Add u_buy_monster talk effect (CleverRaven#33446)

* Add u_buy_monster talk effect

* Update u_buy_monster name to be translatable

doc/NPCs.md

@@ -449,6 +449,8 @@ Effect | Description
 `add_debt: mod_list` | Increases the NPC's debt to the player by the values in the `mod_list`.<br/>The following would increase the NPC's debt to the player by 1500x the NPC's altruism and 1000x the NPC's opinion of the player's value: `{ "effect": { "add_debt": [ [ "ALTRUISM", 3 ], [ "VALUE", 2 ], [ "TOTAL", 500 ] ] } }`
 `u_consume_item`, `npc_consume_item: item_string`, (*optional* `count: count_num`) | You or the NPC will delete the item or `count_num` copies of the item from their inventory.<br/>This effect will fail if the you or NPC does not have at least `count_num` copies of the item, so it should be checked with `u_has_items` or `npc_has_items`.
 `u_remove_item_with`, `npc_remove_item_with: item_string` | You or the NPC will delete any instances of item in inventory.<br/>This is an unconditional remove and will not fail if you or the NPC does not have the item.
+`u_buy_monster: monster_type_string`, (*optional* `cost: cost_num`, *optional* `count: count_num`, *optional* `name: name_string`, *optional* `pacified: pacified_bool`) | The NPC will give your character `count_num` (default 1) instances of the monster as pets and will subtract `cost_num` from `op_of_u.owed` if specified.  If the `op_o_u.owed` is less than `cost_num`, the trade window will open and the player will have to trade to make up the difference; the NPC will not give the player the item unless `cost_num` is satisfied.<br/>If cost isn't present, the NPC gives your character the item at no charge.<br/>If `name_string` is specified the monster(s) will have the specified name. If `pacified_bool` is set to true, the monster will have the pacified effect applied.
+
 
 #### Behaviour / AI
 

src/npctalk.cpp

@@ -32,6 +32,7 @@
 #include "json.h"
 #include "line.h"
 #include "map.h"
+#include "map_iterator.h"
 #include "mapgen_functions.h"
 #include "martialarts.h"
 #include "messages.h"
@@ -2303,6 +2304,14 @@ void talk_effect_t::parse_sub_effect( JsonObject jo )
         subeffect_fun.set_npc_cbm_recharge_rule( setting );
     } else if( jo.has_member( "mapgen_update" ) ) {
         subeffect_fun.set_mapgen_update( jo, "mapgen_update" );
+    } else if( jo.has_string( "u_buy_monster" ) ) {
+        const std::string &monster_type_id = jo.get_string( "u_buy_monster" );
+        const int cost = jo.get_int( "cost", 0 );
+        const int count = jo.get_int( "count", 1 );
+        const bool pacified = jo.get_bool( "pacified", false );
+        translation name;
+        jo.read( "name", name );
+        subeffect_fun.set_u_buy_monster( monster_type_id, cost, count, pacified, name );
     } else {
         jo.throw_error( "invalid sub effect syntax :" + jo.str() );
     }