Make power grids easier to split up, reconnect, and merge parts to (#…

…73056)

* Write message if grids are successfully merged

* Stop dragging appliance if merging it to a grid

This was a bug that let you drag power grids and break the game

* Remove power cords linked between merging grids

Extension cords are dropped to the ground

* Add functions for removing all but one power grid part

The appliance menu can now exit `app_loop` manually by setting `veh` to nullptr. I needed to add this because it'd be ambiguous which of the split-apart vehicles the menu is targeting otherwise.

* Move app menu's Merge functionality into Plug

If the connected appliances are adjacent & mergable powergrids, then merge them. Otherwise, connect with a power cord.

* Rename "power grid" to part name if split down to one part

* Ask to split part off from power grid when trying to drag it

(unless the part is wall mounted)

* Recalc powergrid pos & pivot when it gets split up

* Improve clarity of power grid removal section

* Remove CANT_DRAG tag. Instead, determine draggability when trying to grab

* Do cleanup after merging, as power cords between merged vehicles now get disconnected

* Adjust cable disconnection messages in menu

Disconnect cables -> Disconnect items / tow cables / items and tow cables

* Clang fixes

data/raw/keybindings.json

@@ -1760,10 +1760,10 @@
   },
   {
     "type": "keybinding",
-    "id": "MERGE",
+    "id": "DISCONNECT_GRID",
     "category": "APP_INTERACT",
-    "name": "Merge power grids",
-    "bindings": [ { "input_method": "keyboard_any", "key": "m" } ]
+    "name": "Separate from power grid",
+    "bindings": [ { "input_method": "keyboard_any", "key": "c" } ]
   },
   {
     "type": "keybinding",

src/handle_action.cpp

@@ -173,8 +173,6 @@ static const zone_type_id zone_type_UNLOAD_ALL( "UNLOAD_ALL" );
 static const zone_type_id zone_type_VEHICLE_DECONSTRUCT( "VEHICLE_DECONSTRUCT" );
 static const zone_type_id zone_type_VEHICLE_REPAIR( "VEHICLE_REPAIR" );
 
-static const std::string flag_CANT_DRAG( "CANT_DRAG" );
-
 #define dbg(x) DebugLog((x),D_GAME) << __FILE__ << ":" << __LINE__ << ": "
 
 #if defined(__ANDROID__)
@@ -710,15 +708,32 @@ static void grab()
     }
 
     if( const optional_vpart_position vp = here.veh_at( grabp ) ) {
+        std::string veh_name = vp->vehicle().name;
         if( !vp->vehicle().handle_potential_theft( you ) ) {
             return;
         }
-        if( vp->vehicle().has_tag( flag_CANT_DRAG ) ) {
-            add_msg( m_info, _( "There's nothing to grab there!" ) );
+        if( vp.part_with_feature( VPFLAG_WALL_MOUNTED, false ) ) {
+            add_msg( m_info, _( "You can't move that, it's attached to the wall." ) );
             return;
         }
+        // Powergrids with more than one part are undraggable.
+        // Offer to split the targeted part off onto its own, making it draggable.
+        if( vp->vehicle().is_powergrid() && vp->vehicle().part_count() > 1 ) {
+            if( !query_yn(
+                    _( "That's part of a power grid.  Separate it from the grid so you can move it?" ) ) ) {
+                return;
+            }
+            get_player_character().pause();
+            vp->vehicle().separate_from_grid( vp.value().mount() );
+            if( const optional_vpart_position split_vp = here.veh_at( grabp ) ) {
+                veh_name = split_vp->vehicle().name;
+            } else {
+                debugmsg( "Lost the part to drag after splitting power grid!" );
+                return;
+            }
+        }
         you.grab( object_type::VEHICLE, grabp - you.pos() );
-        add_msg( _( "You grab the %s." ), vp->vehicle().name );
+        add_msg( _( "You grab the %s." ), veh_name );
     } else if( here.has_furn( grabp ) ) { // If not, grab furniture if present
         if( !here.furn( grabp ).obj().is_movable() ) {
             add_msg( _( "You can not grab the %s." ), here.furnname( grabp ) );

src/iuse_actor.cpp

@@ -4864,17 +4864,30 @@ std::optional<int> link_up_actor::link_to_veh_app( Character *p, item &it,
     } else {
 
         // Connecting two vehicles together.
+        const bool using_power_cord = it.typeId() == itype_power_cord;
+        if( using_power_cord && it.link().t_veh->is_powergrid() && sel_vp->vehicle().is_powergrid() ) {
+            // If both vehicles are adjacent power grids, try to merge them together first.
+            const point prev_pos = here.bub_from_abs( it.link().t_veh->coord_translate( it.link().t_mount ) +
+                                   it.link().t_abs_pos ).xy().raw();
+            if( selection.xy().distance( prev_pos ) <= 1.5f &&
+                it.link().t_veh->merge_appliance_into_grid( sel_vp->vehicle() ) ) {
+                it.link().t_veh->part_removal_cleanup();
+                p->add_msg_if_player( _( "You merge the two power grids." ) );
+                return 1;
+            }
+            // Unable to merge, so connect them with a power cord instead.
+        }
         ret_val<void> result = it.link_to( sel_vp, to_ports ? link_state::vehicle_port :
                                            link_state::vehicle_battery );
         if( !result.success() ) {
             p->add_msg_if_player( m_bad, result.str() );
             return 0;
         }
-        if( p->has_item( it ) ) {
+        if( using_power_cord || p->has_item( it ) ) {
             p->add_msg_if_player( m_good, result.str() );
         }
 
