DB: Reset the priority on played kara

MPD specifies that a music that has been played should have its priority
reset to the default, here the minimal priority. Only do that on next
kara for the moment.

inc/lektor/common.h

@@ -44,6 +44,8 @@ extern EXIT_FUNCTION ___not_implemented(const char *func, char *file, int line);
         }                           \
     }
 
+#define unless(cond) if (!(cond))
+
 #define FAIL_UNLESS(cond, ...)        FAIL_IF(!(cond), __VA_ARGS__)
 #define GOTO_UNLESS(cond, msg, label) GOTO_IF(!(cond), msg, label)
 #define RETURN_UNLESS(cond, msg, ret) RETURN_IF(!(cond), msg, ret)

inc/lektor/internal/dbmacro.h

@@ -62,6 +62,8 @@
 #define SQLITE_STEP_ROW(db, stmt, error)  SQLITE_STEP(db, stmt, SQLITE_ROW, error)
 #define SQLITE_STEP_DONE(db, stmt, error) SQLITE_STEP(db, stmt, SQLITE_DONE, error)
 
+#define SQLITE_BEGIN_TRANSATION(db, error) SQLITE_EXEC(db, "BEGIN TRANSATION;", error)
+#define SQLITE_END_TRANSATION(db, error)   SQLITE_EXEC(db, "END TRANSATION;", error)
 #define SQLITE_DO_ROLLBACK(db)                \
     LOG_WARN("DB-DEBUG", "DO ROLLBACK \\o/"); \
     sqlite3_exec((sqlite3 *)db, "ROLLBACK TRANSACTION;\n", NULL, NULL, NULL);

src/database/queue.c

@@ -369,6 +369,8 @@ error:
 bool
 database_queue_del_pos(lkt_db *db, int pos)
 {
+    /* /!\ WARNING: UGLY GOTOS AT THE END OF THE FUNCTION /!\ */
+
     bool sta                     = false;
     sqlite3_stmt *stmt           = NULL;
     struct lkt_queue_state queue = { .current = -1 };
@@ -435,6 +437,23 @@ error_no_rollback:
     return sta;
 }
 
+/* When a kara has been played, MPD specify that its priority shall be reset,
+ * thus we set it to 1 before passing to the next kara. It's not done when
+ * passing to the previous kara because the reorder operation would break
+ * everything in the queue. */
+PRIVATE_FUNCTION bool
+___database_queue_reset_current_priority(lkt_db *db)
+{
+    static const char *SQL_STMT = "UPDATE queue"
+                                  "  SET priority = 1"
+                                  "  WHERE position = (SELECT current FROM queue_state LIMIT 1);";
+    SQLITE_EXEC(db, SQL_STMT, error);
+    return true;
+error:
+    LOG_ERROR("DB", "Failed to reset the priority of played kara!");
+    return false;
+}
+
 bool
 database_queue_next(lkt_db *db, char filepath[PATH_MAX])
 {
@@ -454,6 +473,9 @@ database_queue_next(lkt_db *db, char filepath[PATH_MAX])
     int code           = SQLITE_OK, id;
     sqlite3_stmt *stmt = NULL;
 
+    SQLITE_BEGIN_TRANSATION(db, error_no_stmt);
+    unless (___database_queue_reset_current_priority(db))
+        goto error_no_stmt;
     SQLITE_PREPARE(db, stmt, SQL_STMT, error);
 
     code = sqlite3_step(stmt);
@@ -482,9 +504,12 @@ database_queue_next(lkt_db *db, char filepath[PATH_MAX])
     }
 
     SQLITE_EXEC(db, SQL_UPDATE, error);
+    SQLITE_END_TRANSATION(db, error);
     status = true;
 error:
     sqlite3_finalize(stmt);
+error_no_stmt:
+    SQLITE_DO_ROLLBACK(db);
     return status;
 }