import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../../models/profile.model.dart';
import '../../../models/programmer_day_sheet.model.dart';
import '../../../providers/profile_provider.dart';
import '../../../providers/programmer_day_sheets_provider.dart';
import '../../../providers/reports_provider.dart';
import '../../../theme/app_status_colors.dart';
import '../../../utils/app_time.dart';
import '../../../utils/programmer_task_ledger.dart';
import '../../../widgets/app_state_view.dart';
import '../../../widgets/app_status_summary.dart';
import '../../../widgets/tech_chip.dart';
import '../../reports/report_date_filter.dart';
import 'day_sheet_snapshot_builder.dart';
import '../report/accomplishment_report_dialog.dart';

/// Admin tab for reviewing and bulk-approving programmer day sheets.
///
/// Features:
/// * Status filter chips: Pending (default) / Awaiting justification / Approved.
/// * Programmer dropdown: All programmers or a specific person.
/// * Controlled date range filter (default: this month).
/// * Cards grouped by work-date; pending cards have selection checkboxes.
/// * "Approve selected (n)" button that calls [buildSnapshotForSheet] for each
///   selected sheet before calling the bulk-approve RPC.
class ApprovalsTab extends ConsumerStatefulWidget {
  const ApprovalsTab({super.key});

  @override
  ConsumerState<ApprovalsTab> createState() => _ApprovalsTabState();
}

class _ApprovalsTabState extends ConsumerState<ApprovalsTab> {
  /// Active status filter — one of the [DaySheetStatus] constants.
  String _filter = DaySheetStatus.pending;

  /// Selected programmer ID, or null for "all programmers".
  String? _programmerFilter;

  late ReportDateRange _dateRange;

  /// IDs of pending sheets selected for bulk approval.
  final Set<String> _selected = {};

  bool _approving = false;

  @override
  void initState() {
    super.initState();
    _dateRange = thisMonthRange(AppTime.now());
  }

  // ---------------------------------------------------------------------------
  // Helpers
  // ---------------------------------------------------------------------------

  bool _inDateRange(DateTime workDate) =>
      !workDate.isBefore(_dateRange.start) && workDate.isBefore(_dateRange.end);

  // ---------------------------------------------------------------------------
  // Actions
  // ---------------------------------------------------------------------------

  Future<void> _onApprove(List<ProgrammerDaySheet> allSheets) async {
    setState(() => _approving = true);
    try {
      final toApprove = allSheets
          .where((s) =>
              _selected.contains(s.id) &&
              s.status == DaySheetStatus.pending)
          .toList();

      final items = <({String sheetId, DaySheetSnapshot snapshot})>[];
      for (final sheet in toApprove) {
        final snapshot = await buildSnapshotForSheet(ref, sheet);
        items.add((sheetId: sheet.id, snapshot: snapshot));
      }

      final result = await ref.read(daySheetsControllerProvider).approve(items);

      if (!mounted) return;
      setState(() {
        _selected.clear();
        _approving = false;
      });

      final buf = StringBuffer('Approved ${result.approvedIds.length}');
      if (result.skippedIds.isNotEmpty) {
        buf.write(', ${result.skippedIds.length} already reviewed');
      }
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(buf.toString())));
    } on DaySheetActionException catch (e) {
      if (!mounted) return;
      setState(() => _approving = false);
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(e.message)));
    } catch (e) {
      if (!mounted) return;
      setState(() => _approving = false);
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(e.toString())));
    }
  }

  // ---------------------------------------------------------------------------
  // Build
  // ---------------------------------------------------------------------------

  @override
  Widget build(BuildContext context) {
    final allSheets = ref.watch(allDaySheetsProvider).valueOrNull ?? const [];
    final profiles = ref.watch(profilesProvider).valueOrNull ?? const [];

    final profileById = {for (final p in profiles) p.id: p};
    final programmerProfiles =
        profiles.where((p) => p.role == 'programmer').toList()
          ..sort((a, b) => a.fullName.compareTo(b.fullName));

    // Sheets passing the date + programmer filters (used for chip counts).
    final dateAndProgFiltered = allSheets.where((s) {
      return _inDateRange(s.workDate) &&
          (_programmerFilter == null || s.programmerId == _programmerFilter);
    }).toList();

    final counts = approvalCounts(dateAndProgFiltered);

    // Sheets also matching the status filter (displayed in the list).
    final filtered =
        dateAndProgFiltered.where((s) => s.status == _filter).toList();

    final grouped = groupSheetsByDate(filtered);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        // ── Status filter chips ────────────────────────────────────────────
        Padding(
          padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
          child: AppStatusSummaryRow(
            items: [
              AppStatusSummaryItem(
                label: 'Pending',
                count: counts.pending,
                kind: StatusKind.info,
                selected: _filter == DaySheetStatus.pending,
                onTap: () => setState(() {
                  _filter = DaySheetStatus.pending;
                  _selected.clear();
                }),
              ),
              AppStatusSummaryItem(
                label: 'Awaiting justification',
                count: counts.awaiting,
                kind: StatusKind.warning,
                selected: _filter == DaySheetStatus.disapproved,
                onTap: () => setState(() {
                  _filter = DaySheetStatus.disapproved;
                  _selected.clear();
                }),
              ),
              AppStatusSummaryItem(
                label: 'Approved',
                count: counts.approved,
                kind: StatusKind.success,
                selected: _filter == DaySheetStatus.approved,
                onTap: () => setState(() {
                  _filter = DaySheetStatus.approved;
                  _selected.clear();
                }),
              ),
            ],
          ),
        ),

