import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:intl/intl.dart';
import 'package:path_provider/path_provider.dart';
import 'package:open_filex/open_filex.dart';
import 'package:universal_html/html.dart' as html;

import '../models/user_profile.dart';
import '../models/cycle_entry.dart';
import '../theme/app_theme.dart';

class PdfService {
  static Future<void> generateCycleReport(UserProfile user, List<CycleEntry> entries) async {
    final pdf = pw.Document();

    final primaryColor = PdfColor.fromInt(AppColors.sageGreen.value);
    final accentColor = PdfColor.fromInt(AppColors.rose.value);
    final textColor = PdfColor.fromInt(AppColors.charcoal.value);

    // Sort entries by date for the report
    entries.sort((a, b) => a.date.compareTo(b.date));

    pdf.addPage(
      pw.MultiPage(
        pageFormat: PdfPageFormat.a4,
        build: (pw.Context context) => [
          _buildHeader(user, primaryColor, accentColor, textColor),
          pw.SizedBox(height: 20),
          _buildCycleSummary(user, textColor),
          pw.SizedBox(height: 20),
          _buildEntriesTable(entries, primaryColor, textColor),
        ],
      ),
    );

    final String fileName = 'cycle_report_${DateFormat('yyyyMMdd').format(DateTime.now())}.pdf';

    if (kIsWeb) {
      // Web platform
      final bytes = await pdf.save();
      final blob = html.Blob([bytes], 'application/pdf');
      final url = html.Url.createObjectUrlFromBlob(blob);
      html.AnchorElement(href: url)
        ..setAttribute('download', fileName)
        ..click();
      html.Url.revokeObjectUrl(url);
    } else {
      // Mobile platform
      final directory = await getApplicationDocumentsDirectory();
      final filePath = '${directory.path}/$fileName';
      final file = File(filePath);
      await file.writeAsBytes(await pdf.save());
      await OpenFilex.open(filePath);
    }
  }

  static pw.Widget _buildHeader(UserProfile user, PdfColor primaryColor, PdfColor accentColor, PdfColor textColor) {
    return pw.Container(
      padding: pw.EdgeInsets.all(10),
      decoration: pw.BoxDecoration(
        color: primaryColor.lighter(30),
        borderRadius: pw.BorderRadius.circular(8),
      ),
      child: pw.Column(
        crossAxisAlignment: pw.CrossAxisAlignment.start,
        children: [
          pw.Text(
            'Cycle Report for ${user.name}',
            style: pw.TextStyle(
              fontSize: 24,
              fontWeight: pw.FontWeight.bold,
              color: primaryColor.isLight ? primaryColor.darker(50) : PdfColors.white,
            ),
          ),
          pw.SizedBox(height: 5),
          pw.Text(
            'Generated on: ${DateFormat('MMMM d, yyyy').format(DateTime.now())}',
            style: pw.TextStyle(fontSize: 12, color: primaryColor.isLight ? primaryColor.darker(30) : PdfColors.white.darker(10)),
          ),
        ],
      ),
    );
  }

  static pw.Widget _buildCycleSummary(UserProfile user, PdfColor textColor) {
    return pw.Column(
      crossAxisAlignment: pw.CrossAxisAlignment.start,
      children: [
        pw.Text(
          'Summary',
          style: pw.TextStyle(fontSize: 18, fontWeight: pw.FontWeight.bold, color: textColor),
        ),
        pw.SizedBox(height: 10),
        pw.Text('Average Cycle Length: ${user.averageCycleLength} days', style: pw.TextStyle(color: textColor)),
        pw.Text('Average Period Length: ${user.averagePeriodLength} days', style: pw.TextStyle(color: textColor)),
        if (user.lastPeriodStartDate != null)
          pw.Text('Last Period Start: ${DateFormat.yMMMMd().format(user.lastPeriodStartDate!)}', style: pw.TextStyle(color: textColor)),
        pw.Text('Irregular Cycle: ${user.isIrregularCycle ? 'Yes' : 'No'}', style: pw.TextStyle(color: textColor)),
      ],
    );
  }

  static pw.Widget _buildEntriesTable(List<CycleEntry> entries, PdfColor primaryColor, PdfColor textColor) {
    final headers = ['Date', 'Period', 'Mood', 'Symptoms', 'Notes'];

    return pw.Table.fromTextArray(
      headers: headers,
      data: entries.map((entry) {
        return [
          DateFormat.yMMMd().format(entry.date),
          entry.isPeriodDay ? 'Yes' : 'No',
          entry.mood != null ? entry.mood!.label : 'N/A',
          entry.hasSymptoms ? entry.symptomCount.toString() : 'No',
          entry.notes != null && entry.notes!.isNotEmpty ? entry.notes! : 'N/A',
        ];
      }).toList(),
      border: pw.TableBorder.all(color: primaryColor.lighter(10)),
      headerStyle: pw.TextStyle(fontWeight: pw.FontWeight.bold, color: primaryColor),
      cellStyle: pw.TextStyle(color: textColor),
      cellAlignment: pw.Alignment.centerLeft,
      headerDecoration: pw.BoxDecoration(color: primaryColor.lighter(20)),
      rowDecoration: pw.BoxDecoration(color: PdfColors.grey100),
      tableWidth: pw.TableWidth.min,
    );
  }
}

// Extension to determine if a color is light or dark for text contrast
extension on PdfColor {
  bool get isLight {
    // Calculate luminance (Y from YIQ)
    // Formula: Y = (R*299 + G*587 + B*114) / 1000
    final r = red * 255;
    final g = green * 255;
    final b = blue * 255;
    final luminance = (r * 299 + g * 587 + b * 114) / 1000;
    return luminance > 128; // Using 128 as a threshold
  }
  
  PdfColor lighter(int amount) {
    double factor = 1 + (amount / 100.0);
    return PdfColor(
      red * factor > 1.0 ? 1.0 : red * factor,
      green * factor > 1.0 ? 1.0 : green * factor,
      blue * factor > 1.0 ? 1.0 : blue * factor,
    );
  }

  PdfColor darker(int amount) {
    double factor = 1 - (amount / 100.0);
    return PdfColor(
      red * factor < 0.0 ? 0.0 : red * factor,
      green * factor < 0.0 ? 0.0 : green * factor,
      blue * factor < 0.0 ? 0.0 : blue * factor,
    );
  }
}