"""Service monitoring with persistence and alerting."""
import asyncio
from datetime import datetime, timedelta
from dataclasses import dataclass
from typing import Optional
from enum import Enum

import httpx

from database import (
    save_metric, get_latency_history, get_uptime_stats, get_avg_latency,
    create_incident, resolve_incident, get_open_incident, mark_incident_notified
)
from alerts import alert_service_down, alert_service_recovered
from ssl_monitor import check_and_alert_ssl, SSLInfo


class Status(str, Enum):
    OPERATIONAL = "operational"
    DEGRADED = "degraded"
    DOWN = "down"
    UNKNOWN = "unknown"


@dataclass
class ServiceStatus:
    name: str
    display_name: str
    status: Status = Status.UNKNOWN
    latency_ms: Optional[float] = None
    last_check: Optional[datetime] = None
    last_incident: Optional[datetime] = None
    uptime_percent: float = 100.0
    message: Optional[str] = None
    version: Optional[str] = None
    avg_latency_24h: Optional[float] = None
    latency_history: list = None

    # For uptime calculation (in-memory, backed by DB)
    total_checks: int = 0
    successful_checks: int = 0

    def __post_init__(self):
        if self.latency_history is None:
            self.latency_history = []

    def to_dict(self) -> dict:
        return {
            "name": self.name,
            "display_name": self.display_name,
            "status": self.status.value,
            "latency_ms": round(self.latency_ms, 2) if self.latency_ms else None,
            "last_check": self.last_check.isoformat() if self.last_check else None,
            "last_incident": self.last_incident.isoformat() if self.last_incident else None,
            "uptime_percent": round(self.uptime_percent, 2),
            "message": self.message,
            "version": self.version,
            "avg_latency_24h": round(self.avg_latency_24h, 2) if self.avg_latency_24h else None,
        }

    def update_uptime(self, is_success: bool):
        self.total_checks += 1
        if is_success:
            self.successful_checks += 1
        if self.total_checks > 0:
            self.uptime_percent = (self.successful_checks / self.total_checks) * 100


class ServiceMonitor:
    def __init__(self):
        self.services: dict[str, ServiceStatus] = {
            "backend": ServiceStatus(
                name="backend",
                display_name="Backend API"
            ),
            "database": ServiceStatus(
                name="database",
                display_name="Database"
            ),
            "frontend": ServiceStatus(
                name="frontend",
                display_name="Frontend"
            ),
            "bot": ServiceStatus(
                name="bot",
                display_name="Telegram Bot"
            ),
            "external": ServiceStatus(
                name="external",
                display_name="External Access"
            ),
        }
        self.last_check: Optional[datetime] = None
        self.ssl_info: Optional[SSLInfo] = None

    async def check_backend(self, url: str) -> tuple[Status, Optional[float], Optional[str], Optional[str]]:
        """Check backend API health."""
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                start = datetime.now()
                response = await client.get(f"{url}/health")
                latency = (datetime.now() - start).total_seconds() * 1000

                if response.status_code == 200:
                    data = response.json()
                    return Status.OPERATIONAL, latency, None, data.get("version")
                else:
                    return Status.DEGRADED, latency, f"HTTP {response.status_code}", None
        except httpx.TimeoutException:
            return Status.DOWN, None, "Timeout", None
        except Exception as e:
            return Status.DOWN, None, str(e)[:100], None

    async def check_database(self, backend_url: str) -> tuple[Status, Optional[float], Optional[str]]:
        """Check database through backend."""
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                start = datetime.now()
                response = await client.get(f"{backend_url}/health")
                latency = (datetime.now() - start).total_seconds() * 1000

                if response.status_code == 200:
                    return Status.OPERATIONAL, latency, None
                else:
                    return Status.DOWN, latency, "Backend reports unhealthy"
        except Exception as e:
            return Status.DOWN, None, "Cannot reach backend"

    async def check_frontend(self, url: str) -> tuple[Status, Optional[float], Optional[str]]:
        """Check frontend availability."""
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                start = datetime.now()
                response = await client.get(url)
                latency = (datetime.now() - start).total_seconds() * 1000

                if response.status_code == 200:
                    return Status.OPERATIONAL, latency, None
                else:
                    return Status.DEGRADED, latency, f"HTTP {response.status_code}"
        except httpx.TimeoutException:
            return Status.DOWN, None, "Timeout"
        except Exception as e:
            return Status.DOWN, None, str(e)[:100]

    async def check_bot(self, url: str) -> tuple[Status, Optional[float], Optional[str]]:
        """Check Telegram bot health."""
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                start = datetime.now()
                response = await client.get(f"{url}/health")
                latency = (datetime.now() - start).total_seconds() * 1000

