Make it possible to launch main binary without database and/or library (#88)

Closes #87

Reviewed-on: #88

src/bin/musichoard-edit.rs

@@ -16,7 +16,7 @@ type MH = MusicHoard<NoLibrary, JsonDatabase<JsonDatabaseFileBackend>>;
 struct Opt {
     #[structopt(
         long = "database",
-        name = "database file path",
+        help = "Database file path",
         default_value = "database.json"
     )]
     database_file_path: PathBuf,

src/lib.rs

@@ -788,46 +788,35 @@ impl<LIB: ILibrary, DB: IDatabase> MusicHoard<LIB, DB> {
     }
 
     pub fn rescan_library(&mut self) -> Result<(), Error> {
-        match self.library {
-            Some(ref mut library) => {
+        if let Some(ref mut library) = self.library {
             let items = library.list(&Query::new())?;
             let mut library_collection = Self::items_to_artists(items);
             Self::sort(&mut library_collection);
 
             let collection = mem::take(&mut self.collection);
             self.collection = Self::merge(library_collection, collection);
-
+        }
         Ok(())
     }
-            None => Err(Error::LibraryError(String::from("library not provided"))),
-        }
-    }
 
     pub fn load_from_database(&mut self) -> Result<(), Error> {
-        match self.database {
-            Some(ref mut database) => {
+        if let Some(ref mut database) = self.database {
             let mut database_collection: Collection = vec![];
             database.load(&mut database_collection)?;
             Self::sort(&mut database_collection);
 
             let collection = mem::take(&mut self.collection);
             self.collection = Self::merge(collection, database_collection);
-
+        }
         Ok(())
     }
-            None => Err(Error::DatabaseError(String::from("database not provided"))),
-        }
-    }
 
     pub fn save_to_database(&mut self) -> Result<(), Error> {
-        match self.database {
-            Some(ref mut database) => {
+        if let Some(ref mut database) = self.database {
             database.save(&self.collection)?;
+        }
         Ok(())
     }
-            None => Err(Error::DatabaseError(String::from("database not provided"))),
-        }
-    }
 
     pub fn add_artist<ID: Into<ArtistId>>(&mut self, artist_id: ID) {
         let artist_id: ArtistId = artist_id.into();
@@ -1963,10 +1952,7 @@ mod tests {
         let database = Some(MockIDatabase::new());
         let mut music_hoard = MusicHoard::new(library, database);
 
-        let actual_err = music_hoard.rescan_library().unwrap_err();
-        let expected_err = Error::LibraryError(String::from("library not provided"));
-
-        assert_eq!(actual_err, expected_err);
+        assert!(music_hoard.rescan_library().is_ok());
     }
 
     #[test]
@@ -1997,15 +1983,8 @@ mod tests {
         let database: Option<NoDatabase> = None;
         let mut music_hoard = MusicHoard::new(library, database);
 
-        let expected_err = Error::DatabaseError(String::from("database not provided"));
-
-        let actual_err = music_hoard.load_from_database().unwrap_err();
-        assert_eq!(actual_err, expected_err);
-        assert_eq!(actual_err.to_string(), expected_err.to_string());
-
-        let actual_err = music_hoard.save_to_database().unwrap_err();
-        assert_eq!(actual_err, expected_err);
-        assert_eq!(actual_err.to_string(), expected_err.to_string());
+        assert!(music_hoard.load_from_database().is_ok());
+        assert!(music_hoard.save_to_database().is_ok());
     }
 
     #[test]

src/main.rs

@@ -2,6 +2,8 @@ use std::fs::OpenOptions;
 use std::path::PathBuf;
 use std::{ffi::OsString, io};
 
+use musichoard::database::NoDatabase;
+use musichoard::library::NoLibrary;
 use musichoard::Collection;
 use ratatui::{backend::CrosstermBackend, Terminal};
 use structopt::StructOpt;
@@ -27,22 +29,28 @@ use tui::{event::EventChannel, handler::EventHandler, listener::EventListener, T
 
 #[derive(StructOpt)]
 struct Opt {
-    #[structopt(long = "ssh", name = "beets SSH URI")]
+    #[structopt(long = "ssh", help = "Beets SSH URI")]
     beets_ssh_uri: Option<OsString>,
 
-    #[structopt(long = "beets", name = "beets config file path")]
+    #[structopt(long = "beets", help = "Beets config file path")]
     beets_config_file_path: Option<OsString>,
 
+    #[structopt(long = "no-library", help = "Do not connect to the library")]
+    no_library: bool,
+
     #[structopt(
         long = "database",
-        name = "database file path",
+        help = "Database file path",
         default_value = "database.json"
     )]
     database_file_path: PathBuf,
+
+    #[structopt(long = "no-database", help = "Do not read from/write to the database")]
+    no_database: bool,
 }
 
-fn with<LIB: ILibrary, DB: IDatabase>(lib: LIB, db: DB) {
-    let music_hoard = MusicHoard::new(Some(lib), Some(db));
+fn with<LIB: ILibrary, DB: IDatabase>(lib: Option<LIB>, db: Option<DB>) {
+    let music_hoard = MusicHoard::new(lib, db);
 
     // Initialize the terminal user interface.
     let backend = CrosstermBackend::new(io::stdout());
@@ -58,9 +66,32 @@ fn with<LIB: ILibrary, DB: IDatabase>(lib: LIB, db: DB) {
     Tui::run(terminal, ui, handler, listener).expect("failed to run tui");
 }
 
+fn with_database<DB: IDatabase>(opt: Opt, db: Option<DB>) {
+    if opt.no_library {
+        with(None::<NoLibrary>, db);
+    } else if let Some(uri) = opt.beets_ssh_uri {
+        let uri = uri.into_string().expect("invalid SSH URI");
+        let beets_config_file_path = opt
+            .beets_config_file_path
+            .map(|s| s.into_string())
+            .transpose()
+            .expect("failed to extract beets config file path");
+        let lib_exec = BeetsLibrarySshExecutor::new(uri)
+            .expect("failed to initialise beets")
+            .config(beets_config_file_path);
+        with(Some(BeetsLibrary::new(lib_exec)), db);
+    } else {
+        let lib_exec = BeetsLibraryProcessExecutor::default().config(opt.beets_config_file_path);
+        with(Some(BeetsLibrary::new(lib_exec)), db);
+    }
+}
+
 fn main() {
     let opt = Opt::from_args();
 
+    if opt.no_database {
+        with_database(opt, None::<NoDatabase>);
+    } else {
         // Create an empty database file if it does not exist.
         match OpenOptions::new()
             .write(true)
@@ -79,23 +110,9 @@ fn main() {
             },
         }
 
-    // Create the application.
         let db_exec = JsonDatabaseFileBackend::new(&opt.database_file_path);
-    if let Some(uri) = opt.beets_ssh_uri {
-        let uri = uri.into_string().expect("invalid SSH URI");
-        let beets_config_file_path = opt
-            .beets_config_file_path
-            .map(|s| s.into_string())
-            .transpose()
-            .expect("failed to extract beets config file path");
-        let lib_exec = BeetsLibrarySshExecutor::new(uri)
-            .expect("failed to initialise beets")
-            .config(beets_config_file_path);
-        with(BeetsLibrary::new(lib_exec), JsonDatabase::new(db_exec));
-    } else {
-        let lib_exec = BeetsLibraryProcessExecutor::default().config(opt.beets_config_file_path);
-        with(BeetsLibrary::new(lib_exec), JsonDatabase::new(db_exec));
-    }
+        with_database(opt, Some(JsonDatabase::new(db_exec)));
+    };
 }
 
 #[cfg(test)]