jsonize spell skills

src/activity_handlers.cpp

@@ -4605,8 +4605,8 @@ void activity_handlers::study_spell_finish( player_activity *act, player *p )
     if( act->get_str_value( 1 ) == "study" ) {
         p->add_msg_if_player( m_good, _( "You gained %i experience from your study session." ),
                               total_exp_gained );
-        p->practice( skill_id( "spellcraft" ), total_exp_gained,
-                     p->magic.get_spell( spell_id( act->name ) ).get_difficulty() );
+        const spell &sp = p->magic.get_spell( spell_id( act->name ) );
+        p->practice( sp.skill(), total_exp_gained, sp.get_difficulty() );
     } else if( act->get_str_value( 1 ) == "learn" && act->values[2] == 0 ) {
         p->magic.learn_spell( act->name, *p );
     }

src/magic.cpp

@@ -24,6 +24,7 @@
 #include "mutation.h"
 #include "output.h"
 #include "player.h"
+#include "skill.h"
 #include "sounds.h"
 #include "translations.h"
 #include "ui.h"
@@ -231,6 +232,7 @@ void spell_type::load( const JsonObject &jo, const std::string & )
     mandatory( jo, was_loaded, "id", id );
     mandatory( jo, was_loaded, "name", name );
     mandatory( jo, was_loaded, "description", description );
+    optional( jo, was_loaded, "skill", skill, skill_id( "spellcraft" ) );
     optional( jo, was_loaded, "message", message, to_translation( "You cast %s!" ) );
     optional( jo, was_loaded, "sound_description", sound_description,
               to_translation( "an explosion" ) );
@@ -445,6 +447,11 @@ trait_id spell::spell_class() const
     return type->spell_class;
 }
 
+skill_id spell::skill() const
+{
+    return type->skill;
+}
+
 int spell::field_intensity() const
 {
     return std::min( type->max_field_intensity,
@@ -706,7 +713,7 @@ float spell::spell_fail( const player &p ) const
     // effective skill of 8 (8 int, 0 spellcraft, 0 spell level, spell difficulty 0) is ~50% failure
     // effective skill of 30 is 0% failure
     const float effective_skill = 2 * ( get_level() - get_difficulty() ) + p.get_int() +
-                                  p.get_skill_level( skill_id( "spellcraft" ) );
+                                  p.get_skill_level( skill() );
     // add an if statement in here because sufficiently large numbers will definitely overflow because of exponents
     if( effective_skill > 30.0f ) {
         return 0.0f;
@@ -1022,7 +1029,7 @@ float spell::exp_modifier( const player &p ) const
 {
     const float int_modifier = ( p.get_int() - 8.0f ) / 8.0f;
     const float difficulty_modifier = get_difficulty() / 20.0f;
-    const float spellcraft_modifier = p.get_skill_level( skill_id( "spellcraft" ) ) / 10.0f;
+    const float spellcraft_modifier = p.get_skill_level( skill() ) / 10.0f;
 
     return ( int_modifier + difficulty_modifier + spellcraft_modifier ) / 5.0f + 1.0f;
 }
@@ -1431,8 +1438,8 @@ int known_magic::time_to_learn_spell( const player &p, const std::string &str )
 int known_magic::time_to_learn_spell( const player &p, const spell_id &sp ) const
 {
     const int base_time = to_moves<int>( 30_minutes );
-    return base_time * ( 1.0 + sp.obj().difficulty / ( 1.0 + ( p.get_int() - 8.0 ) / 8.0 ) +
-                         ( p.get_skill_level( skill_id( "spellcraft" ) ) / 10.0 ) );
+    return base_time * ( 1.0 + sp->difficulty / ( 1.0 + ( p.get_int() - 8.0 ) / 8.0 ) +
+                         ( p.get_skill_level( sp->skill ) / 10.0 ) );
 }
 
 int known_magic::get_spellname_max_width()

src/magic.h

@@ -132,6 +132,7 @@ class spell_type
         translation message;
         // spell sound effect
         translation sound_description;
+        skill_id skill;
         sounds::sound_t sound_type = sounds::sound_t::_LAST;
         bool sound_ambient = false;
         std::string sound_id;
@@ -352,6 +353,8 @@ class spell
         spell_id id() const;
         // get spell class (from type)
         trait_id spell_class() const;
+        // get skill id
+        skill_id skill() const;
         // get spell effect string (from type)
         std::string effect() const;
         // get spell effect_str data