
    } finally {
    }
  }

  Future<void> _save() async {
    if (!_formKey.currentState!.validate()) return;
    setState(() => _saving = true);
    try {
      final contract = await createContract({
        'title': _titleCtrl.text.trim(),
        'company_id': _companyId,
        'vendor_id': _vendorId,
        if (_periodStart != null) 'period_start': DateFormat('yyyy-MM-dd').format(_periodStart!),
        if (_periodEnd != null)   'period_end':   DateFormat('yyyy-MM-dd').format(_periodEnd!),
        if (_analysis != null) 'body': _analysis!.summary,
      });
      // Upload the PDF file
      if (_file != null) {
        await uploadContractFile(contract.id, _file!.path, _file!.path.split('/').last);
      }
      if (mounted) {
        context.pop();
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Contract saved successfully'), backgroundColor: AppColors.primary));
      }
    } on ApiException catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message), backgroundColor: AppColors.danger));
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  Future<void> _pickDate(bool isStart) async {
    final picked = await showDatePicker(
      context: context,
      initialDate: (isStart ? _periodStart : _periodEnd) ?? DateTime.now(),
      firstDate: DateTime(2000), lastDate: DateTime(2035),
    );
    if (picked != null) setState(() => isStart ? _periodStart = picked : _periodEnd = picked);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Upload Contract')),
      body: Column(
        children: [
          // Step indicator
          Padding(
            padding: const EdgeInsets.all(16),
            child: Row(
              children: List.generate(3, (i) {
                final done = i < _step;
                final active = i == _step;
                final labels = ['Upload PDF', 'AI Analysis', 'Fill Form'];
                return Expanded(child: Row(children: [
                  if (i > 0) Expanded(child: Container(height: 2,
                      color: done ? AppColors.primary : AppColors.border)),
                  Column(children: [
                    CircleAvatar(
                      radius: 14,
                      backgroundColor: active || done ? AppColors.primary : AppColors.border,
                      child: done
                          ? const Icon(Icons.check, size: 14, color: Colors.white)
                          : Text('${i + 1}', style: TextStyle(
                              color: active ? Colors.white : AppColors.textSub,
                              fontSize: 12, fontWeight: FontWeight.w700)),
                    ),
                    const SizedBox(height: 4),
                    Text(labels[i], style: TextStyle(
                        fontSize: 10,
                        color: active || done ? AppColors.primary : AppColors.textSub,
                        fontWeight: FontWeight.w600)),
                  ]),
                  if (i < 2) Expanded(child: Container(height: 2,
                      color: done ? AppColors.primary : AppColors.border)),
                ]));
              }),
            ),
          ),
          const Divider(height: 1),
          Expanded(child: _buildStep()),
        ],
      ),
    );
  }

  Widget _buildStep() {
    return switch (_step) {
      0 => _buildUploadStep(),
      1 => _buildAnalyzingStep(),
      2 => _buildFormStep(),
      _ => const SizedBox(),
    };
  }

  Widget _buildUploadStep() => Padding(
    padding: const EdgeInsets.all(24),
    child: Column(
      children: [
        GestureDetector(
          onTap: _pickFile,
          child: Container(
            width: double.infinity, height: 180,
            decoration: BoxDecoration(
              color: AppColors.primaryLight,
              borderRadius: BorderRadius.circular(12),
              border: Border.all(color: AppColors.primary, style: BorderStyle.solid, width: 2),
            ),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Icon(_file != null ? Icons.picture_as_pdf : Icons.upload_file,
                    size: 48, color: AppColors.primary),
                const SizedBox(height: 12),
                Text(
                  _file != null ? _file!.path.split('/').last : 'Tap to select PDF',
                  style: TextStyle(color: AppColors.primary,
                      fontWeight: FontWeight.w600, fontSize: _file != null ? 13 : 15),
                  textAlign: TextAlign.center,
                  maxLines: 2, overflow: TextOverflow.ellipsis,
                ),
                if (_file != null) ...[
                  const SizedBox(height: 6),
                  TextButton(onPressed: _pickFile, child: const Text('Change file')),
                ],
              ],
            ),
          ),
        ),
        const SizedBox(height: 32),
        LoadingButton(
          loading: false,
          label: 'Analisis dengan AI',
          onPressed: _file != null ? _analyze : null,
        ),
      ],
    ),
  );

