Add alternative DB interface and implementation

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

heromodels/src/db.rs

@@ -0,0 +1,69 @@
+use crate::models::{Index, Model};
+use serde::{Deserialize, Serialize};
+
+pub mod fjall;
+pub mod hero;
+
+pub trait Db {
+    /// Error type returned by database operations.
+    type Error: std::fmt::Debug;
+
+    /// Open the collection for a specific model. This method must create the collection if it does not exist.
+    fn collection<M: Model>(&self) -> Result<impl Collection<&str, M>, Error<Self::Error>>;
+}
+
+/// A collection stores a specific model under a specific key
+pub trait Collection<K, V>
+where
+    K: Serialize,
+    V: Serialize + for<'a> Deserialize<'a>,
+{
+    /// Error type for database operations
+    type Error: std::fmt::Debug;
+
+    /// Get all items where the given index field is equal to key.
+    fn get<I>(&self, key: K) -> Result<Vec<V>, Error<Self::Error>>
+    where
+        I: Index<Model = V>;
+
+    /// Get an object from its ID. This does not use an index lookup
+    fn get_by_id(&self, id: u32) -> Result<Option<V>, Error<Self::Error>>;
+
+    /// Store an item in the DB.
+    fn set(&self, value: &V) -> Result<(), Error<Self::Error>>;
+
+    /// Delete all items from the db with a given index.
+    fn delete<I>(&self, key: K) -> Result<(), Error<Self::Error>>
+    where
+        I: Index<Model = V>;
+
+    /// Delete an object with a given ID
+    fn delete_by_id(&self, id: u32) -> Result<(), Error<Self::Error>>;
+
+    /// Get all objects from the colelction
+    fn get_all(&self) -> Result<Vec<V>, Error<Self::Error>>;
+}
+
+/// Errors returned by the DB implementation
+#[derive(Debug)]
+pub enum Error<E> {
+    /// Error in the underlying database
+    DB(E),
+    /// Error decoding a stored model
+    Decode(bincode::error::DecodeError),
+    /// Error encoding a model for storage
+    Encode(bincode::error::EncodeError),
+}
+
+impl<E> From<bincode::error::DecodeError> for Error<E> {
+    fn from(value: bincode::error::DecodeError) -> Self {
+        Error::Decode(value)
+    }
+}
+
+impl<E> From<bincode::error::EncodeError> for Error<E> {
+    fn from(value: bincode::error::EncodeError) -> Self {
+        Error::Encode(value)
+    }
+}
+