#!/usr/bin/env python3
"""FR24 monitoring service — checks disk, DB size, capture lag, throughput every 60s."""

import os
import time
import logging
import subprocess
import psycopg2

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s %(levelname)s %(message)s",
    datefmt="%Y-%m-%dT%H:%M:%S",
)
log = logging.getLogger("monitor")

DB_DSN = (
    f"host={os.environ.get('POSTGRES_HOST', 'postgres')} "
    f"port={os.environ.get('POSTGRES_PORT', '5432')} "
    f"dbname={os.environ.get('POSTGRES_DB', 'fr24')} "
    f"user={os.environ.get('POSTGRES_USER', 'fr24')} "
    f"password={os.environ.get('POSTGRES_PASSWORD', 'change-me')}"
)
INTERVAL = int(os.environ.get("MONITORING_INTERVAL_SECONDS", "60"))
DISK_WARN_PCT = 80
LAG_WARN_SEC = 300  # 5 minutes
METRICS_KEEP = 100  # rows to retain in monitoring_metrics


def ensure_metrics_table(conn):
    """Create fr24.monitoring_metrics if it doesn't exist."""
    with conn.cursor() as cur:
        cur.execute("""
            CREATE TABLE IF NOT EXISTS fr24.monitoring_metrics (
                id SERIAL PRIMARY KEY,
                collected_at TIMESTAMPTZ DEFAULT now(),
                disk_pct INTEGER,
                db_size_mb FLOAT,
                capture_lag_sec INTEGER,
                throughput_5min INTEGER
            )
        """)
    conn.commit()
    log.info("monitoring_metrics table ready")


def get_disk_usage() -> str:
    """Return disk usage percent for / as integer string, e.g. '45'."""
    try:
        result = subprocess.run(
            ["df", "-P", "/"],
            capture_output=True, text=True, timeout=5
        )
        # last line: Filesystem 1024-blocks Used Available Capacity Mounted
        line = result.stdout.strip().splitlines()[-1]
        pct = line.split()[4].rstrip("%")
        return pct
    except Exception as e:
        log.warning("disk check failed: %s", e)
        return "?"


def run_checks():
    disk_pct_str = get_disk_usage()

    try:
        conn = psycopg2.connect(DB_DSN, connect_timeout=5)
        conn.autocommit = True
        cur = conn.cursor()

        # DB size
        cur.execute("SELECT pg_database_size(current_database())")
        db_bytes = cur.fetchone()[0]
        db_size_gb = db_bytes / (1024 ** 3)
        db_size_str = f"{db_size_gb:.2f}GB" if db_size_gb >= 1 else f"{db_bytes / (1024**2):.1f}MB"

        # Capture lag
        cur.execute("SELECT EXTRACT(EPOCH FROM (now() - MAX(observed_at))) FROM fr24.raw_packets")
        row = cur.fetchone()
        lag_sec = int(row[0]) if row and row[0] is not None else None
        lag_str = f"{lag_sec}s" if lag_sec is not None else "N/A"

        # Throughput: packets in last 5 minutes
        cur.execute(
            "SELECT COUNT(*) FROM fr24.raw_packets "
            "WHERE observed_at >= now() - INTERVAL '5 minutes'"
        )
        throughput = cur.fetchone()[0]

        # Write metrics row
        disk_pct_int = int(disk_pct_str) if disk_pct_str not in ("?",) else None
        db_size_mb = db_bytes / (1024 ** 2)
        cur.execute(
            """
            INSERT INTO fr24.monitoring_metrics (disk_pct, db_size_mb, capture_lag_sec, throughput_5min)
            VALUES (%s, %s, %s, %s)
            """,
            (disk_pct_int, round(db_size_mb, 2), lag_sec, int(throughput)),
        )
        # Prune old rows, keep last METRICS_KEEP
        cur.execute(
            """
            DELETE FROM fr24.monitoring_metrics
            WHERE id NOT IN (
                SELECT id FROM fr24.monitoring_metrics ORDER BY id DESC LIMIT %s
            )
            """,
            (METRICS_KEEP,),
        )

        cur.close()
        conn.close()

        db_ok = True
    except Exception as e:
        log.warning("db check failed: %s", e)
        db_size_str = "ERR"
        lag_sec = None
        lag_str = "ERR"
        throughput = "ERR"
        db_ok = False

    # Emit metrics line
    disk_display = f"{disk_pct_str}%" if disk_pct_str != "?" else "?"
    print(
        f"[monitor] disk={disk_display} db_size={db_size_str} "
        f"capture_lag={lag_str} throughput={throughput}pkt/5min",
        flush=True,
    )

    # Warnings
    if disk_pct_str not in ("?",) and int(disk_pct_str) > DISK_WARN_PCT:
        log.warning("DISK USAGE HIGH: %s%%", disk_pct_str)

    if db_ok and lag_sec is not None and lag_sec > LAG_WARN_SEC:
        log.warning("CAPTURE LAG HIGH: %ds (threshold %ds)", lag_sec, LAG_WARN_SEC)


def main():
    log.info("FR24 monitoring started (interval=%ds)", INTERVAL)

    # Ensure metrics table exists before first check
    for attempt in range(10):
        try:
            conn = psycopg2.connect(DB_DSN, connect_timeout=5)
            conn.autocommit = False
            ensure_metrics_table(conn)
            conn.close()
            break
        except Exception as e:
            log.warning("waiting for DB (%d/10): %s", attempt + 1, e)
            time.sleep(3)

    # Signal readiness
    open("/tmp/monitoring-ready", "w").close()

    while True:
        try:
            run_checks()
        except Exception as e:
            log.error("unexpected error in run_checks: %s", e)
        time.sleep(INTERVAL)


if __name__ == "__main__":
    main()