tirbofish/dropbear

use proc_macro::TokenStream;
use quote::quote;
use std::path::Path;
use syn::{
    FnArg, GenericArgument, Ident, ItemEnum, ItemFn, LitStr, PathArguments, ReturnType, Token,
    Type,
    parse::{Parse, ParseStream},
    parse_macro_input, parse_quote,
    spanned::Spanned,
};

struct ExportArgs {
    c: Option<CArgs>,
    kotlin: Option<KotlinArgs>,
}

#[derive(Default)]
struct CArgs {
    name: Option<String>,
}

struct KotlinArgs {
    class: String,
    func: String,
    jni_path: Option<syn::Path>,
}

enum ExportItem {
    C(CArgs),
    Kotlin(KotlinArgs),
}

impl Parse for ExportArgs {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let items = syn::punctuated::Punctuated::<ExportItem, Token![,]>::parse_terminated(input)?;
        let mut args = ExportArgs {
            c: None,
            kotlin: None,
        };

        for item in items {
            match item {
                ExportItem::C(c) => args.c = Some(c),
                ExportItem::Kotlin(k) => args.kotlin = Some(k),
            }
        }

        Ok(args)
    }
}

impl Parse for ExportItem {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let ident: Ident = input.parse()?;
        if ident == "c" {
            let args = if input.peek(syn::token::Paren) {
                let content;
                syn::parenthesized!(content in input);
                let mut c_args = CArgs::default();
                while !content.is_empty() {
                    let key: Ident = content.parse()?;
                    content.parse::<Token![=]>()?;
                    let value: LitStr = content.parse()?;
                    if key == "name" {
                        c_args.name = Some(value.value());
                    } else {
                        return Err(syn::Error::new(key.span(), "Unknown c(...) key"));
                    }
                    if content.peek(Token![,]) {
                        content.parse::<Token![,]>()?;
                    }
                }
                c_args
            } else {
                CArgs::default()
            };
            return Ok(ExportItem::C(args));
        }

        if ident == "kotlin" {
            let content;
            syn::parenthesized!(content in input);
            let mut class: Option<String> = None;
            let mut func: Option<String> = None;
            let mut jni_path: Option<syn::Path> = None;
            while !content.is_empty() {
                let key: Ident = content.parse()?;
                content.parse::<Token![=]>()?;
                let value: LitStr = content.parse()?;
                if key == "class" {
                    class = Some(value.value());
                } else if key == "func" {
                    func = Some(value.value());
                } else if key == "jni" {
                    jni_path = Some(syn::parse_str::<syn::Path>(&value.value())?);
                } else {
                    return Err(syn::Error::new(key.span(), "Unknown kotlin(...) key"));
                }
                if content.peek(Token![,]) {
                    content.parse::<Token![,]>()?;
                }
            }

            let class = class
                .ok_or_else(|| syn::Error::new(ident.span(), "kotlin(class = ...) is required"))?;
            let func = func
                .ok_or_else(|| syn::Error::new(ident.span(), "kotlin(func = ...) is required"))?;
            return Ok(ExportItem::Kotlin(KotlinArgs {
                class,
                func,
                jni_path,
            }));
        }

        Err(syn::Error::new(ident.span(), "Expected c or kotlin(...)"))
    }
}

/// Exports a Rust function as C and/or Kotlin/JNI wrappers with minimal boilerplate.
///
/// The function must return `DropbearNativeResult<T>`. Use `#[dropbear_macro::define(...)]`
/// on pointer args and `#[dropbear_macro::entity]` for `hecs::Entity` args.
///
/// # Example
/// ```rust
/// #[dropbear_macro::export(
///     kotlin(class = "com.dropbear.DropbearEngineNative", func = "getEntity"),
///     c(name = "dropbear_engine_get_entity")
/// )]
/// fn get_entity(
///     #[dropbear_macro::define(crate::ptr::WorldPtr)]
///     world: &World,
///     label: String,
/// ) -> DropbearNativeResult<u64> {
///     shared::get_entity(&world, &label)
/// }
/// ```
#[proc_macro_attribute]
pub fn export(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as ExportArgs);
    let mut func = parse_macro_input!(item as ItemFn);

    let original_name = func.sig.ident.clone();
    let inner_name = Ident::new(
        &format!("__dropbear_export_inner_{}", original_name),
        original_name.span(),
    );
    let return_type = func.sig.output.clone();

    let result_inner = match extract_dropbear_result_inner_type(&return_type) {
        Ok(inner) => inner,
        Err(err) => return err.to_compile_error().into(),
    };

    let (is_option, option_inner) = extract_option_inner_type(&result_inner);

    let mut cleaned_inputs = Vec::new();
    let mut arg_specs = Vec::new();

