fix campaign reset wiping player stats

code/menuui/readyroom.cpp

@@ -1575,22 +1575,40 @@ void campaign_room_scroll_info_down()
 
 void campaign_reset(const SCP_string& campaign_file)
 {
+	Assert(Player != nullptr);
+
+	// if the caller is resetting a campaign other than the active one (only reachable via the Lua resetCampaign API),
+	// we can't go through mission_campaign_load(): that would swap the global Campaign struct over to the target
+	// campaign and overwrite Player->stats with the wrong running totals.  Just delete the CSG; the next time the
+	// player activates this campaign, mission_campaign_load() will recreate a fresh one.
+	if (stricmp(campaign_file.c_str(), Campaign.filename) != 0) {
+		mission_campaign_savefile_delete(campaign_file.c_str());
+		return;
+	}
+
 	// note: we do not toss all-time stats from player's performance in campaign up till now
+	// save stats before the reset because csg_reset_data() will zero them when the deleted CSG is not found
+	scoring_struct saved_stats = Player->stats;
+
 	mission_campaign_savefile_delete(campaign_file.c_str());
 
 	const int load_status = mission_campaign_load(campaign_file.c_str(), nullptr, nullptr, 1);
 
+	// restore the stats that were cleared during the campaign reload
+	Player->stats = saved_stats;
+
 	// see if we successfully loaded this campaign
 	if (load_status == 0) {
 		// Goober5000 - reinitialize tech database if needed
 		if ((Campaign.flags & CF_CUSTOM_TECH_DATABASE) || !stricmp(Campaign.filename, "freespace2")) {
 			// reset tech database to what's in the tables
 			tech_reset_to_default();
-
-			// write the savefile so that we don't later load a stale techroom
-			Pilot.save_savefile();
 		}
 
+		// re-save the savefile so the CSG persists the restored stats (and the tech database reset, if applicable);
+		// mission_campaign_load() already wrote a fresh CSG with zeroed stats when it found no existing savefile
+		Pilot.save_savefile();
+
 		if (OnCampaignBeginHook->isActive()) {
 			OnCampaignBeginHook->run(scripting::hook_param_list(scripting::hook_param("Campaign", 's', Campaign.filename)));
 		}

code/playerman/player.h

@@ -123,7 +123,7 @@ class player
 	int				objnum;										// object number for this player
 	button_info		bi;												// structure that holds bit vectors for button presses
 	control_info	ci;											// control info structure for this player
-	scoring_struct	stats;										// scoring and stats info for the player (points to multi_stats or single_stats)	
+	scoring_struct	stats;										// scoring and stats info for the player that are currently accumulating; loaded from multi_stats or all_time_stats
 
 	int				friendly_hits;								//	Number of times hit a friendly ship this mission.
 	float				friendly_damage;							//	Total friendly damage done in mission.  Diminishes over time.

code/scripting/api/objs/player.cpp

@@ -66,14 +66,17 @@ player_h& player_h::operator=(player_h&& other) noexcept
 ADE_OBJ(l_Player, player_h, "player", "Player handle");
 
 
-ADE_VIRTVAR(Stats, l_Player, "scoring_stats stats", "The scoring stats of this player (read-only)", "scoring_stats", "The player stats or invalid handle") {
+ADE_VIRTVAR(Stats, l_Player, "scoring_stats stats", "The scoring stats of this player that are currently accumulating, e.g. from a campaign or multiplayer session; read-only", "scoring_stats", "The player stats or invalid handle") {
 	player_h* plr;
 	if (!ade_get_args(L, "o", l_Player.GetPtr(&plr)))
 		return ade_set_error(L, "o", l_ScoringStats.Set(scoring_stats_h()));
 
 	if (!plr->isValid())
 		return ade_set_error(L, "o", l_ScoringStats.Set(scoring_stats_h()));
 
+	if (ADE_SETTING_VAR)
+		LuaError(L, "This property is read only.");
+
 	return ade_set_args(L, "o", l_ScoringStats.Set(scoring_stats_h(plr->get()->stats, plr->get())));
 }