import 'dart:io';
import 'dart:typed_data';

import 'package:fai_client_sdk/fai_client_sdk.dart' show FlowInputDef;
import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';

import '../data/format.dart';
import '../data/hub.dart';
import '../data/system_actions.dart';
import '../l10n/app_localizations.dart';
import '../theme/theme.dart';
import '../theme/tokens.dart';
import '../widgets/widgets.dart';

class FlowsPage extends StatefulWidget {
  const FlowsPage({super.key});

  @override
  State<FlowsPage> createState() => _FlowsPageState();
}

class _FlowsPageState extends State<FlowsPage> {
  late Future<_FlowsBundle> _future;

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

  /// Pulls the saved flows AND every capability the hub can
  /// execute (WASM modules + built-ins like `system.approval` +
  /// federated MCP/n8n tools) in parallel so the page can
  /// compute "is this flow runnable" per row.
  ///
  /// Using `allCapabilities()` instead of `listModules()` is
  /// load-bearing: built-ins are not WASM modules, so they would
  /// never appear in a module-grouped list — and a flow that
  /// uses `system.approval@^0` would stay stuck on "missing
  /// dependency" forever.
  Future<_FlowsBundle> _load() async {
    final results = await Future.wait([
      HubService.instance.listFlows(),
      HubService.instance
          .allCapabilities()
          .catchError((_) => <CapabilityInfo>[]),
    ]);
    return _FlowsBundle(
      flows: results[0] as List<SavedFlow>,
      installedCapabilities: (results[1] as List<CapabilityInfo>)
          .map((c) => c.capability)
          .toSet(),
    );
  }

  void _refresh() => setState(() {
        _future = _load();
      });

  /// Returns the verbatim `use:` strings whose bare capability
  /// name is not provided by any installed module. The bare
  /// name is everything left of the first `@`; version
  /// constraints are tolerated at this stage — the hub does
  /// the full resolution at run time.
  List<String> _missing(SavedFlow flow, Set<String> installed) {
    final out = <String>[];
    for (final cap in flow.requiredCapabilities) {
      final at = cap.indexOf('@');
      final name = at >= 0 ? cap.substring(0, at) : cap;
      if (!installed.contains(name)) out.add(cap);
    }
    return out;
  }

  Future<void> _runFlow(SavedFlow flow) async {
    final inputs = await _FlowInputDialog.show(context, flow);
    if (inputs == null) return;
    if (!mounted) return;
    showDialog<void>(
      context: context,
      barrierDismissible: false,
      builder: (_) => _FlowRunDialog(
        flow: flow,
        textInputs: inputs.textInputs,
        fileInputs: inputs.fileInputs,
        fileMimeTypes: inputs.fileMimeTypes,
      ),
    );
  }

  /// Walk through one or more capability specs (e.g.
  /// `text.extract@^0`) sequentially, showing per-item progress.
  /// Refreshes the flows page on dismiss so the row updates if
  /// any install actually changed the installed-set.
  Future<void> _installDeps(List<String> specs) async {
    final changed = await showDialog<bool>(
      context: context,
      barrierDismissible: false,
      builder: (_) => _InstallDependenciesDialog(specs: specs),
    );
    if (changed == true && mounted) _refresh();
  }

  /// Hand the YAML file to the OS — `open` on macOS, `xdg-open`
  /// on Linux, `start` on Windows. The operator's default editor
  /// for `.yaml` decides what actually opens.
  Future<void> _openInEditor(SavedFlow flow) async {
    final r = await SystemActions.openInOs(flow.path);
    if (!mounted || r.ok) return;
    final l = AppLocalizations.of(context)!;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(l.flowsOpenInEditorFailed(r.stderr))),
    );
  }

