use reqwest::Url;
use chrono::{DateTime, Utc};
use crate::{
  Result,
  AdapterPool,
  db::ChannelKey,
};

pub struct UnparsedChannel {
  pub id: i64,
  pub title: String,
  pub link: String,
  pub description: Option<String>,
  pub last_fetched: Option<String>,
}
impl UnparsedChannel {
  pub fn parse(self) -> Result<Channel> {
    Ok(Channel {
      key: ChannelKey(self.id),
      title: self.title,
      link: Url::parse(&self.link)?,
      description: self.description,
      last_fetched: self.last_fetched.as_deref()
        .map(DateTime::parse_from_rfc2822)
        .transpose()?
        .map(|dt| dt.with_timezone(&Utc)),
    })
  }
}

pub struct Channel {
  key: ChannelKey,
  title: String,
  link: Url,
  description: Option<String>,
  last_fetched: Option<DateTime<Utc>>,
}

impl Channel {
  pub fn key(&self) -> ChannelKey { self.key }
  pub fn title(&self) -> &str { &self.title }
  pub fn link(&self) -> &Url { &self.link }
  pub fn description(&self) -> Option<&str> { self.description.as_deref() }
  pub fn last_fetched(&self) -> Option<DateTime<Utc>> { self.last_fetched }

  pub async fn get_all(pool: &AdapterPool) -> Result<Vec<Self>> {
    sqlx::query_as!(
      UnparsedChannel,
      "SELECT id, title, link, description, last_fetched FROM channels"
    ).fetch_all(&pool.0).await?.into_iter().map(UnparsedChannel::parse).collect()
  }

  pub async fn get(pool: &AdapterPool, key: ChannelKey) -> Result<Self> {
    sqlx::query_as!(
      UnparsedChannel,
      "SELECT id, title, link, description, last_fetched
       FROM channels
       WHERE id = ?",
      key.0
    ).fetch_one(&pool.0).await?.parse()
  }

  pub async fn get_or_create(
    pool: &AdapterPool, link: Url
  ) -> Result<Self> {
    let link_str = link.as_str();

    sqlx::query_as!(
      UnparsedChannel,
      "INSERT INTO channels (title, link)
       VALUES(?, ?)
       ON CONFLICT(link) DO UPDATE SET link = link
       RETURNING id, title, link, description, last_fetched",
      link_str, link_str // We use the url as a placeholder title
    ).fetch_one(&pool.0).await?.parse()
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::{
    test_utils::{
      FEED1, FEED2, CHANNEL_TITLE, CHANNEL_DESC,
      setup_adapter,
      setup_channel,
    },
  };
  use chrono::TimeZone;

  #[test]
  fn parse_unparsed_item() {
    const CHANNEL_ID: i64 = 1;
    let date: DateTime<Utc> = Utc.with_ymd_and_hms(2020,1,1,0,0,0).unwrap();

    let raw_channel = UnparsedChannel {
      id: CHANNEL_ID,
      title: CHANNEL_TITLE.to_string(),
      link: FEED1.to_string(),
      description: Some(CHANNEL_DESC.to_string()),
      last_fetched: Some(date.to_rfc2822()),
    };
    let channel = raw_channel.parse().unwrap();
    
    assert_eq!(channel.key.0, CHANNEL_ID);
    assert_eq!(channel.title, CHANNEL_TITLE);
    assert_eq!(channel.link.as_str(), FEED1);
    assert_eq!(channel.description, Some(CHANNEL_DESC.to_string()));
    assert_eq!(channel.last_fetched, Some(date));
  }

  #[tokio::test]
  async fn get_all() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let url1 = Url::parse(FEED1).unwrap();
    let url2 = Url::parse(FEED2).unwrap();
    Channel::get_or_create(pool, url1).await.unwrap();
    Channel::get_or_create(pool, url2).await.unwrap();

    let channels = Channel::get_all(pool).await.unwrap();
    assert_eq!(channels.len(), 2);
  }

  #[tokio::test]
  async fn get() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let channel_a = setup_channel(pool).await;

    let channel_b = Channel::get(pool, channel_a.key()).await.unwrap();

    assert_eq!(channel_a.key, channel_b.key);
    assert_eq!(channel_a.title, channel_b.title);
    assert_eq!(channel_a.link, channel_b.link);
    assert_eq!(channel_a.last_fetched, channel_b.last_fetched);
    assert_eq!(channel_a.description, channel_b.description);
  }

  #[tokio::test]
  async fn create() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let url_feed = Url::parse(FEED1).unwrap();

    let channel = Channel::get_or_create(pool, url_feed).await.unwrap();

    assert!(channel.key().0 > 0);
    assert_eq!(channel.link().as_str(), FEED1);
    assert!(channel.title().len() > 0);
  }

  #[tokio::test]
  async fn create_duplicate_returns_existing() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let url_feed = Url::parse(FEED1).unwrap();

    let channel1 = Channel::get_or_create(pool, url_feed.clone()).await.unwrap();
    let channel2 = Channel::get_or_create(pool, url_feed).await.unwrap();

    assert_eq!(channel1.key(), channel2.key());
  }

  #[tokio::test]
  async fn get_all_channels() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let url_feed1 = Url::parse(FEED1).unwrap();
    let url_feed2 = Url::parse(FEED2).unwrap();

    Channel::get_or_create(pool, url_feed1).await.unwrap();
    Channel::get_or_create(pool, url_feed2).await.unwrap();

    let channels = Channel::get_all(pool).await.unwrap();

    assert_eq!(channels.len(), 2);
  }
}