"use client";

import { useState, useEffect, useCallback } from "react";
import { motion } from "framer-motion";
import {
  Activity, Database, Cpu, Wifi, Shield, RefreshCw,
  TrendingUp, AlertTriangle, CheckCircle, Clock
} from "lucide-react";

interface Metrics {
  uptime_seconds: number;
  requests: { total: number; errors: number; auth_failures: number; error_rate_pct: number };
  websocket: { total_connects: number; reconnects: number };
  ai: {
    fallbacks: number;
    by_provider: Record<string, { calls: number; errors: number; avg_latency_ms: number; p95_latency_ms: number | null }>;
  };
  cache: { hits: number; misses: number; hit_ratio_pct: number };
  route_timings: Record<string, { calls: number; avg_ms: number; max_ms: number }>;
  recent_errors: Array<{ ts: string; path: string; status: number; detail: string }>;
}

interface ApiStatus {
  ai_backend: string;
  ai_available: boolean;
  db_type: string;
  cache_type: string;
  version: string;
}

const API = process.env.NEXT_PUBLIC_API_URL || "";

function formatUptime(s: number) {
  if (s < 60) return `${s}s`;
  if (s < 3600) return `${Math.floor(s / 60)}m ${Math.floor(s % 60)}s`;
  return `${Math.floor(s / 3600)}h ${Math.floor((s % 3600) / 60)}m`;
}

function StatusDot({ ok }: { ok: boolean }) {
  return (
    <span className={`inline-block h-2 w-2 rounded-full ${ok ? "bg-emerald-400" : "bg-red-400"} ${ok ? "animate-pulse" : ""}`} />
  );
}

function MetricCard({ label, value, sub, icon: Icon, color = "text-zinc-400" }: {
  label: string; value: string | number; sub?: string;
  icon: React.ElementType; color?: string;
}) {
  return (
    <motion.div
      whileHover={{ scale: 1.02 }}
      className="glass-card p-5"
    >
      <div className="flex items-start justify-between mb-3">
        <p className="text-xs text-zinc-500 uppercase tracking-wider">{label}</p>
        <Icon className={`h-4 w-4 ${color}`} />
      </div>
      <p className="text-2xl font-bold text-white">{value}</p>
      {sub && <p className="text-xs text-zinc-500 mt-1">{sub}</p>}
    </motion.div>
  );
}

const containerVariants = {
  hidden: { opacity: 0 },
  visible: { opacity: 1, transition: { staggerChildren: 0.06 } },
};
const itemVariants = {
  hidden: { opacity: 0, y: 14 },
  visible: { opacity: 1, y: 0, transition: { duration: 0.4 } },
};

export default function StatusPage() {
  const [metrics, setMetrics] = useState<Metrics | null>(null);
  const [status, setStatus] = useState<ApiStatus | null>(null);
  const [loading, setLoading] = useState(true);
  const [lastRefresh, setLastRefresh] = useState<Date | null>(null);
  const [backendOnline, setBackendOnline] = useState(false);

  const load = useCallback(async () => {
    setLoading(true);
    try {
      const [m, s] = await Promise.all([
        fetch(`${API}/api/metrics`).then((r) => r.json()),
        fetch(`${API}/api/status`).then((r) => r.json()),
      ]);
      setMetrics(m);
      setStatus(s);
      setBackendOnline(true);
      setLastRefresh(new Date());
    } catch {
      setBackendOnline(false);
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    load();
    const interval = setInterval(load, 15000); // auto-refresh every 15s
    return () => clearInterval(interval);
  }, [load]);

  const aiProviders = metrics ? Object.entries(metrics.ai.by_provider) : [];
  const topRoutes = metrics
    ? Object.entries(metrics.route_timings).sort((a, b) => b[1].avg_ms - a[1].avg_ms).slice(0, 6)
    : [];

  return (
    <motion.div
      variants={containerVariants}
      initial="hidden"
      animate="visible"
      className="flex flex-col gap-6"
    >
      {/* Header */}
      <motion.div variants={itemVariants} className="flex items-center justify-between">
        <div>
          <h1 className="text-3xl font-bold tracking-tight text-white">System Status</h1>
          <p className="text-zinc-400 mt-1 text-sm">
            Live observability — auto-refreshes every 15s
            {lastRefresh && (
              <span className="ml-2 text-zinc-600">
                · Last updated {lastRefresh.toLocaleTimeString()}
              </span>
            )}
          </p>
        </div>
        <button
          onClick={load}
          className="flex items-center gap-2 rounded-xl border border-white/10 bg-white/5 px-3 py-2 text-xs text-zinc-400 hover:text-white transition-colors"
        >
          <RefreshCw className={`h-3.5 w-3.5 ${loading ? "animate-spin" : ""}`} />
          Refresh
        </button>
      </motion.div>

