stringid_macros 0.1.0

use proc_macro2::Span;
use syn::{
	spanned::Spanned, Data, DataStruct, DeriveInput, Error, Field, Fields, Result, Type, TypePath,
};

pub(crate) fn get_data_struct(input: &DeriveInput) -> Result<&DataStruct> {
	match &input.data {
		Data::Struct(data_struct) => Ok(data_struct),
		Data::Enum(_) => Err(Error::new(input.ident.span(), "Enum are not managed!")),
		Data::Union(_) => Err(Error::new(input.ident.span(), "Union are not managed!")),
	}
}

pub(crate) fn get_unnamed_field(data_struct: &DataStruct) -> Result<&Field> {
	match &data_struct.fields {
		Fields::Named(_) => Err(Error::new(
			Span::call_site(),
			"Macro don't manage Struct with Named field",
		)),
		Fields::Unnamed(fields) => {
			let fields = &fields.unnamed;
			if fields.len() == 1 {
				Ok(fields.iter().next().unwrap())
			} else if fields.is_empty() {
				Err(Error::new(
					Span::call_site(),
					"Macro only manage struct with 1 unamed field. Don't managed unit struct",
				))
			} else {
				Err(Error::new(
                    Span::call_site(),"Macro only manage struct with 1 unamed field. Don't managed struct with multiple field"))
			}
		}
		Fields::Unit => Err(Error::new(
			Span::call_site(),
			"Macro don't manage Struct with Unit",
		)),
	}
}

pub(crate) fn check_unittype(data_struct: &DataStruct) -> Result<()> {
	match data_struct.fields {
		Fields::Named(_) => Err(Error::new(
			Span::call_site(),
			"Remove named field(s) from struct, this macro is intended to be used with Unit Struct",
		)),
		Fields::Unnamed(_) =>  Err(Error::new(
			Span::call_site(),
						"Remove Unnamed field(s) from struct. The macro is intended to be used with Unit Struct"
					)),
		Fields::Unit => {
			Ok(())
		},
	}
}

pub(crate) fn get_field_path(field: &Field) -> Result<&TypePath> {
	let field_type = &field.ty;
	match field_type {
		Type::Path(path) => Ok(path),
		_ => Err(Error::new(
			field.ident.span(),
			"Other type than Path are not managed",
		)),
	}
}