  @override
  Widget build(BuildContext context) {
    final l = AppLocalizations.of(context)!;
    return Scaffold(
      backgroundColor: Theme.of(context).scaffoldBackgroundColor,
      appBar: AppBar(
        title: Text(l.flowsTitle),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh, size: 18),
            tooltip: l.flowsReloadTooltip,
            onPressed: _refresh,
          ),
          const SizedBox(width: FaiSpace.sm),
        ],
      ),
      body: FutureBuilder<_FlowsBundle>(
        future: _future,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return FaiEmptyState(
              icon: Icons.cloud_off_outlined,
              iconColor: Theme.of(context).colorScheme.error,
              title: l.hubUnreachable,
              hint: l.hubUnreachableHint,
              action: FilledButton.tonal(
                onPressed: _refresh,
                child: Text(l.buttonRetry),
              ),
            );
          }
          final bundle = snapshot.data ?? const _FlowsBundle.empty();
          final flows = bundle.flows;
          if (flows.isEmpty) {
            return FaiEmptyState(
              icon: Icons.account_tree_outlined,
              title: l.flowsNoneTitle,
              hint: l.flowsNoneHint,
            );
          }
          return ListView.separated(
            padding: const EdgeInsets.all(FaiSpace.xl),
            itemCount: flows.length,
            separatorBuilder: (_, _) => const SizedBox(height: FaiSpace.md),
            itemBuilder: (context, i) {
              final flow = flows[i];
              final missing = _missing(flow, bundle.installedCapabilities);
              return _FlowCard(
                flow: flow,
                missingCapabilities: missing,
                onRun: missing.isEmpty ? () => _runFlow(flow) : null,
                onInstallSingle: (spec) => _installDeps([spec]),
                onInstallAll: missing.length > 1
                    ? () => _installDeps(missing)
                    : null,
                onOpenInEditor: () => _openInEditor(flow),
              );
            },
          );
        },
      ),
    );
  }
}

/// Snapshot of everything the Flows page needs in one render
/// pass: the saved flows themselves and the set of installed
/// capability names. Stored as a single Future so the
/// FutureBuilder transitions atomically (no flicker between
/// "flows loaded but modules pending").
class _FlowsBundle {
  final List<SavedFlow> flows;
  final Set<String> installedCapabilities;
  const _FlowsBundle({
    required this.flows,
    required this.installedCapabilities,
  });
  const _FlowsBundle.empty()
      : flows = const [],
        installedCapabilities = const {};
}

class _FlowCard extends StatelessWidget {
  final SavedFlow flow;
  final List<String> missingCapabilities;
  /// Null when the flow can't run (missing modules); the
  /// Run button greys out + a tooltip points the operator
  /// at the install path. Non-null otherwise.
  final VoidCallback? onRun;
  /// Install a single capability spec (verbatim `use:` string,
  /// version constraint included — the dialog strips the `@`
  /// suffix before calling installModule).
  final ValueChanged<String> onInstallSingle;
  /// Install every missing capability in sequence. Null when
  /// only one is missing (the single-install pill is enough).
  final VoidCallback? onInstallAll;
  /// Hand the flow YAML to the OS so the operator's default
  /// editor opens it.
  final VoidCallback onOpenInEditor;

