import 'dart:async';

import 'package:aves/model/image_entry.dart';
import 'package:aves/model/metadata_service.dart';
import 'package:aves/widgets/fullscreen/info/info_page.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class MetadataSection extends StatefulWidget {
  final ImageEntry entry;

  const MetadataSection({this.entry});

  @override
  State<StatefulWidget> createState() => MetadataSectionState();
}

class MetadataSectionState extends State<MetadataSection> {
  Future<Map> _metadataLoader;

  static const int maxValueLength = 140;

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

  @override
  void didUpdateWidget(MetadataSection oldWidget) {
    super.didUpdateWidget(oldWidget);
    _initMetadataLoader();
  }

  Future<void> _initMetadataLoader() async {
    _metadataLoader = MetadataService.getAllMetadata(widget.entry);
  }

  @override
  Widget build(BuildContext context) {
    return Selector<MediaQueryData, double>(
      selector: (c, mq) => mq.size.width,
      builder: (c, mqWidth, child) => FutureBuilder(
        future: _metadataLoader,
        builder: (futureContext, AsyncSnapshot<Map> snapshot) {
          if (snapshot.hasError) return Text(snapshot.error.toString());
          if (snapshot.connectionState != ConnectionState.done) return const SizedBox.shrink();
          final metadataMap = snapshot.data.cast<String, Map>();
          final directoryNames = metadataMap.keys.toList()..sort();

          Widget content;
          if (mqWidth > 400) {
            final first = <String>[], second = <String>[];
            var firstItemCount = 0, secondItemCount = 0;
            var firstIndex = 0, secondIndex = directoryNames.length - 1;
            while (firstIndex <= secondIndex) {
              if (firstItemCount <= secondItemCount) {
                final directoryName = directoryNames[firstIndex++];
                first.add(directoryName);
                firstItemCount += 2 + metadataMap[directoryName].length;
              } else {
                final directoryName = directoryNames[secondIndex--];
                second.insert(0, directoryName);
                secondItemCount += 2 + metadataMap[directoryName].length;
              }
            }
            content = Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Expanded(child: getMetadataColumn(metadataMap, first)),
                const SizedBox(width: 8),
                Expanded(child: getMetadataColumn(metadataMap, second)),
              ],
            );
          } else {
            content = getMetadataColumn(metadataMap, directoryNames);
          }

          return Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const SectionRow('Metadata'),
              content,
            ],
          );
        },
      ),
    );
  }

  Widget getMetadataColumn(Map<String, Map> metadataMap, Iterable<String> directoryNames) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        ...directoryNames.expand((directoryName) {
          final directory = metadataMap[directoryName];
          final tagKeys = directory.keys.toList()..sort();
          return [
            if (directoryName.isNotEmpty)
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 4.0),
                child: Text(directoryName,
                    style: const TextStyle(
                      fontSize: 18,
                      fontFamily: 'Concourse Caps',
                    )),
              ),
            ...tagKeys.map((tagKey) {
              final value = directory[tagKey] as String;
              if (value == null || value.isEmpty) return const SizedBox.shrink();
              return InfoRow(tagKey, value.length > maxValueLength ? '${value.substring(0, maxValueLength)}…' : value);
            }),
            const SizedBox(height: 16),
          ];
        }),
      ],
    );
  }
}