feat: WIP add secrets module and macro crate

harmony_secrets_derive/src/lib.rsglm45

@@ -0,0 +1,100 @@
+use proc_macro::TokenStream;
+use syn::{parse_macro_input, DeriveInput, Attribute, Meta};
+use quote::quote;
+use proc_macro_crate::crate_name;
+
+#[proc_macro_derive(Secret, attributes(secret))]
+pub fn derive_secret(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    
+    // Verify this is a unit struct
+    if !matches!(&input.data, syn::Data::Struct(data) if data.fields.is_empty()) {
+        return syn::Error::new_spanned(
+            input.ident,
+            "#[derive(Secret)] only supports unit structs (e.g., `struct MySecret;`)",
+        )
+        .to_compile_error()
+        .into();
+    }
+
+    // Parse the #[secret(...)] attribute
+    let (namespace, key, value_type) = match parse_secret_attributes(&input.attrs) {
+        Ok(attrs) => attrs,
+        Err(e) => return e.into_compile_error().into(),
+    };
+
+    // Get the path to the harmony_secrets crate
+    let secret_crate_path = match crate_name("harmony-secrets") {
+        Ok(proc_macro_crate::FoundCrate::Itself) => quote!(crate),
+        Ok(proc_macro_crate::FoundCrate::Name(name)) => {
+            let ident = quote::format_ident!("{}", name);
+            quote!(::#ident)
+        }
+        Err(_) => {
+            return syn::Error::new_spanned(
+                &input.ident,
+                "harmony-secrets crate not found in dependencies",
+            )
+            .to_compile_error()
+            .into();
+        }
+    };
+
+    let struct_ident = input.ident;
+
+    TokenStream::from(quote! {
+        impl #secret_crate_path::Secret for #struct_ident {
+            type Value = #value_type;
+            const NAMESPACE: &'static str = #namespace;
+            const KEY: &'static str = #key;
+        }
+    })
+}
+
+fn parse_secret_attributes(attrs: &[Attribute]) -> syn::Result<(String, String, syn::Type)> {
+    let secret_attr = attrs
+        .iter()
+        .find(|attr| attr.path().is_ident("secret"))
+        .ok_or_else(|| {
+            syn::Error::new_spanned(
+                attrs.first().unwrap_or_else(|| &attrs[0]),
+                "missing #[secret(...)] attribute",
+            )
+        })?;
+
+    let mut namespace = None;
+    let mut key = None;
+    let mut value_type = None;
+
+    if let Meta::List(meta_list) = &secret_attr.parse_meta()? {
+        for nested in &meta_list.nested {
+            if let syn::NestedMeta::Meta(Meta::NameValue(nv)) = nested {
+                if nv.path.is_ident("namespace") {
+                    if let syn::Lit::Str(lit) = &nv.lit {
+                        namespace = Some(lit.value());
+                    }
+                } else if nv.path.is_ident("key") {
+                    if let syn::Lit::Str(lit) = &nv.lit {
+                        key = Some(lit.value());
+                    }
+                } else if nv.path.is_ident("value_type") {
+                    if let syn::Lit::Str(lit) = &nv.lit {
+                        value_type = Some(syn::parse_str::<syn::Type>(&lit.value())?);
+                    }
+                }
+            }
+        }
+    }
+
+    Ok((
+        namespace.ok_or_else(|| {
+            syn::Error::new_spanned(secret_attr, "missing `namespace` in #[secret(...)]")
+        })?,
+        key.ok_or_else(|| {
+            syn::Error::new_spanned(secret_attr, "missing `key` in #[secret(...)]")
+        })?,
+        value_type.ok_or_else(|| {
+            syn::Error::new_spanned(secret_attr, "missing `value_type` in #[secret(...)]")
+        })?,
+    ))
+}