use crate::{
  check_is_apub_id_valid,
  extensions::signatures::sign_and_send,
  insert_activity,
  ActorType,
};
use activitystreams::{
  base::{BaseExt, Extends, ExtendsExt},
  object::AsObject,
};
use anyhow::{anyhow, Context, Error};
use background_jobs::{
  create_server,
  memory_storage::Storage,
  ActixJob,
  Backoff,
  MaxRetries,
  QueueHandle,
  WorkerConfig,
};
use itertools::Itertools;
use lemmy_db::{community::Community, user::User_, DbPool};
use lemmy_utils::{location_info, settings::Settings, LemmyError};
use lemmy_websocket::LemmyContext;
use log::{debug, warn};
use reqwest::Client;
use serde::{export::fmt::Debug, Deserialize, Serialize};
use std::{collections::BTreeMap, future::Future, pin::Pin};
use url::Url;

/// Sends a local activity to a single, remote actor.
///
/// * `activity` the apub activity to be sent
/// * `creator` the local actor which created the activity
/// * `inbox` the inbox url where the activity should be delivered to
pub(crate) async fn send_activity_single_dest<T, Kind>(
  activity: T,
  creator: &dyn ActorType,
  inbox: Url,
  context: &LemmyContext,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind> + Extends<Kind> + Debug + BaseExt<Kind>,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  if check_is_apub_id_valid(&inbox).is_ok() {
    debug!(
      "Sending activity {:?} to {}",
      &activity.id_unchecked(),
      &inbox
    );
    send_activity_internal(
      context.activity_queue(),
      activity,
      creator,
      vec![inbox],
      context.pool(),
      true,
      true,
    )
    .await?;
  }

  Ok(())
}

/// From a local community, send activity to all remote followers.
///
/// * `activity` the apub activity to send
/// * `community` the sending community
/// * `sender_shared_inbox` in case of an announce, this should be the shared inbox of the inner
///                         activities creator, as receiving a known activity will cause an error
pub(crate) async fn send_to_community_followers<T, Kind>(
  activity: T,
  community: &Community,
  context: &LemmyContext,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind> + Extends<Kind> + Debug + BaseExt<Kind>,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  let follower_inboxes: Vec<Url> = community
    .get_follower_inboxes(context.pool())
    .await?
    .iter()
    .unique()
    .filter(|inbox| inbox.host_str() != Some(&Settings::get().hostname))
    .filter(|inbox| check_is_apub_id_valid(inbox).is_ok())
    .map(|inbox| inbox.to_owned())
    .collect();
  debug!(
    "Sending activity {:?} to followers of {}",
    &activity.id_unchecked(),
    &community.actor_id
  );

  send_activity_internal(
    context.activity_queue(),
    activity,
    community,
    follower_inboxes,
    context.pool(),
    true,
    false,
  )
  .await?;

  Ok(())
}

/// Sends an activity from a local user to a remote community.
///
/// * `activity` the activity to send
/// * `creator` the creator of the activity
/// * `community` the destination community
///
pub(crate) async fn send_to_community<T, Kind>(
  activity: T,
  creator: &User_,
  community: &Community,
  context: &LemmyContext,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind> + Extends<Kind> + Debug + BaseExt<Kind>,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  // if this is a local community, we need to do an announce from the community instead
  if community.local {
    community
      .send_announce(activity.into_any_base()?, context)
      .await?;
  } else {
    let inbox = community.get_shared_inbox_url()?;
    check_is_apub_id_valid(&inbox)?;
    debug!(
      "Sending activity {:?} to community {}",
      &activity.id_unchecked(),
      &community.actor_id
    );
    send_activity_internal(
      context.activity_queue(),
      activity,
      creator,
      vec![inbox],
      context.pool(),
      true,
      false,
    )
    .await?;
  }

  Ok(())
}

/// Sends notification to any users mentioned in a comment
///
/// * `creator` user who created the comment
/// * `mentions` list of inboxes of users which are mentioned in the comment
/// * `activity` either a `Create/Note` or `Update/Note`
pub(crate) async fn send_comment_mentions<T, Kind>(
  creator: &User_,
  mentions: Vec<Url>,
  activity: T,
  context: &LemmyContext,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind> + Extends<Kind> + Debug + BaseExt<Kind>,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  debug!(
    "Sending mentions activity {:?} to {:?}",
    &activity.id_unchecked(),
    &mentions
  );
  let mentions = mentions
    .iter()
    .filter(|inbox| check_is_apub_id_valid(inbox).is_ok())
    .map(|i| i.to_owned())
    .collect();
  send_activity_internal(
    context.activity_queue(),
    activity,
    creator,
    mentions,
    context.pool(),
    false, // Don't create a new DB row
    false,
  )
  .await?;
  Ok(())
}

/// Create new `SendActivityTasks`, which will deliver the given activity to inboxes, as well as
/// handling signing and retrying failed deliveres.
///
/// The caller of this function needs to remove any blocked domains from `to`,
/// using `check_is_apub_id_valid()`.
async fn send_activity_internal<T, Kind>(
  activity_sender: &QueueHandle,
  activity: T,
  actor: &dyn ActorType,
  inboxes: Vec<Url>,
  pool: &DbPool,
  insert_into_db: bool,
  sensitive: bool,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind> + Extends<Kind> + Debug,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  if !Settings::get().federation.enabled || inboxes.is_empty() {
    return Ok(());
  }

  let activity = activity.into_any_base()?;
  let serialised_activity = serde_json::to_string(&activity)?;

  // This is necessary because send_comment and send_comment_mentions
  // might send the same ap_id
  if insert_into_db {
    let id = activity.id().context(location_info!())?;
    insert_activity(id, activity.clone(), true, sensitive, pool).await?;
  }

  for i in inboxes {
    let message = SendActivityTask {
      activity: serialised_activity.to_owned(),
      inbox: i,
      actor_id: actor.actor_id()?,
      private_key: actor.private_key().context(location_info!())?,
    };
    activity_sender.queue::<SendActivityTask>(message)?;
  }

  Ok(())
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct SendActivityTask {
  activity: String,
  inbox: Url,
  actor_id: Url,
  private_key: String,
}

/// Signs the activity with the sending actor's key, and delivers to the given inbox. Also retries
/// if the delivery failed.
impl ActixJob for SendActivityTask {
  type State = MyState;
  type Future = Pin<Box<dyn Future<Output = Result<(), Error>>>>;
  const NAME: &'static str = "SendActivityTask";

  const MAX_RETRIES: MaxRetries = MaxRetries::Count(10);
  const BACKOFF: Backoff = Backoff::Exponential(2);

  fn run(self, state: Self::State) -> Self::Future {
    Box::pin(async move {
      let mut headers = BTreeMap::<String, String>::new();
      headers.insert("Content-Type".into(), "application/json".into());
      let result = sign_and_send(
        &state.client,
        headers,
        &self.inbox,
        self.activity.clone(),
        &self.actor_id,
        self.private_key.to_owned(),
      )
      .await;

      if let Err(e) = result {
        warn!("{}", e);
        return Err(anyhow!(
          "Failed to send activity {} to {}",
          &self.activity,
          self.inbox
        ));
      }
      Ok(())
    })
  }
}

pub fn create_activity_queue() -> QueueHandle {
  // Start the application server. This guards access to to the jobs store
  let queue_handle = create_server(Storage::new());

  // Configure and start our workers
  WorkerConfig::new(|| MyState {
    client: Client::default(),
  })
  .register::<SendActivityTask>()
  .start(queue_handle.clone());

  queue_handle
}

#[derive(Clone)]
struct MyState {
  pub client: Client,
}