      {/* Overall health banner */}
      <motion.div
        variants={itemVariants}
        className={`flex items-center gap-3 rounded-2xl border px-5 py-3 ${
          backendOnline
            ? "border-emerald-500/20 bg-emerald-500/5"
            : "border-red-500/20 bg-red-500/5"
        }`}
      >
        {backendOnline ? (
          <CheckCircle className="h-4 w-4 text-emerald-400 flex-shrink-0" />
        ) : (
          <AlertTriangle className="h-4 w-4 text-red-400 flex-shrink-0" />
        )}
        <div>
          <p className={`text-sm font-semibold ${backendOnline ? "text-emerald-400" : "text-red-400"}`}>
            {backendOnline ? "All Systems Operational" : "Backend Offline"}
          </p>
          <p className="text-xs text-zinc-500 mt-0.5">
            {backendOnline
              ? `API v${status?.version || "2.0.0"} · ${status?.db_type?.toUpperCase()} · ${status?.cache_type?.toUpperCase()} cache · Uptime ${formatUptime(metrics?.uptime_seconds || 0)}`
              : "Cannot reach backend. Start with: uvicorn app.main:app --port 8000"}
          </p>
        </div>
      </motion.div>

      {/* System info cards */}
      {status && (
        <motion.div variants={itemVariants} className="grid grid-cols-2 sm:grid-cols-4 gap-4">
          {[
            {
              label: "AI Backend",
              value: status.ai_backend.toUpperCase(),
              sub: status.ai_available ? "Available" : "Unavailable",
              icon: Cpu,
              color: status.ai_available ? "text-emerald-400" : "text-red-400",
            },
            {
              label: "Database",
              value: status.db_type.toUpperCase(),
              sub: "Connected",
              icon: Database,
              color: "text-blue-400",
            },
            {
              label: "Cache",
              value: status.cache_type.toUpperCase(),
              sub: metrics ? `${metrics.cache.hit_ratio_pct}% hit rate` : "—",
              icon: Activity,
              color: "text-purple-400",
            },
            {
              label: "Uptime",
              value: formatUptime(metrics?.uptime_seconds || 0),
              sub: "Since last restart",
              icon: Clock,
              color: "text-amber-400",
            },
          ].map((c) => (
            <MetricCard key={c.label} {...c} />
          ))}
        </motion.div>
      )}

      {/* Request metrics */}
      {metrics && (
        <motion.div variants={itemVariants} className="grid grid-cols-2 sm:grid-cols-4 gap-4">
          <MetricCard
            label="Total Requests"
            value={metrics.requests.total.toLocaleString()}
            sub="Since startup"
            icon={TrendingUp}
            color="text-emerald-400"
          />
          <MetricCard
            label="Error Rate"
            value={`${metrics.requests.error_rate_pct}%`}
            sub={`${metrics.requests.errors} errors`}
            icon={AlertTriangle}
            color={metrics.requests.error_rate_pct > 5 ? "text-red-400" : "text-emerald-400"}
          />
          <MetricCard
            label="Auth Failures"
            value={metrics.requests.auth_failures}
            sub="401 responses"
            icon={Shield}
            color={metrics.requests.auth_failures > 10 ? "text-amber-400" : "text-zinc-400"}
          />
          <MetricCard
            label="WebSocket Connects"
            value={metrics.websocket.total_connects}
            sub={`${metrics.websocket.reconnects} reconnects`}
            icon={Wifi}
            color="text-cyan-400"
          />
        </motion.div>
      )}

      <div className="grid gap-6 lg:grid-cols-2">
        {/* AI Provider Health */}
        <motion.div variants={itemVariants} className="glass-card p-6">
          <div className="flex items-center gap-2 mb-5">
            <Cpu className="h-4 w-4 text-emerald-400" />
            <h2 className="text-sm font-semibold text-white">AI Provider Health</h2>
          </div>
          {aiProviders.length === 0 ? (
            <div className="flex flex-col items-center gap-2 py-8 text-center">
              <Cpu className="h-8 w-8 text-zinc-700" />
              <p className="text-sm text-zinc-500">No AI calls recorded yet</p>
              <p className="text-xs text-zinc-600">Use the chat or briefing endpoints to generate AI calls</p>
            </div>
          ) : (
            <div className="space-y-4">
              {aiProviders.map(([provider, data]) => {
                const errorRate = data.calls > 0 ? (data.errors / data.calls) * 100 : 0;
                return (
                  <div key={provider} className="space-y-2">
                    <div className="flex items-center justify-between">
                      <div className="flex items-center gap-2">
                        <StatusDot ok={errorRate < 10} />
                        <span className="text-sm font-medium text-white capitalize">{provider}</span>
                      </div>
                      <div className="flex items-center gap-4 text-xs text-zinc-400">
                        <span>{data.calls} calls</span>
                        <span className={errorRate > 10 ? "text-red-400" : "text-emerald-400"}>
                          {errorRate.toFixed(1)}% errors
                        </span>
                        <span>{data.avg_latency_ms}ms avg</span>
                      </div>
                    </div>
                    <div className="h-1.5 w-full rounded-full bg-white/5 overflow-hidden">
                      <div
                        className="h-full rounded-full bg-emerald-400 transition-all duration-500"
                        style={{ width: `${Math.min(100 - errorRate, 100)}%` }}
                      />
                    </div>
                  </div>
                );
              })}
              <div className="pt-2 border-t border-white/8">
                <p className="text-xs text-zinc-500">
                  AI fallbacks: <span className="text-white font-medium">{metrics?.ai.fallbacks || 0}</span>
                </p>
              </div>
            </div>
          )}
        </motion.div>

