import 'dart:async';

import 'package:flutter/material.dart';

import '../data/error_presentation.dart';
import '../data/friendly_error.dart';
import '../data/hub.dart';
import '../data/workspace.dart';
import '../l10n/app_localizations.dart';
import '../main.dart' show StudioShellState;
import '../theme/tokens.dart';
import '../widgets/widgets.dart';
import 'welcome.dart' show showFaiDoc;

/// Detached-runs monitor (T3 parity): the invocations submitted with
/// `detach: true`, with a cancel button while they are still running.
/// Workspace-scoped like Audit and Approvals. Detached invocations are
/// opt-in (`detached.enabled`), so an empty list is the normal case
/// for most operators — the empty state says so plainly.
class RunsPage extends StatefulWidget {
  const RunsPage({super.key});

  @override
  State<RunsPage> createState() => _RunsPageState();
}

/// Why the runs monitor could not load its list. The page used to
/// fold every failure into "hub not reachable", which contradicted
/// the sidebar's green "connected" dot whenever the hub answered
/// with an RPC-level error (usertest finding: a 0.21 hub without
/// the ListInvocations RPC). Top-level so the unit test drives the
/// classification directly.
enum RunsLoadIssue {
  /// The hub itself cannot be reached (socket-level failure or
  /// gRPC UNAVAILABLE / DEADLINE_EXCEEDED).
  unreachable,

  /// The hub answered, but its version predates the
  /// ListInvocations RPC (gRPC UNIMPLEMENTED) — connected, just
  /// too old for this view.
  unsupported,

  /// The hub answered and refused because detached invocations
  /// are switched off (gRPC FAILED_PRECONDITION from the detached
  /// gate) — show the regular feature-off empty state, not a
  /// connection error.
  featureDisabled,

  /// Anything else — show the friendly error with copyable detail.
  other,
}

/// Classify a [HubService.listDetachedRuns] failure into the view
/// state the page should render.
RunsLoadIssue classifyRunsLoadError(Object error) {
  switch (grpcCodeOf(error)) {
    case 12: // UNIMPLEMENTED — hub predates the RPC
      return RunsLoadIssue.unsupported;
    case 9: // FAILED_PRECONDITION — the hub's detached gate
      final msg = (grpcMessageOf(error) ?? '').toLowerCase();
      return msg.contains('detached')
          ? RunsLoadIssue.featureDisabled
          : RunsLoadIssue.other;
    case 4: // DEADLINE_EXCEEDED
    case 14: // UNAVAILABLE
      return RunsLoadIssue.unreachable;
  }
  // Non-gRPC failures: only clear socket-level shapes count as
  // "unreachable"; everything else keeps its real story.
  final s = error.toString().toLowerCase();
  if (s.contains('socketexception') ||
      s.contains('connection refused') ||
      s.contains('connection terminated') ||
      s.contains('failed to connect')) {
    return RunsLoadIssue.unreachable;
  }
  return RunsLoadIssue.other;
}

/// The error rendition of the runs monitor — public + callback-driven
/// so the widget test can pump each variant without a live hub.
class RunsLoadErrorView extends StatelessWidget {
  final Object error;
  final RunsLoadIssue issue;

  /// Opens the runs guide (the feature-off empty state's CTA).
  final VoidCallback onOpenGuide;

  /// Opens the doctor page (the "hub too old" state's CTA, where
  /// the update banner lives). Null hides the button.
  final VoidCallback? onOpenDoctor;

