import 'dart:io';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:path/path.dart' as path;

enum FilesSelectorMode {
  files,
  directory,
}

class FilesSelector extends StatefulWidget {
  final FilesSelectorMode mode;
  final String baseDirectory;

  FilesSelector({
    this.mode = FilesSelectorMode.files,
    this.baseDirectory,
  });

  @override
  _FilesSelectorState createState() => _FilesSelectorState();
}

class _FilesSelectorState extends State<FilesSelector> {
  static const platform = MethodChannel('de.johrpan.musicus/platform');

  Directory baseDirectory;
  List<Directory> storageRoots;
  List<Directory> directories = [];
  List<FileSystemEntity> contents = [];
  Set<String> selectedPaths = {};

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

    if (widget.baseDirectory == null) {
      platform.invokeListMethod<String>('getStorageRoots').then((sr) {
        setState(() {
          storageRoots = sr.map((path) => Directory(path)).toList();
        });
      });
    } else {
      baseDirectory = Directory(widget.baseDirectory);
      openDirectory(baseDirectory);
    }
  }

  @override
  Widget build(BuildContext context) {
    String titleText;
    Widget body;

    if (directories.isEmpty && storageRoots != null) {
      titleText = 'Storage devices';
      body = ListView(
        children: storageRoots
            .map((dir) => ListTile(
                  leading: const Icon(Icons.storage),
                  title: Text(dir.path),
                  onTap: () {
                    setState(() {
                      directories.add(dir);
                    });

                    openDirectory(dir);
                  },
                ))
            .toList(),
      );
    } else if (contents != null) {
      if (directories.isEmpty) {
        titleText = 'Base directory';
      } else {
        titleText = path.basename(directories.last.path);
      }

      body = ListView(
        children: contents.map((fse) {
          Widget result;

          if (fse is Directory) {
            result = ListTile(
              leading: const Icon(Icons.folder),
              title: Text(path.basename(fse.path)),
              onTap: () {
                setState(() {
                  directories.add(fse);
                });

                openDirectory(fse);
              },
            );
          } else if (fse is File) {
            if (widget.mode == FilesSelectorMode.files) {
              result = CheckboxListTile(
                value: selectedPaths.contains(fse.path),
                secondary: Icon(Icons.insert_drive_file),
                title: Text(path.basename(fse.path)),
                onChanged: (selected) {
                  setState(() {
                    if (selected) {
                      selectedPaths.add(fse.path);
                    } else {
                      selectedPaths.remove(fse.path);
                    }
                  });
                },
              );
            } else {
              result = ListTile(
                leading: const Icon(Icons.insert_drive_file),
                title: Text(path.basename(fse.path)),
              );
            }
          }

          return result;
        }).toList(),
      );
    } else {
      body = Container();
    }

    return WillPopScope(
      child: Scaffold(
        appBar: AppBar(
          title: Text('Choose files'),
          leading: IconButton(
            icon: const Icon(Icons.close),
            onPressed: () {
              Navigator.pop(context);
            },
          ),
          actions: <Widget>[
            FlatButton(
              child: Text(
                  widget.mode == FilesSelectorMode.files ? 'DONE' : 'SELECT'),
              onPressed: () {
                Navigator.pop(
                    context,
                    widget.mode == FilesSelectorMode.files
                        ? selectedPaths
                        : directories.last?.path);
              },
            ),
          ],
        ),
        body: Column(
          children: <Widget>[
            Material(
              elevation: 2.0,
              child: ListTile(
                leading: directories.isNotEmpty
                    ? IconButton(
                        icon: const Icon(Icons.arrow_upward),
                        onPressed: up,
                      )
                    : null,
                title: Text(titleText),
              ),
            ),
            Expanded(
              child: body,
            ),
          ],
        ),
      ),
      onWillPop: () {
        if (directories.isNotEmpty) {
          up();
          return Future.value(false);
        } else {
          return Future.value(true);
        }
      },
    );
  }

  Future<void> openDirectory(Directory directory) async {
    setState(() {
      contents.clear();
    });

    final fses = await directory.list().toList();
    fses.sort((fse1, fse2) {
      int compareBasenames() =>
          path.basename(fse1.path).compareTo(path.basename(fse2.path));

      if (fse1 is Directory) {
        if (fse2 is Directory) {
          return compareBasenames();
        } else {
          return -1;
        }
      } else if (fse2 is Directory) {
        return 1;
      } else {
        return compareBasenames();
      }
    });

    setState(() {
      contents = fses;
    });
  }

  void up() {
    if (directories.isNotEmpty) {
      setState(() {
        directories.removeLast();
      });

      if (directories.isNotEmpty) {
        openDirectory(directories.last);
      } else if (baseDirectory != null) {
        openDirectory(baseDirectory);
      }
    }
  }
}