Base: Start work on database backends

Cargo.toml

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+[package]
+name = "ogs_chat_node"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+redis = { version = "0.21.6", optional = true }
+sqlite = { version = "0.27.0", optional = true }
+
+[features]
+redis_db = ["dep:redis"]
+sqlite_db = ["dep:sqlite"]

src/db/mod.rs

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+mod sqlite;
+mod redis;
+
+pub trait DbBackend {
+
+}
+
+pub fn get_backend_names() -> Vec<&'static str> {
+    vec![
+        #[cfg(feature = "sqlite_db")]
+        "sqlite",
+        #[cfg(feature = "redis_db")]
+        "redis"
+    ]
+}
+
+pub fn get_backend(db_type: &str) -> Box<dyn DbBackend> {
+    #[cfg(not(any(feature = "sqlite_db", feature = "redis_db")))]
+        compile_error!("No database backend selected");
+    return match db_type {
+        #[cfg(feature = "sqlite_db")]
+            "sqlite" => Box::new(sqlite::SqliteBackend::new()),
+        #[cfg(feature = "redis_db")]
+            "redis" => Box::new(redis::RedisBackend::new()),
+        _ => panic!("Unknown database type"),
+    };
+}
+

src/db/redis/mod.rs

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+use crate::db::DbBackend;
+
+pub(crate) struct RedisBackend {
+
+}
+
+impl RedisBackend {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+}
+
+impl DbBackend for RedisBackend {
+}

src/db/sqlite/mod.rs

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+use crate::db::DbBackend;
+
+pub(crate) struct SqliteBackend {
+
+}
+
+impl SqliteBackend {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+}
+
+impl DbBackend for SqliteBackend {
+}

src/main.rs

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+mod db;
+
+fn main() {
+    db::get_backend("redis");
+    println!("{}", db::get_backend_names().join(", "));
+}