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use std::fmt;

use serde::{
    de::{self, Deserialize, Deserializer, Visitor},
    ser::{Serialize, Serializer},
};

/// Protocol Version
#[derive(Debug, PartialEq, Clone, Copy, Hash, Eq)]
pub enum Version {
    /// JSON-RPC 2.0
    V2,
}

impl Serialize for Version {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        match *self {
            Version::V2 => serializer.serialize_str("2.0"),
        }
    }
}

impl<'a> Deserialize<'a> for Version {
    fn deserialize<D>(deserializer: D) -> Result<Version, D::Error>
    where
        D: Deserializer<'a>,
    {
        deserializer.deserialize_identifier(VersionVisitor)
    }
}

struct VersionVisitor;

impl<'a> Visitor<'a> for VersionVisitor {
    type Value = Version;

    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter.write_str("a string")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where
        E: de::Error,
    {
        match value {
            "2.0" => Ok(Version::V2),
            _ => Err(de::Error::custom("invalid version")),
        }
    }
}