    for input in func.sig.inputs.iter_mut() {
        match input {
            FnArg::Receiver(_) => {
                return syn::Error::new(input.span(), "export does not support methods")
                    .to_compile_error()
                    .into();
            }
            FnArg::Typed(pat_ty) => {
                let (define_ty, is_entity) = extract_arg_markers(&mut pat_ty.attrs);
                let (arg_name, arg_ty) = match &*pat_ty.pat {
                    syn::Pat::Ident(ident) => (ident.ident.clone(), (*pat_ty.ty).clone()),
                    _ => {
                        return syn::Error::new(
                            pat_ty.span(),
                            "export only supports identifier arguments",
                        )
                        .to_compile_error()
                        .into();
                    }
                };

                cleaned_inputs.push(FnArg::Typed(pat_ty.clone()));
                arg_specs.push(ArgSpec {
                    name: arg_name,
                    ty: arg_ty,
                    define_ty,
                    is_entity,
                });
            }
        }
    }

    func.sig.ident = inner_name.clone();
    func.sig.inputs = syn::punctuated::Punctuated::from_iter(cleaned_inputs);

    let c_wrapper = match args.c {
        Some(c_args) => build_c_wrapper(
            &original_name,
            &inner_name,
            &arg_specs,
            &result_inner,
            is_option,
            option_inner.as_ref(),
            c_args,
        ),
        None => quote! {},
    };

    let kotlin_wrapper = match args.kotlin {
        Some(k_args) => build_kotlin_wrapper(
            &original_name,
            &inner_name,
            &arg_specs,
            &result_inner,
            is_option,
            option_inner.as_ref(),
            k_args,
        ),
        None => quote! {},
    };

    let expanded = quote! {
        #func
        #c_wrapper
        #kotlin_wrapper
    };

    expanded.into()
}

#[proc_macro_attribute]
pub fn repr_c_enum(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = parse_macro_input!(item as ItemEnum);
    let enum_ident = input.ident.clone();
    let enum_name = enum_ident.to_string();
    let mod_ident = Ident::new(
        &format!("{}_ffi", to_snake_case(&enum_name)),
        enum_ident.span(),
    );
    let tag_ident = Ident::new(&format!("{}Tag", enum_name), enum_ident.span());
    let data_ident = Ident::new(&format!("{}Data", enum_name), enum_ident.span());
    let ffi_ident = Ident::new(&format!("{}Ffi", enum_name), enum_ident.span());

    let mut tag_variants = Vec::new();
    let mut variant_structs = Vec::new();
    let mut data_union_fields = Vec::new();
    let mut match_arms = Vec::new();
    let mut array_structs = std::collections::BTreeMap::new();

    for (index, variant) in input.variants.iter().enumerate() {
        let variant_ident = &variant.ident;
        let variant_name = variant_ident.to_string();
        let variant_struct_ident = Ident::new(
            &format!("{}{}", enum_name, variant_name),
            variant_ident.span(),
        );

        let index = index as u32;
        tag_variants.push(quote! { #variant_ident = #index });
        data_union_fields.push(quote! {
            pub #variant_ident: ::std::mem::ManuallyDrop<#variant_struct_ident>
        });

        let (fields, field_inits, match_pattern) =
            build_variant_fields(&enum_ident, variant, &mut array_structs);

        variant_structs.push(quote! {
            #[repr(C)]
            #[derive(Clone, Debug)]
            pub struct #variant_struct_ident {
                #(#fields)*
            }
        });

        match_arms.push(quote! {
            #match_pattern => {
                let data = #data_ident {
                    #variant_ident: ::std::mem::ManuallyDrop::new(#variant_struct_ident { #(#field_inits)* })
                };
                #ffi_ident { tag: #tag_ident::#variant_ident, data }
            }
        });
    }

    let array_struct_defs = array_structs.values().cloned().collect::<Vec<_>>();

    let expanded = quote! {
        #input

        #[allow(non_snake_case)]
        pub mod #mod_ident {
            use super::*;

            #(#array_struct_defs)*

            #[repr(u32)]
            #[derive(Clone, Copy, Debug, PartialEq, Eq)]
            pub enum #tag_ident {
                #(#tag_variants,)*
            }

            #(#variant_structs)*

            #[repr(C)]
            #[allow(non_snake_case)]
            pub union #data_ident {
                #(#data_union_fields,)*
            }

            #[repr(C)]
            pub struct #ffi_ident {
                pub tag: #tag_ident,
                pub data: #data_ident,
            }

            impl From<&#enum_ident> for #ffi_ident {
                fn from(value: &#enum_ident) -> Self {
                    match value {
                        #(#match_arms)*
                    }
                }
            }
        }
    };

    expanded.into()
}

fn build_variant_fields(
    enum_ident: &Ident,
    variant: &syn::Variant,
    array_structs: &mut std::collections::BTreeMap<String, proc_macro2::TokenStream>,
) -> (
    Vec<proc_macro2::TokenStream>,
    Vec<proc_macro2::TokenStream>,
    proc_macro2::TokenStream,
) {
    let mut fields = Vec::new();
    let mut field_inits = Vec::new();

