Don't display 'no item' response if another PC can shop. (#679)

These are the rules:

- If the active PC gets an empty shop, iterate from the first to last PC until finding someone who can see a shop item
    - If none can shop, show the 'no item' response
- When the active PC buys something, if this clears out the shop, iterate from the first to last PC until finding someone who can see a shop item
    - if none can see an item, stay on the empty shop of the PC that was active when the last item was bought.
- When shopping ends, if the shop interface was the last thing to change the player's active PC, it puts it back how it was.

Fix #669

src/game/boe.actions.cpp

@@ -895,6 +895,14 @@ void handle_switch_pc(short which_pc, bool& need_redraw, bool& need_reprint) {
 		add_string_to_buf("Set active: PC must be here & active.");
 	else {
 		univ.cur_pc = which_pc;
+
+		// The shop interface may have taken control of the active PC. If the player
+		// manually sets active PC before shopping ends, don't restore the active PC from before
+		// shopping switched it. Unless the player buys something again, forcing it to store again.
+		extern short store_cur_pc;
+		if(store_cur_pc != -1)
+			store_cur_pc = -1;
+
 		set_stat_window_for_pc(which_pc);
 		add_string_to_buf("Now " + std::string(overall_mode == MODE_SHOPPING ? "shopping" : "active") + ": " + pc.name);
 		adjust_spell_menus();

src/game/boe.dlgutil.cpp

@@ -98,8 +98,38 @@ std::vector<int> shop_array;
 
 cShop active_shop;
 short active_shop_num;
+short store_cur_pc = -1;
 
-bool start_shop_mode(short which,short cost_adj,std::string store_name, bool cancel_when_empty) {
+// For healing shops, other PCs might be able to buy something if
+// the active PC can't
+bool start_shop_mode_other_pc(bool allow_empty = false) {
+	// The shop might change the current PC multiple times, but we want to restore
+	// it to the original active PC when shopping ends, so only store if we're
+	// not yet storing
+	if(store_cur_pc == -1)
+		store_cur_pc = univ.cur_pc;
+
+	// But I actually want to store the PC that's active now, so if no one can buy anything but
+	// we want to leave an empty shop, we can leave the PC selection where it is.
+	short pc_buying = univ.cur_pc;
+
+	bool other_pc_can_buy = false;
+	for(int i = 0; i < 6; ++i){
+		if(univ.party[i].main_status != eMainStatus::ABSENT){
+			univ.cur_pc = i;
+			if(start_shop_mode(active_shop_num,active_shop.getCostAdjust(),save_talk_str1,true,true)){
+				other_pc_can_buy = true;
+				break;
+			}
+		}
+	}
+	if(!other_pc_can_buy && allow_empty){
+		start_shop_mode(active_shop_num,active_shop.getCostAdjust(),save_talk_str1,false,true);
+	}
+	return other_pc_can_buy;
+}
+
+bool start_shop_mode(short which,short cost_adj,std::string store_name, bool cancel_when_empty, bool already_started) {
 	rectangle area_rect;
 	if(which < 0 || which >= univ.scenario.shops.size()) {
 		showError("The scenario tried to place you in a nonexistent shop!");
@@ -138,7 +168,8 @@ bool start_shop_mode(short which,short cost_adj,std::string store_name, bool can
 	area_rect = talk_area_rect;
 	talk_gworld().create(area_rect.width(), area_rect.height());
 
-	store_pre_shop_mode = overall_mode;
+	if(!already_started)
+		store_pre_shop_mode = overall_mode;
 	overall_mode = MODE_SHOPPING;
 	stat_screen_mode = MODE_SHOP;
 	shop_sbar->setPosition(0);
@@ -167,6 +198,11 @@ void end_shop_mode() {
 		record_action("end_shop_mode", "");
 	}
 
+	if(store_cur_pc >= 0){
+		univ.cur_pc = store_cur_pc;
+		store_cur_pc = -1;
+	}
+
 	rectangle dummy_rect = {0,0,0,0};
 	
 	// This would be a place to show the text box, if I add it (and if this is not an outdoor shop).
@@ -427,8 +463,12 @@ void handle_sale(int i) {
 	// This looks to be redundant, but I'm just preserving the previous behavior of the code.
 	set_up_shop_array();
 	draw_shop_graphics(false,false,{});
-}
 
+	// When buying from a healer, we want to select the next PC who needs healing
+	if(shop_array.empty()){
+		start_shop_mode_other_pc(true);
+	}
+}
 
 void handle_info_request(int what_picked) {
 	if(recording){
@@ -899,12 +939,16 @@ void handle_talk_node(int which_talk_entry) {
 			
 		case eTalkNode::SHOP:
 			if(!start_shop_mode(b,a,save_talk_str1,true)){
-				// Second string of shop talk node: Custom message for when shop is empty
-				if(!save_talk_str2.empty()){
-					save_talk_str1 = save_talk_str2;
-					save_talk_str2 = "";
-				}else{
-					save_talk_str1 = "There is nothing available to buy.";
+				if(!start_shop_mode_other_pc()){
+					univ.cur_pc = store_cur_pc;
+
+					// Second string of shop talk node: Custom message for when shop is empty
+					if(!save_talk_str2.empty()){
+						save_talk_str1 = save_talk_str2;
+						save_talk_str2 = "";
+					}else{
+						save_talk_str1 = "There is nothing available to buy.";
+					}
 				}
 			}else{
 				can_save_talk = false;

src/game/boe.dlgutil.hpp

@@ -5,7 +5,7 @@
 #include "dialogxml/dialogs/dialog.hpp"
 #include "scenario/shop.hpp"
 
-bool start_shop_mode(short which,short cost_adj,std::string store_name, bool cancel_when_empty = false);
+bool start_shop_mode(short which,short cost_adj,std::string store_name, bool cancel_when_empty = false, bool already_started = false);
 void end_shop_mode();
 bool handle_shop_event(location p, cFramerateLimiter& fps_limiter);
 void handle_sale(int i);