what2watch/src/main.rs

use std::{net::SocketAddr, time::Duration};

use axum::{
    async_trait,
    extract::{FromRef, FromRequestParts, State},
    http::{request::Parts, StatusCode},
    routing::get,
    Router,
};
use sqlx::sqlite::{SqliteConnectOptions, SqlitePool, SqlitePoolOptions};
// use tokio::net::TcpListener;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};

#[tokio::main]
async fn main() {
    tracing_subscriber::registry()
        .with(
            tracing_subscriber::EnvFilter::try_from_default_env()
                .unwrap_or_else(|_| "ww_main=debug".into()),
        )
        .with(tracing_subscriber::fmt::layer())
        .init();

    let db_filename = {
        std::env::var("DATABASE_FILE").unwrap_or_else(|_| {
            let home =
                std::env::var("HOME").expect("Could not determine $HOME for finding db file");
            format!("{home}/.witch-watch.db")
        })
    };

    let conn_opts = SqliteConnectOptions::new()
        .foreign_keys(true)
        .auto_vacuum(sqlx::sqlite::SqliteAutoVacuum::Incremental)
        .filename(&db_filename);

    // setup connection pool
    let pool = SqlitePoolOptions::new()
        .max_connections(5)
        .connect_timeout(Duration::from_secs(3))
        .connect_with(conn_opts)
        .await
        .expect("can't connect to database");

    // build our application with some routes
    let app = Router::new()
        .route(
            "/",
            get(using_connection_pool_extractor).post(using_connection_extractor),
        )
        .with_state(pool);

    // run it with hyper
    //let listener = TcpListener::bind("127.0.0.1:3000").await.unwrap();
    //axum::serve(listener, app).await.unwrap();
    tracing::info!("binding to 0.0.0.0:3000");
    axum::Server::bind(&SocketAddr::from(([0, 0, 0, 0], 3000)))
        .serve(app.into_make_service())
        .await
        .unwrap();
}

// we can extract the connection pool with `State`
async fn using_connection_pool_extractor(
    State(pool): State<SqlitePool>,
) -> Result<String, (StatusCode, String)> {
    sqlx::query_scalar("select 'hello world from sqlite get'")
        .fetch_one(&pool)
        .await
        .map_err(internal_error)
}

// we can also write a custom extractor that grabs a connection from the pool
// which setup is appropriate depends on your application
struct DatabaseConnection(sqlx::pool::PoolConnection<sqlx::Sqlite>);

#[async_trait]
impl<S> FromRequestParts<S> for DatabaseConnection
where
    SqlitePool: FromRef<S>,
    S: Send + Sync,
{
    type Rejection = (StatusCode, String);

    async fn from_request_parts(_parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
        let pool = SqlitePool::from_ref(state);

        let conn = pool.acquire().await.map_err(internal_error)?;

        Ok(Self(conn))
    }
}

async fn using_connection_extractor(
    DatabaseConnection(conn): DatabaseConnection,
) -> Result<String, (StatusCode, String)> {
    let mut conn = conn;
    sqlx::query_scalar("select 'hello world from sqlite post'")
        .fetch_one(&mut conn)
        .await
        .map_err(internal_error)
}

/// Utility function for mapping any error into a `500 Internal Server Error`
/// response.
fn internal_error<E>(err: E) -> (StatusCode, String)
where
    E: std::error::Error,
{
    (StatusCode::INTERNAL_SERVER_ERROR, err.to_string())
}