Mod Compatibility: Only load files within "mod_interactions" if requisite mod is loaded

doc/MOD_COMPATABILITY.md

@@ -0,0 +1,33 @@
+# Mod Compatability
+
+## Summary
+
+Mods are capable of dynamically loading directories based on if other mods are loaded in the world.  This will prevent file contents within the mod_interactions folder from being read unless they are part of a folder named after a loaded mod's id.
+
+## Guide
+
+In order to dynamically load mod content, files must be placed within subdirectories named after other mod ids (capitalization is checked) within the mod_interactions folder.
+
+Example:
+Mod 1: Mind Over Matter (id:mindovermatter)
+Mod 2: Xedra Evolved (id:xedra_evolved)
+
+If Xedra wishes to load a file only when Mind Over Matter is active: mom_compat_data.json, it must be located as such:
+Xedra_Evolved/mod_interactions/mindovermatter/mom_compat_data.json
+
+Files located within the mod_interactions folders are always loaded after other mod content for every mod is loaded.
+
+## Limitations
+
+Currently, this functionality only loads / unloads files based on if other mods are active for the particular world.  It does not suppress any other warnings beyond this function.
+
+In particular, when designing mod compatability content an author will likely want to redefine certain ids to have new definitions, flags, etc.  If attempting to do this within the same overall mod folder, this will throw a duplicate definition error.  To get around this, instead of a mod redefining its own content within its own mod_interactions folder, the author should redefine its own content using the other mods mod_interaction folder.
+
+Example:
+Mod 1: Mind Over Matter (id:mindovermatter)
+Mod 2: Xedra Evolved (id:xedra_evolved)
+
+If xedra wants an item to have extra damage while Mind Over Matter is loaded, the author should place the new definition in the following:
+MindOverMatter/mod_interactions/xedra_evolved/xedra_compat_data.json
+
+TODO: remove this limitation entirely by adjusting the check to take into account the mod_interaction id source as well

src/filesystem.cpp

@@ -281,9 +281,15 @@ bool is_directory( const fs::directory_entry &entry )
 // If at_end is true, returns whether entry's name ends in match.
 // Otherwise, returns whether entry's name contains match.
 //--------------------------------------------------------------------------------------------------
-bool name_contains( const fs::directory_entry &entry, const std::string &match, const bool at_end )
-{
-    std::string entry_name = entry.path().filename().u8string();
+bool name_contains( const fs::directory_entry &entry, const std::string &match, const bool at_end,
+                    const bool match_path )
+{
+    std::string entry_name;
+    if( match_path ) {
+        entry_name = entry.path().u8string();
+    } else {
+        entry_name = entry.path().filename().u8string();
+    }
     const size_t len_fname = entry_name.length();
     const size_t len_match = match.length();
 
@@ -421,15 +427,36 @@ std::vector<std::string> get_files_from_path( const std::string &pattern,
 {
     return find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
-        return name_contains( entry, pattern, match_extension );
+        return name_contains( entry, pattern, match_extension, false );
     } );
 }
 std::vector<cata_path> get_files_from_path( const std::string &pattern,
         const cata_path &root_path, const bool recursive_search, const bool match_extension )
 {
     return find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
-        return name_contains( entry, pattern, match_extension );
+        return name_contains( entry, pattern, match_extension, false );
+    } );
+}
+
+std::vector<std::string> get_files_from_path_with_path_exclusion( const std::string &pattern,
+        const std::string &pattern_clash,
+        const std::string &root_path, const bool recursive_search, const bool match_extension )
+{
+    return find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
+    bool ) {
+        return name_contains( entry, pattern, match_extension, false ) &&
+               !name_contains( entry, pattern_clash, false, true );
+    } );
+}
+std::vector<cata_path> get_files_from_path_with_path_exclusion( const std::string &pattern,
+        const std::string &pattern_clash,
+        const cata_path &root_path, const bool recursive_search, const bool match_extension )
+{
+    return find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
+    bool ) {
+        return name_contains( entry, pattern, match_extension, false ) &&
+               !name_contains( entry, pattern_clash, false, true );
     } );
 }
 
