From a9c686a6afaea2393929e5e333e7a536161aeafa Mon Sep 17 00:00:00 2001
From: Reonu <danileon95@gmail.com>
Date: Wed, 22 May 2024 21:16:29 +0100
Subject: [PATCH] init automatic save backup system

---
 src/recomp/pi.cpp | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/recomp/pi.cpp b/src/recomp/pi.cpp
index 0c8a09d..224e7b0 100644
--- a/src/recomp/pi.cpp
+++ b/src/recomp/pi.cpp
@@ -96,20 +96,36 @@ struct {
 
 const std::u8string save_folder = u8"saves";
 const std::u8string save_filename = std::u8string{recomp::mm_game_id} + u8".bin";
+const std::u8string save_filename_temp = std::u8string{recomp::mm_game_id} + u8".bin.temp";
+const std::u8string save_filename_backup = std::u8string{recomp::mm_game_id} + u8".bin.bak";
 
 std::filesystem::path get_save_file_path() {
     return recomp::get_app_folder_path() / save_folder / save_filename;
 }
 
+std::filesystem::path get_save_file_path_temp() {
+    return recomp::get_app_folder_path() / save_folder / save_filename_temp;
+}
+
+std::filesystem::path get_save_file_path_backup() {
+    return recomp::get_app_folder_path() / save_folder / save_filename_backup;
+}
+
 void update_save_file() {
-    std::ofstream save_file{ get_save_file_path(), std::ios_base::binary };
+    std::ofstream save_file{ get_save_file_path_temp(), std::ios_base::binary };
 
     if (save_file.good()) {
         std::lock_guard lock{ save_context.save_buffer_mutex };
         save_file.write(save_context.save_buffer.data(), save_context.save_buffer.size());
+        if (std::filesystem::exists(get_save_file_path())) {
+            std::filesystem::rename(get_save_file_path(),get_save_file_path_backup());
+        } else {
+            printf("\nSavefile doesn't exist. Skip renaming.");
+        }
+        std::filesystem::rename(get_save_file_path_temp(),get_save_file_path());
     } else {
-        fprintf(stderr, "Failed to save!\n");
-        std::exit(EXIT_FAILURE);
+        recomp::message_box("Failed to write to the save file. Check your file permissions. If you have moved your appdata folder to Dropbox or similar, this can cause issues.");
+        //std::exit(EXIT_FAILURE);
     }
 }
 
@@ -176,6 +192,7 @@ void save_clear(uint32_t start, uint32_t size, char value) {
 
 void ultramodern::init_saving(RDRAM_ARG1) {
     std::filesystem::path save_file_path = get_save_file_path();
+    std::filesystem::path save_file_path_backup = get_save_file_path_backup();
 
     // Ensure the save file directory exists.
     std::filesystem::create_directories(save_file_path.parent_path());
@@ -185,8 +202,14 @@ void ultramodern::init_saving(RDRAM_ARG1) {
     if (save_file.good()) {
         save_file.read(save_context.save_buffer.data(), save_context.save_buffer.size());
     } else {
-        // Otherwise clear the save file to all zeroes.
-        save_context.save_buffer.fill(0);
+        // Reading the save file faield, so try to read the backup save file.
+        std::ifstream save_file_backup{ save_file_path_backup, std::ios_base::binary };
+        if (save_file_backup.good()) {
+            save_file_backup.read(save_context.save_buffer.data(), save_context.save_buffer.size());
+        } else {
+            // Otherwise clear the save file to all zeroes.
+            save_context.save_buffer.fill(0);
+        }
     }
 
     save_context.saving_thread = std::thread{saving_thread_func, PASS_RDRAM};