use axum::extract::State;
use axum_extra::extract::Query;
use futures::{
    future,
    stream::{self, StreamExt as _},
};

use super::get;
use crate::{
    event::Sequenced as _,
    test::fixtures::{self, future::Immediately as _},
};

#[tokio::test]
async fn includes_historical_message() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
    let message = fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await;

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;
    let get::Response(events) = get::handler(State(app), subscriber, None, Query::default())
        .await
        .expect("subscribe never fails");

    // Verify the structure of the response.

    let event = events
        .filter_map(fixtures::message::events)
        .next()
        .immediately()
        .await
        .expect("delivered stored message");

    assert!(fixtures::event::message_sent(&event, &message));
}

#[tokio::test]
async fn includes_live_message() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;
    let get::Response(events) =
        get::handler(State(app.clone()), subscriber, None, Query::default())
            .await
            .expect("subscribe never fails");

    // Verify the semantics

    let sender = fixtures::login::create(&app, &fixtures::now()).await;
    let message = fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await;

    let event = events
        .filter_map(fixtures::message::events)
        .next()
        .immediately()
        .await
        .expect("delivered live message");

    assert!(fixtures::event::message_sent(&event, &message));
}

#[tokio::test]
async fn includes_multiple_channels() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;

    let channels = [
        fixtures::channel::create(&app, &fixtures::now()).await,
        fixtures::channel::create(&app, &fixtures::now()).await,
    ];

    let messages = stream::iter(channels)
        .then(|channel| {
            let app = app.clone();
            let sender = sender.clone();
            let channel = channel.clone();
            async move { fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await }
        })
        .collect::<Vec<_>>()
        .await;

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;
    let get::Response(events) = get::handler(State(app), subscriber, None, Query::default())
        .await
        .expect("subscribe never fails");

    // Verify the structure of the response.

    let events = events
        .filter_map(fixtures::message::events)
        .take(messages.len())
        .collect::<Vec<_>>()
        .immediately()
        .await;

    for message in &messages {
        assert!(events
            .iter()
            .any(|event| fixtures::event::message_sent(event, message)));
    }
}

#[tokio::test]
async fn sequential_messages() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;

    let messages = vec![
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
    ];

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;
    let get::Response(events) = get::handler(State(app), subscriber, None, Query::default())
        .await
        .expect("subscribe never fails");

    // Verify the structure of the response.

    let mut events = events
        .filter_map(fixtures::message::events)
        .filter(|event| {
            future::ready(
                messages
                    .iter()
                    .any(|message| fixtures::event::message_sent(event, message)),
            )
        });

    // Verify delivery in order
    for message in &messages {
        let event = events
            .next()
            .immediately()
            .await
            .expect("undelivered messages remaining");

        assert!(fixtures::event::message_sent(&event, message));
    }
}

#[tokio::test]
async fn resumes_from() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;

    let initial_message = fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await;

    let later_messages = vec![
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
    ];

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;

    let resume_at = {
        // First subscription
        let get::Response(events) = get::handler(
            State(app.clone()),
            subscriber.clone(),
            None,
            Query::default(),
        )
        .await
        .expect("subscribe never fails");

        let event = events
            .filter_map(fixtures::message::events)
            .next()
            .immediately()
            .await
            .expect("delivered events");

        assert!(fixtures::event::message_sent(&event, &initial_message));

        event.sequence()
    };

    // Resume after disconnect
    let get::Response(resumed) = get::handler(
        State(app),
        subscriber,
        Some(resume_at.into()),
        Query::default(),
    )
    .await
    .expect("subscribe never fails");

    // Verify the structure of the response.

    let events = resumed
        .filter_map(fixtures::message::events)
        .take(later_messages.len())
        .collect::<Vec<_>>()
        .immediately()
        .await;

    for message in &later_messages {
        assert!(events
            .iter()
            .any(|event| fixtures::event::message_sent(event, message)));
    }
}

// This test verifies a real bug I hit developing the vector-of-sequences
// approach to resuming events. A small omission caused the event IDs in a
// resumed stream to _omit_ channels that were in the original stream until
// those channels also appeared in the resumed stream.
//
// Clients would see something like
// * In the original stream, Cfoo=5,Cbar=8
// * In the resumed stream, Cfoo=6 (no Cbar sequence number)
//
// Disconnecting and reconnecting a second time, using event IDs from that
// initial period of the first resume attempt, would then cause the second
// resume attempt to restart all other channels from the beginning, and not
// from where the first disconnection happened.
//
// This is a real and valid behaviour for clients!
#[tokio::test]
async fn serial_resume() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;
    let channel_a = fixtures::channel::create(&app, &fixtures::now()).await;
    let channel_b = fixtures::channel::create(&app, &fixtures::now()).await;