  const _FlowCard({
    required this.flow,
    required this.missingCapabilities,
    required this.onRun,
    required this.onInstallSingle,
    required this.onInstallAll,
    required this.onOpenInEditor,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    final isRunnable = missingCapabilities.isEmpty;
    return FaiCard(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Icon(
                Icons.account_tree_outlined,
                size: 20,
                color: theme.colorScheme.primary,
              ),
              const SizedBox(width: FaiSpace.md),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      flow.name,
                      style: theme.textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                    const SizedBox(height: 2),
                    Text(
                      flow.path,
                      style: FaiTheme.mono(
                        size: 11,
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ],
                ),
              ),
              FaiPill(
                label: humanBytes(flow.sizeBytes),
                tone: FaiPillTone.neutral,
                monospace: true,
              ),
              const SizedBox(width: FaiSpace.sm),
              IconButton(
                icon: const Icon(Icons.edit_outlined, size: 18),
                tooltip: l.flowsOpenInEditorTooltip,
                onPressed: onOpenInEditor,
              ),
              const SizedBox(width: FaiSpace.xs),
              Tooltip(
                message: isRunnable ? '' : l.flowsRunDisabledTooltip,
                child: FilledButton.icon(
                  onPressed: onRun,
                  icon: const Icon(Icons.play_arrow, size: 16),
                  label: Text(l.flowsRunButton),
                ),
              ),
            ],
          ),
          if (!isRunnable) ...[
            const SizedBox(height: FaiSpace.sm),
            Padding(
              padding: const EdgeInsets.only(left: 32),
              child: Wrap(
                spacing: FaiSpace.xs,
                runSpacing: FaiSpace.xs,
                crossAxisAlignment: WrapCrossAlignment.center,
                children: [
                  Text(
                    l.flowsMissingModulesLabel,
                    style: theme.textTheme.labelSmall?.copyWith(
                      color: theme.colorScheme.error,
                      letterSpacing: 0.4,
                    ),
                  ),
                  for (final cap in missingCapabilities)
                    _ClickablePill(
                      label: cap,
                      tooltip: l.flowsInstallPillTooltip,
                      onTap: () => onInstallSingle(cap),
                    ),
                  if (onInstallAll != null)
                    Padding(
                      padding: const EdgeInsets.only(left: FaiSpace.sm),
                      child: FilledButton.tonalIcon(
                        onPressed: onInstallAll,
                        icon: const Icon(Icons.download_outlined, size: 14),
                        label: Text(
                          l.flowsInstallAllButton(missingCapabilities.length),
                        ),
                        style: FilledButton.styleFrom(
                          padding: const EdgeInsets.symmetric(
                            horizontal: FaiSpace.md,
                            vertical: 0,
                          ),
                          minimumSize: const Size(0, 28),
                          tapTargetSize: MaterialTapTargetSize.shrinkWrap,
                        ),
                      ),
                    ),
                ],
              ),
            ),
          ],
        ],
      ),
    );
  }
}

/// Tappable variant of `FaiPill` used for the missing-capability
/// row. Wraps the pill in `InkWell` + `Tooltip` so the operator
/// gets a click affordance and a "Click to install" hint.
class _ClickablePill extends StatelessWidget {
  final String label;
  final String tooltip;
  final VoidCallback onTap;

  const _ClickablePill({
    required this.label,
    required this.tooltip,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    return Tooltip(
      message: tooltip,
      child: Material(
        color: Colors.transparent,
        borderRadius: BorderRadius.circular(FaiRadius.sm),
        child: InkWell(
          borderRadius: BorderRadius.circular(FaiRadius.sm),
          onTap: onTap,
          child: FaiPill(
            label: label,
            tone: FaiPillTone.danger,
            icon: Icons.download_outlined,
            monospace: true,
          ),
        ),
      ),
    );
  }
}

/// Inputs collected by `_FlowInputDialog` and forwarded to
/// the run dialog. Text and file values arrive in separate
/// maps so the SDK can wrap each as the appropriate Payload
/// variant.
class _FlowRunInputs {
  final Map<String, String> textInputs;
  final Map<String, Uint8List> fileInputs;
  /// Parallel to [fileInputs]; same keys. Modules like
  /// `text.extract` reject `application/octet-stream`, so we
  /// derive a real MIME type from the picked file's extension
  /// and forward it to the hub.
  final Map<String, String> fileMimeTypes;
  const _FlowRunInputs({
    required this.textInputs,
    required this.fileInputs,
    required this.fileMimeTypes,
  });
}

class _PickedFile {
  final String name;
  final Uint8List bytes;
  /// MIME derived from the file extension at pick time. Empty
  /// when the extension is unknown — the SDK then falls back to
  /// `application/octet-stream`.
  final String mimeType;
  const _PickedFile({
    required this.name,
    required this.bytes,
    required this.mimeType,
  });
}

