use crate::Perform;
use actix_web::web::Data;
use anyhow::Context;
use lemmy_api_common::{
  community::{GetCommunityResponse, TransferCommunity},
  context::LemmyContext,
  utils::{is_admin, is_top_mod, local_user_view_from_jwt},
};
use lemmy_db_schema::{
  source::{
    community::{CommunityModerator, CommunityModeratorForm},
    moderator::{ModTransferCommunity, ModTransferCommunityForm},
  },
  traits::{Crud, Joinable},
};
use lemmy_db_views_actor::structs::{CommunityModeratorView, CommunityView};
use lemmy_utils::{
  error::{LemmyError, LemmyErrorExt, LemmyErrorType},
  location_info,
};

// TODO: we dont do anything for federation here, it should be updated the next time the community
//       gets fetched. i hope we can get rid of the community creator role soon.
#[async_trait::async_trait(?Send)]
impl Perform for TransferCommunity {
  type Response = GetCommunityResponse;

  #[tracing::instrument(skip(context))]
  async fn perform(
    &self,
    context: &Data<LemmyContext>,
  ) -> Result<GetCommunityResponse, LemmyError> {
    let data: &TransferCommunity = self;
    let local_user_view = local_user_view_from_jwt(&data.auth, context).await?;

    // Fetch the community mods
    let community_id = data.community_id;
    let mut community_mods =
      CommunityModeratorView::for_community(&mut context.pool(), community_id).await?;

    // Make sure transferrer is either the top community mod, or an admin
    if !(is_top_mod(&local_user_view, &community_mods).is_ok()
      || is_admin(&local_user_view).is_ok())
    {
      return Err(LemmyErrorType::NotAnAdmin)?;
    }

    // You have to re-do the community_moderator table, reordering it.
    // Add the transferee to the top
    let creator_index = community_mods
      .iter()
      .position(|r| r.moderator.id == data.person_id)
      .context(location_info!())?;
    let creator_person = community_mods.remove(creator_index);
    community_mods.insert(0, creator_person);

    // Delete all the mods
    let community_id = data.community_id;

    CommunityModerator::delete_for_community(&mut context.pool(), community_id).await?;

    // TODO: this should probably be a bulk operation
    // Re-add the mods, in the new order
    for cmod in &community_mods {
      let community_moderator_form = CommunityModeratorForm {
        community_id: cmod.community.id,
        person_id: cmod.moderator.id,
      };

      CommunityModerator::join(&mut context.pool(), &community_moderator_form)
        .await
        .with_lemmy_type(LemmyErrorType::CommunityModeratorAlreadyExists)?;
    }

    // Mod tables
    let form = ModTransferCommunityForm {
      mod_person_id: local_user_view.person.id,
      other_person_id: data.person_id,
      community_id: data.community_id,
    };

    ModTransferCommunity::create(&mut context.pool(), &form).await?;

    let community_id = data.community_id;
    let person_id = local_user_view.person.id;
    let community_view =
      CommunityView::read(&mut context.pool(), community_id, Some(person_id), None)
        .await
        .with_lemmy_type(LemmyErrorType::CouldntFindCommunity)?;

    let community_id = data.community_id;
    let moderators = CommunityModeratorView::for_community(&mut context.pool(), community_id)
      .await
      .with_lemmy_type(LemmyErrorType::CouldntFindCommunity)?;

    // Return the jwt
    Ok(GetCommunityResponse {
      community_view,
      site: None,
      moderators,
      discussion_languages: vec![],
    })
  }
}