use crate::structs::PersonMentionView;
use diesel::{
  dsl::now,
  pg::Pg,
  result::Error,
  BoolExpressionMethods,
  ExpressionMethods,
  JoinOnDsl,
  NullableExpressionMethods,
  QueryDsl,
};
use diesel_async::RunQueryDsl;
use lemmy_db_schema::{
  aliases,
  newtypes::{PersonId, PersonMentionId},
  schema::{
    comment,
    comment_aggregates,
    comment_like,
    comment_saved,
    community,
    community_follower,
    community_moderator,
    community_person_ban,
    person,
    person_block,
    person_mention,
    post,
  },
  source::community::CommunityFollower,
  utils::{get_conn, limit_and_offset, DbConn, DbPool, ListFn, Queries, ReadFn},
  CommentSortType,
};

fn queries<'a>() -> Queries<
  impl ReadFn<'a, PersonMentionView, (PersonMentionId, Option<PersonId>)>,
  impl ListFn<'a, PersonMentionView, PersonMentionQuery>,
> {
  let all_joins = |query: person_mention::BoxedQuery<'a, Pg>, my_person_id: Option<PersonId>| {
    // The left join below will return None in this case
    let person_id_join = my_person_id.unwrap_or(PersonId(-1));

    query
      .inner_join(comment::table)
      .inner_join(person::table.on(comment::creator_id.eq(person::id)))
      .inner_join(post::table.on(comment::post_id.eq(post::id)))
      .inner_join(community::table.on(post::community_id.eq(community::id)))
      .inner_join(aliases::person1)
      .inner_join(comment_aggregates::table.on(comment::id.eq(comment_aggregates::comment_id)))
      .left_join(
        community_follower::table.on(
          post::community_id
            .eq(community_follower::community_id)
            .and(community_follower::person_id.eq(person_id_join)),
        ),
      )
      .left_join(
        comment_saved::table.on(
          comment::id
            .eq(comment_saved::comment_id)
            .and(comment_saved::person_id.eq(person_id_join)),
        ),
      )
      .left_join(
        person_block::table.on(
          comment::creator_id
            .eq(person_block::target_id)
            .and(person_block::person_id.eq(person_id_join)),
        ),
      )
      .left_join(
        comment_like::table.on(
          comment::id
            .eq(comment_like::comment_id)
            .and(comment_like::person_id.eq(person_id_join)),
        ),
      )
  };

  let selection = (
    person_mention::all_columns,
    comment::all_columns,
    person::all_columns,
    post::all_columns,
    community::all_columns,
    aliases::person1.fields(person::all_columns),
    comment_aggregates::all_columns,
    community_person_ban::community_id.nullable().is_not_null(),
    community_moderator::community_id.nullable().is_not_null(),
    CommunityFollower::select_subscribed_type(),
    comment_saved::comment_id.nullable().is_not_null(),
    person_block::person_id.nullable().is_not_null(),
    comment_like::score.nullable(),
  );

  let read =
    move |mut conn: DbConn<'a>,
          (person_mention_id, my_person_id): (PersonMentionId, Option<PersonId>)| async move {
      all_joins(
        person_mention::table.find(person_mention_id).into_boxed(),
        my_person_id,
      )
      .left_join(
        community_person_ban::table.on(
          community::id
            .eq(community_person_ban::community_id)
            .and(community_person_ban::person_id.eq(comment::creator_id)),
        ),
      )
      .left_join(
        community_moderator::table.on(
          community::id
            .eq(community_moderator::community_id)
            .and(community_moderator::person_id.eq(comment::creator_id)),
        ),
      )
      .select(selection)
      .first::<PersonMentionView>(&mut conn)
      .await
    };

  let list = move |mut conn: DbConn<'a>, options: PersonMentionQuery| async move {
    let mut query = all_joins(person_mention::table.into_boxed(), options.my_person_id)
      .left_join(
        community_person_ban::table.on(
          community::id
            .eq(community_person_ban::community_id)
            .and(community_person_ban::person_id.eq(comment::creator_id))
            .and(
              community_person_ban::expires
                .is_null()
                .or(community_person_ban::expires.gt(now)),
            ),
        ),
      )
      .left_join(
        community_moderator::table.on(
          community::id
            .eq(community_moderator::community_id)
            .and(community_moderator::person_id.eq(comment::creator_id)),
        ),
      )
      .select(selection);

    if let Some(recipient_id) = options.recipient_id {
      query = query.filter(person_mention::recipient_id.eq(recipient_id));
    }

    if options.unread_only {
      query = query.filter(person_mention::read.eq(false));
    }

    if !options.show_bot_accounts {
      query = query.filter(person::bot_account.eq(false));
    };

    query = match options.sort.unwrap_or(CommentSortType::Hot) {
      CommentSortType::Hot => query.then_order_by(comment_aggregates::hot_rank.desc()),
      CommentSortType::Controversial => {
        query.then_order_by(comment_aggregates::controversy_rank.desc())
      }
      CommentSortType::New => query.then_order_by(comment::published.desc()),
      CommentSortType::Old => query.then_order_by(comment::published.asc()),
      CommentSortType::Top => query.order_by(comment_aggregates::score.desc()),
    };

    let (limit, offset) = limit_and_offset(options.page, options.limit)?;

    query
      .limit(limit)
      .offset(offset)
      .load::<PersonMentionView>(&mut conn)
      .await
  };

  Queries::new(read, list)
}

impl PersonMentionView {
  pub async fn read(
    pool: &mut DbPool<'_>,
    person_mention_id: PersonMentionId,
    my_person_id: Option<PersonId>,
  ) -> Result<Self, Error> {
    queries()
      .read(pool, (person_mention_id, my_person_id))
      .await
  }

  /// Gets the number of unread mentions
  pub async fn get_unread_mentions(
    pool: &mut DbPool<'_>,
    my_person_id: PersonId,
  ) -> Result<i64, Error> {
    use diesel::dsl::count;
    let conn = &mut get_conn(pool).await?;

    person_mention::table
      .inner_join(comment::table)
      .filter(person_mention::recipient_id.eq(my_person_id))
      .filter(person_mention::read.eq(false))
      .filter(comment::deleted.eq(false))
      .filter(comment::removed.eq(false))
      .select(count(person_mention::id))
      .first::<i64>(conn)
      .await
  }
}

#[derive(Default)]
pub struct PersonMentionQuery {
  pub my_person_id: Option<PersonId>,
  pub recipient_id: Option<PersonId>,
  pub sort: Option<CommentSortType>,
  pub unread_only: bool,
  pub show_bot_accounts: bool,
  pub page: Option<i64>,
  pub limit: Option<i64>,
}

impl PersonMentionQuery {
  pub async fn list(self, pool: &mut DbPool<'_>) -> Result<Vec<PersonMentionView>, Error> {
    queries().list(pool, self).await
  }
}