@@ -449,7 +476,7 @@ std::vector<std::string> get_directories_with( const std::string &pattern,
 
     auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
-        return name_contains( entry, pattern, true );
+        return name_contains( entry, pattern, true, false );
     } );
 
     // Chop off the file names. Dir path MUST be splitted by '/'
@@ -471,7 +498,7 @@ std::vector<cata_path> get_directories_with( const std::string &pattern,
 
     auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
-        return name_contains( entry, pattern, true );
+        return name_contains( entry, pattern, true, false );
     } );
 
     // Chop off the file names. Dir path MUST be splitted by '/'
@@ -504,7 +531,7 @@ std::vector<std::string> get_directories_with( const std::vector<std::string> &p
     auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
         return std::any_of( ext_beg, ext_end, [&]( const std::string & ext ) {
-            return name_contains( entry, ext, true );
+            return name_contains( entry, ext, true, false );
         } );
     } );
 
@@ -532,7 +559,7 @@ std::vector<cata_path> get_directories_with( const std::vector<std::string> &pat
     auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
     bool ) {
         return std::any_of( ext_beg, ext_end, [&]( const std::string & ext ) {
-            return name_contains( entry, ext, true );
+            return name_contains( entry, ext, true, false );
         } );
     } );
 
@@ -547,6 +574,43 @@ std::vector<cata_path> get_directories_with( const std::vector<std::string> &pat
     return files;
 }
 
+/**
+ * Finds all directories within given path
+ * @param root_path Search root.
+ * @param recursive_search Be recurse or not.
+ * @return vector or directories without pattern filename at end.
+ */
+std::vector<std::string> get_directories( const std::string &root_path,
+        const bool recursive_search )
+{
+    auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
+    bool ) {
+        return dir_exist( entry.path() );
+    } );
+
+    files.erase( std::unique( std::begin( files ), std::end( files ) ), std::end( files ) );
+
+    return files;
+}
+
+/**
+ * Finds all directories within given path
+ * @param root_path Search root.
+ * @param recursive_search Be recurse or not.
+ * @return vector or directories without pattern filename at end.
+ */
+std::vector<cata_path> get_directories( const cata_path &root_path, const bool recursive_search )
+{
+    auto files = find_file_if_bfs( root_path, recursive_search, [&]( const fs::directory_entry & entry,
+    bool ) {
+        return dir_exist( entry.path() );
+    } );
+
+    files.erase( std::unique( std::begin( files ), std::end( files ) ), std::end( files ) );
+
+    return files;
+}
+
 bool copy_file( const std::string &source_path, const std::string &dest_path )
 {
     std::ifstream source_stream( fs::u8path( source_path ),

src/filesystem.h

@@ -72,6 +72,27 @@ std::vector<std::string> get_files_from_path( const std::string &pattern,
 std::vector<cata_path> get_files_from_path( const std::string &pattern,
         const cata_path &root_path, bool recursive_search = false,
         bool match_extension = false );
+/**
+ * Returns a vector of files or directories matching pattern at @p root_path excluding those who's path matches @p pattern_clash.
+ *
+ * Searches through the directory tree breadth-first. Directories are searched in lexical
+ * order. Matching files within in each directory are also ordered lexically.
+ *
+ * @param pattern The sub-string to match.
+ * @param pattern_clash The sub-string to exclude files whose paths match.
+ * @param root_path The path relative to the current working directory to search; empty means ".".
+ * @param recursive_search Whether to recursively search sub directories.
+ * @param match_extension If true, match pattern at the end of file names. Otherwise, match anywhere
+ *                        in the file name.
+ */
+std::vector<std::string> get_files_from_path_with_path_exclusion( const std::string &pattern,
+        const std::string &pattern_clash,
+        const std::string &root_path = "", bool recursive_search = false,
+        bool match_extension = false );
+std::vector<cata_path> get_files_from_path_with_path_exclusion( const std::string &pattern,
+        const std::string &pattern_clash,
+        const cata_path &root_path, bool recursive_search = false,
+        bool match_extension = false );
 