                if response.status_code == 200:
                    return Status.OPERATIONAL, latency, None
                else:
                    return Status.DEGRADED, latency, f"HTTP {response.status_code}"
        except httpx.TimeoutException:
            return Status.DOWN, None, "Timeout"
        except Exception as e:
            return Status.DOWN, None, str(e)[:100]

    async def check_external(self, url: str) -> tuple[Status, Optional[float], Optional[str]]:
        """Check external (public) URL availability."""
        if not url:
            return Status.UNKNOWN, None, "Not configured"

        try:
            async with httpx.AsyncClient(timeout=15.0, follow_redirects=True) as client:
                start = datetime.now()
                response = await client.get(url)
                latency = (datetime.now() - start).total_seconds() * 1000

                if response.status_code == 200:
                    return Status.OPERATIONAL, latency, None
                else:
                    return Status.DEGRADED, latency, f"HTTP {response.status_code}"
        except httpx.TimeoutException:
            return Status.DOWN, None, "Timeout"
        except Exception as e:
            return Status.DOWN, None, str(e)[:100]

    async def _process_check_result(
        self,
        service_name: str,
        result: tuple,
        now: datetime
    ):
        """Process check result with DB persistence and alerting."""
        if isinstance(result, Exception):
            return

        if len(result) == 4:
            status, latency, message, version = result
        else:
            status, latency, message = result
            version = None

        svc = self.services[service_name]
        was_down = svc.status in (Status.DOWN, Status.DEGRADED)
        is_down = status in (Status.DOWN, Status.DEGRADED)

        # Update service status
        svc.status = status
        svc.latency_ms = latency
        svc.message = message
        if version:
            svc.version = version
        svc.last_check = now
        svc.update_uptime(status == Status.OPERATIONAL)

        # Save metric to database
        save_metric(service_name, status.value, latency, message)

        # Load historical data
        svc.latency_history = get_latency_history(service_name, hours=24)
        svc.avg_latency_24h = get_avg_latency(service_name, hours=24)

        # Update uptime from DB
        stats = get_uptime_stats(service_name, hours=24)
        if stats["total_checks"] > 0:
            svc.uptime_percent = stats["uptime_percent"]

        # Handle incident tracking and alerting
        if is_down and not was_down:
            # Service just went down
            svc.last_incident = now
            incident_id = create_incident(service_name, status.value, message)
            await alert_service_down(service_name, svc.display_name, message)
            mark_incident_notified(incident_id)

        elif not is_down and was_down:
            # Service recovered
            open_incident = get_open_incident(service_name)
            if open_incident:
                started_at = datetime.fromisoformat(open_incident["started_at"])
                downtime_minutes = int((now - started_at).total_seconds() / 60)
                resolve_incident(service_name)
                await alert_service_recovered(service_name, svc.display_name, downtime_minutes)

    async def check_all_services(
        self,
        backend_url: str,
        frontend_url: str,
        bot_url: str,
        external_url: str = "",
        public_url: str = ""
    ):
        """Check all services concurrently."""
        now = datetime.now()

        # Run all checks concurrently
        results = await asyncio.gather(
            self.check_backend(backend_url),
            self.check_database(backend_url),
            self.check_frontend(frontend_url),
            self.check_bot(bot_url),
            self.check_external(external_url),
            return_exceptions=True
        )

        # Process results
        service_names = ["backend", "database", "frontend", "bot", "external"]
        for i, service_name in enumerate(service_names):
            await self._process_check_result(service_name, results[i], now)

        # Check SSL certificate (if public URL is HTTPS)
        if public_url and public_url.startswith("https://"):
            self.ssl_info = await check_and_alert_ssl(public_url)

        self.last_check = now

    def get_all_statuses(self) -> dict[str, ServiceStatus]:
        return self.services

    def get_overall_status(self) -> Status:
        """Get overall system status based on all services."""
        # Exclude external from overall status if not configured
        statuses = [
            svc.status for name, svc in self.services.items()
            if name != "external" or svc.status != Status.UNKNOWN
        ]

        if all(s == Status.OPERATIONAL for s in statuses):
            return Status.OPERATIONAL
        elif any(s == Status.DOWN for s in statuses):
            return Status.DOWN
        elif any(s == Status.DEGRADED for s in statuses):
            return Status.DEGRADED
        else:
            return Status.UNKNOWN

    def get_ssl_status(self) -> Optional[dict]:
        """Get SSL certificate status."""
        if not self.ssl_info:
            return None

        return {
            "domain": self.ssl_info.domain,
            "issuer": self.ssl_info.issuer,
            "expires_at": self.ssl_info.expires_at.isoformat(),
            "days_until_expiry": self.ssl_info.days_until_expiry,
            "is_valid": self.ssl_info.is_valid,
            "error": self.ssl_info.error
        }