feat(playlist): add M3U parser with UTF-8/Cyrillic filename support

Adds a new M3UParser class that reads .m3u and .m3u8 playlist files
and loads presets into the playlist. Handles UTF-8 encoded filenames
including Cyrillic and other non-ASCII characters correctly by:
- Opening files in binary mode to preserve UTF-8 bytes
- Stripping Windows CR line endings safely
- Using direct char comparison for '#' (0x23) instead of ctype
  functions that would misinterpret high-byte UTF-8 sequences

Fixes #962

Author: Dipendra367

src/playlist/CMakeLists.txt

@@ -26,6 +26,8 @@ add_library(projectM_playlist_main OBJECT
         Playlist.hpp
         PlaylistCWrapper.cpp
         PlaylistCWrapper.hpp
+        M3UParser.cpp
+        M3UParser.hpp
         )
 
 target_include_directories(projectM_playlist_main
@@ -188,3 +190,4 @@ if(ENABLE_INSTALL)
     endif()
 
 endif()
+

src/playlist/M3UParser.cpp

@@ -0,0 +1,64 @@
+#include "M3UParser.hpp"
+#include "Playlist.hpp"
+
+#include <fstream>
+#include <string>
+
+namespace libprojectM {
+namespace Playlist {
+
+auto M3UParser::LoadM3U(const std::string& filename,
+                        Playlist& playlist,
+                        bool allowDuplicates) -> uint32_t
+{
+    // Open in binary mode to avoid any platform newline translation
+    // that could corrupt multi-byte UTF-8 sequences
+    std::ifstream file(filename, std::ios::binary);
+    if (!file.is_open())
+    {
+        return 0;
+    }
+
+    uint32_t addedCount{0};
+    std::string line;
+
+    while (std::getline(file, line))
+    {
+        // Strip Windows-style \r (CR) from line endings.
+        // Must be done before any other checks so we don't treat
+        // "\r" as a non-empty path.
+        if (!line.empty() && line.back() == '\r')
+        {
+            line.pop_back();
+        }
+
+        // Skip empty lines
+        if (line.empty())
+        {
+            continue;
+        }
+
+        // Safe ASCII check: '#' is 0x23, always a single byte in UTF-8.
+        // We compare the raw char value directly — no ctype functions —
+        // so high-byte UTF-8 characters (e.g. Cyrillic 0xD0-0xBF) are
+        // never misidentified as comments or skipped.
+        if (line[0] == '#')
+        {
+            // M3U metadata line (e.g. #EXTM3U, #EXTINF) — skip it.
+            continue;
+        }
+
+        // Everything else is treated as a preset file path.
+        // std::string handles UTF-8 bytes transparently, so Cyrillic
+        // and other non-ASCII paths are passed through unchanged.
+        if (playlist.AddItem(line, Playlist::InsertAtEnd, allowDuplicates))
+        {
+            addedCount++;
+        }
+    }
+
+    return addedCount;
+}
+
+} // namespace Playlist
+} // namespace libprojectM

src/playlist/M3UParser.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace libprojectM {
+namespace Playlist {
+
+class Playlist;
+
+/**
+ * @brief Parses M3U and extended M3U (M3U8) playlist files.
+ *
+ * Supports UTF-8 encoded filenames, including non-ASCII characters
+ * such as Cyrillic, CJK, and other Unicode scripts.
+ */
+class M3UParser
+{
+public:
+    /**
+     * @brief Loads presets from an M3U file into the given playlist.
+     * @param filename Path to the .m3u or .m3u8 file.
+     * @param playlist The playlist to add items to.
+     * @param allowDuplicates If true, duplicate entries are allowed.
+     * @return Number of presets successfully added.
+     */
+    static auto LoadM3U(const std::string& filename,
+                        Playlist& playlist,
+                        bool allowDuplicates) -> uint32_t;
+};
+
+} // namespace Playlist
+} // namespace libprojectM