use crate::{
    core::signatures::{sign_request, PublicKey},
    Error,
    LocalInstance,
    APUB_JSON_CONTENT_TYPE,
};
use anyhow::anyhow;
use background_jobs::{
    memory_storage::Storage,
    ActixJob,
    Backoff,
    Manager,
    MaxRetries,
    WorkerConfig,
};
use http::{header::HeaderName, HeaderMap, HeaderValue};
use reqwest_middleware::ClientWithMiddleware;
use serde::{Deserialize, Serialize};
use std::{fmt::Debug, future::Future, pin::Pin, time::Duration};
use tracing::{info, warn};
use url::Url;

/// Necessary data for sending out an activity
#[derive(Debug)]
pub struct SendActivity {
    /// Id of the sent activity, used for logging
    pub activity_id: Url,
    /// Public key and actor id of the sender
    pub actor_public_key: PublicKey,
    /// Signing key of sender for HTTP signatures
    pub actor_private_key: String,
    /// List of Activitypub inboxes that the activity gets delivered to
    pub inboxes: Vec<Url>,
    /// Activity json
    pub activity: String,
}

impl SendActivity {
    /// Send out the given activity to all inboxes, automatically generating the HTTP signatures. By
    /// default, sending is done on a background thread, and automatically retried on failure with
    /// exponential backoff.
    ///
    /// For debugging or testing, you might want to set [[InstanceSettings.testing_send_sync]].
    pub async fn send(self, instance: &LocalInstance) -> Result<(), Error> {
        let activity_queue = &instance.activity_queue;
        for inbox in self.inboxes {
            let message = SendActivityTask {
                activity_id: self.activity_id.clone(),
                inbox,
                activity: self.activity.clone(),
                public_key: self.actor_public_key.clone(),
                private_key: self.actor_private_key.clone(),
            };
            if instance.settings.testing_send_sync {
                let res =
                    do_send(message, &instance.client, instance.settings.request_timeout).await;
                // Don't fail on error, as we intentionally do some invalid actions in tests, to verify that
                // they are rejected on the receiving side. These errors shouldn't bubble up to make the API
                // call fail. This matches the behaviour in production.
                if let Err(e) = res {
                    warn!("{}", e);
                }
            } else {
                activity_queue.queue::<SendActivityTask>(message).await?;
                let stats = activity_queue.get_stats().await?;
                info!(
        "Activity queue stats: pending: {}, running: {}, dead (this hour): {}, complete (this hour): {}",
        stats.pending,
        stats.running,
        stats.dead.this_hour(),
        stats.complete.this_hour()
      );
            }
        }

        Ok(())
    }
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct SendActivityTask {
    activity_id: Url,
    inbox: Url,
    activity: String,
    public_key: PublicKey,
    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<(), anyhow::Error>>>>;
    const NAME: &'static str = "SendActivityTask";

    /// With these params, retries are made at the following intervals:
    ///          3s
    ///          9s
    ///         27s
    ///      1m 21s
    ///      4m  3s
    ///     12m  9s
    ///     36m 27s
    ///  1h 49m 21s
    ///  5h 28m  3s
    /// 16h 24m  9s
    const MAX_RETRIES: MaxRetries = MaxRetries::Count(10);
    const BACKOFF: Backoff = Backoff::Exponential(3);

    fn run(self, state: Self::State) -> Self::Future {
        Box::pin(async move { do_send(self, &state.client, state.timeout).await })
    }
}

async fn do_send(
    task: SendActivityTask,
    client: &ClientWithMiddleware,
    timeout: Duration,
) -> Result<(), anyhow::Error> {
    info!("Sending {} to {}", task.activity_id, task.inbox);
    let request_builder = client
        .post(&task.inbox.to_string())
        .timeout(timeout)
        .headers(generate_request_headers(&task.inbox));
    let request = sign_request(
        request_builder,
        task.activity.clone(),
        task.public_key.clone(),
        task.private_key.to_owned(),
    )
    .await?;
    let response = client.execute(request).await;

    match response {
        Ok(o) => {
            if o.status().is_success() {
                Ok(())
            } else {
                let status = o.status();
                let text = o.text().await.map_err(Error::conv)?;

                Err(anyhow!(
                    "Send {} to {} failed with status {}: {}",
                    task.activity_id,
                    task.inbox,
                    status,
                    text,
                ))
            }
        }
        Err(e) => Err(anyhow!(
            "Failed to send activity {} to {}: {}",
            &task.activity_id,
            task.inbox,
            e
        )),
    }
}

fn generate_request_headers(inbox_url: &Url) -> HeaderMap {
    let mut host = inbox_url.domain().expect("read inbox domain").to_string();
    if let Some(port) = inbox_url.port() {
        host = format!("{}:{}", host, port);
    }

    let mut headers = HeaderMap::new();
    headers.insert(
        HeaderName::from_static("content-type"),
        HeaderValue::from_static(APUB_JSON_CONTENT_TYPE),
    );
    headers.insert(
        HeaderName::from_static("host"),
        HeaderValue::from_str(&host).expect("Hostname is valid"),
    );
    headers
}

pub(crate) fn create_activity_queue(
    client: ClientWithMiddleware,
    worker_count: u64,
    timeout: Duration,
) -> Manager {
    // Configure and start our workers
    WorkerConfig::new_managed(Storage::new(), move |_| MyState {
        client: client.clone(),
        timeout,
    })
    .register::<SendActivityTask>()
    .set_worker_count("default", worker_count)
    .start()
}

#[derive(Clone)]
struct MyState {
    client: ClientWithMiddleware,
    timeout: Duration,
}