added first version of m3u parser (only parse what we need)

2018-12-07 23:30:48 +01:00
parent f1bd8a63fc
commit d36d91cfbc
4 changed files with 192 additions and 0 deletions
--- a/Parser/IPlaylistParser.cs
+++ b/Parser/IPlaylistParser.cs
@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+
+namespace Tv7Playlist.Parser
+{
+    public interface IPlaylistParser
+    {
+        Task<IReadOnlyCollection<ParsedTrack>> ParseFromStream(Stream stream);
+    }
+}
--- a/Parser/M3UParser.cs
+++ b/Parser/M3UParser.cs
@@ -0,0 +1,129 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Internal;
+using Microsoft.Extensions.Logging;
+
+namespace Tv7Playlist.Parser
+{
+    internal class M3UParser : IPlaylistParser
+    {
+        private const string ExtInfStartTag = "#EXTINF:";
+        private const string ExtFileStartTag = "#EXTM3U"; 
+
+        private readonly ILogger<M3UParser> _logger;
+
+        public M3UParser(ILogger<M3UParser> logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public async Task<IReadOnlyCollection<ParsedTrack>> ParseFromStream(Stream stream)
+        {
+            if (stream == null) throw new ArgumentNullException(nameof(stream));
+
+            _logger.LogInformation(LoggingEvents.ParsingM3uPlayList, "Parsing m3u file content");
+            
+            EnsureStreamIsAtBeginning(stream);
+            
+            using (var reader = new StreamReader(stream))
+            {
+                var tracks = await ParseTracksFromStreamAsync(reader);
+                
+                _logger.LogInformation(LoggingEvents.ParsingM3uPlayList, "Parsing m3u file finished");
+
+                return tracks;
+            }
+        }
+
+        private async Task<IReadOnlyCollection<ParsedTrack>> ParseTracksFromStreamAsync(StreamReader reader)
+        {
+            if (reader == null) throw new ArgumentNullException(nameof(reader));
+
+            if (!await StreamHasValidStartTagAsync(reader))
+            {
+                _logger.LogError(LoggingEvents.ParsingM3uPlayList, $"Could not parse stream as it did not start with {ExtFileStartTag}");
+                return new List<ParsedTrack>(300);
+            }
+
+            var tracks = new List<ParsedTrack>(300);
+            var currentId = 1000;
+
+            while (!reader.EndOfStream)
+            {
+                await ParseTracksAsync(reader, tracks, currentId);
+                currentId++;
+            }
+
+            return tracks;
+        }
+
+        private static async Task<bool> StreamHasValidStartTagAsync(StreamReader reader)
+        {
+            var startLine = await ReadLineSafeAsync(reader);
+            var stramHasValidStartTag = !startLine.Trim().ToUpper().Equals(ExtInfStartTag);
+            return stramHasValidStartTag;
+        }
+
+        private void EnsureStreamIsAtBeginning(Stream stream)
+        {
+            if (stream.Position == 0) return;
+            
+            _logger.LogWarning(LoggingEvents.ParsingM3uPlayList, "Stream not positioned at the beginning. Repositioning!");
+            stream.Position = 0;
+        }
+
+        private async Task ParseTracksAsync(TextReader reader, ICollection<ParsedTrack> tracks, int currentId)
+        {
+            if (reader == null) throw new ArgumentNullException(nameof(reader));
+            if (tracks == null) throw new ArgumentNullException(nameof(tracks));
+            if (currentId <= 0) throw new ArgumentOutOfRangeException(nameof(currentId));
+
+            var metaLine = await ReadLineSafeAsync(reader);            
+            if (!metaLine.StartsWith(ExtInfStartTag))
+            {
+                _logger.LogDebug(LoggingEvents.ParsingM3uPlayList,
+                    "Line {lineNumber} {metaLine} is not a valid start channel start line",
+                    currentId.ToString(), metaLine);
+                return;
+            }
+
+            var url = await ReadLineSafeAsync(reader);
+            var track = CreateTrack(currentId, metaLine, url);
+            if (track != null)
+            {
+                tracks.Add(track);
+                _logger.LogDebug(LoggingEvents.ParsingM3uPlayList, "Parsed track {track}", track);
+            }
+            else
+            {
+                _logger.LogWarning(LoggingEvents.ParsingM3uPlayList,
+                    "Could not parse lines {metaLine} with url {url}", metaLine, url);
+            }
+        }
+
+        private static async Task<string> ReadLineSafeAsync(TextReader reader)
+        {
+            if (reader == null) throw new ArgumentNullException(nameof(reader));
+            
+            var line = await reader.ReadLineAsync();
+            
+            return line ?? string.Empty;
+        }
+
+        private ParsedTrack CreateTrack(int currentId, string metaLine, string url)
+        {
+            if (string.IsNullOrWhiteSpace(metaLine))
+                return null;
+
+            if (string.IsNullOrWhiteSpace(url))
+                return null;
+
+            var fields = metaLine.Replace(ExtInfStartTag, string.Empty).Split(",");
+            var name = fields.Length >= 2 ? fields[1] : $"{currentId}-unknown";
+            
+            return new ParsedTrack(currentId, name, url);
+        }
+    }
+}
--- a/Parser/ParsedTrack.cs
+++ b/Parser/ParsedTrack.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Diagnostics;
+
+namespace Tv7Playlist.Parser
+{
+    [DebuggerDisplay("ParsedTrack-{Id}(Name:{Name}, Url:{Url})")]
+    public class ParsedTrack
+    {
+        public ParsedTrack(int id, string name, string url)
+        {
+            Id = id;
+            Name = name;
+            Url = url ?? throw new ArgumentNullException(nameof(url));
+        }
+
+        public int Id { get; }
+
+        public string Name { get; }
+
+        public string Url { get; }
+
+        protected bool Equals(ParsedTrack other)
+        {
+            return Id == other.Id && string.Equals(Name, other.Name) && string.Equals(Url, other.Url);
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(null, obj)) return false;
+            if (ReferenceEquals(this, obj)) return true;
+            if (obj.GetType() != GetType()) return false;
+            return Equals((ParsedTrack) obj);
+        }
+
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                var hashCode = Id;
+                hashCode = (hashCode * 397) ^ (Name != null ? Name.GetHashCode() : 0);
+                hashCode = (hashCode * 397) ^ (Url != null ? Url.GetHashCode() : 0);
+                return hashCode;
+            }
+        }
+
+        public override string ToString()
+        {
+            return $"{nameof(Id)}: {Id}, {nameof(Name)}: {Name}, {nameof(Url)}: {Url}";
+        }
+    }
+}