bo4e-edifact-types 0.14.1

//! Serde helpers for the generated typed entities.

use crate::code_enum::MapKey;
use serde::de::{self, DeserializeOwned, Deserializer, MapAccess, SeqAccess, Visitor};
use serde::{Deserialize, Serialize};
use std::collections::BTreeMap;
use std::fmt;
use std::marker::PhantomData;

/// Deserialize `Option<BTreeMap<K, V>>` from array, object, or null.
///
/// Array input: each element is a V; the key K is extracted by trying each
/// string field on the element as a potential K value (via serde deserialization).
///
/// Object input: standard BTreeMap deserialization.
pub fn deserialize_map_or_vec<'de, D, K, V>(
    deserializer: D,
) -> Result<Option<BTreeMap<K, V>>, D::Error>
where
    D: Deserializer<'de>,
    K: DeserializeOwned + Ord + Serialize,
    V: DeserializeOwned,
{
    struct MapOrVecVisitor<K, V>(PhantomData<(K, V)>);

    impl<'de, K, V> Visitor<'de> for MapOrVecVisitor<K, V>
    where
        K: DeserializeOwned + Ord + Serialize,
        V: DeserializeOwned,
    {
        type Value = Option<BTreeMap<K, V>>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("a map, an array, or null")
        }

        fn visit_none<E: de::Error>(self) -> Result<Self::Value, E> {
            Ok(None)
        }

        fn visit_unit<E: de::Error>(self) -> Result<Self::Value, E> {
            Ok(None)
        }

        fn visit_map<M: MapAccess<'de>>(self, map: M) -> Result<Self::Value, M::Error> {
            // Collect as JSON Value first to support both keyed-map and single-entity inputs.
            let val: serde_json::Value =
                Deserialize::deserialize(de::value::MapAccessDeserializer::new(map))?;
            // Try standard BTreeMap deserialization (keys = qualifier codes like "Z04")
            if let Ok(btree) = serde_json::from_value::<BTreeMap<K, V>>(val.clone()) {
                return Ok(Some(btree));
            }
            // Fallback: treat as a single entity object and extract the key from its fields
            if let Some(key) = find_key_in_value::<K>(&val) {
                let entity: V = serde_json::from_value(val).map_err(de::Error::custom)?;
                let mut map = BTreeMap::new();
                map.insert(key, entity);
                return Ok(Some(map));
            }
            Err(de::Error::custom(
                "map value is neither a keyed BTreeMap nor a single entity with a valid key field",
            ))
        }

        fn visit_seq<S: SeqAccess<'de>>(self, mut seq: S) -> Result<Self::Value, S::Error> {
            let mut map = BTreeMap::new();
            while let Some(val) = seq.next_element::<serde_json::Value>()? {
                let key = find_key_in_value::<K>(&val)
                    .ok_or_else(|| de::Error::custom("array element has no valid map key field"))?;
                let entity: V = serde_json::from_value(val).map_err(de::Error::custom)?;
                map.insert(key, entity);
            }
            Ok(Some(map))
        }
    }

