split out codegen parts

crates/dagger-codegen/src/handlers/mod.rs

@@ -0,0 +1,82 @@
+use std::sync::Arc;
+
+use genco::prelude::rust::Tokens;
+use genco::prelude::*;
+use graphql_introspection_query::introspection_response::FullType;
+
+pub trait Handler {
+    fn predicate(&self, t: &FullType) -> bool {
+        false
+    }
+
+    fn render(&self, t: &FullType) -> eyre::Result<String> {
+        let mut s = String::new();
+
+        s.push_str("\n");
+        s.push_str(self.render_struct(t)?.to_string()?.as_str());
+        s.push_str("\n");
+        s.push_str(self.render_impl(t)?.to_string()?.as_str());
+        s.push_str("\n");
+
+        Ok(s)
+    }
+
+    fn render_struct(&self, t: &FullType) -> eyre::Result<Tokens> {
+        let name = t.name.as_ref().ok_or(eyre::anyhow!("name not found"))?;
+
+        Ok(quote! {
+            pub $name {} {
+                // TODO: Add fields
+            }
+        })
+    }
+
+    fn render_impl(&self, t: &FullType) -> eyre::Result<Tokens> {
+        let name = t.name.as_ref().ok_or(eyre::anyhow!("name not found"))?;
+
+        Ok(quote! {
+            pub $name {} {
+                // TODO: Add fields
+            }
+        })
+    }
+}
+
+pub type DynHandler = Arc<dyn Handler + Send + Sync>;
+pub type Handlers = Vec<DynHandler>;
+
+#[cfg(test)]
+mod tests {
+    use graphql_introspection_query::introspection_response::FullType;
+
+    use super::Handler;
+
+    struct DefaultHandler;
+    impl Handler for DefaultHandler {}
+
+    #[test]
+    fn render_returns_expected() {
+        let handler = DefaultHandler {};
+        let t = FullType {
+            kind: None,
+            name: Some("SomeName".into()),
+            description: None,
+            fields: None,
+            input_fields: None,
+            interfaces: None,
+            enum_values: None,
+            possible_types: None,
+        };
+
+        let res = handler.render(&t).unwrap();
+
+        assert_eq!(
+            res,
+            "
+pub SomeName {} { }
+pub SomeName {} { }
+"
+            .to_string()
+        );
+    }
+}