"""Supabase pinger con API FastAPI, storage storico a buffer circolare e dashboard."""

from __future__ import annotations

import logging
import os
import sqlite3
import sys
import threading
import time
from contextlib import asynccontextmanager
from dataclasses import dataclass
from pathlib import Path
from typing import Any

import psycopg2
import uvicorn
from dotenv import load_dotenv
from fastapi import FastAPI, HTTPException, Query, Request
from fastapi.responses import HTMLResponse


logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s  %(levelname)-8s  %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
    stream=sys.stdout,
)
log = logging.getLogger("supabase-pinger")

REQUIRED_VARS = [
    "SUPABASE_DB_HOST",
    "SUPABASE_DB_PORT",
    "SUPABASE_DB_NAME",
    "SUPABASE_DB_USER",
    "SUPABASE_DB_PASSWORD",
]


@dataclass
class Settings:
    db_host: str
    db_port: int
    db_name: str
    db_user: str
    db_password: str
    ping_query: str
    ping_interval_minutes: int
    web_host: str
    web_port: int
    rrd_db_path: str
    rrd_retention_hours: int

    @property
    def max_samples(self) -> int:
        samples = int((self.rrd_retention_hours * 60) / self.ping_interval_minutes)
        return max(1, samples)


def load_config() -> Settings:
    """Carica e valida la configurazione da ambiente/.env."""
    load_dotenv()

    missing = [name for name in REQUIRED_VARS if not os.environ.get(name)]
    if missing:
        raise RuntimeError(
            f"Variabili obbligatorie mancanti: {', '.join(missing)}"
        )

    try:
        db_port = int(os.environ["SUPABASE_DB_PORT"])
        ping_interval = float(os.environ.get("PING_INTERVAL_MINUTES", "4320"))
        web_port = int(os.environ.get("WEB_PORT", "8080"))
        retention_hours = int(os.environ.get("RRD_RETENTION_HOURS", "48"))
        if ping_interval <= 0 or web_port <= 0 or retention_hours <= 0:
            raise ValueError
    except ValueError as exc:
        raise RuntimeError(
            "SUPABASE_DB_PORT, PING_INTERVAL_MINUTES, WEB_PORT e "
            "RRD_RETENTION_HOURS devono essere numeri positivi."
        ) from exc

    return Settings(
        db_host=os.environ["SUPABASE_DB_HOST"],
        db_port=db_port,
        db_name=os.environ["SUPABASE_DB_NAME"],
        db_user=os.environ["SUPABASE_DB_USER"],
        db_password=os.environ["SUPABASE_DB_PASSWORD"],
        ping_query=os.environ.get("PING_QUERY", "SELECT 1;"),
        ping_interval_minutes=ping_interval,
        web_host=os.environ.get("WEB_HOST", "0.0.0.0"),
        web_port=web_port,
        rrd_db_path=os.environ.get("RRD_DB_PATH", "data/connection_rrd.sqlite3"),
        rrd_retention_hours=retention_hours,
    )


class RRDStore:
    """Storage storico a buffer circolare, dimensionato a finestra 48h."""

    def __init__(self, path: str, max_samples: int) -> None:
        self.path = path
        self.max_samples = max_samples
        Path(path).parent.mkdir(parents=True, exist_ok=True)
        self._init_db()

    def _connect(self) -> sqlite3.Connection:
        conn = sqlite3.connect(self.path)
        conn.row_factory = sqlite3.Row
        return conn

    def _init_db(self) -> None:
        with self._connect() as conn:
            conn.execute(
                """
                CREATE TABLE IF NOT EXISTS samples (
                    id INTEGER PRIMARY KEY AUTOINCREMENT,
                    ts INTEGER NOT NULL,
                    success INTEGER NOT NULL,
                    latency_ms REAL,
                    error_message TEXT
                );
                """
            )
            conn.commit()

    def add_sample(
        self, *, ts: int, success: bool, latency_ms: float | None, error_message: str | None
    ) -> None:
        with self._connect() as conn:
            conn.execute(
                """
                INSERT INTO samples (ts, success, latency_ms, error_message)
                VALUES (?, ?, ?, ?)
                """,
                (ts, 1 if success else 0, latency_ms, error_message),
            )
            conn.execute(
                """
                DELETE FROM samples
                WHERE id NOT IN (
                    SELECT id FROM samples ORDER BY id DESC LIMIT ?
                )
                """,
                (self.max_samples,),
            )
            conn.commit()

    def latest(self) -> dict[str, Any] | None:
        with self._connect() as conn:
            row = conn.execute(
                """
                SELECT ts, success, latency_ms, error_message
                FROM samples
                ORDER BY id DESC
                LIMIT 1
                """
            ).fetchone()
        return self._row_to_dict(row) if row else None

    def history(self, hours: int) -> list[dict[str, Any]]:
        min_ts = int(time.time()) - (hours * 3600)
        with self._connect() as conn:
            rows = conn.execute(
                """
                SELECT ts, success, latency_ms, error_message
                FROM samples
                WHERE ts >= ?
                ORDER BY ts ASC
                """,
                (min_ts,),
            ).fetchall()
        return [self._row_to_dict(row) for row in rows]