        const SizedBox(height: 8),

        // ── Programmer dropdown + date filter ──────────────────────────────
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16),
          child: Row(
            children: [
              DropdownButton<String?>(
                value: _programmerFilter,
                hint: const Text('All programmers'),
                underline: const SizedBox.shrink(),
                items: [
                  const DropdownMenuItem<String?>(
                    value: null,
                    child: Text('All programmers'),
                  ),
                  for (final p in programmerProfiles)
                    DropdownMenuItem<String?>(
                      value: p.id,
                      child: Text(p.fullName),
                    ),
                ],
                onChanged: (v) => setState(() {
                  _programmerFilter = v;
                  _selected.clear();
                }),
              ),
              const SizedBox(width: 8),
              Expanded(
                child: ReportDateFilter.controlled(
                  value: _dateRange,
                  onChanged: (r) => setState(() {
                    _dateRange = r;
                    _selected.clear();
                  }),
                ),
              ),
              const SizedBox(width: 4),
              IconButton(
                icon: const Icon(Icons.description_outlined),
                tooltip: 'Accomplishment Report',
                onPressed: () => showAccomplishmentReportDialog(
                  context,
                  ref,
                  programmerId: _programmerFilter,
                ),
              ),
            ],
          ),
        ),

        const SizedBox(height: 8),

        // ── Card list ──────────────────────────────────────────────────────
        Expanded(
          child: filtered.isEmpty
              ? AppEmptyView(
                  icon: Icons.check_circle_outline,
                  title: _filter == DaySheetStatus.pending
                      ? 'No pending sheets'
                      : 'Nothing here',
                  subtitle: 'All caught up!',
                )
              : ListView.builder(
                  padding:
                      const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                  itemCount: grouped.length,
                  itemBuilder: (context, groupIdx) {
                    final dateKey = grouped.keys.elementAt(groupIdx);
                    final groupSheets = grouped[dateKey]!;
                    return Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Padding(
                          padding: const EdgeInsets.only(top: 8, bottom: 4),
                          child: Text(
                            AppTime.formatDate(dateKey),
                            style: Theme.of(context)
                                .textTheme
                                .labelMedium
                                ?.copyWith(
                                  color: Theme.of(context)
                                      .colorScheme
                                      .onSurfaceVariant,
                                ),
                          ),
                        ),
                        for (final sheet in groupSheets)
                          _SheetApprovalCard(
                            sheet: sheet,
                            profile: profileById[sheet.programmerId],
                            showCheckbox: _filter == DaySheetStatus.pending,
                            selected: _selected.contains(sheet.id),
                            totalSecs: sheet.approvedSnapshot?.totalSeconds,
                            taskCount: sheet.approvedSnapshot?.rows.length,
                            onToggle: _filter == DaySheetStatus.pending
                                ? (v) => setState(() {
                                      if (v == true) {
                                        _selected.add(sheet.id);
                                      } else {
                                        _selected.remove(sheet.id);
                                      }
                                    })
                                : null,
                            onTap: () => context.pushNamed(
                              'daySheetDetail',
                              pathParameters: {'id': sheet.id},
                            ),
                          ),
                      ],
                    );
                  },
                ),
        ),

        // ── Approve button ─────────────────────────────────────────────────
        if (_selected.isNotEmpty)
          SafeArea(
            top: false,
            child: Padding(
              padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
              child: FilledButton(
                onPressed: _approving ? null : () => _onApprove(allSheets),
                child: _approving
                    ? const SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : Text('Approve selected (${_selected.length})'),
              ),
            ),
          ),
      ],
    );
  }
}

// ---------------------------------------------------------------------------
// Card widget
// ---------------------------------------------------------------------------

class _SheetApprovalCard extends StatelessWidget {
  const _SheetApprovalCard({
    required this.sheet,
    required this.profile,
    required this.showCheckbox,
    required this.selected,
    required this.onToggle,
    required this.onTap,
    this.totalSecs,
    this.taskCount,
  });

  final ProgrammerDaySheet sheet;
  final Profile? profile;
  final bool showCheckbox;
  final bool selected;
  final ValueChanged<bool?>? onToggle;
  final VoidCallback onTap;
  /// Null when no approved snapshot exists yet (pending/disapproved sheets).
  final int? totalSecs;
  final int? taskCount;

  @override
  Widget build(BuildContext context) {
    final roundNum = sheet.resubmissions + 1;

    return Card(
      margin: const EdgeInsets.only(bottom: 8),
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(12),
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.center,
            children: [
              if (showCheckbox && onToggle != null) ...[
                Checkbox(value: selected, onChanged: onToggle),
                const SizedBox(width: 4),
              ],
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      profile?.fullName ?? sheet.programmerId,
                      style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                            fontWeight: FontWeight.w600,
                          ),
                    ),
                    const SizedBox(height: 6),
                    Wrap(
                      spacing: 6,
                      runSpacing: 4,
                      children: [
                        TechChip(
                          totalSecs != null
                              ? formatDurationHm(Duration(seconds: totalSecs!))
                              : '—',
                        ),
                        TechChip(
                          taskCount != null ? '$taskCount tasks' : '—',
                        ),
                        if (sheet.autoSubmitted)
                          const TechChip('Auto', status: StatusKind.info)
                        else
                          const TechChip('Early', status: StatusKind.neutral),
                        if (roundNum > 1)
                          TechChip(
                            'Round $roundNum',
                            status: StatusKind.warning,
                          ),
                      ],
                    ),
                  ],
                ),
              ),
              Icon(
                Icons.chevron_right,
                color: Theme.of(context).colorScheme.onSurfaceVariant,
              ),
            ],
          ),
        ),
      ),
    );
  }
}