RUST: Update the databse SQL file

src/rust/liblektor-rs/migrations/2022-09-30-204512_initial/down.sql

 DROP TABLE repo;
-DROP TABLE kara_repo;
+DROP TABLE repo_kara;
 DROP TABLE kara;
 DROP TABLE kara_makers;
 DROP TABLE kara_tag;
 DROP TABLE tag;
 DROP TABLE kara_tags;
 DROP TABLE history;
+DROP TABLE ISO_639_1;
\ No newline at end of file

src/rust/liblektor-rs/migrations/2022-09-30-204512_initial/up.sql

+-- A list of repos karas where downloaded from. All repos should have different
+-- names! Their IDs are local to the client.
 CREATE TABLE repo
   ( id   INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT
   , name TEXT    NOT NULL UNIQUE
   );
 
+-- Link a kara in the local referencial to its reference in the distant repo.
+-- Local IDs are all uniques and every client should be expected to have
+-- different ones.
 CREATE TABLE repo_kara
   ( repo_id       INTEGER NOT NULL REFERENCES repo(id)
   , repo_kara_id  INTEGER NOT NULL
@@ -10,6 +15,7 @@ CREATE TABLE repo_kara
   , PRIMARY KEY (repo_id, repo_kara_id, local_kara_id)
   );
 
+-- A kara entry in the databse.
 CREATE TABLE kara
   ( id          INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT
   , is_dl       BOOLEAN NOT NULL DEFAULT false
@@ -17,21 +23,25 @@ CREATE TABLE kara
   , song_type   TEXT    NOT NULL
   , song_origin TEXT    NOT NULL
   , source_name TEXT    NOT NULL
-  , language    TEXT    NOT NULL
+  , language    TEXT    NOT NULL REFERENCES ISO_639_1(code)
   , kara_hash   TEXT    NOT NULL -- TEXT ABOVE + HASH OF FILE IN FS
   );
 
+-- We can have multiple kara makers for one kara.
 CREATE TABLE kara_makers
   ( id   INTEGER NOT NULL REFERENCES kara ON DELETE CASCADE
   , name TEXT    NOT NULL
   , PRIMARY KEY (id, name)
   );
 
+-- Tags are informations used to be able to make queries in a easier way.
 CREATE TABLE tag
   ( id   INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT
   , name TEXT    NOT NULL UNIQUE
   );
 
+-- The content of a tag for kara. Multiple tags for a single kara with the same
+-- tag id means that there a list of values.
 CREATE TABLE kara_tags
   ( kara_id INTEGER NOT NULL REFERENCES kara(id) ON DELETE CASCADE
   , tag_id  INTEGER NOT NULL REFERENCES tag(id)  ON DELETE CASCADE
@@ -39,7 +49,16 @@ CREATE TABLE kara_tags
   , PRIMARY KEY (kara_id, tag_id, value)
   );
 
+-- Store the history of played karas from the queue. For now we allow a kara to
+-- appear multiple times in the history.
 CREATE TABLE history
   ( id      INTEGER NOT NULL REFERENCES kara(id) ON DELETE CASCADE
   , epoch   INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT
   );
+
+-- The list of ISO 639-1 languages with their associated codes.
+-- Should add an entry in the api to query available languages.
+CREATE TABLE ISO_639_1
+  ( code    TEXT NOT NULL PRIMARY KEY
+  , name_en TEXT NOT NULL UNIQUE
+  );
\ No newline at end of file

src/rust/liblektor-rs/src/database/schema.rs

 // @generated automatically by Diesel CLI.
 
+diesel::table! {
+    ISO_639_1 (code) {
+        code -> Text,
+        name_en -> Text,
+    }
+}
+
 diesel::table! {
     history (epoch) {
         id -> Integer,
@@ -58,6 +65,7 @@ diesel::table! {
 }
 
 diesel::joinable!(history -> kara (id));
+diesel::joinable!(kara -> ISO_639_1 (language));
 diesel::joinable!(kara_makers -> kara (id));
 diesel::joinable!(kara_tags -> kara (kara_id));
 diesel::joinable!(kara_tags -> tag (tag_id));
@@ -65,6 +73,7 @@ diesel::joinable!(repo_kara -> kara (local_kara_id));
 diesel::joinable!(repo_kara -> repo (repo_id));
 
 diesel::allow_tables_to_appear_in_same_query!(
+    ISO_639_1,
     history,
     kara,
     kara_makers,