    // Call the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber = fixtures::identity::identity(&app, &subscriber_creds, &fixtures::now()).await;

    let resume_at = {
        let initial_messages = [
            fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
            fixtures::message::send(&app, &channel_b, &sender, &fixtures::now()).await,
        ];

        // First subscription
        let get::Response(events) = get::handler(
            State(app.clone()),
            subscriber.clone(),
            None,
            Query::default(),
        )
        .await
        .expect("subscribe never fails");

        let events = events
            .filter_map(fixtures::message::events)
            .take(initial_messages.len())
            .collect::<Vec<_>>()
            .immediately()
            .await;

        for message in &initial_messages {
            assert!(events
                .iter()
                .any(|event| fixtures::event::message_sent(event, message)));
        }

        let event = events.last().expect("this vec is non-empty");

        event.sequence()
    };

    // Resume after disconnect
    let resume_at = {
        let resume_messages = [
            // Note that channel_b does not appear here. The buggy behaviour
            // would be masked if channel_b happened to send a new message
            // into the resumed event stream.
            fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
            fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
        ];

        // Second subscription
        let get::Response(events) = get::handler(
            State(app.clone()),
            subscriber.clone(),
            Some(resume_at.into()),
            Query::default(),
        )
        .await
        .expect("subscribe never fails");

        let events = events
            .filter_map(fixtures::message::events)
            .take(resume_messages.len())
            .collect::<Vec<_>>()
            .immediately()
            .await;

        for message in &resume_messages {
            assert!(events
                .iter()
                .any(|event| fixtures::event::message_sent(event, message)));
        }

        let event = events.last().expect("this vec is non-empty");

        event.sequence()
    };

    // Resume after disconnect a second time
    {
        // At this point, we can send on either channel and demonstrate the
        // problem. The resume point should before both of these messages, but
        // after _all_ prior messages.
        let final_messages = [
            fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
            fixtures::message::send(&app, &channel_b, &sender, &fixtures::now()).await,
        ];

        // Third subscription
        let get::Response(events) = get::handler(
            State(app.clone()),
            subscriber.clone(),
            Some(resume_at.into()),
            Query::default(),
        )
        .await
        .expect("subscribe never fails");

        let events = events
            .filter_map(fixtures::message::events)
            .take(final_messages.len())
            .collect::<Vec<_>>()
            .immediately()
            .await;

        // This set of messages, in particular, _should not_ include any prior
        // messages from `initial_messages` or `resume_messages`.
        for message in &final_messages {
            assert!(events
                .iter()
                .any(|event| fixtures::event::message_sent(event, message)));
        }
    };
}

#[tokio::test]
async fn terminates_on_token_expiry() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;

    // Subscribe via the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber =
        fixtures::identity::identity(&app, &subscriber_creds, &fixtures::ancient()).await;

    let get::Response(events) =
        get::handler(State(app.clone()), subscriber, None, Query::default())
            .await
            .expect("subscribe never fails");

    // Verify the resulting stream's behaviour

    app.tokens()
        .expire(&fixtures::now())
        .await
        .expect("expiring tokens succeeds");

    // These should not be delivered.
    let messages = [
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
    ];

    assert!(events
        .filter_map(fixtures::message::events)
        .filter(|event| future::ready(
            messages
                .iter()
                .any(|message| fixtures::event::message_sent(event, message))
        ))
        .next()
        .immediately()
        .await
        .is_none());
}

#[tokio::test]
async fn terminates_on_logout() {
    // Set up the environment

    let app = fixtures::scratch_app().await;
    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
    let sender = fixtures::login::create(&app, &fixtures::now()).await;

    // Subscribe via the endpoint

    let subscriber_creds = fixtures::login::create_with_password(&app, &fixtures::now()).await;
    let subscriber_token =
        fixtures::identity::logged_in(&app, &subscriber_creds, &fixtures::now()).await;
    let subscriber =
        fixtures::identity::from_token(&app, &subscriber_token, &fixtures::now()).await;

    let get::Response(events) = get::handler(
        State(app.clone()),
        subscriber.clone(),
        None,
        Query::default(),
    )
    .await
    .expect("subscribe never fails");

    // Verify the resulting stream's behaviour

    app.tokens()
        .logout(&subscriber.token)
        .await
        .expect("expiring tokens succeeds");

    // These should not be delivered.
    let messages = [
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
        fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
    ];

    assert!(events
        .filter_map(fixtures::message::events)
        .filter(|event| future::ready(
            messages
                .iter()
                .any(|message| fixtures::event::message_sent(event, message))
        ))
        .next()
        .immediately()
        .await
        .is_none());
}