flabk/src/astreams/serde_ext.rs

use super::resolve::Resolver;
use std::{fmt, marker::PhantomData};

use serde::{de::Visitor, Deserialize, Deserializer};
static TYPE_STR: &str = std::any::type_name::<&str>();
static TYPE_STRING: &str = std::any::type_name::<String>();

// Allows a value that's a string to be expanded into an object AND the serialization of that object itself
// TODO: deserializing the actual object isnt supported atm LOL
pub(super) fn expand<'de, D, Out>(deserializer: D) -> Result<Out, D::Error>
where
    D: Deserializer<'de>,
    Out: for<'dt> serde::Deserialize<'dt>,
{
    let resolver = Resolver::new();
    struct ResolveVisitor<Out> {
        resolver: Resolver,
        _type: PhantomData<Out>,
    }

    impl<'de, Out> Visitor<'de> for ResolveVisitor<Out>
    where
        Out: for<'dt> serde::Deserialize<'dt>,
    {
        type Value = Out;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str(std::any::type_name::<Out>())
        }

        fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
        where
            E: serde::de::Error,
        {
            tokio::runtime::Runtime::new()
                .unwrap()
                .block_on(self.resolver.resolve_into::<Out>(value.to_string()))
                .map_err(|e| {
                    let name = std::any::type_name::<Out>();
                    serde::de::Error::invalid_value(
                        serde::de::Unexpected::Other(
                            format!("failed resolving iri [{}]: {}", value, e.0).as_str(),
                        ),
                        &name,
                    )
                })
        }

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

    let type_name = std::any::type_name::<Out>();
    if type_name == TYPE_STR || type_name == TYPE_STRING {
        deserializer.deserialize_any(ResolveVisitor {
            resolver: resolver,
            _type: PhantomData,
        })
    } else {
        Out::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, Out>(deserializer: D) -> Result<Vec<Out>, D::Error>
where
    D: Deserializer<'de>,
    Out: From<String> + serde::Deserialize<'de>,
{
    struct VecVisitor<Out>(PhantomData<Vec<Out>>);

    impl<'de, Out> Visitor<'de> for VecVisitor<Out>
    where
        Out: From<String> + serde::Deserialize<'de>,
    {
        type Value = Vec<Out>;

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

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

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

    deserializer.deserialize_any(VecVisitor(PhantomData))
}

#[cfg(test)]
mod tests {
    use serde::Deserialize;

    use super::expand;

    #[test]
    fn expand_context_from_iri() {
        #[derive(Deserialize)]
        struct WithContext {
            #[serde(deserialize_with = "expand")]
            pub context: super::super::context::Context,
        }

        const JSONLD_INPUT: &str = r#"{"context": "https://www.w3.org/ns/activitystreams"}"#;
        let result =
            serde_json::from_str::<WithContext>(JSONLD_INPUT).expect("deserializing with expand");

        assert!(result.context.ctx.xsd == "http://www.w3.org/2001/XMLSchema#")
    }

    #[test]
    fn expand_when_json_isnt_iri_but_the_object_itself() {
        #[derive(Deserialize)]
        struct Expanded {
            pub id: String,
            pub truth: bool,
        }

        #[derive(Deserialize)]
        struct Expandable {
            #[serde(deserialize_with = "expand")]
            pub expansive: Expanded,
        }

        const JSONLD_INPUT: &str = r#"{"expansive": { "id": "1", "truth": true }}"#;
        let result =
            serde_json::from_str::<Expandable>(JSONLD_INPUT).expect("deserializing with expand");

        assert!(result.expansive.id == "1");
        assert!(result.expansive.truth)
    }
}