daemon: Start bringing up contexts and state loading/saving

src/daemon/config.rs

@@ -5,8 +5,40 @@
  * SPDX-License-Identifier: MIT
  */
 
-use anyhow::Result;
+use anyhow::{anyhow, Result};
+use std::io::ErrorKind;
+use tokio::fs::{create_dir_all, read_to_string, write};
+use tracing::{error, info};
 
-pub(in crate::daemon) async fn read_config() -> Result<()> {
+use crate::daemon::DaemonContext;
+
+pub(in crate::daemon) async fn read_state<C: DaemonContext>(context: &C) -> Result<C::State> {
+    let path = context.state_path()?;
+    let state = match read_to_string(path).await {
+        Ok(state) => state,
+        Err(e) => {
+            if e.kind() == ErrorKind::NotFound {
+                info!("No state file found, reloading default state");
+                return Ok(C::State::default());
+            }
+            error!("Error loading state: {e}");
+            return Err(e.into());
+        }
+    };
+    Ok(toml::from_str(state.as_str())?)
+}
+
+pub(in crate::daemon) async fn write_state<C: DaemonContext>(context: &C) -> Result<()> {
+    let path = context.state_path()?;
+    create_dir_all(path.parent().ok_or(anyhow!(
+        "Context path {} has no parent dir",
+        path.to_string_lossy()
+    ))?)
+    .await?;
+    let state = toml::to_string_pretty(&context.state())?;
+    Ok(write(path, state.as_bytes()).await?)
+}
+
+pub(in crate::daemon) async fn read_config<C: DaemonContext>(_context: &C) -> Result<C::Config> {
     todo!();
 }