import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart' show rootBundle;
import 'package:intl/intl.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:pdf/pdf.dart' as pdf;
import 'package:printing/printing.dart';
import 'package:pdfrx/pdfrx.dart';

// ─── DTOs ─────────────────────────────────────────────────────────────────

class DtrEntry {
  const DtrEntry({
    required this.date,
    required this.shiftLabel,
    required this.checkInAt,
    this.checkOutAt,
    required this.checkIn,
    required this.checkOut,
    required this.duration,
    required this.isAbsent,
    required this.isLeave,
    required this.isLate,
    this.leaveType,
    this.justification,
    this.passSlips = const [],
  });

  final DateTime date;
  final String shiftLabel;
  final DateTime checkInAt;
  final DateTime? checkOutAt;
  final String checkIn;
  final String checkOut;
  final String duration;
  final bool isAbsent;
  final bool isLeave;
  final bool isLate;
  final String? leaveType;
  final String? justification;
  final List<DtrPassSlipEntry> passSlips;
}

class DtrPassSlipEntry {
  const DtrPassSlipEntry({
    required this.reason,
    required this.timeRange,
    required this.status,
  });

  final String reason;
  final String timeRange;
  final String status;
}

// ─── Public entry points ──────────────────────────────────────────────────

void showDtrPdfDialog(
  BuildContext context, {
  required String employeeName,
  required String role,
  required DateTimeRange period,
  required List<DtrEntry> entries,
}) {
  showDialog(
    context: context,
    builder: (_) => _DtrPdfDialog(
      title: 'DTR – $employeeName',
      filename: 'DTR - $employeeName.pdf',
      buildBytes: () => _buildPdf([(employeeName, role, entries)], period),
    ),
  );
}

void showDtrPdfDialogMulti(
  BuildContext context, {
  required List<(String, String, List<DtrEntry>)> users,
  required DateTimeRange period,
}) {
  showDialog(
    context: context,
    builder: (_) => _DtrPdfDialog(
      title: 'DTR Export (${users.length} employees)',
      filename: 'DTR Export.pdf',
      buildBytes: () => _buildPdf(users, period),
    ),
  );
}

Future<Uint8List> buildDtrPdfBytes({
  required String employeeName,
  required String role,
  required DateTimeRange period,
  required List<DtrEntry> entries,
}) =>
    _buildPdf([(employeeName, role, entries)], period);

// ─── PDF builder ──────────────────────────────────────────────────────────

Future<Uint8List> _buildPdf(
  List<(String, String, List<DtrEntry>)> users,
  DateTimeRange period,
) async {
  final logoData = await rootBundle.load('assets/crmc_logo.png');
  final logoImage = pw.MemoryImage(logoData.buffer.asUint8List());

  final regular = pw.Font.ttf(
    await rootBundle.load('assets/fonts/Roboto-Regular.ttf'),
  );
  final bold = pw.Font.ttf(
    await rootBundle.load('assets/fonts/Roboto-Bold.ttf'),
  );

  final doc = pw.Document();

  for (final (name, role, entries) in users) {
    // Sort ascending (oldest first) for a chronological time record.
    final sorted = [...entries]..sort((a, b) => a.date.compareTo(b.date));

    doc.addPage(
      pw.MultiPage(
        pageFormat: pdf.PdfPageFormat.a4,
        margin: const pw.EdgeInsets.all(32),
        theme: pw.ThemeData.withFont(base: regular, bold: bold),
        footer: (ctx) => pw.Align(
          alignment: pw.Alignment.centerRight,
          child: pw.Text(
            'Page ${ctx.pageNumber} of ${ctx.pagesCount}',
            style: pw.TextStyle(
              font: regular,
              fontSize: 8,
              color: pdf.PdfColors.grey600,
            ),
          ),
        ),
        build: (ctx) => [
          _header(logoImage, regular, bold),
          pw.SizedBox(height: 8),
          pw.Center(
            child: pw.Text(
              'DAILY TIME RECORD (DTR)',
              style: pw.TextStyle(font: bold, fontSize: 14, letterSpacing: 1.5),
            ),
          ),
          pw.SizedBox(height: 10),
          _employeeInfo(name, role, period, regular, bold),
          pw.SizedBox(height: 10),
          _attendanceTable(sorted, regular, bold),
          if (sorted.any((e) => e.passSlips.isNotEmpty)) ...[
            pw.SizedBox(height: 8),
            _passSlipsSection(sorted, regular, bold),
          ],
          pw.SizedBox(height: 10),
          _summary(sorted, regular, bold),
        ],
      ),
    );
  }

