//! Prometheus metrics for the server.
//!
//! All counters/histograms/gauges use the `metrics` crate and are exported
//! via metrics-exporter-prometheus on a configurable HTTP port (e.g. /metrics).

/// Record one enqueue (success). Call after a message is enqueued.
pub fn record_enqueue_total() {
    metrics::counter!("enqueue_total").increment(1);
}

/// Record enqueued payload size in bytes.
pub fn record_enqueue_bytes(bytes: u64) {
    metrics::counter!("enqueue_bytes_total").increment(bytes);
}

/// Record one fetch (success). Call when fetch returns.
pub fn record_fetch_total() {
    metrics::counter!("fetch_total").increment(1);
}

/// Record one fetch_wait (success). Call when fetch_wait returns.
pub fn record_fetch_wait_total() {
    metrics::counter!("fetch_wait_total").increment(1);
}

/// Set the delivery queue depth gauge (sample). Updated at enqueue/fetch time.
pub fn record_delivery_queue_depth(depth: usize) {
    metrics::gauge!("delivery_queue_depth").set(depth as f64);
}

/// Record one KeyPackage upload (success).
pub fn record_key_package_upload_total() {
    metrics::counter!("key_package_upload_total").increment(1);
}

/// Record successful auth login (session token issued).
pub fn record_auth_login_success_total() {
    metrics::counter!("auth_login_success_total").increment(1);
}

/// Record failed auth login attempt.
pub fn record_auth_login_failure_total() {
    metrics::counter!("auth_login_failure_total").increment(1);
}

/// Record rate limit hit (enqueue rejected).
pub fn record_rate_limit_hit_total() {
    metrics::counter!("rate_limit_hit_total").increment(1);
}

// ── Storage operation latency ───────────────────────────────────────────────

/// Record storage operation latency. Called by instrumented Store wrappers.
pub fn record_storage_latency(operation: &'static str, duration: std::time::Duration) {
    metrics::histogram!("storage_operation_duration_seconds", "op" => operation)
        .record(duration.as_secs_f64());
}

// ── In-flight RPCs ────────────────────────────────────────────────────────

/// Record the current number of in-flight RPCs (connections being served).
pub fn record_in_flight_rpcs(count: usize) {
    metrics::gauge!("server_in_flight_rpcs").set(count as f64);
}

// ── Server info ────────────────────────────────────────────────────────────

/// Record the server uptime in seconds (set periodically).
pub fn record_uptime_seconds(secs: f64) {
    metrics::gauge!("server_uptime_seconds").set(secs);
}