"""
Simple demo API for the Ghaymah SRE exam (Q1).

Endpoints:
  GET /            -> basic welcome message
  GET /health       -> liveness/readiness probe used by Ghaymah + monitoring script
  GET /metrics      -> lightweight JSON metrics used by the dashboard
                       (uptime, request count, avg response time)
"""

import time
from flask import Flask, jsonify

app = Flask(__name__)

START_TIME = time.time()
REQUEST_COUNT = 0
TOTAL_RESPONSE_TIME = 0.0


@app.before_request
def _start_timer():
    global REQUEST_COUNT
    REQUEST_COUNT += 1
    app.config["_req_start"] = time.time()


@app.after_request
def _record_timing(response):
    global TOTAL_RESPONSE_TIME
    elapsed = time.time() - app.config.get("_req_start", time.time())
    TOTAL_RESPONSE_TIME += elapsed
    response.headers["X-Response-Time-ms"] = f"{elapsed * 1000:.2f}"
    return response


@app.route("/")
def index():
    return jsonify(message="Ghaymah SRE exam demo API is running", status="ok")


@app.route("/health")
def health():
    """Used by: Ghaymah container platform health checks, and the
    external monitoring script (health-check.sh)."""
    return jsonify(status="healthy", uptime_seconds=round(time.time() - START_TIME, 2)), 200


@app.route("/metrics")
def metrics():
    """Used by the dashboard.html to render status / avg response time / request count."""
    avg_response_ms = (
        (TOTAL_RESPONSE_TIME / REQUEST_COUNT) * 1000 if REQUEST_COUNT else 0
    )
    return jsonify(
        status="healthy",
        uptime_seconds=round(time.time() - START_TIME, 2),
        request_count=REQUEST_COUNT,
        avg_response_time_ms=round(avg_response_ms, 2),
    )


if __name__ == "__main__":
    # For local testing only; production uses gunicorn (see Dockerfile CMD)
    app.run(host="0.0.0.0", port=8080)