        {/* Cache Performance */}
        <motion.div variants={itemVariants} className="glass-card p-6">
          <div className="flex items-center gap-2 mb-5">
            <Activity className="h-4 w-4 text-purple-400" />
            <h2 className="text-sm font-semibold text-white">Cache Performance</h2>
          </div>
          {metrics && (
            <div className="space-y-4">
              <div className="flex items-center justify-between">
                <span className="text-sm text-zinc-400">Hit Ratio</span>
                <span className={`text-sm font-bold ${metrics.cache.hit_ratio_pct > 60 ? "text-emerald-400" : "text-amber-400"}`}>
                  {metrics.cache.hit_ratio_pct}%
                </span>
              </div>
              <div className="h-3 w-full rounded-full bg-white/5 overflow-hidden">
                <motion.div
                  initial={{ width: 0 }}
                  animate={{ width: `${metrics.cache.hit_ratio_pct}%` }}
                  transition={{ duration: 0.8, ease: "easeOut" }}
                  className="h-full rounded-full bg-gradient-to-r from-purple-500 to-blue-500"
                />
              </div>
              <div className="grid grid-cols-2 gap-4 pt-2">
                <div className="rounded-xl bg-white/5 p-3 text-center">
                  <p className="text-lg font-bold text-emerald-400">{metrics.cache.hits}</p>
                  <p className="text-xs text-zinc-500 mt-0.5">Cache Hits</p>
                </div>
                <div className="rounded-xl bg-white/5 p-3 text-center">
                  <p className="text-lg font-bold text-zinc-400">{metrics.cache.misses}</p>
                  <p className="text-xs text-zinc-500 mt-0.5">Cache Misses</p>
                </div>
              </div>
            </div>
          )}
        </motion.div>
      </div>

      {/* Route Timings */}
      {topRoutes.length > 0 && (
        <motion.div variants={itemVariants} className="glass-card p-6">
          <div className="flex items-center gap-2 mb-5">
            <Clock className="h-4 w-4 text-amber-400" />
            <h2 className="text-sm font-semibold text-white">Route Performance</h2>
            <span className="text-xs text-zinc-500 ml-auto">Sorted by avg response time</span>
          </div>
          <div className="space-y-2">
            {topRoutes.map(([path, data]) => {
              const isSlow = data.avg_ms > 500;
              const barWidth = Math.min((data.avg_ms / 2000) * 100, 100);
              return (
                <div key={path} className="flex items-center gap-4">
                  <code className="text-xs text-zinc-400 w-56 truncate flex-shrink-0">{path}</code>
                  <div className="flex-1 h-1.5 rounded-full bg-white/5 overflow-hidden">
                    <div
                      className={`h-full rounded-full transition-all duration-500 ${isSlow ? "bg-amber-400" : "bg-emerald-400"}`}
                      style={{ width: `${barWidth}%` }}
                    />
                  </div>
                  <div className="flex items-center gap-3 text-xs text-zinc-400 w-40 flex-shrink-0 text-right">
                    <span className={`font-medium ${isSlow ? "text-amber-400" : "text-emerald-400"}`}>
                      {data.avg_ms}ms avg
                    </span>
                    <span className="text-zinc-600">{data.max_ms}ms max</span>
                    <span className="text-zinc-600">{data.calls} calls</span>
                  </div>
                </div>
              );
            })}
          </div>
        </motion.div>
      )}

      {/* Recent Errors */}
      {metrics && metrics.recent_errors.length > 0 && (
        <motion.div variants={itemVariants} className="glass-card p-6">
          <div className="flex items-center gap-2 mb-5">
            <AlertTriangle className="h-4 w-4 text-red-400" />
            <h2 className="text-sm font-semibold text-white">Recent Errors</h2>
            <span className="text-xs text-zinc-500 ml-auto">Last 10</span>
          </div>
          <div className="space-y-2">
            {metrics.recent_errors.map((err, i) => (
              <div key={i} className="flex items-center gap-3 rounded-xl bg-red-500/5 border border-red-500/10 px-3 py-2">
                <span className={`text-xs font-bold px-1.5 py-0.5 rounded ${
                  err.status >= 500 ? "bg-red-500/20 text-red-400" : "bg-amber-500/20 text-amber-400"
                }`}>
                  {err.status}
                </span>
                <code className="text-xs text-zinc-400 flex-1 truncate">{err.path}</code>
                <span className="text-xs text-zinc-600 flex-shrink-0">
                  {new Date(err.ts).toLocaleTimeString()}
                </span>
              </div>
            ))}
          </div>
        </motion.div>
      )}
    </motion.div>
  );
}