use chrono::Utc;
use serde::{Deserializer, Serializer};
use std::fmt;

pub fn serialize_datetime<S>(
    date: &Option<chrono::DateTime<Utc>>,
    serializer: S,
) -> Result<S::Ok, S::Error>
where
    S: Serializer,
{
    serializer.serialize_str(&date.unwrap().to_rfc3339())
}

pub fn deserialize_datetime<'de, D>(
    deserializer: D,
) -> Result<Option<chrono::DateTime<Utc>>, D::Error>
where
    D: Deserializer<'de>,
{
    struct DateTimeVisitor;

    impl<'de> serde::de::Visitor<'de> for DateTimeVisitor {
        type Value = Option<chrono::DateTime<Utc>>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("an ISO 8601 formatted date string or null")
        }

        fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
        where
            E: serde::de::Error,
        {
            match chrono::DateTime::parse_from_rfc3339(value) {
                Ok(dt) => Ok(Some(dt.with_timezone(&Utc))),
                Err(e) => Err(E::custom(format!("Failed to parse datetime: {}", e))),
            }
        }

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

        fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
        where
            D: Deserializer<'de>,
        {
            deserializer.deserialize_str(self)
        }
    }

    deserializer.deserialize_option(DateTimeVisitor)
}