    deserializer.deserialize_any(MapOrVecVisitor(PhantomData))
}

/// Deserialize `Option<BTreeMap<K, V>>` for a map-keyed entity collection.
///
/// Accepts `null`, an array of elements (the engine's form), a single element,
/// or a map keyed by qualifier code (the typed form). An element's key is
/// resolved from its qualifier fields the way the reverse mapping resolves the
/// qualifier ([`MapKey::of_element`]); in keyed-map input, missing qualifier
/// fields are filled in from the key, and present ones must agree with it.
/// Two elements with the same key are an error — never an overwrite.
pub fn deserialize_keyed_map<'de, D, K, V>(
    deserializer: D,
) -> Result<Option<BTreeMap<K, V>>, D::Error>
where
    D: Deserializer<'de>,
    K: MapKey,
    V: DeserializeOwned,
{
    let Some(value) = Option::<serde_json::Value>::deserialize(deserializer)? else {
        return Ok(None);
    };
    let mut map = BTreeMap::new();
    let mut insert = |key: K, element: serde_json::Value| -> Result<(), D::Error> {
        let entity: V = serde_json::from_value(element).map_err(de::Error::custom)?;
        let code = key.as_str().to_string();
        if map.insert(key, entity).is_some() {
            return Err(de::Error::custom(format!(
                "duplicate map key `{code}`: two elements carry the same qualifier"
            )));
        }
        Ok(())
    };
    match value {
        serde_json::Value::Null => return Ok(None),
        serde_json::Value::Array(items) => {
            for element in items {
                let key = K::of_element(&element).map_err(de::Error::custom)?;
                insert(key, element)?;
            }
        }
        serde_json::Value::Object(obj) => {
            let keyed = !obj.is_empty()
                && obj.iter().all(|(k, v)| {
                    v.is_object() && K::from_code(k).is_some_and(|key| key.as_str() == k)
                });
            if keyed {
                for (k, mut element) in obj {
                    let key = K::from_code(&k).expect("checked above");
                    if element.get(K::FIELD).is_some() {
                        let derived = K::of_element(&element).map_err(de::Error::custom)?;
                        if derived != key {
                            return Err(de::Error::custom(format!(
                                "map key `{k}` disagrees with the element's `{}` (`{}`)",
                                K::FIELD,
                                derived.as_str()
                            )));
                        }
                    }
                    key.fill_element(&mut element);
                    insert(key, element)?;
                }
            } else {
                let element = serde_json::Value::Object(obj);
                let key = K::of_element(&element).map_err(de::Error::custom)?;
                insert(key, element)?;
            }
        }
        other => {
            return Err(de::Error::custom(format!(
                "expected a map, an array or null, got {other}"
            )))
        }
    }
    Ok(Some(map))
}

/// Serialize a map-keyed entity collection as the engine emits it — one element
/// as a plain object, several as an array: the elements in key order (the PID schema's qualifier order), each carrying its
/// qualifier fields.
///
/// A JSON object would not keep that order (`serde_json` sorts object keys).
/// The reverse mapping does not depend on it — it orders group repetitions by
/// MIG variant — but a stable, schema-ordered array is easier to read and diff.
pub fn serialize_keyed_map<S, K, V>(
    map: &Option<BTreeMap<K, V>>,
    serializer: S,
) -> Result<S::Ok, S::Error>
where
    S: serde::Serializer,
    K: MapKey,
    V: Serialize,
{
    use serde::ser::{Error, SerializeSeq};
    let Some(map) = map else {
        return serializer.serialize_none();
    };
    if map.len() == 1 {
        let (key, value) = map.iter().next().expect("one element");
        let mut element = serde_json::to_value(value).map_err(S::Error::custom)?;
        key.fill_element(&mut element);
        return element.serialize(serializer);
    }
    let mut seq = serializer.serialize_seq(Some(map.len()))?;
    for (key, value) in map {
        let mut element = serde_json::to_value(value).map_err(S::Error::custom)?;
        key.fill_element(&mut element);
        seq.serialize_element(&element)?;
    }
    seq.end()
}

/// Serialize `Option<Vec<T>>` the way the forward mapping emits an entity: one
/// element as a plain object, several as an array. The reverse mapping treats
/// the two forms differently for some groups (e.g. root-level entities), so a
/// single element must not become a one-element array.
pub fn serialize_vec_or_single<S, T>(
    value: &Option<Vec<T>>,
    serializer: S,
) -> Result<S::Ok, S::Error>
where
    S: serde::Serializer,
    T: Serialize,
{
    match value.as_deref() {
        None => serializer.serialize_none(),
        Some([single]) => single.serialize(serializer),
        Some(items) => items.serialize(serializer),
    }
}

