//! Metric name constants.

use std::time::Duration;

use anyhow::Context as _;
use metrics::{describe_counter, describe_gauge};
use metrics_exporter_prometheus::PrometheusBuilder;

use crate::config;

/// Authorization failed. Counter.
pub(crate) const AUTH_FAILED: &str = "bluepds.auth.failed";
/// Firehose history. Gauge.
pub(crate) const FIREHOSE_HISTORY: &str = "bluepds.firehose.history";
/// Firehose listeners. Gauge.
pub(crate) const FIREHOSE_LISTENERS: &str = "bluepds.firehose.listeners";
/// Firehose messages. Counter.
pub(crate) const FIREHOSE_MESSAGES: &str = "bluepds.firehose.messages";
/// Firehose sequence. Counter.
pub(crate) const FIREHOSE_SEQUENCE: &str = "bluepds.firehose.sequence";
/// Repository commits. Counter.
pub(crate) const REPO_COMMITS: &str = "bluepds.repo.commits";
/// Repository operation create. Counter.
pub(crate) const REPO_OP_CREATE: &str = "bluepds.repo.op.create";
/// Repository operation update. Counter.
pub(crate) const REPO_OP_UPDATE: &str = "bluepds.repo.op.update";
/// Repository operation delete. Counter.
pub(crate) const REPO_OP_DELETE: &str = "bluepds.repo.op.delete";

/// Must be ran exactly once on startup. This will declare all of the instruments for `metrics`.
pub(crate) fn setup(config: Option<&config::MetricConfig>) -> anyhow::Result<()> {
    describe_counter!(AUTH_FAILED, "The number of failed authentication attempts.");

    describe_gauge!(FIREHOSE_HISTORY, "The size of the firehose history buffer.");
    describe_gauge!(
        FIREHOSE_LISTENERS,
        "The number of active consumers on the firehose."
    );
    describe_counter!(
        FIREHOSE_MESSAGES,
        "All messages that have been broadcast on the firehose."
    );
    describe_counter!(
        FIREHOSE_SEQUENCE,
        "The current sequence number on the firehose."
    );

    describe_counter!(
        REPO_COMMITS,
        "The count of commits created for all repositories."
    );
    describe_counter!(REPO_OP_CREATE, "The count of created records.");
    describe_counter!(REPO_OP_UPDATE, "The count of updated records.");
    describe_counter!(REPO_OP_DELETE, "The count of deleted records.");

    if let Some(config) = config {
        match *config {
            config::MetricConfig::PrometheusPush(ref prometheus_config) => {
                PrometheusBuilder::new()
                    .with_push_gateway(
                        prometheus_config.url.clone(),
                        Duration::from_secs(10),
                        None,
                        None,
                    )
                    .context("failed to set up push gateway")?
                    .install()
                    .context("failed to install metrics exporter")?;
            }
        }
    }

    Ok(())
}