use crate::args;
use crate::utils::{check_reserved_name, get_crate_name};
use proc_macro::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput, Error, Fields, Result, Type};
pub fn generate(interface_args: &args::Interface, input: &DeriveInput) -> Result<TokenStream> {
let crate_name = get_crate_name(interface_args.internal);
let ident = &input.ident;
let generics = &input.generics;
let attrs = &input.attrs;
let vis = &input.vis;
let s = match &input.data {
Data::Struct(s) => s,
_ => return Err(Error::new_spanned(input, "It should be a struct.")),
};
let fields = match &s.fields {
Fields::Unnamed(fields) => fields,
_ => return Err(Error::new_spanned(input, "All fields must be unnamed.")),
};
let mut enum_names = Vec::new();
let mut enum_items = Vec::new();
let mut type_into_impls = Vec::new();
let gql_typename = interface_args
.name
.clone()
.unwrap_or_else(|| ident.to_string());
check_reserved_name(&gql_typename, interface_args.internal)?;
let desc = interface_args
.desc
.as_ref()
.map(|s| quote! {Some(#s)})
.unwrap_or_else(|| quote! {None});
let mut registry_types = Vec::new();
let mut possible_types = Vec::new();
let mut collect_inline_fields = Vec::new();
for field in &fields.unnamed {
if let Type::Path(p) = &field.ty {
let enum_name = &p.path.segments.last().unwrap().ident;
enum_names.push(enum_name);
enum_items.push(quote! { #enum_name(#p) });
type_into_impls.push(quote! {
impl #generics From<#p> for #ident #generics {
fn from(obj: #p) -> Self {
#ident::#enum_name(obj)
}
}
});
registry_types.push(quote! {
<#p as #crate_name::Type>::create_type_info(registry);
});
possible_types.push(quote! {
possible_types.insert(<#p as #crate_name::Type>::type_name().to_string());
});
collect_inline_fields.push(quote! {
if name == <#p as #crate_name::Type>::type_name() {
if let #ident::#enum_name(obj) = self {
return #crate_name::collect_fields(ctx, obj, futures);
}
unreachable!()
}
});
} else {
return Err(Error::new_spanned(field, "Invalid type"));
}
}
let expanded = quote! {
#(#attrs)*
#vis enum #ident #generics { #(#enum_items),* }
#(#type_into_impls)*
impl #generics #crate_name::Type for #ident #generics {
fn type_name() -> std::borrow::Cow<'static, str> {
std::borrow::Cow::Borrowed(#gql_typename)
}
fn create_type_info(registry: &mut #crate_name::registry::Registry) -> String {
registry.create_type::<Self, _>(|registry| {
#(#registry_types)*
#crate_name::registry::Type::Union {
name: #gql_typename.to_string(),
description: #desc,
possible_types: {
let mut possible_types = std::collections::HashSet::new();
#(#possible_types)*
possible_types
}
}
})
}
}
#[#crate_name::async_trait::async_trait]
impl #generics #crate_name::ObjectType for #ident #generics {
async fn resolve_field(&self, ctx: &#crate_name::Context<'_>, field: &#crate_name::graphql_parser::query::Field) -> #crate_name::Result<#crate_name::serde_json::Value> {
use #crate_name::ErrorWithPosition;
anyhow::bail!(#crate_name::QueryError::FieldNotFound {
field_name: field.name.clone(),
object: #gql_typename.to_string(),
}
.with_position(field.position));
}
fn collect_inline_fields<'a>(
&'a self,
name: &str,
ctx: &#crate_name::ContextSelectionSet<'a>,
futures: &mut Vec<#crate_name::BoxFieldFuture<'a>>,
) -> #crate_name::Result<()> {
#(#collect_inline_fields)*
#crate_name::anyhow::bail!(#crate_name::QueryError::UnrecognizedInlineFragment {
object: #gql_typename.to_string(),
name: name.to_string(),
});
}
}
#[#crate_name::async_trait::async_trait]
impl #generics #crate_name::OutputValueType for #ident #generics {
async fn resolve(value: &Self, ctx: &#crate_name::ContextSelectionSet<'_>) -> #crate_name::Result<#crate_name::serde_json::Value> {
#crate_name::do_resolve(ctx, value).await
}
}
};
Ok(expanded.into())
}