From 9f617cd0387e8ac3147f7cce6ca03a14fe9010d8 Mon Sep 17 00:00:00 2001
From: Leon Styhre <leon@leonstyhre.com>
Date: Mon, 19 Oct 2020 19:51:19 +0200
Subject: [PATCH] Entries for missing files are now retained for custom
 collections.

---
 es-app/src/CollectionSystemManager.cpp | 50 +++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/es-app/src/CollectionSystemManager.cpp b/es-app/src/CollectionSystemManager.cpp
index 38857a6ca..09c642dda 100644
--- a/es-app/src/CollectionSystemManager.cpp
+++ b/es-app/src/CollectionSystemManager.cpp
@@ -142,13 +142,36 @@ void CollectionSystemManager::saveCustomCollection(SystemData* sys)
     if (found) {
         CollectionSystemData sysData = mCustomCollectionSystemsData.at(name);
         if (sysData.needsSave) {
-            std::ofstream configFile;
+            // Read back any entries from the configuration file for game files that are
+            // currently missing, and combine them with the active content. If we wouldn't do
+            // this, they would be purged from the collection. Maybe a directory has been
+            // temporarily moved or the files are not reachable for whatever reason. It would
+            // be incredibly annoying to have entries purged from the collection in such
+            // instances. Using the logic below, the handling of custom collections corresponds
+            // to the handling of gamelist.xml files, i.e. it's up to the user to make a
+            // conscious decision of what entries to remove.
+            std::vector<std::string> fileGameEntries;
+            std::vector<std::string> activeGameEntries;
+            std::ifstream configFileIn;
+            std::ofstream configFileOut;
+
             #if defined(_WIN64)
-            configFile.open(Utils::String::
+            configFileIn.open(Utils::String::
                     stringToWideString(getCustomCollectionConfigPath(name)).c_str());
             #else
-            configFile.open(getCustomCollectionConfigPath(name));
+            configFileIn.open(getCustomCollectionConfigPath(name));
             #endif
+            for (std::string gameEntry; getline(configFileIn, gameEntry); ) {
+                std::string gamePath = Utils::String::replace(gameEntry, "%ROMPATH%", rompath);
+                gamePath = Utils::String::replace(gamePath, "//", "/");
+                // Only add the entry if it's not a regular file or a symlink, in other words
+                // only add missing files.
+                if (!Utils::FileSystem::isRegularFile(gamePath) &&
+                        !Utils::FileSystem::isSymlink(gamePath))
+                    fileGameEntries.push_back(gameEntry);
+            }
+            configFileIn.close();
+
             for (std::unordered_map<std::string, FileData*>::const_iterator
                     iter = games.cbegin(); iter != games.cend(); ++iter) {
                 std::string path = iter->first;
@@ -157,9 +180,26 @@ void CollectionSystemManager::saveCustomCollection(SystemData* sys)
                 if (path.find(rompath) == 0)
                     path.replace(0, rompath.size(), "%ROMPATH%/");
 
-                configFile << path << std::endl;
+                activeGameEntries.push_back(path);
             }
-            configFile.close();
+
+            fileGameEntries.insert(fileGameEntries.cend(), activeGameEntries.cbegin(),
+                    activeGameEntries.cend());
+            std::sort(fileGameEntries.begin(), fileGameEntries.end());
+            auto last = std::unique(fileGameEntries.begin(), fileGameEntries.end());
+            fileGameEntries.erase(last, fileGameEntries.end());
+
+            #if defined(_WIN64)
+            configFile.open(Utils::String::
+                    stringToWideString(getCustomCollectionConfigPath(name)).c_str());
+            #else
+            configFileOut.open(getCustomCollectionConfigPath(name));
+            #endif
+
+            for (auto it = fileGameEntries.cbegin(); it != fileGameEntries.cend(); it++)
+                configFileOut << (*it) << std::endl;
+
+            configFileOut.close();
         }
     }
     else {