use chrono::{DateTime, FixedOffset};
use serde::de::{self, Visitor};
use serde::{Deserialize, Deserializer};
use std::collections::HashMap;
use std::fmt;
use std::marker::PhantomData;

#[derive(Deserialize, Debug)]
pub struct Issue {
    pub comments_url: String,
    pub events_url: String,
    pub html_url: String,
    pub node_id: String,
    pub title: String,
    pub user: User,
    pub state: String,
    pub body: String,
    #[serde(deserialize_with = "deserialize_datetime")]
    pub created_at: DateTime<FixedOffset>,
}

#[derive(Deserialize, Debug)]
#[serde(untagged)]
pub enum EventType {
    Comment(Comment),
    Event(Event),
}

#[derive(Deserialize, Debug)]
pub struct Comment {
    pub html_url: String,
    pub node_id: String,
    pub user: User,
    #[serde(deserialize_with = "deserialize_datetime")]
    pub created_at: DateTime<FixedOffset>,
    pub body: String,
}

#[derive(Deserialize, Debug)]
pub struct Event {
    pub url: String,
    pub id: usize,
    pub node_id: String,
    pub actor: User,
    #[serde(deserialize_with = "deserialize_datetime")]
    pub created_at: DateTime<FixedOffset>,
    pub event: String,
    #[serde(flatten)]
    pub extra: HashMap<String, serde_json::Value>,
}

#[derive(Deserialize, Debug)]
pub struct User {
    pub login: String,
}

fn deserialize_datetime<'de, D>(deserializer: D) -> Result<DateTime<FixedOffset>, D::Error>
where
    D: Deserializer<'de>,
{
    struct DeserializeDateTime<T>(PhantomData<fn() -> T>);

    impl<'de> Visitor<'de> for DeserializeDateTime<DateTime<FixedOffset>> {
        type Value = DateTime<FixedOffset>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("RFC3339 datetime string")
        }

        fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            //          https://brokenco.de/2020/08/03/serde-deserialize-with-string.html
            DateTime::parse_from_rfc3339(value).map_err(serde::de::Error::custom)
        }
    }

    deserializer.deserialize_any(DeserializeDateTime(PhantomData))
}