use pingora_http::Method;
use pingora_http::StatusCode;
use pingora_http::Version;
use prometheus::{register_histogram, register_int_counter, register_int_counter_vec, register_int_gauge, Histogram, IntCounter, IntCounterVec, IntGauge};
use std::sync::Arc;
use std::sync::LazyLock;
use std::time::Duration;

pub struct MetricTypes {
    pub method: Method,
    pub upstream: Arc<str>,
    pub code: Option<StatusCode>,
    pub latency: Duration,
    pub version: Version,
}

pub static ACTIVE_SESSIONS: LazyLock<IntGauge> = LazyLock::new(|| register_int_gauge!("aralez_active_sessions", "Current number of active sessions").unwrap());

pub static REQUEST_COUNT: LazyLock<IntCounter> = LazyLock::new(|| register_int_counter!("aralez_requests_total", "Total number of requests handled by Aralez").unwrap());

pub static RESPONSE_CODES: LazyLock<IntCounterVec> =
    LazyLock::new(|| register_int_counter_vec!("aralez_responses_total", "Responses grouped by status code", &["status"]).unwrap());

pub static RESPONSE_LATENCY: LazyLock<Histogram> = LazyLock::new(|| {
    register_histogram!(
        "aralez_response_latency_seconds",
        "Response latency in seconds",
        vec![0.01, 0.05, 0.1, 0.25, 0.5, 1.0, 2.0, 5.0]
    )
    .unwrap()
});

pub static REQUESTS_BY_METHOD: LazyLock<IntCounterVec> =
    LazyLock::new(|| register_int_counter_vec!("aralez_requests_by_method_total", "Number of requests by HTTP method", &["method"]).unwrap());

pub static REQUESTS_BY_UPSTREAM: LazyLock<IntCounterVec> =
    LazyLock::new(|| register_int_counter_vec!("aralez_requests_by_upstream", "Number of requests by UPSTREAM server", &["upstream"]).unwrap());

pub static REQUESTS_BY_VERSION: LazyLock<IntCounterVec> =
    LazyLock::new(|| register_int_counter_vec!("aralez_requests_by_version_total", "Number of requests by HTTP versions", &["version"]).unwrap());

pub fn calc_metrics(metric_types: &MetricTypes) {
    REQUEST_COUNT.inc();
    let version_str = match metric_types.version {
        Version::HTTP_11 => "HTTP/1.1",
        Version::HTTP_2 => "HTTP/2.0",
        Version::HTTP_3 => "HTTP/3.0",
        Version::HTTP_10 => "HTTP/1.0",
        _ => "Unknown",
    };
    REQUESTS_BY_VERSION.with_label_values(&[version_str]).inc();
    RESPONSE_CODES.with_label_values(&[metric_types.code.unwrap_or(StatusCode::GONE).as_str()]).inc();
    REQUESTS_BY_METHOD.with_label_values(&[metric_types.method.as_str()]).inc();
    REQUESTS_BY_UPSTREAM.with_label_values(&[metric_types.upstream.as_ref()]).inc();
    RESPONSE_LATENCY.observe(metric_types.latency.as_secs_f64());
}