'use client';

import * as React from 'react';
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogFooter,
  DialogClose,
} from '@/components/ui/dialog';
import { Button } from '@/components/ui/button';
import {
  ChevronLeft,
  ChevronRight,
  ZoomIn,
  ZoomOut,
  Download,
  Loader2,
  Maximize,
  Minimize,
} from 'lucide-react';
import { Document, Page, pdfjs } from 'react-pdf';
import 'react-pdf/dist/esm/Page/AnnotationLayer.css';
import 'react-pdf/dist/esm/Page/TextLayer.css';
import { cn } from '@/lib/utils';

// Configure the worker to load pdfs.
pdfjs.GlobalWorkerOptions.workerSrc = `/pdf.worker.min.js`;

interface PdfViewerProps {
  isOpen: boolean;
  onOpenChange: (isOpen: boolean) => void;
  fileUrl: string;
  fileName: string;
}

export function PdfViewer({
  isOpen,
  onOpenChange,
  fileUrl,
  fileName,
}: PdfViewerProps) {
  const [numPages, setNumPages] = React.useState<number | null>(null);
  const [pageNumber, setPageNumber] = React.useState(1);
  const [scale, setScale] = React.useState(1.0);
  const [isLoading, setIsLoading] = React.useState(true);
  const [isFullscreen, setIsFullscreen] = React.useState(false);
  const viewerRef = React.useRef<HTMLDivElement>(null);

  function onDocumentLoadSuccess({ numPages }: { numPages: number }) {
    setNumPages(numPages);
    setPageNumber(1);
    setIsLoading(false);
  }

  function onDocumentLoadError(error: Error) {
    console.error('Failed to load PDF:', error);
    setIsLoading(false);
  }

  const goToPrevPage = () => {
    setPageNumber((prevPageNumber) => Math.max(prevPageNumber - 1, 1));
  };

  const goToNextPage = () => {
    setPageNumber((prevPageNumber) =>
      Math.min(prevPageNumber + 1, numPages || 1)
    );
  };

  const zoomIn = () => {
    setScale((prevScale) => Math.min(prevScale + 0.2, 3));
  };

  const zoomOut = () => {
    setScale((prevScale) => Math.max(prevScale - 0.2, 0.5));
  };
  
  const toggleFullscreen = () => {
    if (!viewerRef.current) return;

    if (!document.fullscreenElement) {
        viewerRef.current.requestFullscreen().catch(err => {
            console.error(`Error attempting to enable full-screen mode: ${err.message} (${err.name})`);
        });
    } else {
        document.exitFullscreen();
    }
  };

  React.useEffect(() => {
    const handleFullscreenChange = () => {
        setIsFullscreen(!!document.fullscreenElement);
    };
    document.addEventListener('fullscreenchange', handleFullscreenChange);
    return () => document.removeEventListener('fullscreenchange', handleFullscreenChange);
  }, []);

  React.useEffect(() => {
    if (isOpen) {
      setIsLoading(true);
      setNumPages(null);
      setPageNumber(1);
      setScale(1.0);
    }
  }, [isOpen, fileUrl]);

  return (
    <Dialog open={isOpen} onOpenChange={onOpenChange}>
      <DialogContent className="max-w-4xl w-full h-[90vh] flex flex-col p-0 gap-0">
        <div ref={viewerRef} className="flex flex-col w-full h-full bg-background">
            <DialogHeader className="p-4 border-b shrink-0">
            <DialogTitle className="truncate">{fileName}</DialogTitle>
            </DialogHeader>
            <div className="flex-1 overflow-auto flex items-center justify-center bg-muted/20 relative">
            {isLoading && (
                <div className="absolute inset-0 flex items-center justify-center bg-background/80 z-10">
                    <Loader2 className="h-8 w-8 animate-spin text-primary" />
                </div>
            )}
            <Document
                file={fileUrl}
                onLoadSuccess={onDocumentLoadSuccess}
                onLoadError={onDocumentLoadError}
                loading=""
            >
                <Page
                pageNumber={pageNumber}
                scale={scale}
                renderTextLayer={false}
                renderAnnotationLayer={false}
                loading=""
                className="flex justify-center"
                />
            </Document>
            </div>
            <DialogFooter className="p-2 border-t bg-background flex-wrap justify-between shrink-0">
            <div className="flex items-center gap-2">
                <Button
                variant="outline"
                size="icon"
                onClick={zoomOut}
                disabled={!numPages}
                >
                <ZoomOut className="h-4 w-4" />
                </Button>
                <span className="text-sm text-muted-foreground">{Math.round(scale * 100)}%</span>
                <Button
                variant="outline"
                size="icon"
                onClick={zoomIn}
                disabled={!numPages}
                >
                <ZoomIn className="h-4 w-4" />
                </Button>
                 <Button variant="outline" size="icon" onClick={toggleFullscreen}>
                    {isFullscreen ? <Minimize className="h-4 w-4" /> : <Maximize className="h-4 w-4" />}
                    <span className="sr-only">{isFullscreen ? 'Exit Fullscreen' : 'Enter Fullscreen'}</span>
                </Button>
            </div>
            <div className="flex items-center gap-2">
                <Button
                variant="outline"
                size="icon"
                onClick={goToPrevPage}
                disabled={pageNumber <= 1}
                >
                <ChevronLeft className="h-4 w-4" />
                </Button>
                <span className="text-sm text-muted-foreground">
                Page {pageNumber} of {numPages || '...'}
                </span>
                <Button
                variant="outline"
                size="icon"
                onClick={goToNextPage}
                disabled={!numPages || pageNumber >= numPages}
                >
                <ChevronRight className="h-4 w-4" />
                </Button>
            </div>
            <div className="flex items-center gap-2">
                <a href={fileUrl} download={fileName}>
                    <Button variant="default">
                        <Download className="mr-2 h-4 w-4" />
                        Download
                    </Button>
                </a>
                <DialogClose asChild>
                    <Button variant="outline">Close</Button>
                </DialogClose>
            </div>
            </DialogFooter>
        </div>
      </DialogContent>
    </Dialog>
  );
}