optionable_codegen 0.8.0

use crate::helper::error;
use crate::parsed_input::FieldHandling::{OptionedOnly, Required};
use crate::parsed_input::{FieldParsed, StructParsed};
use crate::{TypeHelperAttributes, TypeHelperAttributesK8sOpenapi, TypeHelperAttributesKube};
use proc_macro2::{Ident, TokenStream};
use quote::{quote, ToTokens};
use syn::{
    parse_quote, Attribute, Data, DeriveInput, Error, ImplGenerics, Path, TypeGenerics, WhereClause,
};

/// We have two useful `Resource` traits and dependent on the user needs we will use one
/// of them for adding the API envelope `apiVersion` and `kind` fields when serializing.
pub(crate) enum ResourceType {
    K8sOpenApi,
    Kube,
}

/// Validates the resource configuration and returns the resource type.
pub(crate) fn k8s_resource_type(
    attrs: &TypeHelperAttributes,
) -> Result<Option<ResourceType>, Error> {
    if attrs.k8s_openapi.is_some() && attrs.kube.is_some() {
        return error(
            "Conflicting configuration. Only one of the `#[optionable(k8s_openapi)]` or `#[optionable(kube)]` attribute is allowed at once per type.",
        );
    }
    if attrs
        .k8s_openapi
        .as_ref()
        .is_some_and(|attr| attr.resource.is_some())
    {
        return Ok(Some(ResourceType::K8sOpenApi));
    }
    if attrs
        .kube
        .as_ref()
        .is_some_and(|attr| attr.resource.is_some())
    {
        return Ok(Some(ResourceType::Kube));
    }
    Ok(None)
}

/// Additional derives to set for `k8s` types.
pub(crate) fn k8s_derives(input: &DeriveInput) -> Option<Vec<String>> {
    match input.data {
        Data::Struct(_) => Some(vec![
            "Clone".to_owned(),
            "std::fmt::Debug".to_owned(),
            "Default".to_owned(),
            "PartialEq".to_owned(),
            "serde::Serialize".to_owned(),
            "serde::Deserialize".to_owned(),
        ]),
        Data::Enum(_) => Some(vec![
            "Clone".to_owned(),
            "std::fmt::Debug".to_owned(),
            "PartialEq".to_owned(),
            "serde::Serialize".to_owned(),
            "serde::Deserialize".to_owned(),
        ]),
        Data::Union(_) => None,
    }
}

/// Adjust the struct fields according to the `Kubernetes` use case.
pub(crate) fn k8s_adjust_fields(
    struct_parsed: &mut StructParsed,
    attr_k8s_openapi: Option<&TypeHelperAttributesK8sOpenapi>,
    attr_kube: Option<&TypeHelperAttributesKube>,
    resource_type: Option<&ResourceType>,
    crate_name: &Path,
) -> Result<(), Error> {
    if attr_k8s_openapi.is_some() {
        k8s_openapi_adjust_field_serde_renames(struct_parsed)?;
    }
    if attr_k8s_openapi.is_some_and(|attr| attr.metadata.is_some())
        || attr_kube.is_some_and(|attr| attr.resource.is_some())
    {
        k8s_openapi_set_metadata_required(struct_parsed);
    }
    if let Some(k8s_resource_type) = &resource_type {
        k8s_openapi_field_resource_adjust(struct_parsed, k8s_resource_type, crate_name);
    }
    Ok(())
}

/// Adjust the parsed struct for the `k8s_openapi::Metadata` requirements.
fn k8s_openapi_set_metadata_required(struct_parsed: &mut StructParsed) {
    struct_parsed
        .fields
        .iter_mut()
        .filter(|f| f.field.ident.as_ref().is_some_and(|f| *f == "metadata"))
        .for_each(|f| f.handling = Required);
}

/// Adjust the serde handling of specific fields to handle fields deviating from just `camelCase`.
/// See the [`get_rust_ident`](https://docs.rs/k8s-openapi-codegen-common/latest/k8s_openapi_codegen_common/fn.get_rust_ident.html) used by `k8s_openapi`.
fn k8s_openapi_adjust_field_serde_renames(struct_parsed: &mut StructParsed) -> Result<(), Error> {
    struct_parsed.fields.iter_mut().try_for_each(|f| {
        if let Some(name) = &f.field.ident
            && let Some(name_serialized) =
                k8s_openapi_serde_rename_revert_special_cases(name.to_string().as_ref())
        {
            f.field
                .attrs
                .push(parse_quote!(#[optionable_attr(serde(rename=#name_serialized))]));
        }
        Ok(())
    })
}

/// Reverts special case handling from `k8s_openapi`.
/// Returns `None` if it is not a special case.
/// See the [`get_rust_ident`](https://docs.rs/k8s-openapi-codegen-common/latest/k8s_openapi_codegen_common/fn.get_rust_ident.html) used by `k8s_openapi`.
fn k8s_openapi_serde_rename_revert_special_cases(input: &str) -> Option<&'static str> {
    match input {
        "cluster_ips" => Some("clusterIPs"),
        "external_ips" => Some("externalIPs"),
        "host_ips" => Some("hostIPs"),
        "non_resource_urls" => Some("nonResourceURLs"),
        "pod_cidrs" => Some("podCIDRs"),
        "pod_ips" => Some("podIPs"),
        "server_address_by_client_cidrs" => Some("serverAddressByClientCIDRs"),
        "target_wwns" => Some("targetWWNs"),
        "schema" => Some("$schema"),
        "as_" => Some("as"),
        "continue_" => Some("continue"),
        "enum_" => Some("enum"),
        "ref_" => Some("ref"),
        "type_" => Some("type"),
        _ => None,
    }
}