    match &variant.fields {
        syn::Fields::Named(named) => {
            let mut pat_fields = Vec::new();
            for field in &named.named {
                let field_ident = field.ident.as_ref().expect("named field");
                let (field_ty, init_expr) =
                    map_field_type(enum_ident, &field.ty, field_ident, array_structs);
                fields.push(quote! { pub #field_ident: #field_ty, });
                field_inits.push(quote! { #field_ident: #init_expr, });
                pat_fields.push(quote! { #field_ident });
            }
            let variant_ident = &variant.ident;
            let match_pattern = quote! { #enum_ident::#variant_ident { #(#pat_fields),* } };
            (fields, field_inits, match_pattern)
        }
        syn::Fields::Unnamed(unnamed) => {
            let mut pat_fields = Vec::new();
            for (idx, field) in unnamed.unnamed.iter().enumerate() {
                let field_ident = Ident::new(&format!("_{}", idx), field.span());
                let (field_ty, init_expr) =
                    map_field_type(enum_ident, &field.ty, &field_ident, array_structs);
                fields.push(quote! { pub #field_ident: #field_ty, });
                field_inits.push(quote! { #field_ident: #init_expr, });
                pat_fields.push(quote! { #field_ident });
            }
            let variant_ident = &variant.ident;
            let match_pattern = quote! { #enum_ident::#variant_ident( #(#pat_fields),* ) };
            (fields, field_inits, match_pattern)
        }
        syn::Fields::Unit => {
            let variant_ident = &variant.ident;
            let match_pattern = quote! { #enum_ident::#variant_ident };
            (fields, field_inits, match_pattern)
        }
    }
}

fn map_field_type(
    _enum_ident: &Ident,
    ty: &Type,
    field_ident: &Ident,
    array_structs: &mut std::collections::BTreeMap<String, proc_macro2::TokenStream>,
) -> (Type, proc_macro2::TokenStream) {
    if let Some(inner) = vec_inner_type(ty) {
        let inner_ident = type_ident_name(&inner).unwrap_or_else(|| "Unknown".to_string());
        let array_ident = Ident::new(&format!("{}ArrayFfi", inner_ident), field_ident.span());
        let array_struct = quote! {
            #[repr(C)]
            #[derive(Clone, Debug)]
            pub struct #array_ident {
                pub ptr: *const #inner,
                pub len: usize,
            }
        };
        array_structs
            .entry(array_ident.to_string())
            .or_insert(array_struct);
        let array_ty: Type = parse_quote!(#array_ident);
        let init_expr =
            quote! { #array_ident { ptr: #field_ident.as_ptr(), len: #field_ident.len() } };
        return (array_ty, init_expr);
    }

    let init_expr = quote! { #field_ident.clone() };
    (ty.clone(), init_expr)
}

fn vec_inner_type(ty: &Type) -> Option<Type> {
    if let Type::Path(path) = ty {
        let last = path.path.segments.last()?;
        if last.ident != "Vec" {
            return None;
        }
        if let PathArguments::AngleBracketed(args) = &last.arguments {
            if let Some(GenericArgument::Type(inner)) = args.args.first() {
                return Some(inner.clone());
            }
        }
    }
    None
}

fn type_ident_name(ty: &Type) -> Option<String> {
    if let Type::Path(path) = ty {
        return path.path.segments.last().map(|s| s.ident.to_string());
    }
    None
}

fn to_snake_case(input: &str) -> String {
    let mut out = String::new();
    for (i, ch) in input.chars().enumerate() {
        if ch.is_uppercase() {
            if i != 0 {
                out.push('_');
            }
            for lc in ch.to_lowercase() {
                out.push(lc);
            }
        } else {
            out.push(ch);
        }
    }
    out
}

struct ArgSpec {
    name: Ident,
    ty: Type,
    define_ty: Option<Type>,
    is_entity: bool,
}

fn extract_arg_markers(attrs: &mut Vec<syn::Attribute>) -> (Option<Type>, bool) {
    let mut define_ty: Option<Type> = None;
    let mut is_entity = false;
    attrs.retain(|attr| {
        let path = &attr.path();
        let ident = path.get_ident().map(|v| v.to_string()).unwrap_or_default();

        if ident == "define"
            || path
                .segments
                .last()
                .map(|s| s.ident == "define")
                .unwrap_or(false)
        {
            if let Ok(ty) = attr.parse_args::<Type>() {
                define_ty = Some(ty);
            }
            return false;
        }

        if ident == "entity"
            || path
                .segments
                .last()
                .map(|s| s.ident == "entity")
                .unwrap_or(false)
        {
            is_entity = true;
            return false;
        }

        true
    });

