import 'dart:convert';

import 'package:flutter/material.dart';

import '../../utils/clipboard_helper.dart';

/// Collapsible tree view for decoded JSON (maps, lists, scalars). Rows are
/// flattened lazily so multi-megabyte cache payloads stay scrollable.
class JsonViewer extends StatefulWidget {
  final String title;
  final Object? data;

  const JsonViewer({required this.data, this.title = 'Rohdaten', super.key});

  static final _encoder = const JsonEncoder.withIndent('  ');

  static String format(Object? data) => _encoder.convert(toEncodable(data));

  /// Makes arbitrary decoded storage values (Hive maps with dynamic keys,
  /// DateTimes, …) JSON-encodable.
  static Object? toEncodable(Object? value) => switch (value) {
    null || bool() || num() || String() => value,
    Map() => {for (final e in value.entries) '${e.key}': toEncodable(e.value)},
    Iterable() => [for (final e in value) toEncodable(e)],
    DateTime() => value.toIso8601String(),
    _ => value.toString(),
  };

  @override
  State<JsonViewer> createState() => _JsonViewerState();
}

class _Row {
  final String path;
  final String? label;
  final Object? value;
  final int depth;

  const _Row(this.path, this.label, this.value, this.depth);

  bool get isContainer => value is Map || value is List;
}

class _JsonViewerState extends State<JsonViewer> {
  late final Object? _data = JsonViewer.toEncodable(widget.data);
  final Set<String> _expanded = {''};
  List<_Row> _rows = const [];

  @override
  void initState() {
    super.initState();
    _rebuildRows();
  }

  void _rebuildRows() {
    final rows = <_Row>[];
    void walk(String path, String? label, Object? value, int depth) {
      rows.add(_Row(path, label, value, depth));
      if (!_expanded.contains(path)) return;
      if (value is Map) {
        for (final e in value.entries) {
          walk('$path/${e.key}', '${e.key}', e.value, depth + 1);
        }
      } else if (value is List) {
        for (var i = 0; i < value.length; i++) {
          walk('$path/$i', '[$i]', value[i], depth + 1);
        }
      }
    }

    walk('', null, _data, 0);
    _rows = rows;
  }

  void _toggle(String path) => setState(() {
    if (!_expanded.remove(path)) _expanded.add(path);
    _rebuildRows();
  });

  void _setAll({required bool expanded}) => setState(() {
    _expanded
      ..clear()
      ..add('');
    if (expanded) {
      void collect(String path, Object? value) {
        if (value is Map) {
          _expanded.add(path);
          for (final e in value.entries) {
            collect('$path/${e.key}', e.value);
          }
        } else if (value is List) {
          _expanded.add(path);
          for (var i = 0; i < value.length; i++) {
            collect('$path/$i', value[i]);
          }
        }
      }

      collect('', _data);
    }
    _rebuildRows();
  });

  @override
  Widget build(BuildContext context) => Scaffold(
    appBar: AppBar(
      title: Text(widget.title),
      actions: [
        IconButton(
          tooltip: 'Alles aufklappen',
          icon: const Icon(Icons.unfold_more),
          onPressed: () => _setAll(expanded: true),
        ),
        IconButton(
          tooltip: 'Alles zuklappen',
          icon: const Icon(Icons.unfold_less),
          onPressed: () => _setAll(expanded: false),
        ),
        PopupMenuButton<bool>(
          onSelected: (pretty) => copyToClipboard(
            context,
            pretty ? JsonViewer.format(_data) : jsonEncode(_data),
            successMessage: pretty
                ? 'Formatiertes JSON kopiert'
                : 'Inline JSON kopiert',
          ),
          itemBuilder: (_) => const [
            PopupMenuItem(value: true, child: Text('JSON kopieren')),
            PopupMenuItem(value: false, child: Text('Inline kopieren')),
          ],
        ),
      ],
    ),
    body: ListView.builder(
      itemCount: _rows.length,
      itemBuilder: (context, index) => _buildRow(context, _rows[index]),
    ),
  );

  Widget _buildRow(BuildContext context, _Row row) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    final mono = theme.textTheme.bodyMedium!.copyWith(fontFamily: 'monospace');
    final value = row.value;
    final expanded = _expanded.contains(row.path);

    final (String text, Color color) = switch (value) {
      Map() => (expanded ? '{' : '{ ${value.length} }', colors.outline),
      List() => (expanded ? '[' : '[ ${value.length} ]', colors.outline),
      String() => ('"$value"', colors.tertiary),
      num() || bool() => ('$value', colors.primary),
      _ => ('null', colors.outline),
    };

    return InkWell(
      onTap: row.isContainer ? () => _toggle(row.path) : null,
      onLongPress: () => copyToClipboard(
        context,
        value is String ? value : JsonViewer.format(value),
      ),
      child: Padding(
        padding: EdgeInsets.only(
          left: 8.0 + row.depth * 16,
          right: 8,
          top: 3,
          bottom: 3,
        ),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            SizedBox(
              width: 20,
              child: row.isContainer
                  ? Icon(
                      expanded ? Icons.arrow_drop_down : Icons.arrow_right,
                      size: 20,
                    )
                  : null,
            ),
            Expanded(
              child: Text.rich(
                TextSpan(
                  style: mono,
                  children: [
                    if (row.label != null)
                      TextSpan(
                        text: '${row.label}: ',
                        style: TextStyle(color: colors.secondary),
                      ),
                    TextSpan(
                      text: text,
                      style: TextStyle(color: color),
                    ),
                  ],
                ),
                maxLines: row.isContainer ? 1 : 8,
                overflow: TextOverflow.ellipsis,
              ),
            ),
          ],
        ),
      ),
    );
  }
}