[ai] alphabetical order

src/DirectoryNode.cpp

@@ -1,5 +1,6 @@
 #include "DirectoryNode.h"
 #include "globals.h"
+#include <algorithm>
 
 DirectoryNode::DirectoryNode(const String &nodeName)
     : name(nodeName), currentPlaying(nullptr)
@@ -97,10 +98,9 @@ void DirectoryNode::buildDirectoryTree(const char *currentPath)
     mp3Files.clear();
     ids.clear();
 
-    // Reserve memory to reduce heap fragmentation (optimization 3)
-    subdirectories.reserve(8); // Reserve space for 8 subdirectories
-    mp3Files.reserve(16);      // Reserve space for 16 MP3 files
-    ids.reserve(16);           // Reserve space for 16 IDs
+    // First collect entries so we can sort them alphabetically
+    std::vector<String> dirNames;
+    std::vector<String> fileNames;
 
     File rootDir = SD.open(currentPath);
     while (true)
@@ -113,22 +113,61 @@ void DirectoryNode::buildDirectoryTree(const char *currentPath)
 
         if (entry.isDirectory() && entry.name()[0] != '.' && strcmp(entry.name(), sys_dir.c_str()))
         {
-            DirectoryNode *newNode = new DirectoryNode(entry.name());
-            subdirectories.push_back(newNode);
-            newNode->buildDirectoryTree((String(currentPath) + entry.name()).c_str());
+            dirNames.push_back(String(entry.name()));
         }
-        else if (String(entry.name()).endsWith(".mp3") || String(entry.name()).endsWith(".MP3"))
+        else
         {
-            String fullPath = String(currentPath);
-            if (!fullPath.endsWith("/"))
-                fullPath += "/";
-            fullPath += entry.name();
-            mp3Files.push_back(fullPath);
-            ids.push_back(getNextId());
+            String entryName = entry.name();
+            if (entryName.endsWith(".mp3") || entryName.endsWith(".MP3"))
+            {
+                fileNames.push_back(entryName);
+            }
         }
         entry.close();
     }
     rootDir.close();
+
+    // Case-insensitive alphabetical sort
+    auto ciLess = [](const String &a, const String &b) {
+        String al = a;
+        String bl = b;
+        al.toLowerCase();
+        bl.toLowerCase();
+        return al.compareTo(bl) < 0;
+    };
+    std::sort(dirNames.begin(), dirNames.end(), ciLess);
+    std::sort(fileNames.begin(), fileNames.end(), ciLess);
+
+    // Reserve memory to reduce heap fragmentation
+    subdirectories.reserve(dirNames.size());
+    mp3Files.reserve(fileNames.size());
+    ids.reserve(fileNames.size());
+
+    // Create subdirectories in alphabetical order
+    for (const String &dirName : dirNames)
+    {
+        DirectoryNode *newNode = new DirectoryNode(dirName);
+        subdirectories.push_back(newNode);
+
+        String childPath = String(currentPath);
+        if (!childPath.endsWith("/"))
+            childPath += "/";
+        childPath += dirName;
+
+        newNode->buildDirectoryTree(childPath.c_str());
+    }
+
+    // Add MP3 files in alphabetical order
+    for (const String &fileName : fileNames)
+    {
+        String fullPath = String(currentPath);
+        if (!fullPath.endsWith("/"))
+            fullPath += "/";
+        fullPath += fileName;
+
+        mp3Files.push_back(fullPath);
+        ids.push_back(getNextId());
+    }
 }
 
 void DirectoryNode::printDirectoryTree(int level) const