    @staticmethod
    def _row_to_dict(row: sqlite3.Row) -> dict[str, Any]:
        return {
            "timestamp": int(row["ts"]),
            "success": bool(row["success"]),
            "latency_ms": row["latency_ms"],
            "error_message": row["error_message"],
        }


def run_ping(settings: Settings) -> tuple[bool, float | None, str | None]:
    """Esegue il keep-alive e restituisce esito, latenza, eventuale errore."""
    conn = None
    started = time.perf_counter()

    try:
        conn = psycopg2.connect(
            host=settings.db_host,
            port=settings.db_port,
            dbname=settings.db_name,
            user=settings.db_user,
            password=settings.db_password,
            connect_timeout=10,
        )
        with conn.cursor() as cur:
            cur.execute(settings.ping_query)
        latency_ms = (time.perf_counter() - started) * 1000
        return True, latency_ms, None
    except psycopg2.Error as exc:
        return False, None, str(exc)
    finally:
        if conn is not None:
            try:
                conn.close()
            except Exception:
                pass


def collector_loop(settings: Settings, store: RRDStore, stop_event: threading.Event) -> None:
    interval_seconds = settings.ping_interval_minutes * 60
    log.info(
        "Collector keep-alive avviato (interval=%s min, retention=%s ore, max_samples=%s)",
        settings.ping_interval_minutes,
        settings.rrd_retention_hours,
        settings.max_samples,
    )

    while not stop_event.is_set():
        success, latency_ms, error_message = run_ping(settings)
        sample_ts = int(time.time())
        store.add_sample(
            ts=sample_ts,
            success=success,
            latency_ms=latency_ms,
            error_message=error_message,
        )

        if success:
            log.info("Keep-alive OK (latency_ms=%.2f)", latency_ms or 0.0)
        else:
            log.warning("Keep-alive failed: %s", error_message)

        wait_seconds = 0
        while wait_seconds < interval_seconds and not stop_event.is_set():
            time.sleep(min(5, interval_seconds - wait_seconds))
            wait_seconds += 5

    log.info("Collector keep-alive arrestato")


def _build_dashboard_html() -> str:
    return """
<!doctype html>
<html lang=\"it\">
<head>
  <meta charset=\"utf-8\" />
  <meta name=\"viewport\" content=\"width=device-width, initial-scale=1\" />
  <title>Supabase Pinger Dashboard</title>
  <style>
    :root {
      --bg: #101418;
      --panel: #17202a;
      --line: #3ecf8e;
      --danger: #ff6b6b;
      --text: #edf2f7;
      --muted: #9fb3c8;
    }
    body { margin: 0; font-family: 'Segoe UI', sans-serif; background: radial-gradient(circle at 20% 20%, #1f2937, var(--bg)); color: var(--text); }
    .wrap { max-width: 1100px; margin: 0 auto; padding: 24px; }
    .panel { background: color-mix(in srgb, var(--panel), #000 15%); border: 1px solid #283544; border-radius: 14px; padding: 18px; }
    .top { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
    .badge { padding: 6px 10px; border-radius: 999px; font-weight: 700; font-size: 13px; }
    .ok { background: rgba(62, 207, 142, .15); color: #7ff5bd; }
    .ko { background: rgba(255, 107, 107, .15); color: #ff9f9f; }
    .meta { color: var(--muted); font-size: 14px; }
    canvas { margin-top: 18px; }
  </style>
</head>
<body>
  <div class=\"wrap\">
    <div class=\"panel\">
      <div class=\"top\">
        <h1>Supabase Pinger - SmokePing Style</h1>
        <div>
          <span id=\"statusBadge\" class=\"badge\">N/A</span>
        </div>
      </div>
      <div class=\"meta\" id=\"meta\">Caricamento...</div>
      <canvas id=\"latencyChart\"></canvas>
    </div>
  </div>
  <script src=\"https://cdn.jsdelivr.net/npm/chart.js\"></script>
  <script>
    const badge = document.getElementById('statusBadge');
    const meta = document.getElementById('meta');
    const ctx = document.getElementById('latencyChart').getContext('2d');
    
