feat(auth): add file merge as base

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

como_auth/src/lib.rs

@@ -1,5 +1,6 @@
 pub use introspection::IntrospectionConfigClap;
 use oauth::{OAuth, ZitadelConfig};
+use serde::{Deserialize, Serialize};
 
 mod introspection;
 mod oauth;
@@ -26,7 +27,12 @@ pub struct AuthClap {
     pub zitadel: ZitadelClap,
 }
 
-#[derive(clap::Args, Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct AuthConfigFile {
+    zitadel: Option<ZitadelClap>,
+}
+
+#[derive(clap::Args, Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 #[group(requires_all = ["auth_url", "client_id", "client_secret", "redirect_url", "token_url", "authority_url"])]
 pub struct ZitadelClap {
     #[arg(env = "ZITADEL_AUTH_URL", long = "zitadel-auth-url")]
@@ -59,6 +65,45 @@ impl TryFrom<AuthClap> for OAuth {
     }
 }
 
+impl AuthClap {
+    pub(crate) fn merge(&mut self, config: AuthConfigFile) -> &mut Self {
+        if let Some(zitadel) = config.zitadel {
+            if let Some(auth_url) = zitadel.auth_url {
+                if let Some(_) = self.zitadel.auth_url {
+                    _ = self.zitadel.auth_url.replace(auth_url);
+                }
+            }
+            if let Some(client_id) = zitadel.client_id {
+                if let Some(_) = self.zitadel.client_id {
+                    _ = self.zitadel.client_id.replace(client_id);
+                }
+            }
+            if let Some(client_secret) = zitadel.client_secret {
+                if let Some(_) = self.zitadel.client_secret {
+                    _ = self.zitadel.client_secret.replace(client_secret);
+                }
+            }
+            if let Some(redirect_url) = zitadel.redirect_url {
+                if let Some(_) = self.zitadel.redirect_url {
+                    _ = self.zitadel.redirect_url.replace(redirect_url);
+                }
+            }
+            if let Some(authority_url) = zitadel.authority_url {
+                if let Some(_) = self.zitadel.authority_url {
+                    _ = self.zitadel.authority_url.replace(authority_url);
+                }
+            }
+            if let Some(token_url) = zitadel.token_url {
+                if let Some(_) = self.zitadel.token_url {
+                    _ = self.zitadel.token_url.replace(token_url);
+                }
+            }
+        }
+
+        self
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::{AuthClap, AuthEngine, ZitadelClap};
@@ -129,8 +174,7 @@ mod test {
         let cli: Cli = Cli::parse_from(&[
             "base",
             "one",
-            "--auth-engine",
+            "--auth-engine=zitadel",
-            "zitadel",
             "--zitadel-client-id=something",
             "--zitadel-client-secret=something",
             "--zitadel-auth-url=https://something",