from prometheus_client import Counter, Histogram, Gauge, start_http_server
 
# Metrikler
cache_hits = Counter('llm_cache_hits_total', 'Cache read tokens')
cache_writes = Counter('llm_cache_writes_total', 'Cache write tokens')
input_tokens = Counter('llm_input_tokens_total', 'Fresh input tokens')
output_tokens = Counter('llm_output_tokens_total', 'Output tokens')
request_latency = Histogram('llm_request_latency_seconds', 'Request latency', buckets=(0.1, 0.5, 1, 2, 5, 10))
request_cost = Counter('llm_request_cost_usd', 'Cost in USD')
 
def instrument_call(start_time, usage):
    """Her LLM call'undan sonra çağır."""
    duration = time.time() - start_time
    request_latency.observe(duration)
 
    cw = usage.cache_creation_input_tokens or 0
    cr = usage.cache_read_input_tokens or 0
 
    cache_writes.inc(cw)
    cache_hits.inc(cr)
    input_tokens.inc(usage.input_tokens)
    output_tokens.inc(usage.output_tokens)
 
    # Cost
    cost = (
        usage.input_tokens / 1e6 * 3.0
        + cw / 1e6 * 3.75
        + cr / 1e6 * 0.30
        + usage.output_tokens / 1e6 * 15.0
    )
    request_cost.inc(cost)
 
# Server başlat
start_http_server(9100)  # /metrics endpoint

# Prometheus alert rules
groups:
  - name: llm_cache
    rules:
      - alert: LowCacheHitRate
        expr: |
          sum(rate(llm_cache_hits_total[10m]))
          /
          (sum(rate(llm_cache_hits_total[10m])) + sum(rate(llm_cache_writes_total[10m])))
          < 0.85
        for: 5m
        annotations:
          summary: "Cache hit rate < 85% for 5 minutes"
 
      - alert: HighRequestLatency
        expr: histogram_quantile(0.95, rate(llm_request_latency_seconds_bucket[5m])) > 5
        for: 5m
        annotations:
          summary: "p95 latency > 5s"
 
      - alert: CostSpike
        expr: |
          sum(increase(llm_request_cost_usd[1h]))
          > 2 * avg_over_time(sum(increase(llm_request_cost_usd[1h]))[24h])
        annotations:
          summary: "Hourly cost 2× baseline"