    // Buffer locale per campioni - mantiene solo i dati nel grafico
    let samples = [];
    const MAX_VISIBLE_SAMPLES = 100; // Limite visualizzazione per performance
    
    const chart = new Chart(ctx, {
      type: 'line',
      data: { labels: [], datasets: [
        { label: 'Latenza ms', data: [], borderColor: '#3ecf8e', tension: 0.2 },
        { label: 'Errori', data: [], borderColor: '#ff6b6b', stepped: true, yAxisID: 'y1' }
      ] },
      options: {
        responsive: true,
        scales: {
          y: { title: { display: true, text: 'ms' } },
          y1: { position: 'right', min: 0, max: 1, ticks: { stepSize: 1 } }
        }
      }
    });

    async function loadHistory() {
      // Carica history iniziale una sola volta
      const historyRes = await fetch('/api/history?hours=48');
      const history = await historyRes.json();
      samples = history.samples || [];
      updateChart();
    }

    function updateChart() {
      // Limita i campioni visibili per performance
      const visibleSamples = samples.slice(-MAX_VISIBLE_SAMPLES);
      
      chart.data.labels = visibleSamples.map(s => {
        const d = new Date(s.timestamp * 1000);
        return d.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
      });
      chart.data.datasets[0].data = visibleSamples.map(s => s.latency_ms);
      chart.data.datasets[1].data = visibleSamples.map(s => s.success ? 0 : 1);
      chart.update('none'); // update senza animazione per performance
    }

    async function pollStatus() {
      try {
        const statusRes = await fetch('/api/status');
        const status = await statusRes.json();
        
        // Aggiorna badge
        if (status.success === true) {
          badge.textContent = 'UP';
          badge.className = 'badge ok';
        } else if (status.success === false) {
          badge.textContent = 'DOWN';
          badge.className = 'badge ko';
        } else {
          badge.textContent = 'N/A';
          badge.className = 'badge';
        }
        
        // Aggiorna meta con timestamp corrente
        meta.textContent = 'Ultimo aggiornamento: ' + new Date().toLocaleTimeString() + ' | Campioni: ' + samples.length;
        
        // Aggiunge nuovo sample se non gia presente
        if (status.timestamp && !samples.find(s => s.timestamp === status.timestamp)) {
          samples.push({
            timestamp: status.timestamp,
            success: status.success,
            latency_ms: status.latency_ms,
            error_message: status.error_message
          });
          
          // Rimuove campioni piu vecchi di 48h
          const cutoff = Math.floor(Date.now() / 1000) - (48 * 3600);
          samples = samples.filter(s => s.timestamp >= cutoff);
          
          updateChart();
        }
      } catch (err) {
        meta.textContent = 'Errore: ' + err.message;
      }
    }

    // Inizializzazione
    loadHistory().catch((err) => {
      meta.textContent = 'Errore caricamento history: ' + err;
    });
    
    // Poll ogni 10 secondi per aggiornamenti real-time
    setInterval(pollStatus, 10000);
  </script>
</body>
</html>
"""


def create_app(
    config_override: Settings | None = None,
    start_collector: bool = True,
) -> FastAPI:
    @asynccontextmanager
    async def lifespan(app: FastAPI):
        settings = config_override or load_config()
        store = RRDStore(settings.rrd_db_path, settings.max_samples)

        app.state.settings = settings
        app.state.store = store
        app.state.collector_stop_event = threading.Event()
        app.state.collector_thread = None

        if start_collector:
            thread = threading.Thread(
                target=collector_loop,
                args=(settings, store, app.state.collector_stop_event),
                daemon=True,
                name="collector-thread",
            )
            thread.start()
            app.state.collector_thread = thread

        yield

        app.state.collector_stop_event.set()
        if app.state.collector_thread is not None:
            app.state.collector_thread.join(timeout=5)

    app = FastAPI(
        title="Supabase Pinger API",
        version="1.1.0",
        description=(
            "API read-only per monitoraggio storico connessione Supabase "
            "(retention RRD 48h) e dashboard SmokePing-style."
        ),
        lifespan=lifespan,
    )

    @app.get("/", response_class=HTMLResponse, tags=["dashboard"])
    def dashboard() -> str:
        return _build_dashboard_html()

    @app.get("/api/status", tags=["monitoring"])
    def api_status(request: Request) -> dict[str, Any]:
        latest = request.app.state.store.latest()
        if latest is None:
            return {
                "success": None,
                "timestamp": None,
                "latency_ms": None,
                "error_message": "Nessun campione disponibile",
            }
        return latest

    @app.get("/api/history", tags=["monitoring"])
    def api_history(
        request: Request,
        hours: int = Query(48, ge=1, le=48),
    ) -> dict[str, Any]:
        if hours > request.app.state.settings.rrd_retention_hours:
            raise HTTPException(status_code=400, detail="Finestra richiesta oltre retention")
        samples = request.app.state.store.history(hours)
        return {
            "hours": hours,
            "count": len(samples),
            "samples": samples,
        }

    return app


app = create_app()


if __name__ == "__main__":
    cfg = load_config()
    uvicorn.run("app:app", host=cfg.web_host, port=cfg.web_port, log_level="info")