Draft code to write database

src/external/database/mod.rs

@@ -1,4 +1,7 @@
 #[cfg(feature = "database-json")]
 pub mod json;
+#[cfg(feature = "database-sqlite")]
+pub mod sql;
+
 #[cfg(feature = "database-json")]
 mod serde;

src/external/database/serde/common.rs

@@ -37,7 +37,7 @@ pub struct AlbumDateDef {
 }
 
 #[derive(Debug, Deserialize, Serialize)]
-pub struct SerdeAlbumDate(#[serde(with = "AlbumDateDef")] AlbumDate);
+pub struct SerdeAlbumDate(#[serde(with = "AlbumDateDef")] pub AlbumDate);
 
 impl From<SerdeAlbumDate> for AlbumDate {
     fn from(value: SerdeAlbumDate) -> Self {

src/external/database/serde/serialize.rs

@@ -24,22 +24,22 @@ impl<'a> From<&'a Collection> for SerializeDatabase<'a> {
 
 #[derive(Debug, Serialize)]
 pub struct SerializeArtist<'a> {
-    name: &'a str,
+    pub name: &'a str,
-    sort: Option<&'a str>,
+    pub sort: Option<&'a str>,
-    musicbrainz: SerializeMbRefOption<'a>,
+    pub musicbrainz: SerializeMbRefOption<'a>,
-    properties: BTreeMap<&'a str, &'a Vec<String>>,
+    pub properties: BTreeMap<&'a str, &'a Vec<String>>,
-    albums: Vec<SerializeAlbum<'a>>,
+    pub albums: Vec<SerializeAlbum<'a>>,
 }
 
 #[derive(Debug, Serialize)]
 pub struct SerializeAlbum<'a> {
-    title: &'a str,
+    pub title: &'a str,
-    lib_id: SerdeAlbumLibId,
+    pub lib_id: SerdeAlbumLibId,
-    date: SerdeAlbumDate,
+    pub date: SerdeAlbumDate,
-    seq: u8,
+    pub seq: u8,
-    musicbrainz: SerializeMbRefOption<'a>,
+    pub musicbrainz: SerializeMbRefOption<'a>,
-    primary_type: Option<SerdeAlbumPrimaryType>,
+    pub primary_type: Option<SerdeAlbumPrimaryType>,
-    secondary_types: Vec<SerdeAlbumSecondaryType>,
+    pub secondary_types: Vec<SerdeAlbumSecondaryType>,
 }
 
 #[derive(Debug, Serialize)]

