extern crate serde;
extern crate tokio;
extern crate chrono;
extern crate reqwest;
extern crate serde_json;
use std::env;
use std::path::Path;
use std::io::Cursor;
use std::process::exit;
use reqwest::Client;
use serde_json::json;
use quick_xml::Writer;
use serde::Deserialize;
use chrono::{Utc, DateTime, NaiveDateTime};
use quick_xml::events::{Event, BytesStart, BytesText, BytesEnd};

const QUERY: &str = r#"query ($id: Int) {
  Media (id: $id) {
    title {
      romaji
      english
    }
    airingSchedule {
      nodes {
        id
        airingAt
        timeUntilAiring
        episode
      }
    }
    episodes
    siteUrl
  }
}"#;

#[derive(Deserialize)]
struct Root {
    pub data: Data
}

#[derive(Deserialize)]
#[serde(rename_all="PascalCase")]
struct Data {
    pub media: Media
}

#[derive(Deserialize)]
#[serde(rename_all="camelCase")]
struct Media {
    pub title: MediaTitle,
    pub airing_schedule: AiringScheduleConnection,
    pub episodes: Option<i32>,
    pub site_url: String
}

#[derive(Deserialize)]
struct MediaTitle {
    pub romaji: String,
    pub english: Option<String>
}

#[derive(Deserialize)]
struct AiringScheduleConnection {
    pub nodes: Vec<AiringSchedule>
}

#[derive(Deserialize)]
#[serde(rename_all="camelCase")]
struct AiringSchedule {
    pub id: i32,
    pub airing_at: i64,
    pub time_until_airing: i64,
    pub episode: i32
}

async fn get_data(anime_id: i32) -> Root {
    let client = Client::new();
    let json = json!({"query": QUERY, "variables": {"id": anime_id}});
    serde_json::from_str(&client.post("https://graphql.anilist.co/")
        .header("Content-Type", "application/json")
        .header("Accept", "application/json")
        .body(json.to_string())
        .send()
        .await
        .unwrap()
        .text()
        .await
        .unwrap()).unwrap()
}

fn main() {
    let mut args = env::args();
    let path = args.next().expect("Cannot get binary path");
    let path = Path::new(&path).file_stem().unwrap().to_str().unwrap();
    let anime_id = match args.next() {
        Some(anime_id) => anime_id.parse::<i32>().unwrap(),
        None => {
            eprintln!("Usage: {} <anime id>", path);
            exit(1);
        }
    };
    let resp = tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(get_data(anime_id));
    let mut pub_date = Utc::now().to_rfc2822();
    let mut last_build_date = pub_date.clone();
    let resp = &resp.data.media;
    let title = resp.title.english.as_ref().unwrap_or(&resp.title.romaji);
    let mut items: Vec<(i32, String, String)> = Vec::with_capacity(resp.airing_schedule.nodes.len());
    for i in &resp.airing_schedule.nodes {
        let i_date = DateTime::<Utc>::from_utc(NaiveDateTime::from_timestamp(i.airing_at, 0), Utc).to_rfc2822();
        pub_date = i_date.clone();
        if i.time_until_airing > 0 {
            break;
        }
        last_build_date = i_date.clone();
        let mut title = format!("{} - {}", title, i.episode);
        if Some(i.episode) == resp.episodes {
            title.push_str(" END");
        }
        items.push((i.id, i_date, title));
    }
    items.reverse();
    let mut writer = Writer::new(Cursor::new(Vec::new()));

    {
        let mut elem = BytesStart::owned(b"rss".to_vec(), 3);
        elem.push_attribute(("version", "2.0"));
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesStart::owned(b"channel".to_vec(), 7);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesStart::owned(b"title".to_vec(), 5);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&title).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"title".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"link".to_vec(), 4);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&resp.site_url).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"link".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"description".to_vec(), 11);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&format!("Aired episodes of {}", &title)).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"description".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"pubDate".to_vec(), 7);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&pub_date).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"pubDate".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"lastBuildDate".to_vec(), 13);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&last_build_date).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"lastBuildDate".to_vec());
        writer.write_event(Event::End(elem)).unwrap();
    }

    for (id, date, title) in items {
        let elem = BytesStart::owned(b"item".to_vec(), 4);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesStart::owned(b"title".to_vec(), 5);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&title).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"title".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"link".to_vec(), 4);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&resp.site_url).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"link".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"guid".to_vec(), 4);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&format!("ran-{}-{}", &anime_id, id)).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"guid".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesStart::owned(b"pubDate".to_vec(), 7);
        writer.write_event(Event::Start(elem)).unwrap();

        let elem = BytesText::from_plain_str(&date).into_owned();
        writer.write_event(Event::Text(elem)).unwrap();

        let elem = BytesEnd::owned(b"pubDate".to_vec());
        writer.write_event(Event::End(elem)).unwrap();

        let elem = BytesEnd::owned(b"item".to_vec());
        writer.write_event(Event::End(elem)).unwrap();
    }

    let elem = BytesEnd::owned(b"channel".to_vec());
    writer.write_event(Event::End(elem)).unwrap();

    let elem = BytesEnd::owned(b"rss".to_vec());
    writer.write_event(Event::End(elem)).unwrap();

    println!("{}", String::from_utf8(writer.into_inner().into_inner()).unwrap());
}