feat: read and parse Simfiles

lib/level.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 
 import 'package:flutter/material.dart';
 import 'package:audioplayers/audioplayers.dart';
+import 'package:sense_the_rhythm/simfile.dart';
 
 class Level extends StatefulWidget {
   const Level({super.key, required this.stepmaniaFolderPath});
@@ -14,6 +15,7 @@ class Level extends StatefulWidget {
 
 class _LevelState extends State<Level> {
   final player = AudioPlayer();
+  Simfile? simfile;
   bool _isPlaying = true;
   Duration? _duration;
   Duration? _position;
@@ -51,10 +53,7 @@ class _LevelState extends State<Level> {
     _positionSubscription = player.onPositionChanged.listen(
       (p) => setState(() => _position = p),
     );
-  }
 
-  @override
-  Widget build(BuildContext context) {
     player.onDurationChanged.listen((Duration d) {
       // print('Max duration: $d');
       setState(() => _duration = d);
@@ -65,12 +64,29 @@ class _LevelState extends State<Level> {
       setState(() => _position = p);
     });
 
+    String simfilePath = Directory(widget.stepmaniaFolderPath)
+        .listSync()
+        .firstWhere((entity) => entity.path.endsWith('.sm'),
+            orElse: () => File(''))
+        .path;
+
     String audioPath = Directory(widget.stepmaniaFolderPath)
         .listSync()
         .firstWhere((entity) => entity.path.endsWith('.ogg'),
             orElse: () => File(''))
         .path;
+
+    simfile = Simfile(simfilePath);
+    simfile!.load();
+
+    print(audioPath);
+
     player.play(DeviceFileSource(audioPath));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+
     return Scaffold(
         appBar: AppBar(
           leading: IconButton(

lib/simfile.dart

@@ -0,0 +1,89 @@
+import 'dart:io';
+
+enum Difficulty { Beginner, Easy, Medium, Hard, Challenge, Edit }
+
+// These are the standard note values:
+//
+//     0 – No note
+//     1 – Normal note
+//     2 – Hold head
+//     3 – Hold/Roll tail
+//     4 – Roll head
+//     M – Mine (or other negative note)
+//
+// Later versions of StepMania accept other note values which may not work in older versions:
+//
+//     K – Automatic keysound
+//     L – Lift note
+//     F – Fake note
+
+RegExp noteTypes = RegExp(r'^([012345MKLF]+)\s*([,;])?');
+
+class Chart {
+  String? chartType;
+  // Description/author
+  String? author;
+  // Difficulty (one of Beginner, Easy, Medium, Hard, Challenge, Edit)
+  Difficulty? difficulty;
+  // Numerical meter
+  int? numericalMeter;
+  // Groove radar values, generated by the program
+  String? radarValues;
+
+  List<List<String>>? measures;
+}
+
+class Simfile {
+  String path;
+  String? lines;
+
+  // tags of simfile
+  Map<String, String> tags = {};
+
+  Chart? chartSimplest;
+
+  Simfile(this.path);
+
+  void load() {
+    lines = File(path).readAsStringSync();
+
+    RegExp commentsRegExp = RegExp(r'//.*$');
+    lines = lines?.replaceAll(commentsRegExp, '');
+    RegExp fieldDataRegExp = RegExp(r'#([^;]+):([^;]*);');
+
+    for (final fieldData in fieldDataRegExp.allMatches(lines!)) {
+      List<String> keys =
+          fieldData[1]!.split(':').map((key) => key.trim()).toList();
+      String value = fieldData[2]!;
+      if (keys[0] != "NOTES") {
+        tags[keys[0]] = value;
+        continue;
+      }
+
+      Chart chart = Chart();
+      chart.chartType = keys[1];
+      chart.author = keys[2];
+      chart.difficulty = Difficulty.values.byName(keys[3]);
+      chart.numericalMeter = int.parse(keys[4]);
+      chart.radarValues = keys[5];
+
+      if (chartSimplest == null ||
+          (chart.difficulty!.index <= chartSimplest!.difficulty!.index &&
+              chart.numericalMeter! <= chartSimplest!.numericalMeter!)) {
+        List<List<String>> measures = [];
+        for (final measureRaw in value.split(',')) {
+          List<String> measure = [];
+          for (final noteRaw in measureRaw.split('\n')) {
+            String note = noteRaw.trim();
+            if (noteTypes.hasMatch(note)) {
+              measure.add(note);
+            }
+          }
+          measures.add(measure);
+        }
+        chart.measures = measures;
+        chartSimplest = chart;
+      }
+    }
+  }
+}