import { useState, useEffect, useRef, useCallback } from 'react';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Label } from '@/components/ui/label';
import { servicesApi } from '@/services/api';
import { Copy, Download, RefreshCw, X } from 'lucide-react';
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select';

interface ServiceLogViewerProps {
  instanceName: string;
  serviceName: string;
  containers?: string[];
  onClose: () => void;
}

export function ServiceLogViewer({
  instanceName,
  serviceName,
  containers = [],
  onClose,
}: ServiceLogViewerProps) {
  const [logs, setLogs] = useState<string[]>([]);
  const [follow, setFollow] = useState(false);
  const [tail, setTail] = useState(100);
  const [container, setContainer] = useState<string | undefined>(containers[0]);
  const [autoScroll, setAutoScroll] = useState(true);
  const logsEndRef = useRef<HTMLDivElement>(null);
  const logsContainerRef = useRef<HTMLDivElement>(null);
  const eventSourceRef = useRef<EventSource | null>(null);

  // Scroll to bottom when logs change and autoScroll is enabled
  useEffect(() => {
    if (autoScroll && logsEndRef.current) {
      logsEndRef.current.scrollIntoView({ behavior: 'smooth' });
    }
  }, [logs, autoScroll]);

  // Fetch initial buffered logs
  const fetchLogs = useCallback(async () => {
    try {
      const url = servicesApi.getLogsUrl(instanceName, serviceName, tail, false, container);
      const response = await fetch(url);
      if (!response.ok) {
        throw new Error(`Failed to fetch logs: ${response.statusText}`);
      }
      const data = await response.json();
      // API returns { lines: string[] }
      if (data.lines && Array.isArray(data.lines)) {
        setLogs(data.lines);
      } else {
        setLogs([]);
      }
    } catch (error) {
      console.error('Error fetching logs:', error);
      setLogs([`Error: ${error instanceof Error ? error.message : 'Failed to fetch logs'}`]);
    }
  }, [instanceName, serviceName, tail, container]);

  // Set up SSE streaming when follow is enabled
  useEffect(() => {
    if (follow) {
      const url = servicesApi.getLogsUrl(instanceName, serviceName, tail, true, container);
      const eventSource = new EventSource(url);
      eventSourceRef.current = eventSource;

      eventSource.onmessage = (event) => {
        const line = event.data;
        if (line && line.trim() !== '') {
          setLogs((prev) => [...prev, line]);
        }
      };

      eventSource.onerror = (error) => {
        console.error('SSE error:', error);
        eventSource.close();
        setFollow(false);
      };

      return () => {
        eventSource.close();
      };
    } else {
      if (eventSourceRef.current) {
        eventSourceRef.current.close();
        eventSourceRef.current = null;
      }
    }
  }, [follow, instanceName, serviceName, tail, container]);

  // Fetch initial logs on mount and when parameters change
  useEffect(() => {
    if (!follow) {
      fetchLogs();
    }
  }, [fetchLogs, follow]);

  const handleCopyLogs = () => {
    const text = logs.join('\n');
    navigator.clipboard.writeText(text);
  };

  const handleDownloadLogs = () => {
    const text = logs.join('\n');
    const blob = new Blob([text], { type: 'text/plain' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = `${serviceName}-logs.txt`;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
  };

  const handleClearLogs = () => {
    setLogs([]);
  };

  const handleRefresh = () => {
    setLogs([]);
    fetchLogs();
  };

  return (
    <Card className="flex flex-col h-full max-h-[80vh]">
      <CardHeader className="flex-shrink-0">
        <div className="flex items-center justify-between">
          <CardTitle>Service Logs: {serviceName}</CardTitle>
          <Button variant="ghost" size="sm" onClick={onClose}>
            <X className="h-4 w-4" />
          </Button>
        </div>

        <div className="flex flex-wrap gap-4 mt-4">
          <div className="flex items-center gap-2">
            <Label htmlFor="tail-select">Lines:</Label>
            <Select value={tail.toString()} onValueChange={(v) => setTail(Number(v))}>
              <SelectTrigger id="tail-select" className="w-24">
                <SelectValue />
              </SelectTrigger>
              <SelectContent>
                <SelectItem value="50">50</SelectItem>
                <SelectItem value="100">100</SelectItem>
                <SelectItem value="200">200</SelectItem>
                <SelectItem value="500">500</SelectItem>
                <SelectItem value="1000">1000</SelectItem>
              </SelectContent>
            </Select>
          </div>

          {containers.length > 1 && (
            <div className="flex items-center gap-2">
              <Label htmlFor="container-select">Container:</Label>
              <Select value={container} onValueChange={setContainer}>
                <SelectTrigger id="container-select" className="w-40">
                  <SelectValue />
                </SelectTrigger>
                <SelectContent>
                  {containers.map((c) => (
                    <SelectItem key={c} value={c}>
                      {c}
                    </SelectItem>
                  ))}
                </SelectContent>
              </Select>
            </div>
          )}

          <div className="flex items-center gap-2">
            <input
              type="checkbox"
              id="follow-checkbox"
              checked={follow}
              onChange={(e) => setFollow(e.target.checked)}
              className="rounded"
            />
            <Label htmlFor="follow-checkbox">Follow</Label>
          </div>

          <div className="flex items-center gap-2">
            <input
              type="checkbox"
              id="autoscroll-checkbox"
              checked={autoScroll}
              onChange={(e) => setAutoScroll(e.target.checked)}
              className="rounded"
            />
            <Label htmlFor="autoscroll-checkbox">Auto-scroll</Label>
          </div>

          <div className="flex gap-2 ml-auto">
            <Button variant="outline" size="sm" onClick={handleRefresh} disabled={follow}>
              <RefreshCw className="h-4 w-4" />
              Refresh
            </Button>
            <Button variant="outline" size="sm" onClick={handleCopyLogs}>
              <Copy className="h-4 w-4" />
              Copy
            </Button>
            <Button variant="outline" size="sm" onClick={handleDownloadLogs}>
              <Download className="h-4 w-4" />
              Download
            </Button>
            <Button variant="outline" size="sm" onClick={handleClearLogs}>
              Clear
            </Button>
          </div>
        </div>
      </CardHeader>

      <CardContent className="flex-1 overflow-hidden p-0">
        <div
          ref={logsContainerRef}
          className="h-full overflow-y-auto bg-slate-950 dark:bg-slate-900 p-4 font-mono text-xs text-green-400"
        >
          {logs.length === 0 ? (
            <div className="text-slate-500">No logs available</div>
          ) : (
            logs.map((line, index) => (
              <div key={index} className="whitespace-pre-wrap break-all">
                {line}
              </div>
            ))
          )}
          <div ref={logsEndRef} />
        </div>
      </CardContent>
    </Card>
  );
}