src/external/database/sql/backend.rs

@@ -0,0 +1,166 @@
+//! Module for storing MusicHoard data in a JSON file database.
+
+use std::path::PathBuf;
+
+use rusqlite::{self, CachedStatement, Connection, Params, Statement};
+
+use crate::external::database::{
+    serde::serialize::{SerializeAlbum, SerializeArtist, SerializeDatabase},
+    sql::{Error, ISqlDatabaseBackend},
+};
+
+/// SQLite database backend that uses SQLite as the implementation.
+pub struct SqlDatabaseSqliteBackend {
+    conn: Connection,
+}
+
+impl SqlDatabaseSqliteBackend {
+    /// Create a [`SqlDatabaseSqliteBackend`] that will read/write to the provided database.
+    pub fn new<P: Into<PathBuf>>(path: P) -> Result<Self, Error> {
+        Ok(SqlDatabaseSqliteBackend {
+            conn: Connection::open(path.into()).map_err(|err| Error::OpenError(err.to_string()))?,
+        })
+    }
+
+    fn prepare(&self, sql: &str) -> Result<Statement, Error> {
+        self.conn
+            .prepare(sql)
+            .map_err(|err| Error::StmtError(err.to_string()))
+    }
+
+    fn prepare_cached(&self, sql: &str) -> Result<CachedStatement, Error> {
+        self.conn
+            .prepare_cached(sql)
+            .map_err(|err| Error::StmtError(err.to_string()))
+    }
+
+    fn execute<P: Params>(stmt: &mut Statement, params: P) -> Result<(), Error> {
+        stmt.execute(params)
+            .map(|_| ())
+            .map_err(|err| Error::ExecError(err.to_string()))
+    }
+}
+
+impl From<serde_json::Error> for Error {
+    fn from(value: serde_json::Error) -> Self {
+        Error::SerDeError(value.to_string())
+    }
+}
+
+impl ISqlDatabaseBackend for SqlDatabaseSqliteBackend {
+    fn begin_transaction(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached("BEGIN TRANSACTION;")?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn commit_transaction(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached("COMMIT;")?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn create_database_metadata_table(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare(
+            "CREATE TABLE IF NOT EXISTS database_metadata (
+                 name TEXT NOT NULL PRIMARY KEY,
+                 value TEXT NOT NULL
+             )",
+        )?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn drop_database_metadata_table(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached("DROP TABLE database_metadata")?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn create_artists_table(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare(
+            "CREATE TABLE IF NOT EXISTS artists (
+                 name TEXT NOT NULL PRIMARY KEY,
+                 sort TEXT NULL,
+                 mbid JSON NOT NULL DEFAULT '\"None\"',
+                 properties JSON NOT NULL DEFAULT '{}'
+             )",
+        )?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn drop_artists_table(&self) -> Result<(),Error> {
+        let mut stmt = self.prepare_cached("DROP TABLE artists")?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn create_albums_table(&self) -> Result<(), Error> {
+        let mut stmt = self.prepare(
+            "CREATE TABLE IF NOT EXISTS albums (
+                 title TEXT NOT NULL PRIMARY KEY,
+                 lib_id JSON NOT NULL DEFAULT '\"None\"',
+                 mbid JSON NOT NULL DEFAULT '\"None\"',
+                 artist_name TEXT NOT NULL,
+                 year INT NULL,
+                 month INT NULL,
+                 day INT NULL,
+                 seq INT NOT NULL,
+                 primary_type JSON NOT NULL DEFAULT 'null',
+                 secondary_types JSON NOT NULL DEFAULT '[]',
+                 FOREIGN KEY (artist_name) REFERENCES artists(name)
+             )",
+        )?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn drop_albums_table(&self) -> Result<(),Error> {
+        let mut stmt = self.prepare_cached("DROP TABLE albums")?;
+        Self::execute(&mut stmt, ())
+    }
+
+    fn insert_database_version<'a>(&self, version: &SerializeDatabase<'a>) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached(
+            "INSERT INTO database_metadata (name, value)
+             VALUES (?1, ?2)",
+        )?;
+        let version = match version {
+            SerializeDatabase::V20250103(_) => "V20250103",
+        };
+        Self::execute(&mut stmt, ("version", version))
+    }
+
+    fn insert_artist<'a>(&self, artist: &SerializeArtist<'a>) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached(
+            "INSERT INTO artists (name, sort, mbid, properties)
+             VALUES (?1, ?2, ?3, ?4)",
+        )?;
+        Self::execute(
+            &mut stmt,
+            (
+                artist.name,
+                artist.sort,
+                serde_json::to_string(&artist.musicbrainz)?,
+                serde_json::to_string(&artist.properties)?,
+            ),
+        )
+    }
+
+    fn insert_album<'a>(&self, artist_name: &str, album: &SerializeAlbum<'a>) -> Result<(), Error> {
+        let mut stmt = self.prepare_cached(
+            "INSERT INTO albums (title, lib_id, mbid, artist_name,
+                                 year, month, day, seq, primary_type, secondary_types)
+             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10)",
+        )?;
+        Self::execute(
+            &mut stmt,
+            (
+                album.title,
+                serde_json::to_string(&album.lib_id)?,
+                serde_json::to_string(&album.musicbrainz)?,
+                artist_name,
+                album.date.0.year,
+                album.date.0.month,
+                album.date.0.day,
+                album.seq,
+                serde_json::to_string(&album.primary_type)?,
+                serde_json::to_string(&album.secondary_types)?,
+            ),
+        )
+    }
+}

