feat: add discovery

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/churn/src/agent/config.rs

@@ -0,0 +1,80 @@
+use anyhow::Context;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+#[derive(Clone)]
+pub struct AgentConfig {
+    pub agent_id: String,
+    pub discovery: String,
+}
+
+impl AgentConfig {
+    pub async fn new() -> anyhow::Result<Self> {
+        let config = ConfigFile::load().await?;
+
+        Ok(Self {
+            agent_id: config.agent_id,
+            discovery: config.discovery,
+        })
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+struct ConfigFile {
+    agent_id: String,
+    discovery: String,
+}
+
+impl ConfigFile {
+    pub async fn load() -> anyhow::Result<Self> {
+        let directory = dirs::data_dir()
+            .ok_or(anyhow::anyhow!("failed to get data dir"))?
+            .join("io.kjuulh.churn-agent")
+            .join("churn-agent.toml");
+
+        if !directory.exists() {
+            anyhow::bail!(
+                "No churn agent file was setup, run `churn agent setup` to setup the defaults"
+            )
+        }
+
+        let contents = tokio::fs::read_to_string(&directory).await?;
+
+        toml::from_str(&contents).context("failed to parse the contents of the churn agent config")
+    }
+
+    pub async fn write_default(discovery: impl Into<String>, force: bool) -> anyhow::Result<Self> {
+        let s = Self {
+            agent_id: Uuid::new_v4().to_string(),
+            discovery: discovery.into(),
+        };
+
+        let directory = dirs::data_dir()
+            .ok_or(anyhow::anyhow!("failed to get data dir"))?
+            .join("io.kjuulh.churn-agent")
+            .join("churn-agent.toml");
+
+        if let Some(parent) = directory.parent() {
+            tokio::fs::create_dir_all(&parent).await?;
+        }
+
+        if !force && directory.exists() {
+            anyhow::bail!("config file already exists, consider moving it to a backup before trying again: {}", directory.display());
+        }
+
+        let contents = toml::to_string_pretty(&s)
+            .context("failed to convert default implementation to string")?;
+
+        tokio::fs::write(directory, contents.as_bytes())
+            .await
+            .context("failed to write to agent file")?;
+
+        Ok(s)
+    }
+}
+
+pub async fn setup_config(discovery: impl Into<String>, force: bool) -> anyhow::Result<()> {
+    ConfigFile::write_default(discovery, force).await?;
+
+    Ok(())
+}