  return doc.save();
}

// ─── Section builders ─────────────────────────────────────────────────────

pw.Widget _header(
  pw.ImageProvider logo,
  pw.Font regular,
  pw.Font bold,
) {
  return pw.Row(
    mainAxisAlignment: pw.MainAxisAlignment.center,
    crossAxisAlignment: pw.CrossAxisAlignment.center,
    children: [
      pw.Image(logo, width: 60, height: 60),
      pw.SizedBox(width: 16),
      pw.Column(
        crossAxisAlignment: pw.CrossAxisAlignment.center,
        children: [
          pw.Text(
            'Republic of the Philippines',
            style: pw.TextStyle(font: regular, fontSize: 9),
          ),
          pw.Text(
            'Department of Health',
            style: pw.TextStyle(font: regular, fontSize: 9),
          ),
          pw.Text(
            'Cotabato Regional and Medical Center',
            style: pw.TextStyle(font: regular, fontSize: 9),
          ),
          pw.SizedBox(height: 3),
          pw.Text(
            'Integrated Hospital Operations and Management Program (IHOMP)',
            style: pw.TextStyle(font: bold, fontSize: 9),
          ),
        ],
      ),
    ],
  );
}

pw.Widget _employeeInfo(
  String name,
  String role,
  DateTimeRange period,
  pw.Font regular,
  pw.Font bold,
) {
  final fmt = DateFormat('MMMM d, yyyy');
  final periodStr = '${fmt.format(period.start)} – ${fmt.format(period.end)}';

  pw.Widget infoRow(String label, String value) => pw.RichText(
        text: pw.TextSpan(
          children: [
            pw.TextSpan(
              text: '$label  ',
              style: pw.TextStyle(font: bold, fontSize: 9),
            ),
            pw.TextSpan(
              text: value,
              style: pw.TextStyle(font: regular, fontSize: 9),
            ),
          ],
        ),
      );

  return pw.Container(
    decoration: pw.BoxDecoration(
      border: pw.Border.all(width: 0.8, color: pdf.PdfColors.grey400),
    ),
    padding: const pw.EdgeInsets.symmetric(horizontal: 10, vertical: 6),
    child: pw.Row(
      children: [
        pw.Expanded(
          child: pw.Column(
            crossAxisAlignment: pw.CrossAxisAlignment.start,
            children: [
              infoRow('Name:', name),
              pw.SizedBox(height: 3),
              infoRow('Position:', _roleLabel(role)),
            ],
          ),
        ),
        pw.Expanded(
          child: infoRow('Period:', periodStr),
        ),
      ],
    ),
  );
}

pw.Widget _attendanceTable(
  List<DtrEntry> entries,
  pw.Font regular,
  pw.Font bold,
) {
  final dayFmt = DateFormat('EEE');
  final dateFmt = DateFormat('MMM d');

  pw.Widget th(String text) => pw.Padding(
        padding: const pw.EdgeInsets.symmetric(horizontal: 4, vertical: 4),
        child: pw.Text(
          text,
          style: pw.TextStyle(font: bold, fontSize: 8),
        ),
      );

  pw.Widget td(String text) => pw.Padding(
        padding: const pw.EdgeInsets.symmetric(horizontal: 4, vertical: 3),
        child: pw.Text(
          text,
          style: pw.TextStyle(font: regular, fontSize: 8),
        ),
      );

  String statusText(DtrEntry e) {
    if (e.isAbsent) return 'Absent';
    if (e.isLeave) return _leaveTypeLabel(e.leaveType);
    if (e.isLate) return 'Late';
    if (e.shiftLabel == 'Overtime') return 'Overtime';
    if (e.duration == 'On duty') return 'Active';
    return 'Present';
  }

  pdf.PdfColor? rowColor(DtrEntry e) {
    if (e.isAbsent) return pdf.PdfColor.fromHex('#FFEBEE');
    if (e.isLeave) return pdf.PdfColor.fromHex('#E3F2FD');
    if (e.shiftLabel == 'Overtime') return pdf.PdfColor.fromHex('#FFF8E1');
    if (e.isLate) return pdf.PdfColor.fromHex('#FFF3E0');
    return null;
  }

