use crate::{
  Result,
  Item,
  Channel,
  channel::{
    UnparsedChannel,
    ChannelId,
  },
  user::UserId,
};
use sqlx::SqlitePool;

#[derive(Copy, Clone)]
pub struct FeedId(i64);
impl From<FeedId> for i64 { fn from(id: FeedId) -> Self { id.0 } }

pub struct UnparsedFeed {
  pub id: i64,
  pub title: String,
}
impl UnparsedFeed {
  pub fn parse(self) -> Result<Feed> {
    Ok(Feed {
      id: FeedId(self.id),
      title: self.title,
    })
  }
}

pub struct Feed {
  id: FeedId,
  title: String,
}

impl Feed {
  pub fn id(&self) -> FeedId { self.id }
  pub fn title(&self) -> &str { &self.title }

  pub async fn get(
    pool: &SqlitePool, id: FeedId
  ) -> Result<Self> {
    let feed = sqlx::query_as!(
      UnparsedFeed,
      "SELECT id, title FROM feeds WHERE id = ?",
      id.0
    ).fetch_one(pool).await?.parse();

    feed
  }

  pub async fn create(
    pool: &SqlitePool, user_id: UserId, title: &str
  ) -> Result<Self> {
    let int_id = i64::from(user_id);
    let new_feed = sqlx::query_as!(
      UnparsedFeed,
      "INSERT INTO feeds (user_id, title) 
       VALUES (?, ?)
       RETURNING id as `id!`, title",
      int_id, title
    ).fetch_one(pool).await?.parse();

    new_feed
  }

  pub async fn update_title(
    pool: &SqlitePool, id: FeedId, new_title: &str
  ) -> Result<()> {
    sqlx::query!(
      "UPDATE feeds SET title = ? WHERE id = ?",
      new_title, id.0
    ).execute(pool).await?;

    Ok(())
  }

  pub async fn add_channel(
    &self, pool: &SqlitePool, channel_id: ChannelId
  ) -> Result<()> {
    sqlx::query!(
      "INSERT INTO feed_channels (feed_id, channel_id)
       VALUES (?, ?)",
      self.id.0, channel_id.0
    ).execute(pool).await?;

    Ok(())
  }

  pub async fn get_items(
    &self, pool: &SqlitePool, limit: u8, offset: u32
  ) -> Result<Vec<Item>> {
    let items = sqlx::query_as!(
      Item,
      "SELECT item_id as id FROM feed_items
       WHERE feed_id = ? AND archived = FALSE
       ORDER BY score DESC
       LIMIT ? OFFSET ?",
      self.id.0, limit, offset
    ).fetch_all(pool).await?;

    Ok(items)
  }

  pub async fn get_channels(
    &self, pool: &SqlitePool
  ) -> Result<Vec<Channel>> {
    let channels: Result<Vec<Channel>> = sqlx::query_as!(
      UnparsedChannel,
      "SELECT c.id as `id!`, c.title, c.link, c.description, c.last_fetched
       FROM channels c
       JOIN feed_channels fc on c.id = fc.channel_id
       WHERE fc.feed_id = ?",
      self.id.0
    ).fetch_all(pool).await?.into_iter()
      .map(UnparsedChannel::parse).collect();

    channels
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::User;
  use sqlx::SqlitePool;

  async fn setup_test_db() -> SqlitePool {
    let pool = SqlitePool::connect("sqlite::memory:").await.unwrap();
    sqlx::migrate!().run(&pool).await.unwrap();
    pool
  }

  #[tokio::test]
  async fn create_feed() {
    let pool = setup_test_db().await;
    let user = User::create(&pool, "Alice").await.unwrap();

    let feed = Feed::create(&pool, user.id(), "Tech News").await.unwrap();

    assert_eq!(feed.title(), "Tech News");
    assert!(feed.id().0 > 0);
  }

  #[tokio::test]
  async fn test_update_title() {
    let pool = setup_test_db().await;
    let user = User::create(&pool, "Alice").await.unwrap();
    let feed = Feed::create(&pool, user.id(), "Tech News").await.unwrap();

    Feed::update_title(&pool, feed.id(), "Technology").await.unwrap();

    let updated = Feed::get(&pool, feed.id()).await.unwrap();
    assert_eq!(updated.title(), "Technology");
  }
}