src/external/database/sql/mod.rs

@@ -0,0 +1,263 @@
+//! Module for storing MusicHoard data in a SQLdatabase.
+
+pub mod backend;
+
+use std::fmt;
+
+#[cfg(test)]
+use mockall::automock;
+
+use crate::{
+    core::{
+        collection::Collection,
+        interface::database::{IDatabase, LoadError, SaveError},
+    },
+    external::database::serde::serialize::{SerializeAlbum, SerializeArtist, SerializeDatabase},
+};
+
+/// Trait for the SQL database backend.
+#[cfg_attr(test, automock)]
+pub trait ISqlDatabaseBackend {
+    /// Begin an SQL transaction.
+    fn begin_transaction(&self) -> Result<(), Error>;
+
+    /// Commit ongoing transaction.
+    fn commit_transaction(&self) -> Result<(), Error>;
+
+    /// Create the database metadata table (if needed).
+    fn create_database_metadata_table(&self) -> Result<(), Error>;
+
+    /// Drop the database metadata table.
+    fn drop_database_metadata_table(&self) -> Result<(), Error>;
+
+    /// Create the artists table (if needed).
+    fn create_artists_table(&self) -> Result<(), Error>;
+
+    /// Drop the artists table.
+    fn drop_artists_table(&self) -> Result<(), Error>;
+
+    /// Create the albums table (if needed).
+    fn create_albums_table(&self) -> Result<(), Error>;
+
+    /// Drop the albums table.
+    fn drop_albums_table(&self) -> Result<(), Error>;
+
+    /// Set the database version.
+    fn insert_database_version<'a>(&self, version: &SerializeDatabase<'a>) -> Result<(), Error>;
+
+    /// Insert an artist into the artist table.
+    fn insert_artist<'a>(&self, artist: &SerializeArtist<'a>) -> Result<(), Error>;
+
+    /// Insert an artist into the artist table.
+    fn insert_album<'a>(&self, artist_name: &str, album: &SerializeAlbum<'a>) -> Result<(), Error>;
+}
+
+/// Errors for SQL database backend.
+#[derive(Debug)]
+pub enum Error {
+    /// An error occurred when connecting to the database.
+    OpenError(String),
+    /// An error occurred when preparing a statement for execution.
+    StmtError(String),
+    /// An error occurred during serialisation.
+    SerDeError(String),
+    /// An error occurred during execution.
+    ExecError(String),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Self::OpenError(ref s) => {
+                write!(f, "an error occurred when connecting to the database: {s}")
+            }
+            Self::StmtError(ref s) => write!(
+                f,
+                "an error occurred when preparing a statement for execution: {s}"
+            ),
+            Self::SerDeError(ref s) => write!(f, "an error occurred during serialisation : {s}"),
+            Self::ExecError(ref s) => write!(f, "an error occurred during execution: {s}"),
+        }
+    }
+}
+
+impl From<Error> for SaveError {
+    fn from(value: Error) -> Self {
+        match value {
+            Error::SerDeError(s) => SaveError::SerDeError(s),
+            _ => SaveError::IoError(value.to_string()),
+        }
+    }
+}
+
+/// SQL database.
+pub struct SqlDatabase<SDB> {
+    backend: SDB,
+}
+
+impl<SDB: ISqlDatabaseBackend> SqlDatabase<SDB> {
+    /// Create a new SQL database with the provided backend, e.g.
+    /// [`backend::SqlDatabaseSqliteBackend`].
+    pub fn new(backend: SDB) -> Result<Self, Error> {
+        let db = SqlDatabase { backend };
+        db.begin_transaction()?;
+        db.create_tables()?;
+        db.commit_transaction()?;
+        Ok(db)
+    }
+
+    fn begin_transaction(&self) -> Result<(), Error> {
+        self.backend.begin_transaction()
+    }
+
+    fn commit_transaction(&self) -> Result<(), Error> {
+        self.backend.commit_transaction()
+    }
+
+    fn create_tables(&self) -> Result<(), Error> {
+        self.backend.create_database_metadata_table()?;
+        self.backend.create_artists_table()?;
+        self.backend.create_albums_table()?;
+        Ok(())
+    }
+
+    fn drop_tables(&self) -> Result<(), Error> {
+        self.backend.drop_database_metadata_table()?;
+        self.backend.drop_artists_table()?;
+        self.backend.drop_albums_table()?;
+        Ok(())
+    }
+}
+
+impl<SDB: ISqlDatabaseBackend> IDatabase for SqlDatabase<SDB> {
