use std::fmt::Write;

use quote::ToTokens;
use syn::punctuated::{Pair, Punctuated};

pub trait SynPathExt
{
    fn new_empty() -> Self;

    /// Converts the [`syn::Path`] to a [`String`].
    fn to_string(&self) -> String;
}

impl SynPathExt for syn::Path
{
    fn new_empty() -> Self
    {
        Self {
            leading_colon: None,
            segments: Punctuated::new(),
        }
    }

    fn to_string(&self) -> String
    {
        self.segments.pairs().map(Pair::into_tuple).fold(
            String::new(),
            |mut acc, (segment, opt_punct)| {
                let segment_ident = &segment.ident;

                write!(
                    acc,
                    "{segment_ident}{}",
                    opt_punct
                        .map(|punct| punct.to_token_stream().to_string())
                        .unwrap_or_default()
                )
                .ok();

                acc
            },
        )
    }
}

macro_rules! syn_path {
    ($first_segment: ident $(::$segment: ident)*) => {
        ::syn::Path {
            leading_colon: None,
            segments: ::syn::punctuated::Punctuated::from_iter([
                $crate::util::syn_path::syn_path_segment!($first_segment),
                $($crate::util::syn_path::syn_path_segment!($segment),)*
            ])
        }
    };
}

macro_rules! syn_path_segment {
    ($segment: ident) => {
        ::syn::PathSegment {
            ident: ::proc_macro2::Ident::new(
                stringify!($segment),
                ::proc_macro2::Span::call_site(),
            ),
            arguments: ::syn::PathArguments::None,
        }
    };
}

pub(crate) use {syn_path, syn_path_segment};