use crate::structs::{CommunityModeratorView, CommunityView, PersonViewSafe};
use diesel::{
  result::Error,
  BoolExpressionMethods,
  ExpressionMethods,
  JoinOnDsl,
  NullableExpressionMethods,
  PgTextExpressionMethods,
  QueryDsl,
};
use diesel_async::RunQueryDsl;
use lemmy_db_schema::{
  aggregates::structs::CommunityAggregates,
  newtypes::{CommunityId, PersonId},
  schema::{community, community_aggregates, community_block, community_follower, local_user},
  source::{
    community::{Community, CommunityFollower, CommunitySafe},
    community_block::CommunityBlock,
    local_user::LocalUser,
  },
  traits::{ToSafe, ViewToVec},
  utils::{functions::hot_rank, fuzzy_search, get_conn, limit_and_offset, DbPool},
  ListingType,
  SortType,
};
use typed_builder::TypedBuilder;

type CommunityViewTuple = (
  CommunitySafe,
  CommunityAggregates,
  Option<CommunityFollower>,
  Option<CommunityBlock>,
);

impl CommunityView {
  pub async fn read(
    pool: &DbPool,
    community_id: CommunityId,
    my_person_id: Option<PersonId>,
  ) -> Result<Self, Error> {
    let conn = &mut get_conn(pool).await?;
    // The left join below will return None in this case
    let person_id_join = my_person_id.unwrap_or(PersonId(-1));

    let (community, counts, follower, blocked) = community::table
      .find(community_id)
      .inner_join(community_aggregates::table)
      .left_join(
        community_follower::table.on(
          community::id
            .eq(community_follower::community_id)
            .and(community_follower::person_id.eq(person_id_join)),
        ),
      )
      .left_join(
        community_block::table.on(
          community::id
            .eq(community_block::community_id)
            .and(community_block::person_id.eq(person_id_join)),
        ),
      )
      .select((
        Community::safe_columns_tuple(),
        community_aggregates::all_columns,
        community_follower::all_columns.nullable(),
        community_block::all_columns.nullable(),
      ))
      .first::<CommunityViewTuple>(conn)
      .await?;

    Ok(CommunityView {
      community,
      subscribed: CommunityFollower::to_subscribed_type(&follower),
      blocked: blocked.is_some(),
      counts,
    })
  }

  pub async fn is_mod_or_admin(
    pool: &DbPool,
    person_id: PersonId,
    community_id: CommunityId,
  ) -> Result<bool, Error> {
    let is_mod = CommunityModeratorView::for_community(pool, community_id)
      .await
      .map(|v| {
        v.into_iter()
          .map(|m| m.moderator.id)
          .collect::<Vec<PersonId>>()
      })
      .unwrap_or_default()
      .contains(&person_id);
    if is_mod {
      return Ok(true);
    }

    let is_admin = PersonViewSafe::admins(pool)
      .await
      .map(|v| {
        v.into_iter()
          .map(|a| a.person.id)
          .collect::<Vec<PersonId>>()
      })
      .unwrap_or_default()
      .contains(&person_id);
    Ok(is_admin)
  }
}

#[derive(TypedBuilder)]
#[builder(field_defaults(default))]
pub struct CommunityQuery<'a> {
  #[builder(!default)]
  pool: &'a DbPool,
  listing_type: Option<ListingType>,
  sort: Option<SortType>,
  local_user: Option<&'a LocalUser>,
  search_term: Option<String>,
  page: Option<i64>,
  limit: Option<i64>,
}

impl<'a> CommunityQuery<'a> {
  pub async fn list(self) -> Result<Vec<CommunityView>, Error> {
    let conn = &mut get_conn(self.pool).await?;

    // The left join below will return None in this case
    let person_id_join = self.local_user.map(|l| l.person_id).unwrap_or(PersonId(-1));

    let mut query = community::table
      .inner_join(community_aggregates::table)
      .left_join(local_user::table.on(local_user::person_id.eq(person_id_join)))
      .left_join(
        community_follower::table.on(
          community::id
            .eq(community_follower::community_id)
            .and(community_follower::person_id.eq(person_id_join)),
        ),
      )
      .left_join(
        community_block::table.on(
          community::id
            .eq(community_block::community_id)
            .and(community_block::person_id.eq(person_id_join)),
        ),
      )
      .select((
        Community::safe_columns_tuple(),
        community_aggregates::all_columns,
        community_follower::all_columns.nullable(),
        community_block::all_columns.nullable(),
      ))
      .into_boxed();

    if let Some(search_term) = self.search_term {
      let searcher = fuzzy_search(&search_term);
      query = query
        .filter(community::name.ilike(searcher.clone()))
        .or_filter(community::title.ilike(searcher));
    };

    match self.sort.unwrap_or(SortType::Hot) {
      SortType::New => query = query.order_by(community::published.desc()),
      SortType::TopAll => query = query.order_by(community_aggregates::subscribers.desc()),
      SortType::TopMonth => query = query.order_by(community_aggregates::users_active_month.desc()),
      SortType::Hot => {
        query = query
          .order_by(
            hot_rank(
              community_aggregates::subscribers,
              community_aggregates::published,
            )
            .desc(),
          )
          .then_order_by(community_aggregates::published.desc());
        // Don't show hidden communities in Hot (trending)
        query = query.filter(
          community::hidden
            .eq(false)
            .or(community_follower::person_id.eq(person_id_join)),
        );
      }
      // Covers all other sorts
      _ => {
        query = query
          .order_by(
            hot_rank(
              community_aggregates::subscribers,
              community_aggregates::published,
            )
            .desc(),
          )
          .then_order_by(community_aggregates::published.desc())
      }
    };

    if let Some(listing_type) = self.listing_type {
      query = match listing_type {
        ListingType::Subscribed => query.filter(community_follower::person_id.is_not_null()), // TODO could be this: and(community_follower::person_id.eq(person_id_join)),
        ListingType::Local => query.filter(community::local.eq(true)),
        _ => query,
      };
    }

    // Don't show blocked communities or nsfw communities if not enabled in profile
    if self.local_user.is_some() {
      query = query.filter(community_block::person_id.is_null());
      query = query.filter(community::nsfw.eq(false).or(local_user::show_nsfw.eq(true)));
    } else {
      // No person in request, only show nsfw communities if show_nsfw passed into request
      if !self.local_user.map(|l| l.show_nsfw).unwrap_or(false) {
        query = query.filter(community::nsfw.eq(false));
      }
    }

    let (limit, offset) = limit_and_offset(self.page, self.limit)?;
    let res = query
      .limit(limit)
      .offset(offset)
      .filter(community::removed.eq(false))
      .filter(community::deleted.eq(false))
      .load::<CommunityViewTuple>(conn)
      .await?;

    Ok(CommunityView::from_tuple_to_vec(res))
  }
}

impl ViewToVec for CommunityView {
  type DbTuple = CommunityViewTuple;
  fn from_tuple_to_vec(items: Vec<Self::DbTuple>) -> Vec<Self> {
    items
      .into_iter()
      .map(|a| Self {
        community: a.0,
        counts: a.1,
        subscribed: CommunityFollower::to_subscribed_type(&a.2),
        blocked: a.3.is_some(),
      })
      .collect::<Vec<Self>>()
  }
}