oter_id: add and use some directional utility functions

Add some functions to parse oter_id and return the base string
without any directional suffixes, or the rotation int for the
the suffix, or the directional suffix itself.

Use these functions to make some code in recipe_groups, conditions,
and mapgen a little more correct.

src/condition.cpp

@@ -20,6 +20,7 @@
 #include "map.h"
 #include "mission.h"
 #include "npc.h"
+#include "overmap.h"
 #include "overmapbuffer.h"
 #include "recipe.h"
 #include "recipe_groups.h"
@@ -375,7 +376,7 @@ void conditional_t<T>::set_at_om_location( JsonObject &jo, const std::string &me
             return !recipe_group::get_recipes_by_id( "all_faction_base_types",
                     omt_ref.id().c_str() ).empty();
         } else {
-            return omt_ref == oter_id( location );
+            return omt_ref == oter_id( oter_no_dir( oter_id( location ) ) );
         }
     };
 }

src/mapgen.cpp

@@ -7913,19 +7913,9 @@ bool update_mapgen_function_json::update_map( const tripoint &omt_pos, const poi
 
     // If the existing map is rotated, we need to rotate it back to the north
     // orientation before applying our updates.
-    int rotation = 0;
-    // Yeah, because a terrain named "tt_east" (length 7) is clearly not rotated and does not to be checked.
-    if( map_id.size() > 7 ) {
-        if( map_id.substr( map_id.size() - 6, 6 ) == "_south" ) {
-            rotation = 2;
-            md.m.rotate( rotation );
-        } else if( map_id.substr( map_id.size() - 5, 5 ) == "_east" ) {
-            rotation = 3;
-            md.m.rotate( rotation );
-        } else if( map_id.substr( map_id.size() - 5, 5 ) == "_west" ) {
-            rotation = 1;
-            md.m.rotate( rotation );
-        }
+    int rotation = oter_get_rotation( overmap_buffer.ter( omt_pos ) );
+    if( rotation > 0 ) {
+        md.m.rotate( rotation );
     }
 
     const bool applied = update_map( md, offset, verify );

src/overmap.cpp

@@ -4467,3 +4467,66 @@ std::string enum_to_string<ot_match_type>( ot_match_type data )
 } // namespace io
 
 constexpr tripoint overmap::invalid_tripoint;
+
+std::string oter_no_dir( const oter_id &oter )
+{
+    std::string base_oter_id = oter.id().c_str();
+    size_t oter_len = base_oter_id.size();
+    if( oter_len > 7 ) {
+        if( base_oter_id.substr( oter_len - 6, 6 ) == "_south" ) {
+            return base_oter_id.substr( 0, oter_len - 6 );
+        } else if( base_oter_id.substr( oter_len - 6, 6 ) == "_north" ) {
+            return base_oter_id.substr( 0, oter_len - 6 );
+        }
+    }
+    if( oter_len > 6 ) {
+        if( base_oter_id.substr( oter_len - 5, 5 ) == "_west" ) {
+            return base_oter_id.substr( 0, oter_len - 5 );
+        } else if( base_oter_id.substr( oter_len - 5, 5 ) == "_east" ) {
+            return base_oter_id.substr( 0, oter_len - 5 );
+        }
+    }
+    return base_oter_id;
+}
+
+int oter_get_rotation( const oter_id &oter )
+{
+    std::string base_oter_id = oter.id().c_str();
+    size_t oter_len = base_oter_id.size();
+    if( oter_len > 7 ) {
+        if( base_oter_id.substr( oter_len - 6, 6 ) == "_south" ) {
+            return 2;
+        } else if( base_oter_id.substr( oter_len - 6, 6 ) == "_north" ) {
+            return 0;
+        }
+    }
+    if( oter_len > 6 ) {
+        if( base_oter_id.substr( oter_len - 5, 5 ) == "_west" ) {
+            return 1;
+        } else if( base_oter_id.substr( oter_len - 5, 5 ) == "_east" ) {
+            return 3;
+        }
+    }
+    return 0;
+}
+
+std::string oter_get_rotation_string( const oter_id &oter )
+{
+    std::string base_oter_id = oter.id().c_str();
+    size_t oter_len = base_oter_id.size();
+    if( oter_len > 7 ) {
+        if( base_oter_id.substr( oter_len - 6, 6 ) == "_south" ) {
+            return "_south";
+        } else if( base_oter_id.substr( oter_len - 6, 6 ) == "_north" ) {
+            return "_north";
+        }
+    }
+    if( oter_len > 6 ) {
+        if( base_oter_id.substr( oter_len - 5, 5 ) == "_west" ) {
+            return "_west";
+        } else if( base_oter_id.substr( oter_len - 5, 5 ) == "_east" ) {
+            return "_east";
+        }
+    }
+    return "";
+}