  return pw.Table(
    border: pw.TableBorder.all(width: 0.5, color: pdf.PdfColors.grey400),
    columnWidths: const {
      0: pw.FixedColumnWidth(56),
      1: pw.FixedColumnWidth(28),
      2: pw.FixedColumnWidth(72),
      3: pw.FixedColumnWidth(60),
      4: pw.FixedColumnWidth(60),
      5: pw.FixedColumnWidth(50),
      6: pw.FlexColumnWidth(),
    },
    children: [
      pw.TableRow(
        decoration: const pw.BoxDecoration(color: pdf.PdfColors.grey200),
        children: [
          th('Date'),
          th('Day'),
          th('Shift'),
          th('Check-In'),
          th('Check-Out'),
          th('Hours'),
          th('Remarks'),
        ],
      ),
      for (final e in entries)
        pw.TableRow(
          decoration: pw.BoxDecoration(color: rowColor(e)),
          children: [
            td(dateFmt.format(e.date)),
            td(dayFmt.format(e.date)),
            td(e.shiftLabel),
            td(e.checkIn),
            td(e.checkOut),
            td(e.duration),
            td(statusText(e)),
          ],
        ),
    ],
  );
}

pw.Widget _passSlipsSection(
  List<DtrEntry> entries,
  pw.Font regular,
  pw.Font bold,
) {
  final dateFmt = DateFormat('MMM d (EEE)');
  final slips = <(String, DtrPassSlipEntry)>[];
  for (final e in entries) {
    for (final s in e.passSlips) {
      slips.add((dateFmt.format(e.date), s));
    }
  }

  pw.Widget th(String text) => pw.Padding(
        padding: const pw.EdgeInsets.symmetric(horizontal: 4, vertical: 3),
        child: pw.Text(text, style: pw.TextStyle(font: bold, fontSize: 8)),
      );

  pw.Widget td(String text) => pw.Padding(
        padding: const pw.EdgeInsets.symmetric(horizontal: 4, vertical: 2),
        child: pw.Text(text, style: pw.TextStyle(font: regular, fontSize: 7.5)),
      );

  return pw.Column(
    crossAxisAlignment: pw.CrossAxisAlignment.start,
    children: [
      pw.Text(
        'Pass Slips',
        style: pw.TextStyle(font: bold, fontSize: 9, letterSpacing: 0.5),
      ),
      pw.SizedBox(height: 4),
      pw.Table(
        border: pw.TableBorder.all(width: 0.5, color: pdf.PdfColors.grey400),
        columnWidths: const {
          0: pw.FixedColumnWidth(88),
          1: pw.FixedColumnWidth(88),
          2: pw.FlexColumnWidth(),
          3: pw.FixedColumnWidth(60),
        },
        children: [
          pw.TableRow(
            decoration: const pw.BoxDecoration(color: pdf.PdfColors.grey200),
            children: [
              th('Date'),
              th('Time Range'),
              th('Reason'),
              th('Status'),
            ],
          ),
          for (final (date, slip) in slips)
            pw.TableRow(
              children: [
                td(date),
                td(slip.timeRange),
                td(slip.reason),
                td(slip.status),
              ],
            ),
        ],
      ),
    ],
  );
}

pw.Widget _summary(List<DtrEntry> entries, pw.Font regular, pw.Font bold) {
  final present = entries.where((e) => !e.isAbsent && !e.isLeave).length;
  final absent = entries.where((e) => e.isAbsent).length;
  final lates = entries.where((e) => e.isLate).length;
  final leaves = entries.where((e) => e.isLeave).toList();

  final leaveByType = <String, int>{};
  for (final l in leaves) {
    final label = _leaveTypeLabel(l.leaveType);
    leaveByType[label] = (leaveByType[label] ?? 0) + 1;
  }
  final leaveSummary = leaveByType.isEmpty
      ? '${leaves.length} day(s)'
      : leaveByType.entries.map((e) => '${e.key}: ${e.value}').join(', ');

  final otEntries =
      entries.where((e) => e.shiftLabel == 'Overtime' && e.checkOutAt != null);
  final otMinutes = otEntries.fold<int>(
    0,
    (sum, e) => sum + e.checkOutAt!.difference(e.checkInAt).inMinutes,
  );
  final otStr =
      otMinutes == 0 ? 'None' : '${otMinutes ~/ 60}h ${otMinutes % 60}m';
  final passSlipTotal =
      entries.fold<int>(0, (s, e) => s + e.passSlips.length);

