add: layouts api

crates/core/src/model/layouts.rs

@@ -1,5 +1,6 @@
 use std::{collections::HashMap, fmt::Display};
 use serde::{Deserialize, Serialize};
+use tetratto_shared::{snow::Snowflake, unix_epoch_timestamp};
 use crate::model::auth::DefaultTimelineChoice;
 
 /// Each different page which can be customized.
@@ -20,10 +21,26 @@ pub struct Layout {
     pub title: String,
     pub privacy: LayoutPrivacy,
     pub pages: Vec<LayoutPage>,
+    pub replaces: CustomizablePage,
+}
+
+impl Layout {
+    /// Create a new [`Layout`].
+    pub fn new(title: String, owner: usize, replaces: CustomizablePage) -> Self {
+        Self {
+            id: Snowflake::new().to_string().parse::<usize>().unwrap(),
+            created: unix_epoch_timestamp(),
+            owner,
+            title,
+            privacy: LayoutPrivacy::Public,
+            pages: Vec::new(),
+            replaces,
+        }
+    }
 }
 
 /// The privacy of the layout, which controls who has the ability to view it.
-#[derive(Serialize, Deserialize)]
+#[derive(Serialize, Deserialize, PartialEq, Eq)]
 pub enum LayoutPrivacy {
     Public,
     Private,