/*
 * Copyright 2024 Luca Fulchir <luca.fulchir@runesauth.com>
 *
 * Licensed under the Apache License, Version 2.0 with LLVM exception (the
 * "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License and of the exception at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *     https://spdx.org/licenses/LLVM-exception.html
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use ::proc_macro::TokenStream;
use ::quote::quote;
use ::syn::parse_macro_input;

pub(crate) fn collection(
    attrs: TokenStream,
    input: TokenStream,
) -> TokenStream {
    let ast = parse_macro_input!(input as ::syn::ItemStruct);
    if ast.ident.to_string() != "Collection" {
        use ::syn::spanned::Spanned;
        return ::syn::Error::new(
            ast.span(),
            "#[::bok_macro::collection(..)] should only be called on `struct \
             Collection{}`",
        )
        .to_compile_error()
        .into();
    }
    use crate::PathList;

    let deps_list = parse_macro_input!(attrs as PathList);
    let mut all_deps_builder = deps_list.0.iter();
    let name = all_deps_builder.next().expect(
        "`#[::bok_macro::collection(..)]` must have at least two arguments, \
         the first is the repo path",
    );

    let mut asdf = Vec::new();
    for d in deps_list.0.iter() {
        let d_str = d
            .segments
            .iter()
            .fold(String::new(), |a, b| a + "_" + &b.ident.to_string());
        asdf.push(::quote::format_ident!("{}", d_str));
    }

    quote! {
        use ::bok_macro::collection_dep;
        #(
            const #asdf : u32 = 42;
        )
        *
        #(#[::bok_macro::collection_dep(#all_deps_builder)])
        *
        #[derive(::core::fmt::Debug)]
        pub struct Collection {
            repo: ::std::sync::Arc<#name>,
            pkgs: ::std::sync::RwLock<
                ::std::vec::Vec<
                    ::std::sync::Arc<
                        dyn ::bok::PkgBuilder>>>,
        }
        impl ::bok::Collection for Collection {
            fn as_any(&self) -> &dyn ::std::any::Any {
                self
            }
            fn as_any_mut(&mut self) -> &mut dyn ::std::any::Any {
                self
            }
        }
    }
    .into()
}

pub(crate) fn collection_dep(
    attrs: TokenStream,
    input: TokenStream,
    __source_path: TokenStream,
) -> TokenStream {
    let local = parse_macro_input!(input as ::syn::ItemStruct);
    let dep = parse_macro_input!(attrs as ::syn::ItemTrait);

    let local_ident = &local.ident;
    let dep_ident = parse_macro_input!(__source_path as ::syn::Path);

    let mut all_deps = Vec::with_capacity(dep.items.len());
    for fn_it in dep.items.iter() {
        let ::syn::TraitItem::Fn(func) = fn_it else {
            continue;
        };
        let sig = &func.sig;
        let pkgbuilder_name = &sig.ident;

        let builder: ::syn::ImplItemFn = ::syn::parse_quote! {
            #sig {
                ::std::boxed::Box::new(
                    self.repo.#pkgbuilder_name()
                )
            }
        };
        all_deps.push(builder);
    }

    quote! {
        #local
        impl #dep_ident for #local_ident {
            #(#all_deps)
            *
        }
    }
    .into()
}