-        if( it.typeId() != itype_power_cord ) {
+        if( using_power_cord ) {
             // Remove linked_flag from attached parts - the just-added cable vehicle parts do the same thing.
             it.reset_link( true, p );
         }

src/veh_appliance.cpp

@@ -4,6 +4,7 @@
 #include "itype.h"
 #include "map_iterator.h"
 #include "action.h"
+#include "messages.h"
 #include "output.h"
 #include "overmapbuffer.h"
 #include "player_activity.h"
@@ -33,8 +34,6 @@ static const vpart_id vpart_ap_standing_lamp( "ap_standing_lamp" );
 static const vproto_id vehicle_prototype_none( "none" );
 
 static const std::string flag_APPLIANCE( "APPLIANCE" );
-static const std::string flag_WALL_MOUNTED( "WALL_MOUNTED" );
-static const std::string flag_CANT_DRAG( "CANT_DRAG" );
 static const std::string flag_WIRING( "WIRING" );
 static const std::string flag_HALF_CIRCLE_LIGHT( "HALF_CIRCLE_LIGHT" );
 
@@ -83,10 +82,6 @@ void place_appliance( const tripoint &p, const vpart_id &vpart, const std::optio
         veh->add_tag( flag_WIRING );
     }
 
-    if( veh->is_powergrid() || vpinfo.has_flag( flag_WALL_MOUNTED ) ) {
-        veh->add_tag( flag_CANT_DRAG );
-    }
-
     // Update the vehicle cache immediately,
     // or the appliance will be invisible for the first couple of turns.
     here.add_vehicle_to_cache( veh );
@@ -100,8 +95,9 @@ void place_appliance( const tripoint &p, const vpart_id &vpart, const std::optio
         }
         vehicle &veh_target = vp->vehicle();
         if( veh_target.has_tag( flag_APPLIANCE ) ) {
-            if( veh->is_powergrid() && veh_target.is_powergrid() ) {
-                veh->merge_appliance_into_grid( veh_target );
+            if( veh->is_powergrid() && veh_target.is_powergrid() &&
+                veh->merge_appliance_into_grid( veh_target ) ) {
+                add_msg( _( "You merge it into the adjacent power grid." ) );
                 continue;
             }
             if( connected_vehicles.find( &veh_target ) == connected_vehicles.end() ) {
@@ -110,6 +106,7 @@ void place_appliance( const tripoint &p, const vpart_id &vpart, const std::optio
             }
         }
     }
+    veh->part_removal_cleanup();
 
     // Make some lighting appliances directed
     if( vpinfo.has_flag( flag_HALF_CIRCLE_LIGHT ) && partnum != -1 ) {
@@ -148,6 +145,7 @@ veh_app_interact::veh_app_interact( vehicle &veh, const point &p )
     ctxt.register_action( "RENAME" );
     ctxt.register_action( "REMOVE" );
     ctxt.register_action( "MERGE" );
+    ctxt.register_action( "DISCONNECT_GRID" );
 }
 
 // @returns true if a battery part exists on any vehicle connected to veh
@@ -325,11 +323,6 @@ bool veh_app_interact::can_siphon()
     return false;
 }
 
-bool veh_app_interact::can_merge()
-{
-    return veh->is_powergrid();
-}
-
 // Helper function for selecting a part in the parts list.
 // If only one part is available, don't prompt the player.
 static vehicle_part *pick_part( const std::vector<vehicle_part *> &parts,
@@ -510,6 +503,23 @@ void veh_app_interact::remove()
     }
 }
 
+bool veh_app_interact::can_disconnect()
+{
+    for( int &i : veh->parts_at_relative( a_point, true ) ) {
+        if( veh->part( i ).has_flag( vp_flag::linked_flag ) ||
+            veh->part( i ).info().has_flag( "TOW_CABLE" ) ) {
+            return false;
+        }
+    }
+    return true;
+}
+
+void veh_app_interact::disconnect()
+{
+    veh->separate_from_grid( a_point );
+    get_player_character().pause();
+}
+
 void veh_app_interact::plug()
 {
     const int part = veh->part_at( veh->coord_translate( a_point ) );
@@ -521,41 +531,6 @@ void veh_app_interact::plug()
     }
 }
 
