gdrust_macros 0.1.0

use crate::compiler::hints::property_hint;
use crate::compiler::properties::{ExportType, Property};
use crate::compiler::signal_args::create_signal_arg;
use crate::compiler::signals::SignalDecl;
use crate::Extends;
use heck::ShoutySnakeCase;
use proc_macro2::{Ident, Span, TokenStream};
use syn::{Expr, ItemStruct};

pub(crate) fn impl_block(
    properties: &[Property],
    signals: &[SignalDecl],
    extends: &Extends,
    item: &ItemStruct,
) -> TokenStream {
    let struct_name = &item.ident;
    let extends = &extends.ty;

    let property_inits = property_inits(properties);
    let register_properties = register_properties(properties, signals);
    let signal_consts = signal_consts(signals);

    quote::quote! {
        impl #struct_name {

            #(#signal_consts)*

            #[allow(clippy::default_trait_access)]
            fn new(_owner: gdnative::prelude::TRef<#extends>) -> Self {
                Self {
                    #(#property_inits,)*
                }
            }

            #register_properties
        }
    }
}

fn property_inits(properties: &[Property]) -> Vec<TokenStream> {
    properties
        .iter()
        .map(|x| {
            let ident = &x.name;
            let default = get_default(x.default.as_ref());
            quote::quote! { #ident: #default}
        })
        .collect()
}

fn register_properties(properties: &[Property], signals: &[SignalDecl]) -> TokenStream {
    let properties: Vec<TokenStream> = properties.iter().map(|x| builder_for_property(x)).collect();
    let signals: Vec<TokenStream> = signals.iter().map(|x| builder_for_signal(x)).collect();
    quote::quote! {
        #[allow(clippy::default_trait_access)]
        fn __register_properties_and_signals(builder: &gdnative::prelude::ClassBuilder<Self>) {
            #(#properties)*

            #(#signals)*
        }
    }
}

fn builder_for_property(property: &Property) -> TokenStream {
    if let ExportType::NoExport = property.export_type {
        return quote::quote! {};
    }
    let ty = &property.ty;
    let ident = &property.name;
    let default = &property.default;
    let ident_str = ident.to_string();
    let hint = property_hint(&property.export_type, &property.ty);
    let setter = quote::quote! { .with_setter(|this, _owner, val| {
        this.#ident = val
    })};
    let getter = quote::quote! { .with_ref_getter(|this, _owner| {
        &this.#ident
    })};
    let default = get_default(default.as_ref());
    quote::quote! {
        builder.add_property::<#ty>(#ident_str)
            #hint
            #getter
            #setter
            .with_default(#default)
            .done();
    }
}

fn builder_for_signal(signal: &SignalDecl) -> TokenStream {
    let name_str = signal.name.to_string();
    let args: Vec<TokenStream> = signal.args.iter().map(|x| create_signal_arg(x)).collect();
    quote::quote! {
        builder.add_signal(gdnative::nativescript::Signal {
            name: #name_str,
            args: &[
                #(#args,)*
            ]
        });
    }
}

fn signal_consts(signals: &[SignalDecl]) -> Vec<TokenStream> {
    signals
        .iter()
        .map(|x| {
            let name_str = x.name.to_string();
            let name = Ident::new(
                x.name.to_string().to_shouty_snake_case().as_str(),
                Span::call_site(),
            );
            quote::quote! {
                const #name: &'static str = #name_str;
            }
        })
        .collect()
}

fn get_default(default: Option<&Expr>) -> TokenStream {
    if let Some(default) = default {
        quote::quote! { #default }
    } else {
        quote::quote! {
            Default::default()
        }
    }
}