/// Minimal extension → MIME map covering the file types that
/// shipped modules actually accept (PDF, DOCX for text.extract;
/// plain text, json, csv for upcoming modules). Keeping it tiny
/// avoids pulling the `mime` package as a new dependency. Returns
/// empty string for unknown extensions so the SDK default
/// (`application/octet-stream`) still applies.
String _mimeForFilename(String filename) {
  final dot = filename.lastIndexOf('.');
  if (dot < 0 || dot == filename.length - 1) return '';
  final ext = filename.substring(dot + 1).toLowerCase();
  switch (ext) {
    case 'pdf':
      return 'application/pdf';
    case 'docx':
      return 'application/vnd.openxmlformats-officedocument'
          '.wordprocessingml.document';
    case 'doc':
      return 'application/msword';
    case 'txt':
      return 'text/plain';
    case 'md':
    case 'markdown':
      return 'text/markdown';
    case 'json':
      return 'application/json';
    case 'csv':
      return 'text/csv';
    case 'xml':
      return 'application/xml';
    case 'yaml':
    case 'yml':
      return 'application/yaml';
    case 'html':
    case 'htm':
      return 'text/html';
    case 'png':
      return 'image/png';
    case 'jpg':
    case 'jpeg':
      return 'image/jpeg';
    default:
      return '';
  }
}

/// Run-flow input dialog. Fetches the flow's declared input
/// schema first via `getFlowDefinition`, then renders one
/// type-aware field per declared input:
///
///   * `bytes` / `file` → "Choose file" button + picked-file
///                         readout. Routes through the OS
///                         file dialog so sandboxed Studio
///                         still gets read access to the
///                         chosen file. `withData: true` so
///                         the bytes flow through the
///                         FilePicker result instead of a
///                         path that may be unreadable.
///   * everything else  → TextField. Opaque type tag is
///                         shown as a pill next to the input
///                         name so a flow author who picks
///                         a less-common type still gets a
///                         hint.
///
/// The Run button enables only when every input has a value
/// — required-field validation happens client-side before
/// the hub sees an empty inputs map.
class _FlowInputDialog extends StatefulWidget {
  final SavedFlow flow;

  const _FlowInputDialog({required this.flow});

  static Future<_FlowRunInputs?> show(
    BuildContext context,
    SavedFlow flow,
  ) {
    return showDialog<_FlowRunInputs>(
      context: context,
      builder: (_) => _FlowInputDialog(flow: flow),
    );
  }

  @override
  State<_FlowInputDialog> createState() => _FlowInputDialogState();
}

class _FlowInputDialogState extends State<_FlowInputDialog> {
  late final Future<List<FlowInputDef>> _defFuture;
  final Map<String, TextEditingController> _textControllers = {};
  final Map<String, _PickedFile> _pickedFiles = {};

  @override
  void initState() {
    super.initState();
    _defFuture = HubService.instance.getFlowDefinition(widget.flow.name);
  }

  @override
  void dispose() {
    for (final c in _textControllers.values) {
      c.dispose();
    }
    super.dispose();
  }

  bool _isBytesType(String type) => type == 'bytes' || type == 'file';

  bool _isComplete(List<FlowInputDef> defs) {
    for (final d in defs) {
      if (_isBytesType(d.type)) {
        if (_pickedFiles[d.name] == null) return false;
      } else {
        final v = _textControllers[d.name]?.text.trim() ?? '';
        if (v.isEmpty) return false;
      }
    }
    return true;
  }

  _FlowRunInputs _collect(List<FlowInputDef> defs) {
    final textInputs = <String, String>{};
    final fileInputs = <String, Uint8List>{};
    final fileMimeTypes = <String, String>{};
    for (final d in defs) {
      if (_isBytesType(d.type)) {
        final picked = _pickedFiles[d.name];
        if (picked != null) {
          fileInputs[d.name] = picked.bytes;
          if (picked.mimeType.isNotEmpty) {
            fileMimeTypes[d.name] = picked.mimeType;
          }
        }
      } else {
        final c = _textControllers[d.name];
        if (c != null) textInputs[d.name] = c.text;
      }
    }
    return _FlowRunInputs(
      textInputs: textInputs,
      fileInputs: fileInputs,
      fileMimeTypes: fileMimeTypes,
    );
  }

