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#[allow(unused_extern_crates)]
extern crate proc_macro;

use proc_macro::*;
use proc_macro_hack::proc_macro_hack;
mod span;
use crate::span::gen_random;

/// Create a TokenStream of an identifier out of a string
fn ident(ident: &str) -> TokenStream {
    TokenTree::from(Ident::new(ident, Span::call_site())).into()
}

#[proc_macro_hack]
pub fn const_random(input: TokenStream) -> TokenStream {
    match &input.to_string()[..] {
        "u8" => TokenTree::from(Literal::u8_suffixed(gen_random())).into(),
        "u16" => TokenTree::from(Literal::u16_suffixed(gen_random())).into(),
        "u32" => TokenTree::from(Literal::u32_suffixed(gen_random())).into(),
        "u64" => TokenTree::from(Literal::u64_suffixed(gen_random())).into(),
        "u128" => TokenTree::from(Literal::u128_suffixed(gen_random())).into(),
        "i8" => TokenTree::from(Literal::i8_suffixed(gen_random())).into(),
        "i16" => TokenTree::from(Literal::i16_suffixed(gen_random())).into(),
        "i32" => TokenTree::from(Literal::i32_suffixed(gen_random())).into(),
        "i64" => TokenTree::from(Literal::i64_suffixed(gen_random())).into(),
        "i128" => TokenTree::from(Literal::i128_suffixed(gen_random())).into(),
        "usize" => {
            let value: TokenStream = TokenTree::from(Literal::u128_suffixed(gen_random())).into();
            let type_cast: TokenStream = [value, ident("as"), ident("usize")]
                .iter()
                .cloned()
                .collect();
            TokenTree::from(Group::new(Delimiter::Parenthesis, type_cast)).into()
        }
        "isize" => {
            let value: TokenStream = TokenTree::from(Literal::i128_suffixed(gen_random())).into();
            let type_cast: TokenStream = [value, ident("as"), ident("isize")]
                .iter()
                .cloned()
                .collect();
            TokenTree::from(Group::new(Delimiter::Parenthesis, type_cast)).into()
        }
        _ => panic!("Invalid integer type"),
    }
}