use crate::internals::ast::{Container, Data};
use crate::internals::{attr, ungroup};
use proc_macro2::Span;
use std::collections::HashSet;
use syn::punctuated::{Pair, Punctuated};
use syn::Token;

// Remove the default from every type parameter because in the generated impls
// they look like associated types: "error: associated type bindings are not
// allowed here".
pub fn without_defaults(generics: &syn::Generics) -> syn::Generics {
    syn::Generics {
        params: generics
            .params
            .iter()
            .map(|param| match param {
                syn::GenericParam::Type(param) => syn::GenericParam::Type(syn::TypeParam {
                    eq_token: None,
                    default: None,
                    ..param.clone()
                }),
                _ => param.clone(),
            })
            .collect(),
        ..generics.clone()
    }
}

pub fn with_where_predicates(
    generics: &syn::Generics,
    predicates: &[syn::WherePredicate],
) -> syn::Generics {
    let mut generics = generics.clone();
    let dst_predicates = &mut generics.make_where_clause().predicates;

    for predicate in predicates {
        dst_predicates.push(predicate.clone());
    }
    generics
}

pub fn with_where_predicates_from_fields(
    cont: &Container,
    generics: &syn::Generics,
    from_field: fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
) -> syn::Generics {
    let mut generics = generics.clone();
    let dst_predicates = &mut generics.make_where_clause().predicates;

    for field in cont.data.all_fields() {
