Add fitness band and heartrate function for character

data/json/item_actions.json

@@ -744,6 +744,11 @@
     "id": "PORTABLE_GAME",
     "name": { "ctxt": "PORTABLE_GAME", "str": "Play" }
   },
+  {
+    "type": "item_action",
+    "id": "FITNESS_CHECK",
+    "name":  "Check health metrics"
+  },
   {
     "type": "item_action",
     "id": "deploy_tent",

data/json/items/tool_armor.json

@@ -178,6 +178,25 @@
     "use_action": "PORTABLE_GAME",
     "magazines": [ [ "battery", [ "light_minus_battery_cell", "light_minus_atomic_battery_cell", "light_minus_disposable_cell" ] ] ]
   },
+  {
+    "type": "TOOL_ARMOR",
+    "id": "fitness_band",
+    "name": "fitness band",
+    "name_plural": "fitness bands",
+    "category": "clothing",
+    "volume": "100 ml",
+    "description": "A fitness band that can track your heartbeat, exercise level and also has a clocks.  Activate to see your metrics.",
+    "weight": "30 g",
+    "to_hit": -1,
+    "color": "light_gray",
+    "covers": [ "HAND_EITHER" ],
+    "price": 5000,
+    "material": [ "plastic" ],
+    "flags": [ "WATCH", "WATER_FRIENDLY", "BELTED", "FRAGILE", "ALLOWS_NATURAL_ATTACKS", "OVERSIZE" ],
+    "coverage": 15,
+    "symbol": "[",
+    "use_action": "FITNESS_CHECK"
+  },
   {
     "id": "holo_cloak",
     "type": "TOOL_ARMOR",

src/character.cpp

@@ -7281,3 +7281,46 @@ void Character::use_fire( const int quantity )
         return;
     }
 }
+
+int Character::heartrate_bpm() const
+{
+    //This function returns heartrate in BPM basing of health, physical state, tiredness, moral effects, stimulators and anything that should fit here. 
+    //Some values are picked to make sense from math point of view and seem correct but effects may vary in real life
+    //This needs more attention from experienced contributors to work more smooth
+    //Average healthy bpm is 60-80. That's a simple imitation of mormal distribution. There's probably a better way to do that. Possibly this value should be generated with player creation.
+    const int average_heartbeat = 70 + rng( -5, 5 ) + rng( -5, 5 );
+    const float stamina_level = float(get_stamina()) / float( get_stamina_max() );
+    float stamina_effect = 0;
+    if( stamina_level >= 0.9 ) {
+        stamina_effect = 0;
+    } else if( stamina_level >= 0.8 ) {
+        stamina_effect = 0.2;
+    } else if( stamina_level >= 0.6 ) {
+        stamina_effect = 0.5;
+    } else if( stamina_level >= 0.4 ) {
+        stamina_effect = 1;
+    } else if( stamina_level >= 0.2 ) {
+        stamina_effect = 1.5;
+    } else {
+        stamina_effect = 2;
+    }
+    int heartbeat = average_heartbeat * ( 1 + stamina_effect );//can triple heartrate
+    const int stim_level = get_stim();
+    int stim_modifer = 0;
+    if ( stim_level > 0 )
+    {
+        //that's asymptotical function that is equal to 1 at around 30 stim level and slows down all the time almost reaching 2. Tweaking x*x multiplier will accordingly change effect accumulation
+        stim_modifer = 2.1 - 2/( 1 + 0.001 * stim_level * stim_level ); 
+    }
+    heartbeat *= 1 + stim_modifer;
+    //add morale effects, mutations, fear(?), medication effects
+    //health effect that can make things better or worse is applied in the end. Based on get_max_healthy that already has bmi factored
+    const int healthy = get_max_healthy();
+    float healthy_modifier = 0;
+    //a bit arbitary formula that can use some love
+    healthy_modifier = -0.05 * round( healthy / 20 );
+    heartbeat *= 1 + healthy_modifier;
+    //A single clamp in the end should be enough  
+    heartbeat = clamp( heartbeat, average_heartbeat, 250 );
+    return heartbeat;
+}

src/character.h

@@ -1550,6 +1550,7 @@ class Character : public Creature, public visitable<Character>
         void drench( int saturation, const body_part_set &flags, bool ignore_waterproof );
         /** Recalculates morale penalty/bonus from wetness based on mutations, equipment and temperature */
         void apply_wetness_morale( int temperature );
+        int heartrate_bpm() const;
 
     protected:
         Character();

src/item_factory.cpp

@@ -706,6 +706,7 @@ void Item_factory::init()
     add_iuse( "PLANTBLECH", &iuse::plantblech );
     add_iuse( "POISON", &iuse::poison );
     add_iuse( "PORTABLE_GAME", &iuse::portable_game );
+    add_iuse( "FITNESS_CHECK", &iuse::fitness_check );
     add_iuse( "PORTAL", &iuse::portal );
     add_iuse( "PROZAC", &iuse::prozac );
     add_iuse( "PURIFIER", &iuse::purifier );

src/iuse.cpp

@@ -4410,6 +4410,22 @@ int iuse::portable_game( player *p, item *it, bool, const tripoint & )
     return it->type->charges_to_use();
 }
 
+int iuse::fitness_check( player *p, item *it, bool, const tripoint & )
+{
+    if( p->has_trait( trait_ILLITERATE ) ) {
+        p->add_msg_if_player( m_info, _( "You're don't know what you're looking at." ) );
+        return 0;
+    } else {
+        //What else should block using f-band?
+        const int bpm = p->heartrate_bpm();
+        p->add_msg_if_player( _( "You check your health metrics on your %s." ), it->tname() );
+		//Maybe should pick better words
+        p->add_msg_if_player( _( "Your heart's BPM is %i." ), bpm );
+        //TODO add exercise level and whatever else makes sense (sleep quality, health level approximation?)
+    }
+    return it->type->charges_to_use();
+}
+
 int iuse::hand_crank( player *p, item *it, bool, const tripoint & )
 {
     if( p->is_npc() ) {