  Future<void> _pickFile(String inputName) async {
    final result = await FilePicker.platform.pickFiles(withData: true);
    if (result == null || result.files.isEmpty) return;
    final f = result.files.first;
    var bytes = f.bytes;
    if (bytes == null && f.path != null) {
      // Some Linux configurations don't honour `withData: true`
      // for large files; fall back to reading via path.
      try {
        bytes = await File(f.path!).readAsBytes();
      } catch (e) {
        if (!mounted) return;
        final l = AppLocalizations.of(context)!;
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(l.flowsFileReadFailed(f.path!, '$e'))),
        );
        return;
      }
    }
    if (bytes == null || !mounted) return;
    setState(() {
      _pickedFiles[inputName] = _PickedFile(
        name: f.name,
        bytes: bytes!,
        mimeType: _mimeForFilename(f.name),
      );
    });
  }

  /// Lazily ensure each text-shaped input has a controller +
  /// a setState-triggering listener so the Run button reflects
  /// validity as the operator types.
  void _ensureTextControllers(List<FlowInputDef> defs) {
    for (final d in defs) {
      if (_isBytesType(d.type)) continue;
      _textControllers.putIfAbsent(d.name, () {
        final c = TextEditingController();
        c.addListener(() {
          if (mounted) setState(() {});
        });
        return c;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return AlertDialog(
      title: Text(l.flowsRunDialogTitle(widget.flow.name)),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(FaiRadius.md),
      ),
      content: ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 540, maxHeight: 540),
        child: FutureBuilder<List<FlowInputDef>>(
          future: _defFuture,
          builder: (context, snap) {
            if (snap.connectionState == ConnectionState.waiting) {
              return Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  const SizedBox(
                    width: 14,
                    height: 14,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  ),
                  const SizedBox(width: FaiSpace.sm),
                  Text(l.flowsLoadingDefinition),
                ],
              );
            }
            if (snap.hasError) {
              return Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    l.flowsDefinitionFailed,
                    style: theme.textTheme.bodyMedium?.copyWith(
                      color: theme.colorScheme.error,
                    ),
                  ),
                  const SizedBox(height: FaiSpace.sm),
                  FaiErrorBox(
                    error: snap.error,
                    isError: true,
                    maxHeight: 200,
                  ),
                ],
              );
            }
            final defs = snap.data ?? const <FlowInputDef>[];
            _ensureTextControllers(defs);
            return SingleChildScrollView(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    l.flowsRunDialogBody,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                  const SizedBox(height: FaiSpace.md),
                  if (defs.isEmpty)
                    Text(
                      l.flowsNoInputs,
                      style: theme.textTheme.bodyMedium,
                    ),
                  for (final d in defs) ...[
                    _InputField(
                      def: d,
                      isBytes: _isBytesType(d.type),
                      textController: _textControllers[d.name],
                      pickedFile: _pickedFiles[d.name],
                      onPick: () => _pickFile(d.name),
                    ),
                    const SizedBox(height: FaiSpace.md),
                  ],
                ],
              ),
            );
          },
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context, null),
          child: Text(l.buttonCancel),
        ),
        FutureBuilder<List<FlowInputDef>>(
          future: _defFuture,
          builder: (context, snap) {
            final defs = snap.data ?? const <FlowInputDef>[];
            final canRun = snap.hasData && _isComplete(defs);
            return FilledButton.icon(
              icon: const Icon(Icons.play_arrow, size: 16),
              label: Text(l.flowsRunButton),
              onPressed: canRun
                  ? () => Navigator.pop(context, _collect(defs))
                  : null,
            );
          },
        ),
      ],
    );
  }
}

class _InputField extends StatelessWidget {
  final FlowInputDef def;
  final bool isBytes;
  final TextEditingController? textController;
  final _PickedFile? pickedFile;
  final VoidCallback onPick;

