npc, sound: pass sound information to NPCs

call process_sound_markers() on all NPCs within MAP_VIEW_DISTANCE of the
player, and have them call a new npc::handle_sound() function for each
sound marker, and then bail before actually placing the sound markers
which remains a player only function.

npc::handle_sound() ignores speech (for not) and sounds from locations
that the NPC can see.  If the NPC currently has a low assessment of
danger and hears combat noises or movement, they will complain to the
player.

data/json/npcs/talk_tags.json

@@ -707,6 +707,28 @@
         "You're gonna rot in hell for this!"
       ]
     },
+    {
+      "type": "snippet",
+      "category": "<combat_noise_warning>",
+      "text": [
+        "That sounds bad.",
+        "Be alert, something is up!",
+        "Did you hear that?",
+        "What's that noise?",
+        "Who's there?"
+      ]
+    },
+    {
+      "type": "snippet",
+      "category": "<movement_noise_warning>",
+      "text": [
+        "I hear something moving - sounded like",
+        "What's that sound?  I heard",
+        "Who's there?  I heard",
+        "Did you hear that?  Sounded like",
+        "Who is making that sound?  I can hear the"
+      ]
+    },
     {
         "type": "snippet",
         "category": "<BGSS_intro_question>",

src/game.cpp

@@ -1529,6 +1529,13 @@ bool game::do_turn()
 
     perhaps_add_random_npc();
 
+    // Process NPC sound events before they move or they hear themselves talking
+    for( npc &guy : all_npcs() ) {
+        if( rl_dist( guy.pos(), u.pos() ) < MAX_VIEW_DISTANCE ) {
+            sounds::process_sound_markers( &guy );
+        }
+    }
+
     process_activity();
 
     // Process sound events into sound markers for display to the player.

src/npc.h

@@ -610,6 +610,10 @@ class npc : public player
         void warn_about( const std::string &type, const time_duration &d = 10_minutes,
                          const std::string &name = "" );
         bool complain(); // Finds something to complain about and complains. Returns if complained.
+
+        void handle_sound( int priority, const std::string &description, int heard_volume,
+                           const tripoint &spos );
+
         /* shift() works much like monster::shift(), and is called when the player moves
          * from one submap to an adjacent submap.  It updates our position (shifting by
          * 12 tiles), as well as our plans.

src/npcmove.cpp

@@ -3214,6 +3214,10 @@ void npc::warn_about( const std::string &type, const time_duration &d, const std
         snip = is_enemy() ? "<kill_npc_h>" : "<kill_npc>";
     } else if( type == "kill_player" ) {
         snip = is_enemy() ? "<kill_player_h>" : "";
+    } else if( type == "combat_noise" ) {
+        snip = "<combat_noise_warning>";
+    } else if( type == "movement_noise" ) {
+        snip = "<movement_noise_warning>";
     } else {
         return;
     }

src/npctalk.cpp

@@ -236,6 +236,32 @@ void game::chat()
     refresh_all();
 }
 
+void npc::handle_sound( int priority, const std::string &description, int heard_volume,
+                        const tripoint &spos )
+{
+    if( priority == 7 || sees( spos ) ) {
+        return;
+    }
+    add_msg( m_debug, "%s heard '%s', priority %d at volume %d from %d:%d, my pos %d:%d",
+             disp_name(), description, priority, heard_volume, spos.x, spos.y, pos().x, pos().y );
+    switch( priority ) {
+    case 6: // combat noise is only worth comment if we're not fighting
+        // TODO: Brave NPCs should be less jumpy
+        if( ai_cache.total_danger < 1.0f ) {
+            warn_about( "combat_noise", rng( 1, 10 ) * 1_minutes );
+        }
+        break;
+    case 4: // movement is is only worth comment if we're not fighting and out of a vehicle
+        if( ai_cache.total_danger < 1.0f && !in_vehicle ) {
+            // replace with warn_about when that merges
+            warn_about( "footsteps", rng( 1, 10 ) * 1_minutes, description );
+        }
+        break;
+    default:
+        break;
+    };
+}
+
 void npc_chatbin::check_missions()
 {
     // TODO: or simply fail them? Some missions might only need to be reported.

src/sounds.cpp

@@ -314,6 +314,11 @@ void sounds::process_sound_markers( player *p )
         }
 
         const std::string &description = sound.description.empty() ? "a noise" : sound.description;
+        if( p->is_npc() ) {
+            npc *guy = dynamic_cast<npc *>( p );
+            guy->handle_sound( static_cast<int>( sound.category ), description, heard_volume, pos );
+            continue;
+        }
 
         // don't print our own noise or things without descriptions
         if( !sound.ambient && ( pos != p->pos() ) && !g->m.pl_sees( pos, distance_to_sound ) ) {