  const RunsLoadErrorView({
    super.key,
    required this.error,
    required this.issue,
    required this.onOpenGuide,
    this.onOpenDoctor,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    switch (issue) {
      case RunsLoadIssue.featureDisabled:
        // Same story as the regular feature-off empty state: the
        // hub is fine, the operator just has not enabled the
        // feature — never claim "not reachable" here.
        return ChainEmptyState(
          icon: Icons.rocket_launch_outlined,
          title: l.runsEmptyTitle,
          hint: l.runsEmptyHint,
          action: OutlinedButton.icon(
            icon: const Icon(Icons.menu_book_outlined, size: 16),
            label: Text(l.runsEmptyGuideButton),
            onPressed: onOpenGuide,
          ),
        );
      case RunsLoadIssue.unsupported:
        return ChainEmptyState(
          icon: Icons.system_update_alt_outlined,
          title: l.runsHubTooOldTitle,
          hint: l.runsHubTooOldHint,
          action: onOpenDoctor == null
              ? null
              : OutlinedButton.icon(
                  icon: const Icon(Icons.health_and_safety_outlined, size: 16),
                  label: Text(l.runsHubTooOldButton),
                  onPressed: onOpenDoctor,
                ),
        );
      case RunsLoadIssue.unreachable:
        return ChainEmptyState(
          icon: Icons.cloud_off_outlined,
          iconColor: theme.colorScheme.error,
          title: l.hubUnreachable,
          hint: l.hubUnreachableHint,
        );
      case RunsLoadIssue.other:
        return ChainEmptyState(
          icon: Icons.error_outline,
          iconColor: theme.colorScheme.error,
          title: l.runsLoadFailedTitle,
          action: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 420),
            child: ChainErrorBox(error: error, isError: true),
          ),
        );
    }
  }
}

class _RunsPageState extends State<RunsPage> {
  List<DetachedRun> _runs = const [];
  bool _detachedEnabled = false;
  Object? _error;
  RunsLoadIssue _issue = RunsLoadIssue.other;
  bool _loaded = false;
  Timer? _poll;
  final Set<String> _cancelling = <String>{};

  @override
  void initState() {
    super.initState();
    Workspace.instance.addListener(_refresh);
    Workspace.instance.ensureLoaded();
    _refresh();
    // A run's phase changes without user action, so poll — same 2 s
    // tick the Audit page uses.
    _poll = Timer.periodic(const Duration(seconds: 2), (_) => _refresh());
  }

  @override
  void dispose() {
    Workspace.instance.removeListener(_refresh);
    _poll?.cancel();
    super.dispose();
  }

  Future<void> _refresh() async {
    try {
      final snapshot = await HubService.instance.listDetachedRuns(
        project: Workspace.instance.activeSlug,
      );
      if (!mounted) return;
      setState(() {
        _runs = snapshot.runs;
        _detachedEnabled = snapshot.enabled;
        _error = null;
        _loaded = true;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _error = e;
        _issue = classifyRunsLoadError(e);
        _loaded = true;
      });
    }
  }