  const _InputField({
    required this.def,
    required this.isBytes,
    required this.textController,
    required this.pickedFile,
    required this.onPick,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Text(
              def.name,
              style: FaiTheme.mono(
                size: 12,
                weight: FontWeight.w600,
                color: theme.colorScheme.onSurface,
              ),
            ),
            const SizedBox(width: FaiSpace.sm),
            FaiPill(
              label: def.type,
              tone: isBytes ? FaiPillTone.warning : FaiPillTone.neutral,
              monospace: true,
            ),
          ],
        ),
        const SizedBox(height: 6),
        if (isBytes)
          Row(
            children: [
              OutlinedButton.icon(
                onPressed: onPick,
                icon: const Icon(Icons.attach_file, size: 14),
                label: Text(
                  pickedFile == null
                      ? l.flowsTypeBytesPick
                      : l.flowsTypeBytesChange,
                ),
              ),
              const SizedBox(width: FaiSpace.md),
              Expanded(
                child: Text(
                  pickedFile == null
                      ? l.flowsTypeBytesNoFile
                      : '${pickedFile!.name} · '
                          '${humanBytes(pickedFile!.bytes.length)}',
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                  overflow: TextOverflow.ellipsis,
                ),
              ),
            ],
          )
        else
          TextField(
            controller: textController,
            decoration: const InputDecoration(
              border: OutlineInputBorder(),
              isDense: true,
            ),
          ),
      ],
    );
  }
}

class _FlowRunDialog extends StatefulWidget {
  final SavedFlow flow;
  final Map<String, String> textInputs;
  final Map<String, Uint8List> fileInputs;
  final Map<String, String> fileMimeTypes;

  const _FlowRunDialog({
    required this.flow,
    required this.textInputs,
    required this.fileInputs,
    required this.fileMimeTypes,
  });

  @override
  State<_FlowRunDialog> createState() => _FlowRunDialogState();
}

class _FlowRunDialogState extends State<_FlowRunDialog> {
  late final Future<Map<String, FlowOutput>> _future;

  @override
  void initState() {
    super.initState();
    _future = HubService.instance.runSavedFlow(
      name: widget.flow.name,
      textInputs: widget.textInputs,
      fileInputs: widget.fileInputs,
      fileMimeTypes: widget.fileMimeTypes,
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return AlertDialog(
      // Title tracks the future's state so the dialog header
      // stops claiming "extract läuft" once the run is over.
      // Recomputed on every snapshot change via FutureBuilder.
      title: FutureBuilder<Map<String, FlowOutput>>(
        future: _future,
        builder: (context, snapshot) {
          final String title;
          if (snapshot.connectionState == ConnectionState.waiting) {
            title = l.flowsRunningTitle(widget.flow.name);
          } else if (snapshot.hasError) {
            title = l.flowsErrorTitle(widget.flow.name);
          } else {
            title = l.flowsResultTitle(widget.flow.name);
          }
          return Text(title);
        },
      ),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(FaiRadius.md),
      ),
      content: ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 560, maxHeight: 480),
        child: FutureBuilder<Map<String, FlowOutput>>(
          future: _future,
          builder: (context, snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              return Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  const SizedBox(height: FaiSpace.md),
                  const CircularProgressIndicator(),
                  const SizedBox(height: FaiSpace.md),
                  Text(
                    l.flowsRunning,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                ],
              );
            }
            if (snapshot.hasError) {
              return SingleChildScrollView(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Row(
                      children: [
                        Icon(
                          Icons.error_outline,
                          color: theme.colorScheme.error,
                          size: 20,
                        ),
                        const SizedBox(width: FaiSpace.sm),
                        Text(
                          l.flowsRunErrorTitle,
                          style: theme.textTheme.titleSmall?.copyWith(
                            color: theme.colorScheme.error,
                            fontWeight: FontWeight.w600,
                          ),
                        ),
                      ],
                    ),
                    const SizedBox(height: FaiSpace.md),
                    FaiErrorBox(
                      error: snapshot.error,
                      isError: true,
                      maxHeight: 280,
                    ),
                  ],
                ),
              );
            }
            final outputs = snapshot.data ?? const {};
            if (outputs.isEmpty) {
              return Text(
                l.flowsNoOutputs,
                style: theme.textTheme.bodyMedium,
              );
            }
            return SingleChildScrollView(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
                children: [
                  for (final entry in outputs.entries) ...[
                    Padding(
                      padding: const EdgeInsets.only(bottom: 4),
                      child: Text(
                        entry.key.toUpperCase(),
                        style: theme.textTheme.labelSmall?.copyWith(
                          color: theme.colorScheme.onSurfaceVariant,
                          letterSpacing: 0.6,
                        ),
                      ),
                    ),
                    FaiFlowOutput(output: entry.value),
                    const SizedBox(height: FaiSpace.md),
                  ],
                ],
              ),
            );
          },
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: Text(l.buttonClose),
        ),
      ],
    );
  }
}