-void veh_app_interact::merge()
-{
-    map &here = get_map();
-
-    const int part = veh->part_at( a_point );
-    const tripoint app_pos = veh->global_part_pos3( part );
-
-    const std::function<bool( const tripoint & )> f = [&here, app_pos]( const tripoint & pnt ) {
-        if( pnt == app_pos ) {
-            return false;
-        }
-        const optional_vpart_position target_vp = here.veh_at( pnt );
-        if( !target_vp ) {
-            return false;
-        }
-        vehicle &target_veh = target_vp->vehicle();
-        if( !target_veh.is_powergrid() ) {
-            return false;
-        }
-        return true;
-    };
-
-    const std::optional<tripoint> target_pos = choose_adjacent_highlight( app_pos,
-            _( "Merge the appliance into which grid?" ), _( "Target must be adjacent." ), f, false, false );
-    if( !target_pos ) {
-        return;
-    }
-    const optional_vpart_position target_vp = here.veh_at( *target_pos );
-    if( !target_vp ) {
-        return;
-    }
-    vehicle &target_veh = target_vp->vehicle();
-    veh->merge_appliance_into_grid( target_veh );
-}
-
 void veh_app_interact::populate_app_actions()
 {
     map &here = get_map();
@@ -602,14 +577,20 @@ void veh_app_interact::populate_app_actions()
         plug();
     } );
     imenu.addentry( -1, true, ctxt.keys_bound_to( "PLUG" ).front(),
-                    ctxt.get_action_name( "PLUG" ) );
-
-    // Merge
-    app_actions.emplace_back( [this]() {
-        merge();
-    } );
-    imenu.addentry( -1, can_merge(), ctxt.keys_bound_to( "MERGE" ).front(),
-                    ctxt.get_action_name( "MERGE" ) );
+                    string_format( "%s%s", ctxt.get_action_name( "PLUG" ),
+                                   //~ An addendum to Plug In's description, as in: Plug in appliance / merge power grid".
+                                   veh->is_powergrid() ? _( " / merge power grid" ) : "" ) );
+
+    if( veh->is_powergrid() && veh->part_count() > 1 && !vp->info().has_flag( VPFLAG_WALL_MOUNTED ) ) {
+        // Disconnect from power grid
+        app_actions.emplace_back( [this]() {
+            disconnect();
+            veh = nullptr;
+        } );
+        const bool can_disc = can_disconnect();
+        imenu.addentry_desc( -1, can_disc, ctxt.keys_bound_to( "DISCONNECT_GRID" ).front(),
+                             ctxt.get_action_name( "DISCONNECT_GRID" ), can_disc ? "" : _( "Remove other cables first" ) );
+    }
 
     /*************** Get part-specific actions ***************/
     veh_menu menu( veh, "IF YOU SEE THIS IT IS A BUG" );
@@ -663,7 +644,7 @@ void veh_app_interact::app_loop()
             app_actions[ret]();
         }
         // Player activity queued up, close interaction menu
-        if( !act.is_null() || !get_player_character().activity.is_null() ) {
+        if( veh == nullptr || !act.is_null() || !get_player_character().activity.is_null() ) {
             done = true;
         }
     }

src/veh_appliance.h

@@ -97,17 +97,6 @@ class veh_app_interact
          * @returns True if a liquid can be siphoned from the appliance.
         */
         bool can_siphon();
-        /**
-         * Checks whether the current appliance is power storage
-         * or powergen or a cable and can thus be merged into a powergrid.
-         * @returns True if the appliance can be merged.
-        */
-        bool can_merge();
-        /**
-         * Function associated with the "MERGE" action.
-         * Merge power grid elements together into a single appliance
-         */
-        void merge();
         /**
          * Function associated with the "REFILL" action.
          * Checks all appliance parts for a watertight container to refill. If multiple
@@ -133,6 +122,17 @@ class veh_app_interact
          * Turns the installed appliance into its base item.
         */
         void remove();
+        /**
+         * Checks whether the part has any items linked to it so it can tell the player
+         * to disconnect those first. This prevents players from doing this by accident.
+         * @returns True if there aren't any tow cable parts or items linked to the mount point.
+        */
+        bool can_disconnect();
+        /**
+         * Function associated with the "DISCONNECT_GRID" action.
+         * Removes appliance from a power grid, allowing it to be moved individually.
+        */
+        void disconnect();
         /**
         * Function associated with the "PLUG" action.
         * Connects the power cable to selected tile.

src/veh_interact.cpp

@@ -3362,10 +3362,13 @@ void veh_interact::complete_vehicle( Character &you )
                 veh.remove_remote_part( *vp );
             }
 
-            // Remove any leftover power cords from the appliance
-            if( appliance_removal && veh.part_count() >= 2 ) {
+            if( appliance_removal && veh.part_count() > 1 ) {
+                // Split up power grids
                 veh.find_and_split_vehicles( here, { vp_index } );
                 veh.part_removal_cleanup();
+                // Ensure the position, pivot, and precalc points are up-to-date
+                veh.pos -= veh.pivot_anchor[0];
+                veh.precalc_mounts( 0, veh.turn_dir, point() );
                 here.rebuild_vehicle_level_caches();
 
                 if( auto newpart = here.veh_at( act_pos ).part_with_feature( VPFLAG_APPLIANCE, false ) ) {