use activitystreams::{public, unparsed::Unparsed};
use anyhow::anyhow;
use serde::{Deserialize, Serialize};
use url::Url;

use lemmy_api_common::blocking;
use lemmy_apub_lib::{
  data::Data,
  traits::{ActivityFields, ActivityHandler, ActorType, ApubObject},
  verify::{verify_domains_match, verify_urls_match},
};
use lemmy_db_schema::{source::community::Community, traits::Crud};
use lemmy_utils::LemmyError;
use lemmy_websocket::{send::send_post_ws_message, LemmyContext, UserOperationCrud};

use crate::{
  activities::{
    check_community_deleted_or_removed,
    community::{
      announce::{AnnouncableActivities, GetCommunity},
      send_to_community,
    },
    generate_activity_id,
    verify_activity,
    verify_is_public,
    verify_mod_action,
    verify_person_in_community,
    CreateOrUpdateType,
  },
  fetcher::object_id::ObjectId,
  objects::{community::ApubCommunity, person::ApubPerson, post::ApubPost},
  protocol::objects::page::Page,
};

#[derive(Clone, Debug, Deserialize, Serialize, ActivityFields)]
#[serde(rename_all = "camelCase")]
pub struct CreateOrUpdatePost {
  actor: ObjectId<ApubPerson>,
  to: Vec<Url>,
  object: Page,
  cc: Vec<Url>,
  #[serde(rename = "type")]
  kind: CreateOrUpdateType,
  id: Url,
  #[serde(flatten)]
  unparsed: Unparsed,
}

impl CreateOrUpdatePost {
  pub(crate) async fn new(
    post: &ApubPost,
    actor: &ApubPerson,
    community: &ApubCommunity,
    kind: CreateOrUpdateType,
    context: &LemmyContext,
  ) -> Result<CreateOrUpdatePost, LemmyError> {
    let id = generate_activity_id(
      kind.clone(),
      &context.settings().get_protocol_and_hostname(),
    )?;
    Ok(CreateOrUpdatePost {
      actor: ObjectId::new(actor.actor_id()),
      to: vec![public()],
      object: post.to_apub(context).await?,
      cc: vec![community.actor_id()],
      kind,
      id: id.clone(),
      unparsed: Default::default(),
    })
  }
  pub async fn send(
    post: &ApubPost,
    actor: &ApubPerson,
    kind: CreateOrUpdateType,
    context: &LemmyContext,
  ) -> Result<(), LemmyError> {
    let community_id = post.community_id;
    let community: ApubCommunity = blocking(context.pool(), move |conn| {
      Community::read(conn, community_id)
    })
    .await??
    .into();
    let create_or_update = CreateOrUpdatePost::new(post, actor, &community, kind, context).await?;
    let id = create_or_update.id.clone();
    let activity = AnnouncableActivities::CreateOrUpdatePost(Box::new(create_or_update));
    send_to_community(activity, &id, actor, &community, vec![], context).await
  }
}

#[async_trait::async_trait(?Send)]
impl ActivityHandler for CreateOrUpdatePost {
  type DataType = LemmyContext;
  async fn verify(
    &self,
    context: &Data<LemmyContext>,
    request_counter: &mut i32,
  ) -> Result<(), LemmyError> {
    verify_is_public(&self.to)?;
    verify_activity(self, &context.settings())?;
    let community = self.get_community(context, request_counter).await?;
    verify_person_in_community(&self.actor, &community, context, request_counter).await?;
    check_community_deleted_or_removed(&community)?;

    match self.kind {
      CreateOrUpdateType::Create => {
        verify_domains_match(self.actor.inner(), self.object.id_unchecked())?;
        verify_urls_match(self.actor(), self.object.attributed_to.inner())?;
        // Check that the post isnt locked or stickied, as that isnt possible for newly created posts.
        // However, when fetching a remote post we generate a new create activity with the current
        // locked/stickied value, so this check may fail. So only check if its a local community,
        // because then we will definitely receive all create and update activities separately.
        let is_stickied_or_locked =
          self.object.stickied == Some(true) || self.object.comments_enabled == Some(false);
        if community.local && is_stickied_or_locked {
          return Err(anyhow!("New post cannot be stickied or locked").into());
        }
      }
      CreateOrUpdateType::Update => {
        let is_mod_action = self.object.is_mod_action(context).await?;
        if is_mod_action {
          verify_mod_action(&self.actor, &community, context, request_counter).await?;
        } else {
          verify_domains_match(self.actor.inner(), self.object.id_unchecked())?;
          verify_urls_match(self.actor(), self.object.attributed_to.inner())?;
        }
      }
    }
    self.object.verify(context, request_counter).await?;
    Ok(())
  }

  async fn receive(
    self,
    context: &Data<LemmyContext>,
    request_counter: &mut i32,
  ) -> Result<(), LemmyError> {
    let actor = self.actor.dereference(context, request_counter).await?;
    let post =
      ApubPost::from_apub(&self.object, context, &actor.actor_id(), request_counter).await?;

    let notif_type = match self.kind {
      CreateOrUpdateType::Create => UserOperationCrud::CreatePost,
      CreateOrUpdateType::Update => UserOperationCrud::EditPost,
    };
    send_post_ws_message(post.id, notif_type, None, None, context).await?;
    Ok(())
  }
}

#[async_trait::async_trait(?Send)]
impl GetCommunity for CreateOrUpdatePost {
  async fn get_community(
    &self,
    context: &LemmyContext,
    request_counter: &mut i32,
  ) -> Result<ApubCommunity, LemmyError> {
    self
      .object
      .extract_community(context, request_counter)
      .await
  }
}