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

use crate::{
    channel::app,
    events::routes,
    repo::channel::{self},
    test::fixtures::{self, future::Immediately as _},
};

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

    let app = fixtures::scratch_app().await;
    let subscriber = fixtures::login::create(&app).await;

    // Call the endpoint

    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery { channels: vec![] };
    let routes::Events(mut events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("empty subscription");

    // Verify the structure of the response.

    assert!(events.next().immediately().await.is_none());
}

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

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

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.id.clone()],
    };
    let routes::Events(mut events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("subscribed to valid channel");

    // Verify the structure of the response.

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

    assert_eq!(channel.id, event.channel);
    assert_eq!(message, 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).await;

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.id.clone()],
    };
    let routes::Events(mut events) = routes::events(
        State(app.clone()),
        subscribed_at,
        subscriber,
        None,
        Query(query),
    )
    .await
    .expect("subscribed to a valid channel");

    // Verify the semantics

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

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

    assert_eq!(channel.id, event.channel);
    assert_eq!(message, event.message);
}

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

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

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![subscribed.id.clone()],
    };
    let routes::Events(mut events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("subscribed to a valid channel");

    // Verify the semantics

    let event = events
        .next()
        .immediately()
        .await
        .expect("delivered at least one message");

    assert_eq!(subscribed.id, event.channel);
    assert_eq!(message, 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).await;

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

    let messages = stream::iter(channels)
        .then(|channel| async {
            let message = fixtures::message::send(&app, &sender, &channel, &fixtures::now()).await;

            (channel, message)
        })
        .collect::<Vec<_>>()
        .await;

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: messages
            .iter()
            .map(|(channel, _)| &channel.id)
            .cloned()
            .collect(),
    };
    let routes::Events(events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("subscribed to valid channels");

    // Verify the structure of the response.

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

    for (channel, message) in messages {
        assert!(events
            .iter()
            .any(|event| { event.channel == channel.id && event.message == message }));
    }
}

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

    let app = fixtures::scratch_app().await;
    let channel = channel::Id::generate();

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.clone()],
    };
    let routes::ErrorResponse(error) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect_err("subscribed to nonexistent channel");

    // Verify the structure of the response.

    fixtures::error::expected!(
        error,
        app::EventsError::ChannelNotFound(error_channel),
        assert_eq!(channel, error_channel)
    );
}

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

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

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

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.id.clone()],
    };
    let routes::Events(events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("subscribed to a valid channel");

    // Verify the structure of the response.

    let mut events = events.filter(|event| future::ready(messages.contains(&event.message)));

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

        assert_eq!(channel.id, event.channel);
        assert_eq!(message, &event.message);
    }
}

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

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

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

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

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.id.clone()],
    };

    let resume_at = {
        // First subscription
        let routes::Events(mut events) = routes::events(
            State(app.clone()),
            subscribed_at,
            subscriber.clone(),
            None,
            Query(query.clone()),
        )
        .await
        .expect("subscribed to a valid channel");

        let event = events.next().immediately().await.expect("delivered events");

        assert_eq!(channel.id, event.channel);
        assert_eq!(initial_message, event.message);

        event.event_id()
    };

    // Resume after disconnect
    let resumed_at = fixtures::now();
    let routes::Events(resumed) = routes::events(
        State(app),
        resumed_at,
        subscriber,
        Some(resume_at.into()),
        Query(query),
    )
    .await
    .expect("subscribed to a valid channel");

    // Verify the structure of the response.

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

    for message in later_messages {
        assert!(events
            .iter()
            .any(|event| event.channel == channel.id && event.message == message));
    }
}

#[tokio::test]
async fn removes_expired_messages() {
    // Set up the environment
    let app = fixtures::scratch_app().await;
    let sender = fixtures::login::create(&app).await;
    let channel = fixtures::channel::create(&app).await;

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

    // Call the endpoint

    let subscriber = fixtures::login::create(&app).await;
    let subscribed_at = fixtures::now();
    let query = routes::EventsQuery {
        channels: vec![channel.id.clone()],
    };
    let routes::Events(mut events) =
        routes::events(State(app), subscribed_at, subscriber, None, Query(query))
            .await
            .expect("subscribed to valid channel");

    // Verify the semantics

    let event = events
        .next()
        .immediately()
        .await
        .expect("delivered messages");

    assert_eq!(channel.id, event.channel);
    assert_eq!(message, event.message);
}