/// Per-spec install state for the dependencies dialog. The
/// dialog walks the list sequentially, advancing each row from
/// `pending` → `installing` → `done` | `failed` so the operator
/// sees one row light up at a time.
enum _InstallStatus { pending, installing, done, failed }

class _InstallItemState {
  /// Verbatim spec from the flow's `use:` line, e.g.
  /// `text.extract@^0`. Shown as-is so the operator recognises
  /// the same string they saw on the flow card.
  final String spec;

  /// Bare capability name (everything left of `@`). What the
  /// hub's `installModule` actually resolves through the store
  /// index — the version constraint is dropped here because
  /// the index already picks a matching version.
  final String bareName;

  _InstallStatus status;
  String? installedVersion;
  /// Original thrown object so the UI can run it through
  /// [friendlyError] later instead of staring at a wall of gRPC
  /// trailers.
  Object? error;

  _InstallItemState(this.spec)
      : bareName = _stripVersion(spec),
        status = _InstallStatus.pending;

  static String _stripVersion(String spec) {
    final at = spec.indexOf('@');
    return at >= 0 ? spec.substring(0, at) : spec;
  }
}

/// Sequential installer for a list of capability specs. Pops
/// with `true` if at least one install completed successfully
/// (so the parent knows to refresh its installed-modules view),
/// `false` otherwise.
class _InstallDependenciesDialog extends StatefulWidget {
  final List<String> specs;

  const _InstallDependenciesDialog({required this.specs});

  @override
  State<_InstallDependenciesDialog> createState() =>
      _InstallDependenciesDialogState();
}

class _InstallDependenciesDialogState
    extends State<_InstallDependenciesDialog> {
  late final List<_InstallItemState> _items;
  bool _running = true;

  @override
  void initState() {
    super.initState();
    _items = widget.specs.map(_InstallItemState.new).toList();
    // Kick off the install sequence after first frame so any
    // initState-time setState calls inside the chain hit a
    // mounted widget.
    WidgetsBinding.instance.addPostFrameCallback((_) => _runAll());
  }

  Future<void> _runAll() async {
    for (final item in _items) {
      if (!mounted) return;
      setState(() => item.status = _InstallStatus.installing);
      try {
        final r = await HubService.instance.installModule(
          source: item.bareName,
        );
        if (!mounted) return;
        setState(() {
          item.status = _InstallStatus.done;
          item.installedVersion = r.version;
        });
      } catch (e) {
        if (!mounted) return;
        setState(() {
          item.status = _InstallStatus.failed;
          item.error = e;
        });
      }
    }
    if (!mounted) return;
    setState(() => _running = false);
  }

  bool get _anySucceeded =>
      _items.any((i) => i.status == _InstallStatus.done);

  int get _doneCount =>
      _items.where((i) => i.status == _InstallStatus.done).length;

  int get _failedCount =>
      _items.where((i) => i.status == _InstallStatus.failed).length;

