use reqwest::Url;
use chrono::{DateTime, Utc};
use crate::{
  Result,
  AdapterPool,
  db::{
    ChannelId,
    Item,
    FeedChannel,
    feed_channel::UnparsedFeedChannel,
    item::UnparsedItem,
  },
  fetch::FetchedRSSChannel,
};

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 {
      id: ChannelId(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 {
  id: ChannelId,
  title: String,
  link: Url,
  description: Option<String>,
  last_fetched: Option<DateTime<Utc>>,
}

impl Channel {
  pub fn id(&self) -> ChannelId { self.id }
  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>> {
    let channels: Result<Vec<Channel>> = sqlx::query_as!(
      UnparsedChannel,
      "SELECT id, title, link, description, last_fetched FROM channels"
    ).fetch_all(&pool.0).await?.into_iter().map(UnparsedChannel::parse).collect();

    channels
  }

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

    channel
  }

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

    let channel = 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();

    channel
  }

  // TODO implement fetch skipping
  pub fn should_skip_fetch(&self) -> bool { false }

  pub async fn update_metadata(
    &self, pool: &AdapterPool, fetched: FetchedRSSChannel
  ) -> Result<()> {
    let title = fetched.title();
    let description = fetched.description();
    let link = fetched.link().as_str();
    let fetched_at = fetched.fetched_at().to_rfc2822();
    sqlx::query!(
      "UPDATE channels
       SET title = ?, link = ?, description = ?, 
        last_fetched = ?
       WHERE id = ?",
      title, link, description, fetched_at,
      self.id.0
    ).execute(&pool.0).await?;

    Ok(())
  }

  async fn get_feed_channels(
    &self, pool: &AdapterPool
  ) -> Result<Vec<FeedChannel>> {
    let feeds: Result<Vec<FeedChannel>> = sqlx::query_as!(
      UnparsedFeedChannel,
      "SELECT channel_id, feed_id
       FROM feed_channels
       WHERE channel_id = ?",
      self.id.0
    ).fetch_all(&pool.0).await?.into_iter()
      .map(UnparsedFeedChannel::parse).collect();

    feeds
  }

  pub async fn update_items(
    &self, pool: &AdapterPool, fetched: FetchedRSSChannel
  ) -> Result<()> {
    let fetched_at = fetched.fetched_at();

    let feed_channels = self.get_feed_channels(pool).await?;

    for rss_item in fetched.items() {
      let new_item = Item::get_or_create(pool, self.id, rss_item.guid()).await?;
      new_item.update_content(pool, rss_item, &fetched_at).await?;
      for feed_channel in &feed_channels {
        feed_channel.add_item(pool, &new_item).await?;
      }
    }

    Ok(())
  }

  pub async fn get_items(&self, pool: &AdapterPool) -> Result<Vec<Item>> {
    let items: Result<Vec<Item>> = sqlx::query_as!(
      UnparsedItem,
      "SELECT id as `id!`, channel_id, fetched_at, title, description,
         content
       FROM items
       WHERE channel_id = ?",
      self.id.0
    ).fetch_all(&pool.0).await?.into_iter().map(UnparsedItem::parse).collect();

    items
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::{
    db::{
      Feed,
      User,
    },
    test_utils::{
      FEED1, FEED2, CHANNEL_TITLE, CHANNEL_DESC, USERNAME, FEED_TITLE,
      FEED_TITLE2, ITEM_GUID, ITEM_GUID2,
      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.id.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.id()).await.unwrap();

    assert_eq!(channel_a.id, channel_b.id);
    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.id().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!(
      i64::from(channel1.id()),
      i64::from(channel2.id())
    );
  }

  #[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);
  }

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

    let user = User::create(pool, USERNAME).await.unwrap();
    let feed1 = Feed::create(pool, user.id(), FEED_TITLE).await.unwrap();
    let feed2 = Feed::create(pool, user.id(), FEED_TITLE2).await.unwrap();

    feed1.add_channel(pool, channel.id).await.unwrap();
    feed2.add_channel(pool, channel.id).await.unwrap();

    let fc_list = channel.get_feed_channels(pool).await.unwrap();

    assert_eq!(fc_list.len(), 2);
  }
  
  #[tokio::test]
  async fn get_channels() {
    let adapter = setup_adapter().await;
    let pool = adapter.get_pool();
    let channel = setup_channel(pool).await;

    let user = User::create(pool, USERNAME).await.unwrap();
    let feed1 = Feed::create(pool, user.id(), FEED_TITLE).await.unwrap();
    let feed2 = Feed::create(pool, user.id(), FEED_TITLE2).await.unwrap();

    feed1.add_channel(pool, channel.id).await.unwrap();
    feed2.add_channel(pool, channel.id).await.unwrap();

    let fc_list = channel.get_feed_channels(pool).await.unwrap();

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

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

    Item::get_or_create(pool, channel.id(), ITEM_GUID).await.unwrap();
    Item::get_or_create(pool, channel.id(), ITEM_GUID2).await.unwrap();

    let items = channel.get_items(pool).await.unwrap();

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