#[test]
fn roundtrip_k8s_openapi_adjust_field_serde() {
    const SPECIAL_KEYS: &[&str] = &[
        "clusterIPs",
        "externalIPs",
        "hostIPs",
        "nonResourceURLs",
        "podCIDRs",
        "podIPs",
        "serverAddressByClientCIDRs",
        "targetWWNs",
        "$schema",
        "as",
        "continue",
        "enum",
        "ref",
        "type",
    ];
    for key in SPECIAL_KEYS {
        let rust_ident = k8s_openapi_codegen_common::get_rust_ident(key);
        let key_roundtrip = k8s_openapi_serde_rename_revert_special_cases(rust_ident.as_ref());
        assert!(key_roundtrip.is_some());
        assert_eq!(key.to_owned(), key_roundtrip.unwrap().to_owned());
    }
}

/// The field type helper attributes for an optioned `Struct` or `Enum`.
pub(crate) fn k8s_type_attr(input: &DeriveInput) -> Option<Attribute> {
    match input.data {
        Data::Struct(_) => Some(parse_quote!(#[serde(rename_all="camelCase")])),
        Data::Enum(_) => Some(parse_quote!(#[serde(rename_all_fields="camelCase")])),
        Data::Union(_) => None,
    }
}

/// Adjust the parsed struct for the `k8s_openapi::Resource` requirements.
fn k8s_openapi_field_resource_adjust(
    struct_parsed: &mut StructParsed,
    resource_type: &ResourceType,
    crate_name: &Path,
) {
    let mut envelope_serde_path = crate_name.to_token_stream().to_string();
    match resource_type {
        ResourceType::K8sOpenApi => {
            envelope_serde_path.push_str("::k8s_openapi");
        }
        ResourceType::Kube => {
            envelope_serde_path.push_str("::kube");
        }
    }
    let mut serialize_fn = envelope_serde_path.clone();
    serialize_fn.push_str("::serialize_api_envelope");
    let mut deserialize_fn = envelope_serde_path;
    deserialize_fn.push_str("::deserialize_api_envelope");
    let field = parse_quote!(
                   #[optionable_attr(serde(flatten,serialize_with=#serialize_fn,deserialize_with=#deserialize_fn))]
                   pub phantom: std::marker::PhantomData<Self>
    );
    struct_parsed.fields.push(FieldParsed {
        field,
        handling: OptionedOnly,
    });
}

/// Derives `k8s_openapi::Resource` for the `T::Optioned` type from the non-optioned type.
/// It has to be ensured that the given `T` implements `k8s_openapi::Resource`.
pub(crate) fn k8s_openapi_impl_resource(
    ty_ident: &Path,
    ty_ident_opt: &Ident,
    impl_generics: &ImplGenerics,
    ty_generics: &TypeGenerics,
    where_clause_impl_optionable: &WhereClause,
) -> TokenStream {
    quote!(
        impl #impl_generics k8s_openapi::Resource for #ty_ident_opt #ty_generics #where_clause_impl_optionable {
            const API_VERSION: &'static str = <#ty_ident #ty_generics as k8s_openapi::Resource>::API_VERSION;
            const GROUP: &'static str = <#ty_ident #ty_generics as k8s_openapi::Resource>::GROUP;
            const KIND: &'static str = <#ty_ident #ty_generics as k8s_openapi::Resource>::KIND;
            const VERSION: &'static str = <#ty_ident #ty_generics as k8s_openapi::Resource>::VERSION;
            const URL_PATH_SEGMENT: &'static str =
               <#ty_ident #ty_generics as k8s_openapi::Resource>::URL_PATH_SEGMENT;
            type Scope = <#ty_ident #ty_generics as k8s_openapi::Resource>::Scope;
        }
    )
}

/// Derives `k8s_openapi::Metadata` for the `T::Optioned` type from the non-optioned type.
/// It has to be ensured that the given `T` implements `k8s_openapi::Metadata`.
pub(crate) fn k8s_openapi_impl_metadata(
    ty_ident: &Path,
    ty_ident_opt: &Ident,
    impl_generics: &ImplGenerics,
    ty_generics: &TypeGenerics,
    where_clause_impl_optionable: &WhereClause,
) -> TokenStream {
    quote!(
        impl #impl_generics k8s_openapi::Metadata for #ty_ident_opt #ty_generics #where_clause_impl_optionable {
            type Ty = <#ty_ident #ty_generics as k8s_openapi::Metadata>::Ty;

            fn metadata(&self) -> &<Self as k8s_openapi::Metadata>::Ty {
                &self.metadata
            }

            fn metadata_mut(&mut self) -> &mut <Self as k8s_openapi::Metadata>::Ty {
                &mut self.metadata
            }
        }
    )
}

/// Errors if `k8s_openapi_*`  or `kube_*` type attributes are set without the corresponding feature being enabled.
/// The feature does nothing besides this on this crate but is used to track that the required features are enabled
/// on the user-facing `optionable`-crate.
// false positive depending on the features enabled
#[allow(unused_variables)]
#[allow(clippy::unnecessary_wraps)]
pub(crate) fn error_missing_features(attrs: &TypeHelperAttributes) -> Result<(), Error> {
    #[cfg(not(feature = "k8s_openapi"))]
    if attrs
        .k8s_openapi
        .as_ref()
        .is_some_and(|attr| attr.resource.is_some())
    {
        return error(
            "helper attributes `#[optionable(k8s_openapi(resource))] require one of the `k8s_openapi_*` features to be enabled for the `optionable` crate.",
        );
    }
    #[cfg(not(feature = "kube"))]
    if attrs
        .kube
        .as_ref()
        .is_some_and(|attr| attr.resource.is_some())
    {
        return error(
            "helper attributes `#[optionable(kube(resource)] require the `kube` feature to be enabled for the `optionable` crate.",
        );
    }
    Ok(())
}