  /// True iff at least one failure carries the v0.10.91+ HTML-instead-
  /// of-bundle signature emitted by `download_to_temp` when the
  /// registry redirects an unauthenticated request to a signin page.
  /// Used to surface a contextual "Open Settings" button so the
  /// operator does not have to read the wall of error text first.
  bool get _anyAuthWallFailure => _items.any(
        (i) =>
            i.status == _InstallStatus.failed && _isAuthWallError(i.error),
      );

  static bool _isAuthWallError(Object? err) {
    if (err == null) return false;
    final msg = err.toString();
    return msg.contains('registry returned an HTML page') ||
        msg.contains('no registry token configured');
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return AlertDialog(
      title: Text(l.flowsInstallDepsTitle),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(FaiRadius.md),
      ),
      content: ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 520, maxHeight: 480),
        child: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                l.flowsInstallDepsBody,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: theme.colorScheme.onSurfaceVariant,
                ),
              ),
              const SizedBox(height: FaiSpace.md),
              for (final item in _items) ...[
                _InstallRow(item: item),
                const SizedBox(height: FaiSpace.sm),
              ],
              if (!_running) ...[
                const SizedBox(height: FaiSpace.xs),
                Text(
                  _failedCount == 0
                      ? l.flowsInstallDepsAllDone
                      : l.flowsInstallDepsAnyFailed(_doneCount, _failedCount),
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: _failedCount == 0
                        ? null
                        : theme.colorScheme.error,
                    fontWeight: FontWeight.w500,
                  ),
                ),
              ],
            ],
          ),
        ),
      ),
      actions: [
        if (!_running && _anyAuthWallFailure)
          FilledButton.icon(
            icon: const Icon(Icons.vpn_key_outlined, size: 16),
            label: Text(l.flowsInstallAuthWallButton),
            onPressed: () async {
              // Close install dialog first so the operator returns
              // to the flow card on Settings dismiss — then they
              // can re-click the pill to retry the install.
              Navigator.pop(context, _anySucceeded);
              await FaiSettingsDialog.show(context);
            },
          ),
        TextButton(
          onPressed: _running
              ? null
              : () => Navigator.pop(context, _anySucceeded),
          child: Text(l.buttonClose),
        ),
      ],
    );
  }
}

/// One row in the install-dependencies dialog. Status icon +
/// capability name + per-state detail line (version on success,
/// truncated error on failure).
class _InstallRow extends StatelessWidget {
  final _InstallItemState item;

  const _InstallRow({required this.item});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        SizedBox(
          width: 20,
          height: 20,
          child: Center(child: _statusIcon(theme)),
        ),
        const SizedBox(width: FaiSpace.sm),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                item.spec,
                style: FaiTheme.mono(
                  size: 12,
                  weight: FontWeight.w600,
                  color: theme.colorScheme.onSurface,
                ),
              ),
              const SizedBox(height: 2),
              Text(
                _detailLine(l),
                style: theme.textTheme.bodySmall?.copyWith(
                  color: item.status == _InstallStatus.failed
                      ? theme.colorScheme.error
                      : theme.colorScheme.onSurfaceVariant,
                ),
              ),
              if (item.status == _InstallStatus.failed &&
                  item.error != null) ...[
                const SizedBox(height: FaiSpace.xs),
                FaiErrorBox(
                  error: item.error,
                  isError: true,
                  maxHeight: 120,
                ),
              ],
            ],
          ),
        ),
      ],
    );
  }

  Widget _statusIcon(ThemeData theme) {
    switch (item.status) {
      case _InstallStatus.pending:
        return Icon(
          Icons.radio_button_unchecked,
          size: 16,
          color: theme.colorScheme.onSurfaceVariant,
        );
      case _InstallStatus.installing:
        return const SizedBox(
          width: 14,
          height: 14,
          child: CircularProgressIndicator(strokeWidth: 2),
        );
      case _InstallStatus.done:
        return Icon(
          Icons.check_circle,
          size: 16,
          color: theme.colorScheme.primary,
        );
      case _InstallStatus.failed:
        return Icon(
          Icons.error_outline,
          size: 16,
          color: theme.colorScheme.error,
        );
    }
  }

  String _detailLine(AppLocalizations l) {
    switch (item.status) {
      case _InstallStatus.pending:
        return l.flowsInstallStatusPending;
      case _InstallStatus.installing:
        return l.flowsInstallStatusInstalling;
      case _InstallStatus.done:
        return l.flowsInstallStatusDone(item.installedVersion ?? '?');
      case _InstallStatus.failed:
        return l.flowsInstallStatusFailed;
    }
  }
}