/// Deserialize `Option<String>` from a string, `null`, or an enriched
/// `{code, meaning, enum}` object (its `code`).
pub fn deserialize_code_string<'de, D>(deserializer: D) -> Result<Option<String>, D::Error>
where
    D: Deserializer<'de>,
{
    match Option::<serde_json::Value>::deserialize(deserializer)? {
        None | Some(serde_json::Value::Null) => Ok(None),
        Some(serde_json::Value::String(s)) => Ok(Some(s)),
        Some(serde_json::Value::Object(obj)) => match obj.get("code") {
            Some(serde_json::Value::String(code)) => Ok(Some(code.clone())),
            _ => Err(de::Error::custom("code object without a string `code`")),
        },
        Some(other) => Err(de::Error::custom(format!(
            "expected a string or a code object, got {other}"
        ))),
    }
}

/// Route engine BO4E JSON through a typed struct and back: deserialize `value`
/// into `T`, then serialize the typed value. Used by the generated
/// `typed_hop_*` dispatchers of the typed PID modules.
pub fn typed_hop<T: DeserializeOwned + Serialize>(
    value: serde_json::Value,
) -> Result<serde_json::Value, serde_json::Error> {
    serde_json::to_value(serde_json::from_value::<T>(value)?)
}

/// Deserialize `Option<Vec<T>>` from array, single object, or null.
///
/// The dynamic forward mapping produces single objects for single-rep entities
/// and arrays for multi-rep entities. Typed structs always use `Vec<T>`.
/// This helper accepts both formats.
pub fn deserialize_vec_or_single<'de, D, T>(deserializer: D) -> Result<Option<Vec<T>>, D::Error>
where
    D: Deserializer<'de>,
    T: DeserializeOwned,
{
    struct VecOrSingleVisitor<T>(PhantomData<T>);

    impl<'de, T: DeserializeOwned> Visitor<'de> for VecOrSingleVisitor<T> {
        type Value = Option<Vec<T>>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("an array, an object, or null")
        }

        fn visit_none<E: de::Error>(self) -> Result<Self::Value, E> {
            Ok(None)
        }

        fn visit_unit<E: de::Error>(self) -> Result<Self::Value, E> {
            Ok(None)
        }

        fn visit_seq<S: SeqAccess<'de>>(self, seq: S) -> Result<Self::Value, S::Error> {
            let vec: Vec<T> = Deserialize::deserialize(de::value::SeqAccessDeserializer::new(seq))?;
            Ok(Some(vec))
        }

        fn visit_map<M: MapAccess<'de>>(self, map: M) -> Result<Self::Value, M::Error> {
            let single: T = Deserialize::deserialize(de::value::MapAccessDeserializer::new(map))?;
            Ok(Some(vec![single]))
        }
    }

    deserializer.deserialize_any(VecOrSingleVisitor(PhantomData))
}

/// Try to find a key of type K in a JSON value by checking all string fields.
/// Also checks one level of nested objects (for companion fields stored in sub-objects).
fn find_key_in_value<K: for<'de> Deserialize<'de>>(val: &serde_json::Value) -> Option<K> {
    let obj = val.as_object()?;
    // Check top-level string fields
    for (_field_name, field_val) in obj {
        if let Some(s) = field_val.as_str() {
            if let Ok(key) = serde_json::from_value::<K>(serde_json::Value::String(s.to_string())) {
                return Some(key);
            }
        }
    }
    // Check one level of nested objects (companion types like geschaeftspartnerEdifact)
    for (_field_name, field_val) in obj {
        if let Some(nested_obj) = field_val.as_object() {
            for (_nested_name, nested_val) in nested_obj {
                if let Some(s) = nested_val.as_str() {
                    if let Ok(key) =
                        serde_json::from_value::<K>(serde_json::Value::String(s.to_string()))
                    {
                        return Some(key);
                    }
                }
            }
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use super::*;

    #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
    enum TestKey {
        #[serde(rename = "MS")]
        Ms,
        #[serde(rename = "MR")]
        Mr,
    }

    #[derive(Debug, Clone, Default, Serialize, Deserialize)]
    #[serde(rename_all = "camelCase")]
    struct TestEntity {
        pub marktrolle: Option<String>,
        pub name: Option<String>,
    }

