use metrics::{
    Counter, Gauge, Histogram, Unit, describe_counter, describe_gauge, describe_histogram,
};

pub fn init() {
    describe_gauge!(
        "aggregator_targets_total",
        Unit::Count,
        "Total number of scrape targets known to the aggregator"
    );
    describe_gauge!(
        "aggregator_targets_healthy",
        Unit::Count,
        "Number of scrape targets that responded last scrape"
    );
    describe_counter!(
        "aggregator_scrape_total",
        Unit::Count,
        "Total number of scrape attempts"
    );
    describe_counter!(
        "aggregator_scrape_success",
        Unit::Count,
        "Successful scrapes"
    );
    describe_counter!(
        "aggregator_scrape_failures",
        Unit::Count,
        "Failed scrape attempts"
    );
    describe_counter!(
        "aggregator_scrape_errors_parse",
        Unit::Count,
        "Scrape failures due to parse errors"
    );
    describe_counter!(
        "aggregator_scrape_errors_timeout",
        Unit::Count,
        "Scrape failures due to timeout"
    );
    describe_counter!(
        "aggregator_scrape_errors_connection",
        Unit::Count,
        "Scrape failures due to connection errors"
    );
    describe_counter!(
        "aggregator_targets_discovered",
        Unit::Count,
        "Total targets discovered"
    );
    describe_counter!(
        "aggregator_targets_lost",
        Unit::Count,
        "Total targets that disappeared"
    );
    describe_histogram!(
        "aggregator_scrape_duration_ms",
        Unit::Milliseconds,
        "Scrape duration in milliseconds"
    );
}

#[derive(Clone)]
#[allow(dead_code)]
pub struct AggMetrics {
    pub targets_total: Gauge,
    pub targets_healthy: Gauge,
    pub scrape_total: Counter,
    pub scrape_success: Counter,
    pub scrape_failures: Counter,
    pub scrape_errors_parse: Counter,
    pub scrape_errors_timeout: Counter,
    pub scrape_errors_connection: Counter,
    pub targets_discovered: Counter,
    pub targets_lost: Counter,
    pub scrape_duration: Histogram,
}

impl Default for AggMetrics {
    fn default() -> Self {
        Self {
            targets_total: metrics::gauge!("aggregator_targets_total"),
            targets_healthy: metrics::gauge!("aggregator_targets_healthy"),
            scrape_total: metrics::counter!("aggregator_scrape_total"),
            scrape_success: metrics::counter!("aggregator_scrape_success"),
            scrape_failures: metrics::counter!("aggregator_scrape_failures"),
            scrape_errors_parse: metrics::counter!("aggregator_scrape_errors_parse"),
            scrape_errors_timeout: metrics::counter!("aggregator_scrape_errors_timeout"),
            scrape_errors_connection: metrics::counter!("aggregator_scrape_errors_connection"),
            targets_discovered: metrics::counter!("aggregator_targets_discovered"),
            targets_lost: metrics::counter!("aggregator_targets_lost"),
            scrape_duration: metrics::histogram!("aggregator_scrape_duration_ms"),
        }
    }
}

impl AggMetrics {
    pub fn new() -> Self {
        Self::default()
    }
}