Transformation use action can pick random item from itemgroups (#77893)

* transformation use action can pick random item from itemgroups

* add some description for use action

doc/JSON_INFO.md

@@ -4508,6 +4508,7 @@ The contents of `use_action` fields can either be a string indicating a built-in
 "use_action": {
   "type": "transform",                      // The type of method, in this case one that transforms the item
   "target": "gasoline_lantern_on",          // The item to transform to
+  "target_group": "twisted_geometry",       // If used, target is a random item from itemgroup
   "variant_type": "condom_plain",           // (optional) Defaults to `<any>`. Specific variant type to set for the transformed item. Special string `<any>` will pick a random variant from all available variants, based on the variant's defined weight
   "active": true,                           // Whether the item is active once transformed
   "ammo_scale": 0,                          // For use when an item automatically transforms into another when its ammo drops to 0, or to allow guns to transform with 0 ammo

src/iuse_actor.cpp

@@ -171,6 +171,11 @@ std::unique_ptr<iuse_actor> iuse_transform::clone() const
 void iuse_transform::load( const JsonObject &obj, const std::string & )
 {
     obj.read( "target", target, true );
+    obj.read( "target_group", target_group, true );
+
+    if( !target.is_empty() && !target_group.is_empty() ) {
+        obj.throw_error_at( "target_group", "Cannot use both target and target_group at once" );
+    }
 
     obj.read( "msg", msg_transform );
     obj.read( "variant_type", variant_type );
@@ -272,7 +277,8 @@ std::optional<int> iuse_transform::use( Character *p, item &it, const tripoint &
         }
     }
 
-    if( it.count_by_charges() != target->count_by_charges() && it.count() > 1 ) {
+    if( target_group.is_empty() && it.count_by_charges() != target->count_by_charges() &&
+        it.count() > 1 ) {
         item take_one = it.split( 1 );
         do_transform( p, take_one, variant_type );
         p->i_add_or_drop( take_one );
@@ -293,8 +299,12 @@ void iuse_transform::do_transform( Character *p, item &it, const std::string &va
     // defined here to allow making a new item assigned to the pointer
     item obj_it;
     if( container.is_empty() ) {
-        obj = &it.convert( target, p );
-        obj->set_itype_variant( variant_type );
+        if( !target_group.is_empty() ) {
+            obj = &it.convert( item_group::item_from( target_group ).typeId(), p );
+        } else {
+            obj = &it.convert( target, p );
+            obj->set_itype_variant( variant_type );
+        }
         if( ammo_qty >= 0 || !random_ammo_qty.empty() ) {
             int qty;
             if( !random_ammo_qty.empty() ) {
@@ -320,7 +330,9 @@ void iuse_transform::do_transform( Character *p, item &it, const std::string &va
         obj->set_itype_variant( variant_type );
         int count = std::max( ammo_qty, 1 );
         item cont;
-        if( target->count_by_charges() ) {
+        if( !target_group.is_empty() ) {
+            cont = item( item_group::item_from( target_group ).typeId(), calendar::turn );
+        } else if( target->count_by_charges() ) {
             cont = item( target, calendar::turn, count );
             count = 1;
         } else {
@@ -423,7 +435,7 @@ std::string iuse_transform::get_name() const
 
 void iuse_transform::finalize( const itype_id & )
 {
-    if( !item::type_is_defined( target ) ) {
+    if( !item::type_is_defined( target ) && target_group.is_empty() ) {
         debugmsg( "Invalid transform target: %s", target.c_str() );
     }
 
@@ -439,6 +451,11 @@ void iuse_transform::finalize( const itype_id & )
 
 void iuse_transform::info( const item &it, std::vector<iteminfo> &dump ) const
 {
+
+    if( !target_group.is_empty() ) {
+        dump.emplace_back( "TOOL", _( "Can transform into one of several items" ) );
+        return;
+    }
     int amount = std::max( ammo_qty, 1 );
     item dummy( target, calendar::turn, target->count_by_charges() ? amount : 1 );
     dummy.set_itype_variant( variant_type );

src/iuse_actor.h

@@ -53,6 +53,9 @@ class iuse_transform : public iuse_actor
         /** type of the resulting item */
         itype_id target;
 
+        /** or one of items from itemgroup */
+        item_group_id target_group;
+
         /** if set transform item to container and place new item (of type @ref target) inside */
         itype_id container;