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

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

import '../data/hub.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<List<SavedFlow>> _future;

  @override
  void initState() {
    super.initState();
    _future = HubService.instance.listFlows();
  }

  void _refresh() => setState(() {
        _future = HubService.instance.listFlows();
      });

  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,
      ),
    );
  }

  @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<List<SavedFlow>>(
        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 flows = snapshot.data ?? [];
          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) =>
                _FlowCard(flow: flows[i], onRun: () => _runFlow(flows[i])),
          );
        },
      ),
    );
  }
}

class _FlowCard extends StatelessWidget {
  final SavedFlow flow;
  final VoidCallback onRun;

  const _FlowCard({required this.flow, required this.onRun});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return FaiCard(
      child: 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: '${flow.sizeBytes} B',
            tone: FaiPillTone.neutral,
            monospace: true,
          ),
          const SizedBox(width: FaiSpace.md),
          FilledButton.icon(
            onPressed: onRun,
            icon: const Icon(Icons.play_arrow, size: 16),
            label: Text(AppLocalizations.of(context)!.flowsRunButton),
          ),
        ],
      ),
    );
  }
}

/// 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;
  const _FlowRunInputs({
    required this.textInputs,
    required this.fileInputs,
  });
}

class _PickedFile {
  final String name;
  final Uint8List bytes;
  const _PickedFile({required this.name, required this.bytes});
}

/// 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>{};
    for (final d in defs) {
      if (_isBytesType(d.type)) {
        final picked = _pickedFiles[d.name];
        if (picked != null) fileInputs[d.name] = picked.bytes;
      } else {
        final c = _textControllers[d.name];
        if (c != null) textInputs[d.name] = c.text;
      }
    }
    return _FlowRunInputs(textInputs: textInputs, fileInputs: fileInputs);
  }

  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!);
    });
  }

  /// 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(
                    text: snap.error.toString(),
                    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
                      : '${pickedFile!.name} · '
                          '${l.flowsTypeBytesSize(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;

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

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

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

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

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final l = AppLocalizations.of(context)!;
    return AlertDialog(
      title: Text(l.flowsRunningTitle(widget.flow.name)),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(FaiRadius.md),
      ),
      content: ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 560, maxHeight: 480),
        child: FutureBuilder<Map<String, String>>(
          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(
                      text: snapshot.error.toString(),
                      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,
                        ),
                      ),
                    ),
                    Container(
                      width: double.infinity,
                      padding: const EdgeInsets.all(FaiSpace.md),
                      decoration: BoxDecoration(
                        color: theme.colorScheme.surfaceContainerHigh,
                        borderRadius: BorderRadius.circular(FaiRadius.sm),
                        border: Border.all(
                          color: theme.colorScheme.outlineVariant,
                        ),
                      ),
                      child: SelectableText(
                        entry.value,
                        style: FaiTheme.mono(size: 11),
                      ),
                    ),
                    const SizedBox(height: FaiSpace.md),
                  ],
                ],
              ),
            );
          },
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: Text(l.buttonClose),
        ),
      ],
    );
  }
}