    #[derive(Debug, Clone, Default, Serialize, Deserialize)]
    struct TestContainer {
        #[serde(default, deserialize_with = "deserialize_map_or_vec")]
        pub items: Option<BTreeMap<TestKey, TestEntity>>,
    }

    #[test]
    fn test_deserialize_from_array() {
        let json = r#"{"items": [
            {"marktrolle": "MS", "name": "Sender"},
            {"marktrolle": "MR", "name": "Recipient"}
        ]}"#;
        let container: TestContainer = serde_json::from_str(json).unwrap();
        let items = container.items.unwrap();
        assert_eq!(items.len(), 2);
        assert_eq!(items[&TestKey::Ms].name.as_deref(), Some("Sender"));
        assert_eq!(items[&TestKey::Mr].name.as_deref(), Some("Recipient"));
    }

    #[test]
    fn test_deserialize_from_map() {
        let json = r#"{"items": {
            "MS": {"name": "Sender"},
            "MR": {"name": "Recipient"}
        }}"#;
        let container: TestContainer = serde_json::from_str(json).unwrap();
        let items = container.items.unwrap();
        assert_eq!(items.len(), 2);
        assert_eq!(items[&TestKey::Ms].name.as_deref(), Some("Sender"));
    }

    #[test]
    fn test_deserialize_null() {
        let json = r#"{"items": null}"#;
        let container: TestContainer = serde_json::from_str(json).unwrap();
        assert!(container.items.is_none());
    }

    #[test]
    fn test_deserialize_missing_field() {
        let json = r#"{}"#;
        let container: TestContainer = serde_json::from_str(json).unwrap();
        assert!(container.items.is_none());
    }

    crate::code_enum::key_enum! {
        enum GpKey {
            Z07 = "Z07",
            Z39 = "Z39",
            Z40 = "Z40",
        }
    }

    crate::code_enum::map_key! {
        GpKey: "partnerrolle", also "datenqualitaet" {
            "Z07" => "kundeMsb", None,
            "Z39" => "kundeLf", Some("base"),
            "Z40" => "kundeLf", Some("informative"),
        }
    }

    #[derive(Debug, Default, Serialize, Deserialize)]
    #[serde(default, rename_all = "camelCase")]
    struct Gp {
        #[serde(
            skip_serializing_if = "Option::is_none",
            deserialize_with = "deserialize_code_string"
        )]
        partnerrolle: Option<String>,
        #[serde(skip_serializing_if = "Option::is_none")]
        datenqualitaet: Option<String>,
        #[serde(skip_serializing_if = "Option::is_none")]
        name1: Option<String>,
    }

    #[derive(Debug, Default, Serialize, Deserialize)]
    #[serde(default)]
    struct GpContainer {
        #[serde(
            skip_serializing_if = "Option::is_none",
            serialize_with = "serialize_keyed_map",
            deserialize_with = "deserialize_keyed_map"
        )]
        gp: Option<BTreeMap<GpKey, Gp>>,
    }

    fn gp(json: serde_json::Value) -> Result<GpContainer, serde_json::Error> {
        serde_json::from_value(serde_json::json!({ "gp": json }))
    }

    #[test]
    fn keyed_map_from_engine_array_resolves_many_to_one() {
        let c = gp(serde_json::json!([
            {"partnerrolle": "kundeLf", "datenqualitaet": "informative", "name1": "b"},
            {"partnerrolle": {"code": "kundeLf", "meaning": null}, "datenqualitaet": "base", "name1": "a"},
            {"partnerrolle": "kundeMsb", "name1": "c"}
        ]))
        .unwrap();
        let map = c.gp.unwrap();
        assert_eq!(map[&GpKey::Z39].name1.as_deref(), Some("a"));
        assert_eq!(map[&GpKey::Z40].name1.as_deref(), Some("b"));
        assert_eq!(map[&GpKey::Z07].name1.as_deref(), Some("c"));
    }

