use proc_macro_crate::{FoundCrate, crate_name};
use proc_macro2::{Span, TokenStream};
use quote::{format_ident, quote};

pub struct CrateIdent {
	gcore: syn::Result<TokenStream>,
	gcore_shaders: syn::Result<TokenStream>,
	wgpu_executor: syn::Result<TokenStream>,
}

impl CrateIdent {
	pub fn gcore(&self) -> syn::Result<&TokenStream> {
		self.gcore.as_ref().map_err(Clone::clone)
	}

	pub fn gcore_shaders(&self) -> syn::Result<&TokenStream> {
		self.gcore_shaders.as_ref().map_err(Clone::clone)
	}

	pub fn wgpu_executor(&self) -> syn::Result<&TokenStream> {
		self.wgpu_executor.as_ref().map_err(Clone::clone)
	}
}

impl Default for CrateIdent {
	fn default() -> Self {
		let find_crate = |orig_name| match crate_name(orig_name) {
			Ok(FoundCrate::Itself) => Ok(quote!(crate)),
			Ok(FoundCrate::Name(name)) => {
				let name = format_ident!("{}", name);
				Ok(quote!(::#name))
			}
			Err(e) => Err(syn::Error::new(Span::call_site(), &format!("Could not find dependency on `{orig_name}`:\n{e}"))),
		};

		let gcore = find_crate("graphene-core");
		let gcore_shaders = find_crate("graphene-core-shaders").or_else(|eshaders| {
			gcore
				.as_ref()
				.map(Clone::clone)
				.map_err(|ecore| syn::Error::new(Span::call_site(), &format!("{ecore}\n\nFallback: {eshaders}")))
		});
		let wgpu_executor = find_crate("wgpu-executor");
		Self { gcore, gcore_shaders, wgpu_executor }
	}
}