    (define_ty, is_entity)
}

fn extract_dropbear_result_inner_type(output: &ReturnType) -> syn::Result<Type> {
    match output {
        ReturnType::Type(_, ty) => {
            if let Type::Path(type_path) = &**ty {
                if let Some(segment) = type_path.path.segments.last() {
                    if segment.ident == "DropbearNativeResult" {
                        if let PathArguments::AngleBracketed(args) = &segment.arguments {
                            if let Some(GenericArgument::Type(inner)) = args.args.first() {
                                return Ok(inner.clone());
                            }
                        }
                    }
                }
            }
            Err(syn::Error::new(
                output.span(),
                "export requires DropbearNativeResult<T> return type",
            ))
        }
        ReturnType::Default => Err(syn::Error::new(
            output.span(),
            "export requires DropbearNativeResult<T> return type",
        )),
    }
}

fn extract_option_inner_type(ty: &Type) -> (bool, Option<Type>) {
    if let Type::Path(type_path) = ty {
        if let Some(segment) = type_path.path.segments.last() {
            if segment.ident == "Option" {
                if let PathArguments::AngleBracketed(args) = &segment.arguments {
                    if let Some(GenericArgument::Type(inner)) = args.args.first() {
                        return (true, Some(inner.clone()));
                    }
                }
            }
        }
    }
    (false, None)
}

fn build_c_wrapper(
    original_name: &Ident,
    inner_name: &Ident,
    arg_specs: &[ArgSpec],
    result_inner: &Type,
    is_option: bool,
    option_inner: Option<&Type>,
    c_args: CArgs,
) -> proc_macro2::TokenStream {
    let module_path = module_path_from_callsite();
    let c_name = c_args
        .name
        .unwrap_or_else(|| default_c_name(original_name, module_path.as_deref()));
    let c_ident = Ident::new(&c_name, original_name.span());

    let mut wrapper_inputs = Vec::new();
    let mut conversions = Vec::new();
    let mut call_args = Vec::new();

    for arg in arg_specs {
        let name = &arg.name;

        if arg.is_entity {
            wrapper_inputs.push(quote! { #name: u64 });
            conversions.push(quote! {
                let #name = match ::hecs::Entity::from_bits(#name) {
                    Some(v) => v,
                    None => return crate::scripting::native::DropbearNativeError::InvalidEntity.code(),
                };
            });
            call_args.push(quote! { #name });
            continue;
        }

        if let Some(define_ty) = &arg.define_ty {
            let (target_ty, is_mut_ref) = match &arg.ty {
                Type::Reference(reference) => (&*reference.elem, reference.mutability.is_some()),
                _ => {
                    return syn::Error::new(
                        arg.ty.span(),
                        "define(...) requires a reference argument",
                    )
                    .to_compile_error();
                }
            };

            wrapper_inputs.push(quote! { #name: #define_ty });

            let convert = if is_mut_ref {
                quote! { let #name = crate::convert_ptr!(mut #name => #target_ty); }
            } else {
                quote! { let #name = crate::convert_ptr!(#name => #target_ty); }
            };
            conversions.push(convert);
            call_args.push(quote! { #name });
            continue;
        }

        if is_string_type(&arg.ty) {
            wrapper_inputs.push(quote! { #name: *const i8 });
            conversions.push(quote! {
                let #name = match {
                    if #name.is_null() { return crate::scripting::native::DropbearNativeError::NullPointer.code(); }
                    unsafe { std::ffi::CStr::from_ptr(#name) }
                }.to_str() {
                    Ok(v) => v.to_string(),
                    Err(_) => return crate::scripting::native::DropbearNativeError::InvalidUTF8.code(),
                };
            });
            call_args.push(quote! { #name });
            continue;
        }

        if is_str_ref(&arg.ty) {
            return syn::Error::new(arg.ty.span(), "&str is not supported by export; use String")
                .to_compile_error();
        }

        if !is_primitive_type(&arg.ty) {
            let (target_ty, is_mut_ref) = match &arg.ty {
                Type::Reference(reference) => (&*reference.elem, reference.mutability.is_some()),
                _ => {
                    return syn::Error::new(arg.ty.span(), "Object inputs must be references")
                        .to_compile_error();
                }
            };

            let ptr_ty = if is_mut_ref {
                quote! { *mut #target_ty }
            } else {
                quote! { *const #target_ty }
            };

            wrapper_inputs.push(quote! { #name: #ptr_ty });
            conversions.push(quote! {
                if #name.is_null() {
                    return crate::scripting::native::DropbearNativeError::NullPointer.code();
                }
            });
            if is_mut_ref {
                conversions.push(quote! { let #name = unsafe { &mut *#name }; });
            } else {
                conversions.push(quote! { let #name = unsafe { &*#name }; });
            }
            call_args.push(quote! { #name });
            continue;
        }

        let ty = &arg.ty;
        wrapper_inputs.push(quote! { #name: #ty });
        call_args.push(quote! { #name });
    }

    let (out_params, out_checks) = if is_unit_type(result_inner) {
        (quote! {}, quote! {})
    } else if is_option {
        let inner = option_inner.expect("option inner");
        (
            quote! { , out0: *mut #inner, out0_present: *mut bool },
            quote! {
                if out0_present.is_null() {
                    return crate::scripting::native::DropbearNativeError::NullPointer.code();
                }
            },
        )
    } else {
        (
            quote! { , out0: *mut #result_inner },
            quote! {
                if out0.is_null() {
                    return crate::scripting::native::DropbearNativeError::NullPointer.code();
                }
            },
        )
    };