    #[test]
    fn keyed_map_single_element_serializes_as_object() {
        let c = gp(serde_json::json!([{"partnerrolle": "Z07", "name1": "a"}])).unwrap();
        assert_eq!(
            serde_json::to_value(&c).unwrap(),
            serde_json::json!({"gp": {"partnerrolle": "Z07", "name1": "a"}})
        );
    }

    #[test]
    fn vec_or_single_serializes_like_the_engine() {
        #[derive(Serialize)]
        struct S {
            #[serde(serialize_with = "serialize_vec_or_single")]
            v: Option<Vec<u8>>,
        }
        let json = |v| serde_json::to_value(S { v }).unwrap();
        assert_eq!(json(Some(vec![1])), serde_json::json!({"v": 1}));
        assert_eq!(json(Some(vec![1, 2])), serde_json::json!({"v": [1, 2]}));
        assert_eq!(json(None), serde_json::json!({"v": null}));
    }

    #[test]
    fn keyed_map_rejects_duplicate_keys() {
        let err = gp(serde_json::json!([
            {"partnerrolle": "kundeMsb", "name1": "a"},
            {"partnerrolle": "Z07", "name1": "b"}
        ]))
        .unwrap_err();
        assert!(err.to_string().contains("duplicate map key `Z07`"), "{err}");
    }

    #[test]
    fn keyed_map_rejects_elements_without_key() {
        assert!(gp(serde_json::json!([{"name1": "a"}])).is_err());
    }

    #[test]
    fn keyed_map_from_typed_map_fills_qualifier_fields() {
        let c = gp(serde_json::json!({"Z40": {"name1": "b"}, "Z07": {"name1": "a"}})).unwrap();
        let json = serde_json::to_value(&c).unwrap();
        // Serialized as the engine's array, in key declaration order.
        assert_eq!(
            json,
            serde_json::json!({"gp": [
                {"partnerrolle": "kundeMsb", "name1": "a"},
                {"partnerrolle": "kundeLf", "datenqualitaet": "informative", "name1": "b"}
            ]})
        );
        // Serialized form deserializes back to the same map.
        let again: GpContainer = serde_json::from_value(json.clone()).unwrap();
        assert_eq!(serde_json::to_value(&again).unwrap(), json);
    }

    #[test]
    fn keyed_map_rejects_key_disagreeing_with_element() {
        let err = gp(serde_json::json!({"Z39": {"partnerrolle": "kundeMsb"}})).unwrap_err();
        assert!(err.to_string().contains("disagrees"), "{err}");
    }

    #[test]
    fn keyed_map_single_element_and_null() {
        let c = gp(serde_json::json!({"partnerrolle": "kundeMsb"})).unwrap();
        assert!(c.gp.unwrap().contains_key(&GpKey::Z07));
        assert!(gp(serde_json::Value::Null).unwrap().gp.is_none());
    }

    #[test]
    fn code_string_accepts_string_or_enriched_object() {
        #[derive(Deserialize)]
        struct S {
            #[serde(default, deserialize_with = "deserialize_code_string")]
            v: Option<String>,
        }
        let s: S = serde_json::from_value(serde_json::json!({"v": "Z01"})).unwrap();
        assert_eq!(s.v.as_deref(), Some("Z01"));
        let s: S =
            serde_json::from_value(serde_json::json!({"v": {"code": "Z01", "meaning": "x"}}))
                .unwrap();
        assert_eq!(s.v.as_deref(), Some("Z01"));
        let s: S = serde_json::from_value(serde_json::json!({})).unwrap();
        assert!(s.v.is_none());
    }

    #[test]
    fn test_serialize_as_map() {
        let mut items = BTreeMap::new();
        items.insert(
            TestKey::Ms,
            TestEntity {
                marktrolle: Some("MS".into()),
                name: Some("Sender".into()),
            },
        );
        let container = TestContainer { items: Some(items) };
        let json = serde_json::to_value(&container).unwrap();
        assert!(json["items"].is_object());
        assert!(json["items"]["MS"].is_object());
    }
}