 //--------------------------------------------------------------------------------------------------
 /**
@@ -92,6 +113,12 @@ std::vector<cata_path> get_directories_with( const std::vector<std::string> &pat
 std::vector<cata_path> get_directories_with( const std::string &pattern,
         const cata_path &root_path = {}, bool recursive_search = false );
 
+std::vector<std::string> get_directories( const std::string &root_path = "",
+        bool recursive_search = false );
+
+std::vector<cata_path> get_directories( const cata_path &root_path = {}, bool recursive_search =
+        false );
+
 bool copy_file( const std::string &source_path, const std::string &dest_path );
 bool copy_file( const cata_path &source_path, const cata_path &dest_path );
 

src/game.cpp

@@ -606,6 +606,15 @@ void game::load_data_from_dir( const cata_path &path, const std::string &src )
     DynamicDataLoader::get_instance().load_data_from_path( path, src );
 }
 
+void game::load_mod_data_from_dir( const cata_path &path, const std::string &src )
+{
+    DynamicDataLoader::get_instance().load_mod_data_from_path( path, src );
+}
+void game::load_mod_interaction_data_from_dir( const cata_path &path, const std::string &src )
+{
+    DynamicDataLoader::get_instance().load_mod_interaction_files_from_path( path, src );
+}
+
 #if defined(TUI)
 // in ncurses_def.cpp
 extern void check_encoding(); // NOLINT
@@ -3233,7 +3242,9 @@ void game::load_world_modfiles()
     load_packs( _( "Loading files" ), mods );
 
     // Load additional mods from that world-specific folder
-    load_data_from_dir( PATH_INFO::world_base_save_path_path() / "mods", "custom" );
+    load_mod_data_from_dir( PATH_INFO::world_base_save_path_path() / "mods", "custom" );
+    load_mod_interaction_data_from_dir( PATH_INFO::world_base_save_path_path() / "mods" /
+                                        "mod_interactions", "custom" );
 
     DynamicDataLoader::get_instance().finalize_loaded_data();
 }
@@ -3258,9 +3269,16 @@ void game::load_packs( const std::string &msg, const std::vector<mod_id> &packs
         if( mod.ident.str() == "test_data" ) {
             check_plural = check_plural_t::none;
         }
-        load_data_from_dir( mod.path, mod.ident.str() );
+        load_mod_data_from_dir( mod.path, mod.ident.str() );
     }
 
+    for( const auto &e : available ) {
+        loading_ui::show( msg, e->name() );
+        const MOD_INFORMATION &mod = *e;
+        load_mod_interaction_data_from_dir( mod.path / "mod_interactions", mod.ident.str() );
+    }
+
+
     std::unordered_set<mod_id> removed_mods {
         MOD_INFORMATION_Graphical_Overmap // Removed in 0.I
     };

src/game.h

@@ -199,6 +199,10 @@ class game
     protected:
         /** Loads dynamic data from the given directory. May throw. */
         void load_data_from_dir( const cata_path &path, const std::string &src );
+        /** Loads dynamic data from the given directory. Excludes files from 'mod_interactions' sub-directory.  May throw. */
+        void load_mod_data_from_dir( const cata_path &path, const std::string &src );
+        /** Loads dynamic data from the folder if it is part of a subdirectory that is named after a currently loaded mod_id.  May throw. */
+        void load_mod_interaction_data_from_dir( const cata_path &path, const std::string &src );
     public:
         void setup();
         /** Saving and loading functions. */

src/init.cpp

@@ -529,6 +529,79 @@ void DynamicDataLoader::load_data_from_path( const cata_path &path, const std::s
     }
 }
 