  pw.Widget cell(String label, String value) => pw.Expanded(
        child: pw.Column(
          crossAxisAlignment: pw.CrossAxisAlignment.start,
          children: [
            pw.Text(label, style: pw.TextStyle(font: bold, fontSize: 8)),
            pw.SizedBox(height: 2),
            pw.Text(value, style: pw.TextStyle(font: regular, fontSize: 9)),
          ],
        ),
      );

  return pw.Container(
    decoration: pw.BoxDecoration(
      border: pw.Border.all(width: 0.8, color: pdf.PdfColors.grey400),
      color: pdf.PdfColors.grey100,
    ),
    padding: const pw.EdgeInsets.all(8),
    child: pw.Column(
      crossAxisAlignment: pw.CrossAxisAlignment.start,
      children: [
        pw.Text(
          'SUMMARY',
          style: pw.TextStyle(font: bold, fontSize: 9, letterSpacing: 1),
        ),
        pw.SizedBox(height: 6),
        pw.Row(
          children: [
            cell('Days Present', '$present'),
            cell('Absences', '$absent'),
            cell('Lates', '$lates'),
            cell('Overtime', otStr),
          ],
        ),
        pw.SizedBox(height: 4),
        pw.Row(
          children: [
            cell('Leaves', leaveSummary),
            cell('Pass Slips', '$passSlipTotal'),
            pw.Expanded(child: pw.SizedBox()),
            pw.Expanded(child: pw.SizedBox()),
          ],
        ),
      ],
    ),
  );
}

// ─── Helpers ──────────────────────────────────────────────────────────────

String _roleLabel(String role) {
  switch (role) {
    case 'admin':
      return 'Administrator';
    case 'dispatcher':
      return 'Dispatcher';
    case 'programmer':
      return 'Programmer';
    case 'it_staff':
      return 'IT Staff';
    default:
      return role.isEmpty ? 'Staff' : role;
  }
}

String _leaveTypeLabel(String? leaveType) {
  switch (leaveType) {
    case 'sick_leave':
      return 'Sick Leave';
    case 'vacation_leave':
      return 'Vacation Leave';
    case 'emergency_leave':
      return 'Emergency Leave';
    case 'parental_leave':
      return 'Parental Leave';
    default:
      return 'On Leave';
  }
}

// ─── Dialog ───────────────────────────────────────────────────────────────

class _DtrPdfDialog extends StatefulWidget {
  const _DtrPdfDialog({
    required this.title,
    required this.filename,
    required this.buildBytes,
  });

  final String title;
  final String filename;
  final Future<Uint8List> Function() buildBytes;

  @override
  State<_DtrPdfDialog> createState() => _DtrPdfDialogState();
}

class _DtrPdfDialogState extends State<_DtrPdfDialog> {
  late final Future<Uint8List> _future;

  @override
  void initState() {
    super.initState();
    _future = widget.buildBytes();
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      contentPadding: EdgeInsets.zero,
      content: SizedBox(
        width: 800,
        height: 900,
        child: Column(
          children: [
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
              child: Row(
                children: [
                  Expanded(
                    child: Text(
                      widget.title,
                      style: const TextStyle(
                        fontSize: 16,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ),
                  IconButton(
                    tooltip: 'Print',
                    icon: const Icon(Icons.print),
                    onPressed: () async {
                      final bytes = await _future;
                      await Printing.layoutPdf(
                        onLayout: (_) async => bytes,
                        name: widget.filename,
                      );
                    },
                  ),
                  IconButton(
                    tooltip: 'Download',
                    icon: const Icon(Icons.download),
                    onPressed: () async {
                      final bytes = await _future;
                      await Printing.sharePdf(
                        bytes: bytes,
                        filename: widget.filename,
                      );
                    },
                  ),
                  IconButton(
                    tooltip: 'Close',
                    icon: const Icon(Icons.close),
                    onPressed: () => Navigator.of(context).pop(),
                  ),
                ],
              ),
            ),
            const Divider(height: 1),
            Expanded(
              child: FutureBuilder<Uint8List>(
                future: _future,
                builder: (context, snapshot) {
                  if (snapshot.connectionState == ConnectionState.waiting) {
                    return const Center(child: CircularProgressIndicator());
                  }
                  if (snapshot.hasError) {
                    return Center(child: Text(snapshot.error.toString()));
                  }
                  final data = snapshot.data;
                  if (data == null) return const SizedBox.shrink();
                  return PdfViewer.data(data, sourceName: 'dtr.pdf');
                },
              ),
            ),
          ],
        ),
      ),
    );
  }
}