  Widget _buildAnalyzingStep() => Center(
    child: Padding(
      padding: const EdgeInsets.all(32),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const CircularProgressIndicator(color: AppColors.primary, strokeWidth: 3),
          const SizedBox(height: 24),
          const Text('Analyzing contract with AI...', style: TextStyle(fontSize: 15, fontWeight: FontWeight.w600)),
          const SizedBox(height: 8),
          const Text('This may take 30–60 seconds for scanned documents',
              textAlign: TextAlign.center,
              style: TextStyle(fontSize: 13, color: AppColors.textSub)),
        ],
      ),
    ),
  );

  Widget _buildFormStep() {
    final companiesAsync = ref.watch(companiesProvider);
    final vendorsAsync = ref.watch(vendorsProvider);

    return Form(
      key: _formKey,
      child: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          if (_analysis != null)
            Container(
              padding: const EdgeInsets.all(12),
              margin: const EdgeInsets.only(bottom: 16),
              decoration: BoxDecoration(
                color: AppColors.primaryLight,
                borderRadius: BorderRadius.circular(10),
              ),
              child: Row(children: [
                const Icon(Icons.auto_awesome, color: AppColors.primary, size: 16),
                const SizedBox(width: 8),
                const Expanded(child: Text('Data has been auto-filled from AI analysis',
                    style: TextStyle(fontSize: 13, color: AppColors.primaryDark, fontWeight: FontWeight.w600))),
              ]),
            ),
          _label('Contract Title'),
          TextFormField(
            controller: _titleCtrl,
            decoration: const InputDecoration(hintText: 'Contract title'),
            validator: (v) => (v == null || v.isEmpty) ? 'Title is required' : null,
          ),
          const SizedBox(height: 16),

          _label('Company'),
          companiesAsync.when(
            loading: () => const LinearProgressIndicator(),
            error: (_, __) => const Text('Failed'),
            data: (list) => DropdownButtonFormField<int>(
              value: _companyId,
              decoration: const InputDecoration(hintText: 'Select company'),
              items: list.map((c) => DropdownMenuItem(value: c.id, child: Text(c.name))).toList(),
              onChanged: (v) => setState(() => _companyId = v),
            ),
          ),
          const SizedBox(height: 16),

          _label('Vendor (optional)'),
          vendorsAsync.when(
            loading: () => const LinearProgressIndicator(),
            error: (_, __) => const Text('Failed'),
            data: (list) => DropdownButtonFormField<int>(
              value: _vendorId,
              decoration: const InputDecoration(hintText: 'Select vendor'),
              items: [
                const DropdownMenuItem(value: null, child: Text('None')),
                ...list.map((v) => DropdownMenuItem(value: v.id, child: Text(v.name))),
              ],
              onChanged: (v) => setState(() => _vendorId = v),
            ),
          ),
          const SizedBox(height: 16),

          Row(children: [
            Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
              _label('Start Date'),
              _datePicker(_periodStart, () => _pickDate(true), 'Select date'),
            ])),
            const SizedBox(width: 12),
            Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
              _label('End Date'),
              _datePicker(_periodEnd, () => _pickDate(false), 'Select date'),
            ])),
          ]),
          const SizedBox(height: 32),
          LoadingButton(loading: _saving, label: 'Save Contract', onPressed: _save),
        ],
      ),
    );
  }

  Widget _datePicker(DateTime? date, VoidCallback onTap, String hint) => GestureDetector(
    onTap: onTap,
    child: Container(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 14),
      decoration: BoxDecoration(
        color: AppColors.surface, border: Border.all(color: AppColors.border),
        borderRadius: BorderRadius.circular(10),
      ),
      child: Text(
        date != null ? DateFormat('d MMM yyyy').format(date) : hint,
        style: TextStyle(fontSize: 13, color: date != null ? AppColors.text : AppColors.textSub),
      ),
    ),
  );

  Widget _label(String text) => Padding(
    padding: const EdgeInsets.only(bottom: 6),
    child: Text(text, style: const TextStyle(fontSize: 13, fontWeight: FontWeight.w600, color: AppColors.text)),
  );
}