1 files changed, 119 insertions, 0 deletions
diff --git a/libs/installer_fomod_plus/share/FOMODData/PluginReader.h b/libs/installer_fomod_plus/share/FOMODData/PluginReader.h
new file mode 100644
index 0000000..dade7e1
--- /dev/null
+++ b/libs/installer_fomod_plus/share/FOMODData/PluginReader.h
@@ -0,0 +1,119 @@
+#pragma once
+
+#include <fstream>
+#include <string>
+#include <vector>
+#include <cstdint>
+#include <unordered_set>
+
+static const std::unordered_set<std::string> VANILLA_MASTERS = {
+    "Skyrim.esm",
+    "Update.esm",
+    "Dawnguard.esm",
+    "HearthFires.esm",
+    "Dragonborn.esm"
+};
+
+class PluginReader {
+public:
+
+    /**
+     * Reads the master files from a Bethesda plugin file (ESP/ESM/ESL)
+     * @param filePath Path to the plugin file
+     * @param trimVanilla Exclude the vanilla game masters or not. Mostly to save DB space.
+     * @return Vector of master filenames
+     */
+    static std::vector<std::string> readMasters(const std::string& filePath, const bool trimVanilla = false)
+    {
+        std::vector<std::string> masters;
+        std::ifstream file(filePath, std::ios::binary);
+
+        if (!file) {
+            return masters;
+        }
+
+        // Check TES4 record signature
+        char signature[4];
+        file.read(signature, 4);
+        if (strncmp(signature, "TES4", 4) != 0) {
+            return masters;
+        }
+
+        // Read record size
+        uint32_t recordSize;
+        file.read(reinterpret_cast<char*>(&recordSize), 4);
+
+        constexpr uint32_t skipSize = sizeof(uint32_t) // flags
+        + sizeof(uint32_t) // formId
+        + sizeof(uint16_t) // timestamp
+        + sizeof(uint16_t) // version control
+        + sizeof(uint16_t) // internal version
+        + sizeof(uint16_t); // unknown
+
+        // Skip header flags, formID, etc. (total 8 bytes)
+        file.seekg(skipSize, std::ios::cur);
+
+        // Calculate where the TES4 record ends
+        std::streampos recordEnd = file.tellg() + static_cast<std::streampos>(recordSize);
+
+        // Read subrecords until we reach the end of the TES4 record
+        while (file && file.tellg() < recordEnd) {
+            char subRecordType[4];
+            uint16_t subRecordSize;
+
+            // Read subrecord type and size
+            file.read(subRecordType, 4);
+            file.read(reinterpret_cast<char*>(&subRecordSize), 2);
+
+            if (strncmp(subRecordType, "MAST", 4) == 0) {
+                // Read master filename (null-terminated string)
+                std::string masterName;
+                masterName.resize(subRecordSize);
+                file.read(masterName.data(), subRecordSize);
+
+                // Remove null terminator if present
+                if (!masterName.empty() && masterName.back() == '\0') {
+                    masterName.pop_back();
+                }
+
+                // Only add if it's not a vanilla master or if we're not trimming
+                if (!trimVanilla || !VANILLA_MASTERS.contains(masterName)) {
+                    masters.push_back(masterName);
+                }
+
+                // Each MAST is followed by a DATA subrecord
+                char dataType[4];
+                uint16_t dataSize;
+                file.read(dataType, 4);
+                file.read(reinterpret_cast<char*>(&dataSize), 2);
+
+                // Skip DATA content (usually an 8-byte value)
+                file.seekg(dataSize, std::ios::cur);
+            } else {
+                // Skip other subrecord types
+                file.seekg(subRecordSize, std::ios::cur);
+            }
+        }
+
+        return masters;
+    }
+
+    /**
+     * Checks if a file is a valid Bethesda plugin (ESP/ESM/ESL)
+     * @param filePath Path to the file
+     * @return True if the file is a valid plugin
+     */
+    static bool isValidPlugin(const std::string& filePath)
+    {
+        std::ifstream file(filePath, std::ios::binary);
+
+        if (!file) {
+            return false;
+        }
+
+        char signature[4];
+        file.read(signature, 4);
+
+        return strncmp(signature, "TES4", 4) == 0;
+    }
+};
+\ No newline at end of file