src/overmap.h

@@ -461,4 +461,19 @@ bool is_ot_match( const std::string &name, const oter_id &oter,
 */
 om_special_sectors get_sectors( int sector_width );
 
+/**
+* Returns the string of oter without any directional suffix
+*/
+std::string oter_no_dir( const oter_id &oter );
+
+/**
+* Return 0, 1, 2, 3 respectively if the suffix is _north, _west, _south, _east
+* Return 0 if theres' no suffix
+*/
+int oter_get_rotation( const oter_id &oter );
+
+/**
+* Return the directional suffix or "" if there isn't one.
+*/
+std::string oter_get_rotation_string( const oter_id &oter );
 #endif

src/recipe_groups.cpp

@@ -8,6 +8,7 @@
 #include "generic_factory.h"
 #include "json.h"
 #include "debug.h"
+#include "overmap.h"
 #include "string_id.h"
 #include "type_id.h"
 
@@ -93,42 +94,13 @@ std::map<recipe_id, translation> recipe_group::get_recipes_by_id( const std::str
     }
     const recipe_group_data &group = recipe_groups_data.obj( group_id( id ) );
     if( om_terrain_id != "ANY" ) {
-        std::string base_om_ter_id = om_terrain_id;
-        size_t om_ter_len = om_terrain_id.size();
-        if( om_ter_len > 7 ) {
-            if( om_terrain_id.substr( om_ter_len - 6, 6 ) == "_south" ) {
-                base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 6 );
-            } else if( om_terrain_id.substr( om_ter_len - 6, 6 ) == "_north" ) {
-                base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 6 );
-            }
-        }
-        if( om_ter_len > 6 ) {
-            if( om_terrain_id.substr( om_ter_len - 5, 5 ) == "_west" ) {
-                base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 5 );
-            } else if( om_terrain_id.substr( om_ter_len - 5, 5 ) == "_east" ) {
-                base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 5 );
-            }
-        }
+        std::string base_om_ter_id = oter_no_dir( oter_id( om_terrain_id ) );
 
         for( const auto &recp : group.recipes ) {
             const auto &recp_terrain = group.om_terrains.find( recp.first );
             if( recp_terrain == group.om_terrains.end() ) {
                 continue;
             }
-            std::string base_om_ter_id = om_terrain_id;
-            size_t om_ter_len = om_terrain_id.size();
-            if( om_ter_len > 7 ) {
-                if( om_terrain_id.substr( om_ter_len - 6, 6 ) == "_south" ) {
-                    base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 6 );
-                } else if( om_terrain_id.substr( om_ter_len - 6, 6 ) == "_north" ) {
-                    base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 6 );
-                } else if( om_terrain_id.substr( om_ter_len - 5, 5 ) == "_west" ) {
-                    base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 5 );
-                } else if( om_terrain_id.substr( om_ter_len - 5, 5 ) == "_east" ) {
-                    base_om_ter_id = om_terrain_id.substr( 0, om_ter_len - 5 );
-                }
-            }
-
             if( recp_terrain->second.find( base_om_ter_id ) != recp_terrain->second.end() ) {
                 all_rec.emplace( recp );
             }