feat(settings): Added max_download_threads setting and separated settings from db

Signed-off-by: quexeky <git@quexeky.dev>

src-tauri/src/settings.rs

@@ -0,0 +1,35 @@
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use crate::DB;
+
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct Settings {
+    pub autostart: bool,
+    pub max_download_threads: usize,
+    // ... other settings ...
+}
+impl Default for Settings {
+    fn default() -> Self {
+        Self {
+            autostart: false,
+            max_download_threads: 4
+        }
+    }
+}
+fn deserialize_into<T>(v: serde_json::Value, t: &mut T) -> Result<(), serde_json::Error>
+    where T: for<'a> Deserialize<'a>
+{
+    *t = serde_json::from_value(v)?;
+    Ok(())
+}
+
+#[tauri::command]
+pub fn amend_settings(new_settings: Value) {
+    let db_lock = DB.borrow_data_mut().unwrap();
+    let mut current_settings = db_lock.settings.clone();
+    let e = deserialize_into(new_settings, &mut current_settings);
+
+    println!("Amend status: {:?}", e);
+    println!("New settings: {:?}", current_settings);
+}