refactor: extract image selection logic into dedicated helper

Introduces a new ImagePicker helper that consolidates duplicate wallpaper
selection logic from Hyprpaper.cpp and ConfigManager.cpp into a single
reusable function.

- Add new ImagePicker.{hpp,cpp} with getRandomImageFromDirectory() helper
- Function handles directory scanning, file extension validation, and random selection
- Supports excluding current wallpaper to avoid duplicate selections
- Updates both wallpaper loading code paths to use the new helper
- Uses std::shuffle instead of random index for better randomization

This change improves code maintainability by removing duplicate logic and
centralizing image selection behavior in a single location.

src/Hyprpaper.cpp

@@ -4,6 +4,7 @@
 #include <signal.h>
 #include <sys/types.h>
 #include "helpers/RandomGenerator.hpp"
+#include "helpers/ImagePicker.hpp"
 
 CHyprpaper::CHyprpaper() = default;
 
@@ -180,21 +181,13 @@ void CHyprpaper::preloadAllWallpapersFromConfig() {
                 unloadWallpaper(path);
             }
 
-            std::vector<std::filesystem::path> images;
-            for (auto& entry : std::filesystem::directory_iterator(wp)) {
-                if (entry.is_regular_file()) {
-                    auto ext = entry.path().extension().string();
-                    if (ext == ".png" || ext == ".jpg" || ext == ".jpeg" || ext == ".webp" || ext == ".jxl")
-                        images.push_back(entry.path());
-                }
-            }
-            if (!images.empty()) {
-                // Use CRandomGenerator instead
-                wp = images[CRandomGenerator::get().getRandomIndex(images.size())].string();
-            } else {
+            // Use our helper to pick a random image.
+            std::string randomImage = getRandomImageFromDirectory(wp);
+            if (randomImage.empty()) {
                 Debug::log(LOG, "No valid images in directory {}", wp);
                 continue;
             }
+            wp = randomImage;
         }
 
         // For non-directory requests, skip if already loaded.

src/config/ConfigManager.cpp

@@ -3,6 +3,7 @@
 #include <hyprutils/path/Path.hpp>
 #include <filesystem>
 #include "../helpers/RandomGenerator.hpp"
+#include "../helpers/ImagePicker.hpp"
 
 // Utility function to safely expand a tilde at the beginning of a path.
 static std::string expandTilde(const std::string& path) {
@@ -61,28 +62,13 @@ static Hyprlang::CParseResult handleWallpaper(const char* C, const char* V) {
             }
         }
 
-        std::vector<std::filesystem::path> images;
-        for (auto& entry : std::filesystem::directory_iterator(WALLPAPER)) {
-            if (entry.is_regular_file()) {
-                auto ext = entry.path().extension().string();
-                if (ext == ".png" || ext == ".jpg" || ext == ".jpeg" || ext == ".webp" || ext == ".jxl") {
-                    if (entry.path().string() != currentWallpaper) {
-                        images.push_back(entry.path());
-                    }
-                }
-            }
+        // Use our helper with an exclusion to avoid reselecting the same image.
+        std::string randomImage = getRandomImageFromDirectory(WALLPAPER, currentWallpaper);
+        if (randomImage.empty()) {
+            result.setError("No valid images in directory");
+            return result;
         }
-        
-        if (images.empty()) {
-            if (!currentWallpaper.empty()) {
-                images.push_back(currentWallpaper);
-            } else {
-                result.setError("No valid images in directory");
-                return result;
-            }
-        }
-
-        WALLPAPER = images[CRandomGenerator::get().getRandomIndex(images.size())].string();
+        WALLPAPER = randomImage;
     }
 
     if (!g_pHyprpaper->isPreloaded(WALLPAPER)) {

src/helpers/ImagePicker.cpp

@@ -0,0 +1,30 @@
+#include "ImagePicker.hpp"
+#include "RandomGenerator.hpp"
+#include <filesystem>
+#include <vector>
+#include <algorithm>
+
+std::string getRandomImageFromDirectory(const std::string &dirPath, const std::string &ignore) {
+    std::vector<std::filesystem::path> images;
+    for (const auto &entry : std::filesystem::directory_iterator(dirPath)) {
+        if (entry.is_regular_file()) {
+            auto ext = entry.path().extension().string();
+            if ((ext == ".png" || ext == ".jpg" || ext == ".jpeg" ||
+                 ext == ".webp" || ext == ".jxl")) {
+                if (ignore.empty() || entry.path().string() != ignore) {
+                    images.push_back(entry.path());
+                }
+            }
+        }
+    }
+
+    if (images.empty()) {
+        // If no alternative was found but the ignored file exists, return it.
+        if (!ignore.empty() && std::filesystem::exists(ignore))
+            return ignore;
+        return "";
+    }
+
+    std::shuffle(images.begin(), images.end(), CRandomGenerator::get().getGenerator());
+    return images.front().string();
+}

src/helpers/ImagePicker.hpp

@@ -0,0 +1,7 @@
+#pragma once
+#include <string>
+
+// Returns a random image path from the given directory.
+// If 'ignore' is provided, that file (if present) will be excluded from the selection.
+// Returns an empty string if no valid image is found.
+std::string getRandomImageFromDirectory(const std::string &dirPath, const std::string &ignore = "");