    let result_match = if is_unit_type(result_inner) {
        quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(()) => crate::scripting::native::DropbearNativeError::Success.code(),
                crate::scripting::result::DropbearNativeResult::Err(e) => e.code(),
            }
        }
    } else if is_option {
        quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(val_opt) => {
                    match val_opt {
                        Some(v) => {
                            if out0.is_null() {
                                return crate::scripting::native::DropbearNativeError::NullPointer.code();
                            }
                            unsafe { *out0 = v; }
                            unsafe { *out0_present = true; }
                        }
                        None => {
                            unsafe { *out0_present = false; }
                        }
                    }
                    crate::scripting::native::DropbearNativeError::Success.code()
                }
                crate::scripting::result::DropbearNativeResult::Err(e) => e.code(),
            }
        }
    } else {
        quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(val) => {
                    unsafe { *out0 = val; }
                    crate::scripting::native::DropbearNativeError::Success.code()
                }
                crate::scripting::result::DropbearNativeResult::Err(e) => e.code(),
            }
        }
    };

    quote! {
        #[unsafe(no_mangle)]
        pub extern "C" fn #c_ident(#(#wrapper_inputs),* #out_params) -> i32 {
            #(#conversions)*
            #out_checks
            #result_match
        }
    }
}

fn build_kotlin_wrapper(
    original_name: &Ident,
    inner_name: &Ident,
    arg_specs: &[ArgSpec],
    result_inner: &Type,
    is_option: bool,
    option_inner: Option<&Type>,
    kotlin_args: KotlinArgs,
) -> proc_macro2::TokenStream {
    let class_name = kotlin_args.class.replace('.', "_");
    let jni_fn_name = format!("Java_{}_{}", class_name, kotlin_args.func);
    let jni_ident = Ident::new(&jni_fn_name, original_name.span());
    let jni_path: syn::Path = kotlin_args.jni_path.unwrap_or_else(|| parse_quote!(::jni));

    let mut wrapper_inputs = vec![
        quote! { mut unowned_env: #jni_path::EnvUnowned<'local> },
        quote! { _: #jni_path::objects::JClass<'local> },
    ];
    let mut conversions = Vec::new();
    let mut call_args = Vec::new();

    for arg in arg_specs {
        let name = &arg.name;
        if arg.is_entity {
            wrapper_inputs.push(quote! { #name: #jni_path::sys::jlong });
            conversions.push(quote! {
                let #name = match ::hecs::Entity::from_bits(#name as u64) {
                    Some(v) => v,
                    None => {
                        let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from("Invalid entity id"));
                        return Ok(crate::ffi_error_return!());
                    }
                };
            });
            call_args.push(quote! { #name });
            continue;
        }

        if let Some(_define_ty) = &arg.define_ty {
            wrapper_inputs.push(quote! { #name: #jni_path::sys::jlong });
            let (target_ty, is_mut_ref) = match &arg.ty {
                Type::Reference(reference) => (&*reference.elem, reference.mutability.is_some()),
                _ => {
                    return syn::Error::new(
                        arg.ty.span(),
                        "define(...) requires a reference argument",
                    )
                    .to_compile_error();
                }
            };
            let convert = if is_mut_ref {
                quote! { let #name = crate::convert_ptr!(mut #name => #target_ty); }
            } else {
                quote! { let #name = crate::convert_ptr!(#name => #target_ty); }
            };
            conversions.push(convert);
            call_args.push(quote! { #name });
            continue;
        }

        if is_string_type(&arg.ty) {
            wrapper_inputs.push(quote! { #name: #jni_path::objects::JString<'local> });
            conversions.push(quote! {
                let #name = match #name.mutf8_chars(&mut env) {
                    Ok(chars) => chars.to_str().into_owned(),
                    Err(e) => {
                        let _ = env.throw_new(
                            #jni_path::strings::JNIString::from("java/lang/RuntimeException"),
                            #jni_path::strings::JNIString::from(format!("Failed to get string from jni: {:?}", e))
                        );
                        return Ok(crate::ffi_error_return!());
                    }
                };
            });
            call_args.push(quote! { #name });
            continue;
        }

        if is_str_ref(&arg.ty) {
            return syn::Error::new(arg.ty.span(), "&str is not supported by export; use String")
                .to_compile_error();
        }

        if !is_primitive_type(&arg.ty) {
            wrapper_inputs.push(quote! { #name: #jni_path::objects::JObject<'local> });
            let (target_ty, is_mut_ref) = match &arg.ty {
                Type::Reference(reference) => (&*reference.elem, reference.mutability.is_some()),
                _ => (&arg.ty, false),
            };

            let value_name = Ident::new(&format!("{}_value", name), name.span());
            conversions.push(quote! {
                let #value_name = match crate::scripting::jni::utils::FromJObject::from_jobject(&mut env, &#name) {
                    Ok(v) => v,
                    Err(e) => {
                        let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Failed to convert object: {:?}", e)));
                        return Ok(crate::ffi_error_return!());
                    }
                };
            });