  Future<void> _cancel(DetachedRun run) async {
    final l = AppLocalizations.of(context)!;
    setState(() => _cancelling.add(run.id));
    try {
      final ok = await HubService.instance.cancelDetachedRun(run.id);
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            ok ? l.runsCancelSignalled(run.flowName) : l.runsCancelTooLate,
          ),
        ),
      );
      await _refresh();
    } catch (e) {
      if (!mounted) return;
      showChainErrorSnack(context, 'runs.cancel', e);
    } finally {
      if (mounted) setState(() => _cancelling.remove(run.id));
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return Scaffold(
      backgroundColor: theme.scaffoldBackgroundColor,
      appBar: AppBar(
        title: Text(l.runsTitle),
        actions: [
          const ChainWorkspaceSwitcher(),
          const SizedBox(width: ChainSpace.md),
          IconButton(
            icon: const Icon(Icons.help_outline, size: 18),
            tooltip: l.helpTooltip,
            onPressed: () => showFaiDoc(context, 'runs'),
          ),
          IconButton(
            icon: const Icon(Icons.refresh, size: 18),
            tooltip: l.runsReloadTooltip,
            onPressed: _refresh,
          ),
          const SizedBox(width: ChainSpace.sm),
        ],
      ),
      body: !_loaded
          ? const Center(child: CircularProgressIndicator())
          : _error != null && _runs.isEmpty
          ? RunsLoadErrorView(
              error: _error!,
              issue: _issue,
              onOpenGuide: () => showFaiDoc(context, 'runs'),
              onOpenDoctor: () =>
                  StudioShellState.of(context)?.navigateTo('doctor'),
            )
          : _runs.isEmpty
          ? ChainEmptyState(
              icon: Icons.rocket_launch_outlined,
              title: l.runsEmptyTitle,
              // The hub reports whether the operator enabled the
              // feature — never claim "switched off" while it is on
              // and there simply are no runs yet (usertest finding).
              hint: _detachedEnabled ? l.runsEmptyEnabledHint : l.runsEmptyHint,
              // The guide carries the plain-language explanation plus
              // the exact operator steps (config snippet) — a click
              // target instead of a raw config key in the hint.
              action: OutlinedButton.icon(
                icon: const Icon(Icons.menu_book_outlined, size: 16),
                label: Text(l.runsEmptyGuideButton),
                onPressed: () => showFaiDoc(context, 'runs'),
              ),
            )
          : ListView.separated(
              padding: const EdgeInsets.all(ChainSpace.lg),
              itemCount: _runs.length,
              separatorBuilder: (_, _) => const SizedBox(height: ChainSpace.sm),
              itemBuilder: (context, i) => _RunRow(
                run: _runs[i],
                cancelling: _cancelling.contains(_runs[i].id),
                onCancel: () => _cancel(_runs[i]),
              ),
            ),
    );
  }
}

class _RunRow extends StatelessWidget {
  final DetachedRun run;
  final bool cancelling;
  final VoidCallback onCancel;

  const _RunRow({
    required this.run,
    required this.cancelling,
    required this.onCancel,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    final (tone, label) = _phaseChip(l);
    return ChainCard(
      child: Row(
        children: [
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  children: [
                    Text(
                      run.flowName.isEmpty ? run.id : run.flowName,
                      style: theme.textTheme.titleSmall,
                    ),
                    const SizedBox(width: ChainSpace.sm),
                    ChainPill(label: label, tone: tone),
                  ],
                ),
                const SizedBox(height: 4),
                Text(
                  _subtitle(l),
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
                if (run.error.isNotEmpty) ...[
                  const SizedBox(height: 4),
                  SelectableText(
                    run.error,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.error,
                    ),
                  ),
                ],
              ],
            ),
          ),
          if (run.isCancellable)
            cancelling
                ? const Padding(
                    padding: EdgeInsets.symmetric(horizontal: 12),
                    child: SizedBox(
                      width: 16,
                      height: 16,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    ),
                  )
                : OutlinedButton.icon(
                    onPressed: onCancel,
                    icon: const Icon(Icons.stop_circle_outlined, size: 16),
                    label: Text(l.runsCancelButton),
                  ),
        ],
      ),
    );
  }

  String _subtitle(AppLocalizations l) {
    final parts = <String>[];
    if (run.currentStep.isNotEmpty) {
      parts.add(l.runsCurrentStep(run.currentStep));
    }
    if (run.project.isNotEmpty) parts.add(run.project);
    parts.add(run.id);
    return parts.join('  ·  ');
  }

  (ChainPillTone, String) _phaseChip(AppLocalizations l) {
    switch (run.phase) {
      case DetachedPhase.pending:
        return (ChainPillTone.neutral, l.runsPhasePending);
      case DetachedPhase.running:
        return (ChainPillTone.accent, l.runsPhaseRunning);
      case DetachedPhase.succeeded:
        return (ChainPillTone.success, l.runsPhaseSucceeded);
      case DetachedPhase.failed:
        return (ChainPillTone.danger, l.runsPhaseFailed);
      case DetachedPhase.cancelled:
        return (ChainPillTone.warning, l.runsPhaseCancelled);
      case DetachedPhase.unknown:
        return (ChainPillTone.neutral, l.runsPhaseUnknown);
    }
  }
}