umadb-client 0.6.2

use futures::StreamExt;
use umadb_client::UmaDbClient;
use umadb_dcb::{
    DcbAppendCondition, DcbError, DcbEvent, DcbEventStoreAsync, DcbQuery, DcbQueryItem,
    TrackingInfo,
};
use uuid::Uuid;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Connect to the gRPC server
    let url = "http://localhost:50051".to_string();
    let client = UmaDbClient::new(url).connect_async().await?;

    // Define a consistency boundary
    let boundary = DcbQuery::new().item(
        DcbQueryItem::new()
            .types(["example"])
            .tags(["tag1", "tag2"]),
    );

    // Read events for a decision model
    let mut read_response = client
        .read(Some(boundary.clone()), None, false, None)
        .await?;

    // Build decision model
    while let Some(result) = read_response.next().await {
        match result {
            Ok(event) => {
                println!(
                    "Got event at position {}: {:?}",
                    event.position, event.event
                );
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Remember the last-known position
    let last_known_position = read_response.head().await?;
    println!("Last known position is: {:?}", last_known_position);

    // Produce new event, attaching some metadata (e.g. provenance) that is
    // stored alongside the event and returned when it is read back.
    let event = DcbEvent::default()
        .event_type("example")
        .tags(["tag1", "tag2"])
        .data(b"Hello, world!")
        .uuid(Uuid::new_v4())
        .metadata_entry("source", "client_async_insecure")
        .metadata_entry("correlation_id", Uuid::new_v4().to_string());

    // Append event in consistency boundary
    let append_condition = DcbAppendCondition {
        fail_if_events_match: boundary.clone(),
        after: last_known_position,
    };
    let position1 = client
        .append(vec![event.clone()], Some(append_condition.clone()), None)
        .await?;

    println!("Appended event at position: {}", position1);

    // Append conflicting event - expect an error
    let conflicting_event = DcbEvent::default()
        .event_type("example")
        .tags(["tag1", "tag2"])
        .data(b"Hello, world!")
        .uuid(Uuid::new_v4()); // different UUID

    let conflicting_result = client
        .append(
            vec![conflicting_event.clone()],
            Some(append_condition.clone()),
            None,
        )
        .await;

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!("Conflicting event was rejected: {:?}", integrity_error);
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    // Appending with identical events IDs and append conditions is idempotent.
    println!(
        "Retrying to append event at position: {:?}",
        last_known_position
    );
    let position2 = client
        .append(vec![event.clone()], Some(append_condition.clone()), None)
        .await?;

    if position1 == position2 {
        println!("Append method returned same commit position: {}", position2);
    } else {
        panic!("Expected idempotent retry!")
    }

    // Subscribe to all events for a projection
    let mut subscription = client.subscribe(None, None).await?;

    // Build an up-to-date view
    while let Some(result) = subscription.next().await {
        match result {
            Ok(ev) => {
                println!("Processing event at {}: {:?}", ev.position, ev.event);
                if ev.position == position2 {
                    println!("Projection has processed new event!");
                    break;
                }
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Track an upstream position
    let upstream_position = client.get_tracking_info("upstream").await?;
    let next_upstream_position = upstream_position.unwrap_or(0) + 1;
    println!("Next upstream position: {next_upstream_position}");
    client
        .append(
            vec![],
            None,
            Some(TrackingInfo {
                source: "upstream".to_string(),
                position: next_upstream_position,
            }),
        )
        .await?;
    assert_eq!(
        next_upstream_position,
        client.get_tracking_info("upstream").await?.unwrap()
    );
    println!("Upstream position tracked okay!");

    // Try recording the same upstream position
    let conflicting_result = client
        .append(
            vec![],
            None,
            Some(TrackingInfo {
                source: "upstream".to_string(),
                position: next_upstream_position,
            }),
        )
        .await;

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!(
                "Conflicting upstream position was rejected: {:?}",
                integrity_error
            );
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    Ok(())
}