            if matches!(&arg.ty, Type::Reference(_)) {
                if is_mut_ref {
                    conversions.push(quote! { let #name = &mut #value_name; });
                } else {
                    conversions.push(quote! { let #name = &#value_name; });
                }
                call_args.push(quote! { #name });
            } else {
                conversions.push(quote! { let #name: #target_ty = #value_name; });
                call_args.push(quote! { #name });
            }
            continue;
        }

        let jni_ty = jni_param_type(&arg.ty, &jni_path);
        wrapper_inputs.push(quote! { #name: #jni_ty });
        let cast = jni_arg_cast(&arg.ty, &quote! { #name });
        call_args.push(cast);
    }

    let (jni_return_ty, result_match) = build_jni_return(
        inner_name,
        &call_args,
        result_inner,
        is_option,
        option_inner,
        &jni_path,
    );

    quote! {
        #[unsafe(no_mangle)]
        #[allow(non_snake_case)]
        pub extern "system" fn #jni_ident<'local>(#(#wrapper_inputs),*) -> #jni_return_ty {
            unowned_env.with_env(|mut env| -> ::std::result::Result<#jni_return_ty, #jni_path::errors::Error> {
                #(#conversions)*
                Ok(#result_match)
            }).resolve::<#jni_path::errors::ThrowRuntimeExAndDefault>()
        }
    }
}

fn build_jni_return(
    inner_name: &Ident,
    call_args: &[proc_macro2::TokenStream],
    result_inner: &Type,
    is_option: bool,
    option_inner: Option<&Type>,
    jni_path: &syn::Path,
) -> (proc_macro2::TokenStream, proc_macro2::TokenStream) {
    if is_unit_type(result_inner) {
        let body = quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(()) => (),
                crate::scripting::result::DropbearNativeResult::Err(e) => {
                    eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                }
            }
        };
        return (quote! { () }, body);
    }

    if is_option {
        let inner = option_inner.expect("option inner");
        if is_primitive_type(inner) {
            let (sig, wrapper, jvalue_expr) = jni_boxing_info(inner, jni_path);
            let body = quote! {
                match #inner_name(#(#call_args),*) {
                    crate::scripting::result::DropbearNativeResult::Ok(val) => match val {
                        Some(v) => {
                            let cls = match env.load_class(#jni_path::strings::JNIString::from(#wrapper)) {
                                Ok(cls) => cls,
                                Err(e) => {
                                    eprintln!("return_boxed failed for {}: {:?}", #wrapper, e);
                                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Boxing failed: {:?}", e)));
                                    return Ok(std::ptr::null_mut());
                                }
                            };

                            let param: #jni_path::objects::JValue = #jvalue_expr;
                            let ret = match env.call_static_method(cls, #jni_path::strings::JNIString::from("valueOf"), #sig, &[param]) {
                                Ok(ret) => ret,
                                Err(e) => {
                                    eprintln!("return_boxed failed for {}: {:?}", #wrapper, e);
                                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Boxing failed: {:?}", e)));
                                    return Ok(std::ptr::null_mut());
                                }
                            };

                            match ret.l() {
                                Ok(obj) => obj.into_raw(),
                                Err(e) => {
                                    eprintln!("return_boxed failed for {}: {:?}", #wrapper, e);
                                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Boxing failed: {:?}", e)));
                                    std::ptr::null_mut()
                                }
                            }
                        }
                        None => std::ptr::null_mut(),
                    },
                    crate::scripting::result::DropbearNativeResult::Err(e) => {
                        eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                        let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                        std::ptr::null_mut()
                    }
                }
            };
            return (quote! { #jni_path::sys::jobject }, body);
        }

        if is_string_type(inner) {
            let body = quote! {
                match #inner_name(#(#call_args),*) {
                    crate::scripting::result::DropbearNativeResult::Ok(val) => match val {
                        Some(v) => match env.new_string(v) {
                            Ok(s) => s.into_raw(),
                            Err(e) => {
                                let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Failed to create jstring: {:?}", e)));
                                std::ptr::null_mut()
                            }
                        },
                        None => std::ptr::null_mut(),
                    },
                    crate::scripting::result::DropbearNativeResult::Err(e) => {
                        eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                        let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                        std::ptr::null_mut()
                    }
                }
            };
            return (quote! { #jni_path::sys::jobject }, body);
        }

        let body = quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(val) => match val {
                    Some(v) => match crate::scripting::jni::utils::ToJObject::to_jobject(&v, &mut env) {
                        Ok(obj) => obj.into_raw(),
                        Err(e) => {
                            let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Failed to convert object: {:?}", e)));
                            std::ptr::null_mut()
                        }
                    },
                    None => std::ptr::null_mut(),
                },
                crate::scripting::result::DropbearNativeResult::Err(e) => {
                    eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                    std::ptr::null_mut()
                }
            }
        };
        return (quote! { #jni_path::sys::jobject }, body);
    }

