use std::{fmt, marker::PhantomData};

use serde::{de, Deserialize, Deserializer};

// Allows deserialization of a single item into a vector of that item
// As long as they implement the From<String> trait
pub(super) fn pull_single_into_vec<'de, D, T>(deserializer: D) -> Result<Vec<T>, D::Error>
where
    D: Deserializer<'de>,
    T: From<String> + serde::Deserialize<'de>,
{
    struct VecComposer<T>(PhantomData<Vec<T>>);

    impl<'de, T> de::Visitor<'de> for VecComposer<T>
    where
        T: From<String> + serde::Deserialize<'de>,
    {
        type Value = Vec<T>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            let name = std::any::type_name::<T>();
            formatter.write_str(format!("expected {} or Vec<{}>", name, name).as_str())
        }

        fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            Ok(vec![value.to_string().into()])
        }

        fn visit_seq<S>(self, visitor: S) -> Result<Self::Value, S::Error>
        where
            S: de::SeqAccess<'de>,
        {
            Deserialize::deserialize(de::value::SeqAccessDeserializer::new(visitor))
        }
    }

    deserializer.deserialize_any(VecComposer(PhantomData))
}