use super::super::MirBuilder;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::OnceLock;

// Dev-only KPI: resolve.choose Known rate
static TOTAL_CHOOSE: AtomicUsize = AtomicUsize::new(0);
static KNOWN_CHOOSE: AtomicUsize = AtomicUsize::new(0);
static KPI_ENABLED: OnceLock<bool> = OnceLock::new();
static SAMPLE_EVERY: OnceLock<usize> = OnceLock::new();

fn kpi_enabled() -> bool {
    *KPI_ENABLED.get_or_init(|| std::env::var("NYASH_DEBUG_KPI_KNOWN").ok().as_deref() == Some("1"))
}

fn sample_every() -> usize {
    *SAMPLE_EVERY.get_or_init(|| {
        std::env::var("NYASH_DEBUG_SAMPLE_EVERY")
            .ok()
            .and_then(|s| s.parse::<usize>().ok())
            .unwrap_or(0)
    })
}

/// Dev‑only: emit a resolve.try event（candidates inspection）。
pub(crate) fn emit_try(builder: &MirBuilder, meta: serde_json::Value) {
    let fn_name = builder.current_function.as_ref().map(|f| f.signature.name.as_str());
    let region = builder.debug_current_region_id();
    crate::debug::hub::emit("resolve", "try", fn_name, region.as_deref(), meta);
}

/// Dev‑only: emit a resolve.choose event（decision）。
pub(crate) fn emit_choose(builder: &MirBuilder, meta: serde_json::Value) {
    let fn_name = builder.current_function.as_ref().map(|f| f.signature.name.as_str());
    let region = builder.debug_current_region_id();
    // KPI (dev-only)
    record_kpi(&meta);
    crate::debug::hub::emit("resolve", "choose", fn_name, region.as_deref(), meta);
}

/// Internal: Call from emit_choose wrapper to record KPI if enabled.
#[allow(dead_code)]
fn record_kpi(meta: &serde_json::Value) {
    if !kpi_enabled() { return; }
    let total = TOTAL_CHOOSE.fetch_add(1, Ordering::Relaxed) + 1;
    let certainty = meta.get("certainty").and_then(|v| v.as_str()).unwrap_or("");
    if certainty == "Known" {
        KNOWN_CHOOSE.fetch_add(1, Ordering::Relaxed);
    }
    let n = sample_every();
    if n > 0 && total % n == 0 {
        let known = KNOWN_CHOOSE.load(Ordering::Relaxed);
        let rate = if total > 0 { (known as f64) * 100.0 / (total as f64) } else { 0.0 };
        eprintln!("[NYASH-KPI] resolve.choose Known={} Total={} ({:.1}%)", known, total, rate);
    }
}