    if is_string_type(result_inner) {
        let body = quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(val) => match env.new_string(val) {
                    Ok(s) => s.into_raw(),
                    Err(e) => {
                        let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Failed to create jstring: {:?}", e)));
                        crate::ffi_error_return!()
                    }
                },
                crate::scripting::result::DropbearNativeResult::Err(e) => {
                    eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                    crate::ffi_error_return!()
                }
            }
        };
        return (quote! { #jni_path::sys::jstring }, body);
    }

    if is_primitive_type(result_inner) {
        let jni_ret = jni_param_type(result_inner, jni_path);
        let cast = jni_value_cast(result_inner, quote! { val }, jni_path);
        let body = quote! {
            match #inner_name(#(#call_args),*) {
                crate::scripting::result::DropbearNativeResult::Ok(val) => #cast,
                crate::scripting::result::DropbearNativeResult::Err(e) => {
                    eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                    crate::ffi_error_return!()
                }
            }
        };
        return (jni_ret, body);
    }

    let body = quote! {
        match #inner_name(#(#call_args),*) {
            crate::scripting::result::DropbearNativeResult::Ok(val) => match crate::scripting::jni::utils::ToJObject::to_jobject(&val, &mut env) {
                Ok(obj) => obj.into_raw(),
                Err(e) => {
                    let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("Failed to convert object: {:?}", e)));
                    std::ptr::null_mut()
                }
            },
            crate::scripting::result::DropbearNativeResult::Err(e) => {
                eprintln!("JNI call failed in {}: {:?}", stringify!(#inner_name), e);
                let _ = env.throw_new(#jni_path::strings::JNIString::from("java/lang/RuntimeException"), #jni_path::strings::JNIString::from(format!("JNI call failed: {:?}", e)));
                std::ptr::null_mut()
            }
        }
    };
    (quote! { #jni_path::sys::jobject }, body)
}

fn jni_param_type(ty: &Type, jni_path: &syn::Path) -> proc_macro2::TokenStream {
    if is_bool_type(ty) {
        return quote! { #jni_path::sys::jboolean };
    }
    if is_float_type(ty) {
        return quote! { #jni_path::sys::jfloat };
    }
    if is_double_type(ty) {
        return quote! { #jni_path::sys::jdouble };
    }
    if is_i8_type(ty) || is_u8_type(ty) {
        return quote! { #jni_path::sys::jbyte };
    }
    if is_i16_type(ty) || is_u16_type(ty) {
        return quote! { #jni_path::sys::jshort };
    }
    if is_i32_type(ty) || is_u32_type(ty) {
        return quote! { #jni_path::sys::jint };
    }
    if is_i64_type(ty) || is_u64_type(ty) || is_isize_type(ty) || is_usize_type(ty) {
        return quote! { #jni_path::sys::jlong };
    }

    quote! { #ty }
}

fn jni_arg_cast(ty: &Type, name: &proc_macro2::TokenStream) -> proc_macro2::TokenStream {
    if is_bool_type(ty) {
        return quote! { #name };
    }
    if is_i8_type(ty) {
        return quote! { #name as i8 };
    }
    if is_u8_type(ty) {
        return quote! { #name as u8 };
    }
    if is_i16_type(ty) {
        return quote! { #name as i16 };
    }
    if is_u16_type(ty) {
        return quote! { #name as u16 };
    }
    if is_i32_type(ty) {
        return quote! { #name as i32 };
    }
    if is_u32_type(ty) {
        return quote! { #name as u32 };
    }
    if is_i64_type(ty) {
        return quote! { #name as i64 };
    }
    if is_u64_type(ty) {
        return quote! { #name as u64 };
    }
    if is_isize_type(ty) {
        return quote! { #name as isize };
    }
    if is_usize_type(ty) {
        return quote! { #name as usize };
    }
    if is_float_type(ty) {
        return quote! { #name as f32 };
    }
    if is_double_type(ty) {
        return quote! { #name as f64 };
    }

    quote! { #name }
}

fn jni_value_cast(
    ty: &Type,
    name: proc_macro2::TokenStream,
    jni_path: &syn::Path,
) -> proc_macro2::TokenStream {
    if is_bool_type(ty) {
        return quote! { #name };
    }
    if is_i8_type(ty) || is_u8_type(ty) {
        return quote! { #name as #jni_path::sys::jbyte };
    }
    if is_i16_type(ty) || is_u16_type(ty) {
        return quote! { #name as #jni_path::sys::jshort };
    }
    if is_i32_type(ty) || is_u32_type(ty) {
        return quote! { #name as #jni_path::sys::jint };
    }
    if is_i64_type(ty) || is_u64_type(ty) || is_isize_type(ty) || is_usize_type(ty) {
        return quote! { #name as #jni_path::sys::jlong };
    }
    if is_float_type(ty) {
        return quote! { #name as #jni_path::sys::jfloat };
    }
    if is_double_type(ty) {
        return quote! { #name as #jni_path::sys::jdouble };
    }

