state-shift 2.1.1

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ImplItem, ItemImpl, Type};

use crate::{extract_macro_args, generate_impl_block_for_method_based_on_require_args};

pub fn impl_state_inner(item: TokenStream) -> TokenStream {
    // Parse the impl block
    let mut input = parse_macro_input!(item as ItemImpl);

    // Extract the type name and generics of the struct being implemented
    let (struct_name, struct_generics) = match *input.self_ty {
        Type::Path(ref type_path) => {
            let last_segment = type_path.path.segments.last().unwrap();
            let struct_name = last_segment.ident.clone();
            let struct_generics = &last_segment.arguments;
            (struct_name, struct_generics)
        }
        _ => panic!("Unsupported type for impl block"),
    };

    // Extract the methods from the impl block
    let mut methods = Vec::new();

    for item in input.items.iter_mut() {
        if let ImplItem::Fn(ref mut method) = item {
            // Extract `#[require]` arguments if they exist
            let require_args = extract_macro_args(&mut method.attrs, "require");

            // Generate the impl block for the method based on the extracted #[require] arguments
            let modified_method = if let Some(require_args) = require_args {
                generate_impl_block_for_method_based_on_require_args(
                    method,
                    &struct_name,
                    &require_args,
                    &input.generics,
                    struct_generics,
                )
            } else {
                quote! { #method }
            };

            // Push the modified method to the list of methods
            methods.push(modified_method);
        }
    }

    // Generate the expanded code with unique modules and traits
    let expanded = quote! {
        #(#methods)*
    };

    expanded.into()
}