"use client";
import { useEffect, useState } from "react";
import { fetchClient } from "@/lib/api-client";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";

interface Status {
  uptimeSeconds: number;
  memory: Record<string, number>;
  versions: Record<string, string>;
  counts: { vendors: number; orders: number; products: number; chats: number };
}

function formatDuration(seconds: number) {
  const h = Math.floor(seconds / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  const s = seconds % 60;
  return `${h}h ${m}m ${s}s`;
}

function formatBytes(bytes: number): string {
  if (bytes === 0) return '0 Bytes';
  if (bytes < 0) return '0 Bytes'; // Handle negative values
  const k = 1024;
  const sizes = ['Bytes', 'KB', 'MB', 'GB'];
  const i = Math.max(0, Math.floor(Math.log(bytes) / Math.log(k))); // Ensure i is at least 0
  // Clamp i to valid array index
  const clampedI = Math.min(i, sizes.length - 1);
  return Math.round(bytes / Math.pow(k, clampedI) * 100) / 100 + ' ' + sizes[clampedI];
}

export default function SystemStatusCard() {
  const [data, setData] = useState<Status | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [showDebug, setShowDebug] = useState(false);

  useEffect(() => {
    let mounted = true;
    (async () => {
      try {
        const res = await fetchClient<Status>("/admin/system-status");
        if (mounted) setData(res);
      } catch (e: any) {
        if (mounted) setError(e?.message || "Failed to load status");
      }
    })();
    return () => { mounted = false; };
  }, []);

  return (
    <div className="space-y-4">
      <div className="rounded-lg border border-border/60 bg-background p-4 h-full min-h-[200px]">
        <div className="flex items-start justify-between">
          <div>
            <h2 className="font-medium">System status</h2>
            <p className="text-sm text-muted-foreground mt-1">Uptime, versions, environment</p>
          </div>
          <div className="flex items-center gap-2">
            <span className="text-xs px-2 py-0.5 rounded bg-emerald-500/15 text-emerald-400">OK</span>
            <Button 
              variant="outline" 
              size="sm"
              onClick={() => setShowDebug(!showDebug)}
            >
              {showDebug ? 'Hide' : 'Show'} Debug
            </Button>
          </div>
        </div>

        {error && <p className="text-sm text-muted-foreground mt-3">{error}</p>}

        {data && (
          <div className="mt-3 grid grid-cols-2 gap-3 text-sm">
            <div className="space-y-1">
              <div className="text-muted-foreground">Uptime</div>
              <div>{formatDuration(data.uptimeSeconds)}</div>
            </div>
            <div className="space-y-1">
              <div className="text-muted-foreground">Node</div>
              <div>{data.versions?.node}</div>
            </div>
            <div className="space-y-1">
              <div className="text-muted-foreground">Vendors</div>
              <div>{data.counts?.vendors}</div>
            </div>
            <div className="space-y-1">
              <div className="text-muted-foreground">Orders</div>
              <div>{data.counts?.orders}</div>
            </div>
          </div>
        )}
      </div>

      {showDebug && data && (
        <Card>
          <CardHeader>
            <CardTitle>Debug: Raw System Status Data</CardTitle>
            <CardDescription>Complete system status response from backend</CardDescription>
          </CardHeader>
          <CardContent>
            <div className="space-y-4 text-xs font-mono">
              <div>
                <div className="font-semibold mb-2">Memory Usage:</div>
                <div className="pl-4 space-y-1">
                  <div>RSS (Resident Set Size): {formatBytes(data.memory?.rss || 0)}</div>
                  <div>Heap Total: {formatBytes(data.memory?.heapTotal || 0)}</div>
                  <div>Heap Used: {formatBytes(data.memory?.heapUsed || 0)}</div>
                  <div>External: {formatBytes(data.memory?.external || 0)}</div>
                  <div>Array Buffers: {formatBytes(data.memory?.arrayBuffers || 0)}</div>
                </div>
              </div>
              
              <div>
                <div className="font-semibold mb-2">Versions:</div>
                <div className="pl-4 space-y-1">
                  {Object.entries(data.versions || {}).map(([key, value]) => (
                    <div key={key}>{key}: {value}</div>
                  ))}
                </div>
              </div>
              
              <div>
                <div className="font-semibold mb-2">Counts:</div>
                <div className="pl-4 space-y-1">
                  <div>Vendors: {data.counts?.vendors || 0}</div>
                  <div>Orders: {data.counts?.orders || 0}</div>
                  <div>Products: {data.counts?.products || 0}</div>
                  <div>Chats: {data.counts?.chats || 0}</div>
                </div>
              </div>
              
              <div>
                <div className="font-semibold mb-2">Uptime:</div>
                <div className="pl-4">
                  {data.uptimeSeconds} seconds ({formatDuration(data.uptimeSeconds)})
                </div>
              </div>
              
              <details className="mt-4">
                <summary className="font-semibold cursor-pointer">Full JSON Response</summary>
                <pre className="mt-2 bg-muted p-4 rounded overflow-auto max-h-96 text-[10px]">
                  {JSON.stringify(data, null, 2)}
                </pre>
              </details>
            </div>
          </CardContent>
        </Card>
      )}
    </div>
  );
}