aj_macro 0.9.1

extern crate proc_macro;

use convert_case::{Case, Casing};
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput, FnArg, ItemFn, Pat, PatType, ReturnType};

#[proc_macro_derive(BackgroundJob)]
pub fn background_job_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = input.ident;

    let expanded = quote! {
        impl BackgroundJob for #name {
            fn queue_name() -> &'static str {
                stringify!(#name)
            }

            fn job(self) -> aj::Job<Self> {
                aj::Job::new(self)
            }
        }
    };

    TokenStream::from(expanded)
}

#[proc_macro_attribute]
pub fn job(_attr: TokenStream, item: TokenStream) -> TokenStream {
    // Parse the input function
    let input_fn = parse_macro_input!(item as ItemFn);
    let fn_name = &input_fn.sig.ident;
    let fn_inputs = &input_fn.sig.inputs;
    let fn_output = &input_fn.sig.output;

    // Check if the function is async
    let is_async = input_fn.sig.asyncness.is_some();

    // Generate struct name by capitalizing function name
    let job_struct_name = syn::Ident::new(
        &format!("Job{}", fn_name.to_string().to_case(Case::Pascal)),
        fn_name.span(),
    );

    // Extract input names and types
    let input_fields: Vec<_> = fn_inputs
        .iter()
        .filter_map(|arg| {
            if let FnArg::Typed(PatType { pat, ty, .. }) = arg {
                if let Pat::Ident(ident) = &**pat {
                    Some(quote! {
                        pub #ident: #ty
                    })
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    // Extract the argument names to pass them later when calling the function
    let struct_as_args: Vec<_> = fn_inputs
        .iter()
        .filter_map(|arg| {
            if let FnArg::Typed(PatType { pat, .. }) = arg {
                if let Pat::Ident(ident) = &**pat {
                    // TODO: This is a not good way to pass variable from struct to fn logic.
                    // IMHO, the best apporach is transform the original fn code to mapping with struct like destructure, etc to remove clone memory value.
                    Some(quote! { self.#ident.clone() })
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    let input_names: Vec<_> = fn_inputs
        .iter()
        .filter_map(|arg| {
            if let FnArg::Typed(PatType { pat, .. }) = arg {
                if let Pat::Ident(ident) = &**pat {
                    Some(quote! { #ident })
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    let fn_output_type = match fn_output {
        ReturnType::Default => quote! { () },
        ReturnType::Type(_, ty) => quote! { #ty },
    };

    let call_fn = if is_async {
        quote! {
            #fn_name(#(#struct_as_args),*).await
        }
    } else {
        quote! {
            #fn_name(#(#struct_as_args),*)
        }
    };

    let expanded = quote! {
        #input_fn

        pub mod #fn_name {
            use aj::{BackgroundJob, JobContext};
            use super::*;

            // Define a new trait
            // Require Debug and Clone
            #[derive(
                Debug,
                Clone,
                BackgroundJob,
                aj::export::core::serde::Serialize,
                aj::export::core::serde::Deserialize,
            )]
            pub struct #job_struct_name {
                #(#input_fields),*
            }

            // Automatically implement the trait for the struct
            #[aj::async_trait]
            impl aj::Executable for #job_struct_name {
                type Output = #fn_output_type;

                async fn execute(&mut self, _context: &JobContext) -> Self::Output {
                    use super::#fn_name;

                    #call_fn
                }
            }

            impl #job_struct_name {
                fn new(#fn_inputs) -> Self {
                    Self {
                        #(#input_names),*
                    }
                }
            }

            pub async fn run(#fn_inputs) -> Result<String, aj::Error> {
                let msg = #job_struct_name::new(#(#input_names),*);
                let job_id = msg.job().run().await?;
                Ok(job_id)
            }

            pub fn just_run(#fn_inputs) {
                let msg = #job_struct_name::new(#(#input_names),*);
                msg.job().just_run();
            }

            pub async fn run_with_context(#fn_inputs, context: aj::JobContext) -> Result<String, aj::Error> {
                let msg = #job_struct_name::new(#(#input_names),*);
                let job_id = msg.job().context(context).run().await?;
                Ok(job_id)
            }

            pub fn just_run_with_context(#fn_inputs, context: aj::JobContext) {
                let msg = #job_struct_name::new(#(#input_names),*);
                msg.job().context(context).just_run();
            }
        }
    };

    TokenStream::from(expanded)
}