rework card storage to use nvs

src/card/model.rs

@@ -1,4 +1,6 @@
+use base64::prelude::*;
 use core::fmt::Display;
+use esp_nvs::Key;
 
 use alloc::{string::String, vec::Vec};
 use num_enum::FromPrimitive;
@@ -22,6 +24,38 @@ pub struct RawCard {
     pub _padding: [u8; 2],
 }
 
+impl Default for RawCard {
+    fn default() -> Self {
+        Self {
+            event_encoding: Default::default(),
+            card_type: Default::default(),
+            card_uuid: Default::default(),
+            _reserved: Default::default(),
+            sprite: [0; 722],
+            packed_card_text: [0; 54],
+            secret: Default::default(),
+            _opaque_trailer: [0; 49],
+            _padding: Default::default(),
+        }
+    }
+}
+
+impl RawCard {
+    pub fn get_uuid(&self) -> u32 {
+        ((u16::from_ne_bytes(self.event_encoding) as u32) << 16)
+            | (u16::from_ne_bytes(self.card_uuid) as u32)
+    }
+
+    pub fn get_nvs_key(&self) -> Key {
+        let uuid = self.get_uuid();
+        Self::nvs_key_from_uuid(uuid)
+    }
+
+    pub fn nvs_key_from_uuid(uuid: u32) -> Key {
+        let base64 = BASE64_STANDARD.encode(uuid.to_ne_bytes());
+        Key::from_str(&base64)
+    }
+}
 static_assertions::const_assert!(RawCard::SERIALIZED_SIZE.is_multiple_of(4));
 
 #[derive(Debug, Clone, Eq, PartialEq, FromPrimitive)]