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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.

use std::str::FromStr;
use std::time::Duration;

use anyhow::{anyhow, bail, Context};
use mz_ore::retry::Retry;
use mz_ore::task;
use mz_tls_util::make_tls;
use tokio_postgres::config::Host;
use tokio_postgres::{Client, Config};
use url::Url;

/// Constructs a URL from PostgreSQL configuration parameters.
///
/// Returns an error if the set of configuration parameters is not representable
/// as a URL, e.g., if there are multiple hosts.
pub fn config_url(config: &Config) -> Result<Url, anyhow::Error> {
    let mut url = Url::parse("postgresql://").unwrap();

    let host = match config.get_hosts() {
        [] => "localhost".into(),
        [Host::Tcp(host)] => host.clone(),
        [Host::Unix(path)] => path.display().to_string(),
        _ => bail!("Materialize URL cannot contain multiple hosts"),
    };
    url.set_host(Some(&host))
        .context("parsing Materialize host")?;

    url.set_port(Some(match config.get_ports() {
        [] => 5432,
        [port] => *port,
        _ => bail!("Materialize URL cannot contain multiple ports"),
    }))
    .expect("known to be valid to set port");

    if let Some(user) = config.get_user() {
        url.set_username(user)
            .expect("known to be valid to set username");
    }

    Ok(url)
}

pub async fn postgres_client(
    url: &str,
    default_timeout: Duration,
) -> Result<(Client, task::JoinHandle<Result<(), tokio_postgres::Error>>), anyhow::Error> {
    let (client, connection) = Retry::default()
        .max_duration(default_timeout)
        .retry_async_canceling(|_| async move {
            let pgconfig = &mut Config::from_str(url)?;
            pgconfig.connect_timeout(default_timeout);
            let tls = make_tls(pgconfig)?;
            pgconfig.connect(tls).await.map_err(|e| anyhow!(e))
        })
        .await?;

    println!("Connecting to PostgreSQL server at {}...", url);
    let handle = task::spawn(|| "postgres_client_task", connection);

    Ok((client, handle))
}