    quote! { #name }
}

fn jni_boxing_info(
    ty: &Type,
    jni_path: &syn::Path,
) -> (
    proc_macro2::TokenStream,
    proc_macro2::TokenStream,
    proc_macro2::TokenStream,
) {
    if is_i32_type(ty) || is_u32_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((int) -> java.lang.Integer) },
            quote! { "java/lang/Integer" },
            quote! { #jni_path::objects::JValue::Int(v as #jni_path::sys::jint) },
        );
    }
    if is_i64_type(ty) || is_u64_type(ty) || is_isize_type(ty) || is_usize_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((long) -> java.lang.Long) },
            quote! { "java/lang/Long" },
            quote! { #jni_path::objects::JValue::Long(v as #jni_path::sys::jlong) },
        );
    }
    if is_i16_type(ty) || is_u16_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((short) -> java.lang.Short) },
            quote! { "java/lang/Short" },
            quote! { #jni_path::objects::JValue::Short(v as #jni_path::sys::jshort) },
        );
    }
    if is_i8_type(ty) || is_u8_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((byte) -> java.lang.Byte) },
            quote! { "java/lang/Byte" },
            quote! { #jni_path::objects::JValue::Byte(v as #jni_path::sys::jbyte) },
        );
    }
    if is_bool_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((boolean) -> java.lang.Boolean) },
            quote! { "java/lang/Boolean" },
            quote! { #jni_path::objects::JValue::Bool(v) },
        );
    }
    if is_float_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((float) -> java.lang.Float) },
            quote! { "java/lang/Float" },
            quote! { #jni_path::objects::JValue::Float(v as #jni_path::sys::jfloat) },
        );
    }
    if is_double_type(ty) {
        return (
            quote! { #jni_path::jni_sig!((double) -> java.lang.Double) },
            quote! { "java/lang/Double" },
            quote! { #jni_path::objects::JValue::Double(v as #jni_path::sys::jdouble) },
        );
    }

    (
        quote! { #jni_path::jni_sig!((long) -> java.lang.Long) },
        quote! { "java/lang/Long" },
        quote! { #jni_path::objects::JValue::Long(v as #jni_path::sys::jlong) },
    )
}

fn module_path_from_callsite() -> Option<String> {
    let path = proc_macro::Span::call_site().local_file()?;
    // proc_macro::Span::call_site().source_text()
    module_path_from_file(&path)
}

fn module_path_from_file(path: &Path) -> Option<String> {
    let components: Vec<String> = path
        .components()
        .map(|c| c.as_os_str().to_string_lossy().to_string())
        .collect();

    let src_index = components.iter().position(|c| c == "src")?;
    if src_index + 1 >= components.len() {
        return None;
    }

    let mut parts = components[src_index + 1..].to_vec();
    let file = parts.pop()?;
    let stem = file.strip_suffix(".rs").unwrap_or(&file);

    if stem != "mod" && stem != "lib" && stem != "main" {
        parts.push(stem.to_string());
    }

    if parts.is_empty() {
        return None;
    }

    let joined = parts.join("_");
    Some(joined.replace('-', "_"))
}

fn default_c_name(original_name: &Ident, module_path: Option<&str>) -> String {
    let mut name = String::from("dropbear");
    if let Some(path) = module_path {
        if !path.is_empty() {
            name.push('_');
            name.push_str(path);
        }
    }
    name.push('_');
    name.push_str(&original_name.to_string());
    name
}

fn is_string_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "String").unwrap_or(false))
}

fn is_str_ref(ty: &Type) -> bool {
    match ty {
        Type::Reference(reference) => {
            matches!(&*reference.elem, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "str").unwrap_or(false))
        }
        _ => false,
    }
}

fn is_primitive_type(ty: &Type) -> bool {
    is_bool_type(ty)
        || is_i8_type(ty)
        || is_i16_type(ty)
        || is_i32_type(ty)
        || is_i64_type(ty)
        || is_isize_type(ty)
        || is_u8_type(ty)
        || is_u16_type(ty)
        || is_u32_type(ty)
        || is_u64_type(ty)
        || is_usize_type(ty)
        || is_float_type(ty)
        || is_double_type(ty)
}

fn is_bool_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "bool").unwrap_or(false))
}

fn is_i8_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "i8").unwrap_or(false))
}

fn is_i16_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "i16").unwrap_or(false))
}

fn is_i32_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "i32").unwrap_or(false))
}

fn is_i64_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "i64").unwrap_or(false))
}

fn is_isize_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "isize").unwrap_or(false))
}

fn is_u8_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "u8").unwrap_or(false))
}

fn is_u16_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "u16").unwrap_or(false))
}

fn is_u32_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "u32").unwrap_or(false))
}

fn is_u64_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "u64").unwrap_or(false))
}

fn is_usize_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "usize").unwrap_or(false))
}

fn is_float_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "f32").unwrap_or(false))
}

fn is_double_type(ty: &Type) -> bool {
    matches!(ty, Type::Path(path) if path.path.segments.last().map(|s| s.ident == "f64").unwrap_or(false))
}

/// Helper to check if type is ()
fn is_unit_type(ty: &Type) -> bool {
    if let Type::Tuple(tuple) = ty {
        return tuple.elems.is_empty();
    }
    false
}