+void DynamicDataLoader::load_mod_data_from_path( const cata_path &path, const std::string &src )
+{
+    cata_assert( !finalized &&
+                 "Can't load additional data after finalization.  Must be unloaded first." );
+    // We assume that each folder is consistent in itself,
+    // and all the previously loaded folders.
+    // E.g. the core might provide a vpart "frame-x"
+    // the first loaded mode might provide a vehicle that uses that frame
+    // But not the other way round.
+
+    std::vector<cata_path> files;
+    // if give path is a directory
+    if( dir_exist( path.get_unrelative_path() ) ) {
+        const std::vector<cata_path> dir_files = get_files_from_path_with_path_exclusion( ".json",
+                "mod_interactions", path, true, false );
+        files.insert( files.end(), dir_files.begin(), dir_files.end() );
+        // if given path is an individual file
+    } else if( file_exist( path.get_unrelative_path() ) ) {
+        files.emplace_back( path );
+    }
+
+    // iterate over each file
+    for( const cata_path &file : files ) {
+        try {
+            // parse it
+            JsonValue jsin = json_loader::from_path( file );
+            load_all_from_json( jsin, src, path, file );
+        } catch( const JsonError &err ) {
+            throw std::runtime_error( err.what() );
+        }
+    }
+}
+
+void DynamicDataLoader::load_mod_interaction_files_from_path( const cata_path &path,
+        const std::string &src )
+{
+    cata_assert( !finalized &&
+                 "Can't load additional data after finalization.  Must be unloaded first." );
+
+    std::vector<mod_id> &loaded_mods = world_generator->active_world->active_mod_order;
+    std::vector<cata_path> files;
+
+    if( dir_exist( path.get_unrelative_path() ) ) {
+
+        // obtain folders within mod_interactions to see if they match loaded mod ids
+        const std::vector<cata_path> interaction_folders = get_directories( path, false );
+
+        for( const cata_path &f : interaction_folders ) {
+            bool is_mod_loaded = false;
+            for( mod_id id : loaded_mods ) {
+                if( id.str() == f.get_unrelative_path().filename().string() ) {
+                    is_mod_loaded = true;
+                }
+            }
+            if( is_mod_loaded ) {
+                const std::vector<cata_path> interaction_files = get_files_from_path( ".json", f, true, true );
+                files.insert( files.end(), interaction_files.begin(), interaction_files.end() );
+            }
+        }
+    }
+
+    // iterate over each file
+    for( const cata_path &file : files ) {
+        try {
+            // parse it
+            JsonValue jsin = json_loader::from_path( file );
+            load_all_from_json( jsin, src, path, file );
+        } catch( const JsonError &err ) {
+            throw std::runtime_error( err.what() );
+        }
+    }
+}
+
 void DynamicDataLoader::load_all_from_json( const JsonValue &jsin, const std::string &src,
         const cata_path &base_path, const cata_path &full_path )
 {

src/init.h

@@ -140,6 +140,25 @@ class DynamicDataLoader
          */
         /*@{*/
         void load_data_from_path( const cata_path &path, const std::string &src );
+        /**
+         * Load all data from json files located in
+         * the path (recursive) except for those within the mod_interactions folder.
+         * @param path Either a folder (recursively load all
+         * files with the extension .json), or a file (load only
+         * that file, don't check extension).
+         * @param src String identifier for mod this data comes from.
+         * @throws std::exception on all kind of errors.
+         */
+        /*@{*/
+        void load_mod_data_from_path( const cata_path &path, const std::string &src );
+        /**
+         * Load directories located within the given path if they are named after a currently loaded mod id.
+         * @param path a folder.
+         * @param src String identifier for mod this data comes from.
+         * @throws std::exception on all kind of errors.
+         */
+        /*@{*/
+        void load_mod_interaction_files_from_path( const cata_path &path, const std::string &src );
         /*@}*/
         /**
          * Deletes and unloads all the data previously loaded with