Add collection manager

src/collection/mod.rs

@@ -0,0 +1,54 @@
+use crate::{database::{Database, self}, library::{Library, Query, self}, Artist};
+
+/// The collection type.
+pub type Collection = Vec<Artist>;
+
+/// Error type for collection manager.
+#[derive(Debug)]
+pub enum Error {
+    /// The [`CollectionManager`] failed to read/write from/to the library.
+    LibraryError(String),
+    /// The [`CollectionManager`] failed to read/write from/to the database.
+    DatabaseError(String),
+}
+
+impl From<library::Error> for Error {
+    fn from(err: library::Error) -> Error {
+        Error::LibraryError(err.to_string())
+    }
+}
+
+impl From<database::Error> for Error {
+    fn from(err: database::Error) -> Error {
+        Error::DatabaseError(err.to_string())
+    }
+}
+
+pub struct CollectionManager {
+    library: Box<dyn Library + Send + Sync>,
+    database: Box<dyn Database + Send + Sync>,
+    collection: Collection,
+}
+
+impl CollectionManager {
+    pub fn new(
+        library: Box<dyn Library + Send + Sync>,
+        database: Box<dyn Database + Send + Sync>,
+    ) -> Self {
+        CollectionManager {
+            library,
+            database,
+            collection: vec![],
+        }
+    }
+
+    pub fn rescan_library(&mut self) -> Result<(), Error> {
+        self.collection = self.library.list(&Query::default())?;
+        Ok(())
+    }
+
+    pub fn save_to_database(&mut self) -> Result<(), Error> {
+        self.database.write(&self.collection)?;
+        Ok(())
+    }
+}

src/database/json.rs

@@ -3,10 +3,15 @@
 use std::fs;
 use std::path::{Path, PathBuf};
 
-use serde::de::DeserializeOwned;
-use serde::Serialize;
+use crate::collection::Collection;
 
-use super::{Database, DatabaseRead, DatabaseWrite};
+use super::{Database, DatabaseRead, DatabaseWrite, Error};
+
+impl From<serde_json::Error> for Error {
+    fn from(err: serde_json::Error) -> Error {
+        Error::SerDeError(err.to_string())
+    }
+}
 
 /// Trait for the JSON database backend.
 pub trait JsonDatabaseBackend {
@@ -19,21 +24,18 @@ pub trait JsonDatabaseBackend {
 
 /// JSON database.
 pub struct JsonDatabase {
-    backend: Box<dyn JsonDatabaseBackend + Send>,
+    backend: Box<dyn JsonDatabaseBackend + Send + Sync>,
 }
 
 impl JsonDatabase {
     /// Create a new JSON database with the provided backend, e.g. [JsonDatabaseFileBackend].
-    pub fn new(backend: Box<dyn JsonDatabaseBackend + Send>) -> Self {
+    pub fn new(backend: Box<dyn JsonDatabaseBackend + Send + Sync>) -> Self {
         JsonDatabase { backend }
     }
 }
 
 impl DatabaseRead for JsonDatabase {
-    fn read<D>(&self, collection: &mut D) -> Result<(), std::io::Error>
-    where
-        D: DeserializeOwned,
-    {
+    fn read(&self, collection: &mut Collection) -> Result<(), Error> {
         let serialized = self.backend.read()?;
         *collection = serde_json::from_str(&serialized)?;
         Ok(())
@@ -41,10 +43,7 @@ impl DatabaseRead for JsonDatabase {
 }
 
 impl DatabaseWrite for JsonDatabase {
-    fn write<S>(&mut self, collection: &S) -> Result<(), std::io::Error>
-    where
-        S: Serialize,
-    {
+    fn write(&mut self, collection: &Collection) -> Result<(), Error> {
         let serialized = serde_json::to_string(&collection)?;
         self.backend.write(&serialized)?;
         Ok(())

src/database/mod.rs

@@ -1,24 +1,47 @@
 //! Module for storing MusicHoard data in a database.
 
-use serde::de::DeserializeOwned;
-use serde::Serialize;
+use std::fmt;
+
+use crate::collection::Collection;
 
 pub mod json;
 
+/// Error type for database calls.
+#[derive(Debug)]
+pub enum Error {
+    /// The database experienced an I/O error.
+    IoError(String),
+    /// The database experienced a (de)serialisation error.
+    SerDeError(String),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Self::IoError(ref s) => write!(f, "the database experienced an I/O error: {s}"),
+            Self::SerDeError(ref s) => {
+                write!(f, "the database experienced a (de)serialisation error: {s}")
+            }
+        }
+    }
+}
+
+impl From<std::io::Error> for Error {
+    fn from(err: std::io::Error) -> Error {
+        Error::IoError(err.to_string())
+    }
+}
+
 /// Trait for database reads.
 pub trait DatabaseRead {
     /// Read collection from the database.
-    fn read<D>(&self, collection: &mut D) -> Result<(), std::io::Error>
-    where
-        D: DeserializeOwned;
+    fn read(&self, collection: &mut Collection) -> Result<(), Error>;
 }
 
 /// Trait for database writes.
 pub trait DatabaseWrite {
     /// Write collection to the database.
-    fn write<S>(&mut self, collection: &S) -> Result<(), std::io::Error>
-    where
-        S: Serialize;
+    fn write(&mut self, collection: &Collection) -> Result<(), Error>;
 }
 
 /// Trait for database reads and writes.

src/lib.rs

@@ -3,6 +3,7 @@
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
 
+pub mod collection;
 pub mod database;
 pub mod library;
 

src/library/beets.rs

@@ -91,7 +91,7 @@ pub trait BeetsLibraryExecutor {
 
 /// Beets library.
 pub struct BeetsLibrary {
-    executor: Box<dyn BeetsLibraryExecutor + Send>,
+    executor: Box<dyn BeetsLibraryExecutor + Send + Sync>,
 }
 
 trait LibraryPrivate {
@@ -107,7 +107,7 @@ trait LibraryPrivate {
 
 impl BeetsLibrary {
     /// Create a new beets library with the provided executor, e.g. [BeetsLibraryCommandExecutor].
-    pub fn new(executor: Box<dyn BeetsLibraryExecutor + Send>) -> BeetsLibrary {
+    pub fn new(executor: Box<dyn BeetsLibraryExecutor + Send + Sync>) -> BeetsLibrary {
         BeetsLibrary { executor }
     }
 }

src/library/mod.rs

@@ -1,6 +1,6 @@
 //! Module for interacting with the music library.
 
-use std::{num::ParseIntError, str::Utf8Error};
+use std::{num::ParseIntError, str::Utf8Error, fmt};
 
 use crate::Artist;
 
@@ -111,6 +111,18 @@ pub enum Error {
     Utf8Error(String),
 }
 
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Self::CmdExecError(ref s) => write!(f, "the library failed to execute a command: {s}"),
+            Self::InvalidData(ref s) => write!(f, "the library returned invalid data: {s}"),
+            Self::IoError(ref s) => write!(f, "the library experienced an I/O error: {s}"),
+            Self::ParseIntError(ref s) => write!(f, "the library returned an invalid integer: {s}"),
+            Self::Utf8Error(ref s) => write!(f, "the library returned invalid UTF-8: {s}"),
+        }
+    }
+}
+
 impl From<std::io::Error> for Error {
     fn from(err: std::io::Error) -> Error {
         Error::IoError(err.to_string())