//! Projections (spec §9.3): tables kept from the ledger in the same

//! transaction as each append, and rebuilt from it by `spectra admin

//! rebuild`. Every table here must be a function of the events alone; the

//! test harness and `spectra admin check` hold them to it.

use crate::event::Event;

use sqlx::SqliteConnection;

/// The projection tables, in the order they are cleared and compared.

pub const TABLES: &[&str] = &["event_counts", "identities", "agents"];

/// Apply one event to every projection.

pub async fn apply(conn: &mut SqliteConnection, e: &Event) -> sqlx::Result<()> {

    sqlx::query("INSERT INTO event_counts (kind, n) VALUES (?, 1) ON CONFLICT(kind) DO UPDATE SET n = n + 1")

        .bind(&e.kind)

        .execute(&mut *conn)

        .await?;

    crate::principals::project(conn, e).await?;

    Ok(())

}