+    fn load(&self) -> Result<Collection, LoadError> {
+        Ok(vec![])
+    }
+
+    fn save(&mut self, collection: &Collection) -> Result<(), SaveError> {
+        let database: SerializeDatabase = collection.into();
+        self.begin_transaction()?;
+
+        self.drop_tables()?;
+        self.create_tables()?;
+
+        self.backend.insert_database_version(&database)?;
+        match database {
+            SerializeDatabase::V20250103(artists) => {
+                for artist in artists.iter() {
+                    self.backend.insert_artist(artist)?;
+                    for album in artist.albums.iter() {
+                        self.backend.insert_album(artist.name, album)?;
+                    }
+                }
+            }
+        }
+
+        self.commit_transaction()?;
+        Ok(())
+    }
+}
+
+// #[cfg(test)]
+// pub mod testmod;
+
+// #[cfg(test)]
+// mod tests {
+//     use std::collections::HashMap;
+
+//     use mockall::predicate;
+
+//     use crate::core::{
+//         collection::{artist::Artist, Collection},
+//         testmod::FULL_COLLECTION,
+//     };
+
+//     use super::*;
+//     use testmod::DATABASE_JSON;
+
+//     fn expected() -> Collection {
+//         let mut expected = FULL_COLLECTION.to_owned();
+//         for artist in expected.iter_mut() {
+//             for album in artist.albums.iter_mut() {
+//                 album.tracks.clear();
+//             }
+//         }
+//         expected
+//     }
+
+//     #[test]
+//     fn save() {
+//         let write_data = FULL_COLLECTION.to_owned();
+//         let input = DATABASE_JSON.to_owned();
+
+//         let mut backend = MockISqlDatabaseBackend::new();
+//         backend
+//             .expect_write()
+//             .with(predicate::eq(input))
+//             .times(1)
+//             .return_once(|_| Ok(()));
+
+//         SqlDatabase::new(backend).save(&write_data).unwrap();
+//     }
+
+//     #[test]
+//     fn load() {
+//         let expected = expected();
+//         let result = Ok(DATABASE_JSON.to_owned());
+//         eprintln!("{DATABASE_JSON}");
+
+//         let mut backend = MockISqlDatabaseBackend::new();
+//         backend.expect_read().times(1).return_once(|| result);
+
+//         let read_data: Vec<Artist> = SqlDatabase::new(backend).load().unwrap();
+
+//         assert_eq!(read_data, expected);
+//     }
+
+//     #[test]
+//     fn reverse() {
+//         let input = DATABASE_JSON.to_owned();
+//         let result = Ok(input.clone());
+
+//         let mut backend = MockISqlDatabaseBackend::new();
+//         backend
+//             .expect_write()
+//             .with(predicate::eq(input))
+//             .times(1)
+//             .return_once(|_| Ok(()));
+//         backend.expect_read().times(1).return_once(|| result);
+//         let mut database = SqlDatabase::new(backend);
+
+//         let write_data = FULL_COLLECTION.to_owned();
+//         database.save(&write_data).unwrap();
+//         let read_data: Vec<Artist> = database.load().unwrap();
+
+//         // Album information is not saved to disk.
+//         let expected = expected();
+//         assert_eq!(read_data, expected);
+//     }
+
+//     #[test]
+//     fn load_errors() {
+//         let json = String::from("");
+//         let serde_err = serde_json::from_str::<DeserializeDatabase>(&json);
+//         assert!(serde_err.is_err());
+
+//         let serde_err: LoadError = serde_err.unwrap_err().into();
+//         assert!(!serde_err.to_string().is_empty());
+//         assert!(!format!("{:?}", serde_err).is_empty());
+//     }
+
+//     #[test]
+//     fn save_errors() {
+//         // serde_json will raise an error as it has certain requirements on keys.
+//         let mut object = HashMap::<Result<(), ()>, String>::new();
+//         object.insert(Ok(()), String::from("string"));
+//         let serde_err = serde_json::to_string(&object);
+//         assert!(serde_err.is_err());
+
+//         let serde_err: SaveError = serde_err.unwrap_err().into();
+//         assert!(!serde_err.to_string().is_empty());
+//         assert!(!format!("{:?}", serde_err).is_empty());
+//     }
+// }