'use client'

import { useState, useRef, useCallback, useEffect } from 'react'

interface DocumentViewerProps {
  fileUrl: string
  fileType: 'pdf' | 'image'
  currentPage: number
  totalPages: number
  onPageChange: (page: number) => void
  children?: React.ReactNode // For annotation overlay
  className?: string
}

export function DocumentViewer({
  fileUrl,
  fileType,
  currentPage,
  totalPages,
  onPageChange,
  children,
  className = '',
}: DocumentViewerProps) {
  const [zoom, setZoom] = useState(1)
  const [isDragging, setIsDragging] = useState(false)
  const [position, setPosition] = useState({ x: 0, y: 0 })
  const [startPos, setStartPos] = useState({ x: 0, y: 0 })
  const containerRef = useRef<HTMLDivElement>(null)

  const handleZoomIn = () => setZoom((prev) => Math.min(prev + 0.25, 3))
  const handleZoomOut = () => setZoom((prev) => Math.max(prev - 0.25, 0.5))
  const handleFit = () => {
    setZoom(1)
    setPosition({ x: 0, y: 0 })
  }

  const handleMouseDown = (e: React.MouseEvent) => {
    if (e.button !== 1 && !e.ctrlKey) return // Middle click or Ctrl+click for pan
    setIsDragging(true)
    setStartPos({ x: e.clientX - position.x, y: e.clientY - position.y })
  }

  const handleMouseMove = useCallback(
    (e: MouseEvent) => {
      if (!isDragging) return
      setPosition({
        x: e.clientX - startPos.x,
        y: e.clientY - startPos.y,
      })
    },
    [isDragging, startPos]
  )

  const handleMouseUp = useCallback(() => {
    setIsDragging(false)
  }, [])

  useEffect(() => {
    if (isDragging) {
      window.addEventListener('mousemove', handleMouseMove)
      window.addEventListener('mouseup', handleMouseUp)
    }
    return () => {
      window.removeEventListener('mousemove', handleMouseMove)
      window.removeEventListener('mouseup', handleMouseUp)
    }
  }, [isDragging, handleMouseMove, handleMouseUp])

  // Keyboard shortcuts
  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key === '+' || e.key === '=') {
        e.preventDefault()
        handleZoomIn()
      } else if (e.key === '-') {
        e.preventDefault()
        handleZoomOut()
      } else if (e.key === '0') {
        e.preventDefault()
        handleFit()
      } else if (e.key === 'ArrowLeft' && currentPage > 1) {
        e.preventDefault()
        onPageChange(currentPage - 1)
      } else if (e.key === 'ArrowRight' && currentPage < totalPages) {
        e.preventDefault()
        onPageChange(currentPage + 1)
      }
    }

    window.addEventListener('keydown', handleKeyDown)
    return () => window.removeEventListener('keydown', handleKeyDown)
  }, [currentPage, totalPages, onPageChange])

  return (
    <div className={`flex flex-col h-full ${className}`}>
      {/* Toolbar */}
      <div className="flex items-center justify-between px-4 py-2 bg-white/5 border-b border-white/10">
        <div className="flex items-center gap-2">
          <button
            onClick={handleZoomOut}
            className="p-2 rounded-lg hover:bg-white/10 text-white/60 hover:text-white transition-colors"
            title="Verkleinern (-)"
          >
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0zM13 10H7" />
            </svg>
          </button>
          <span className="text-white/60 text-sm min-w-[60px] text-center">
            {Math.round(zoom * 100)}%
          </span>
          <button
            onClick={handleZoomIn}
            className="p-2 rounded-lg hover:bg-white/10 text-white/60 hover:text-white transition-colors"
            title="Vergroessern (+)"
          >
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0zM10 7v3m0 0v3m0-3h3m-3 0H7" />
            </svg>
          </button>
          <button
            onClick={handleFit}
            className="p-2 rounded-lg hover:bg-white/10 text-white/60 hover:text-white transition-colors"
            title="Einpassen (0)"
          >
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 8V4m0 0h4M4 4l5 5m11-1V4m0 0h-4m4 0l-5 5M4 16v4m0 0h4m-4 0l5-5m11 5l-5-5m5 5v-4m0 4h-4" />
            </svg>
          </button>
        </div>

        {/* Page Navigation */}
        {totalPages > 1 && (
          <div className="flex items-center gap-2">
            <button
              onClick={() => onPageChange(currentPage - 1)}
              disabled={currentPage <= 1}
              className="p-2 rounded-lg hover:bg-white/10 text-white/60 hover:text-white transition-colors disabled:opacity-30"
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" />
              </svg>
            </button>
            <span className="text-white/60 text-sm">
              {currentPage} / {totalPages}
            </span>
            <button
              onClick={() => onPageChange(currentPage + 1)}
              disabled={currentPage >= totalPages}
              className="p-2 rounded-lg hover:bg-white/10 text-white/60 hover:text-white transition-colors disabled:opacity-30"
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" />
              </svg>
            </button>
          </div>
        )}
      </div>

      {/* Document Area */}
      <div
        ref={containerRef}
        className="flex-1 overflow-hidden bg-slate-800/50 relative"
        onMouseDown={handleMouseDown}
        style={{ cursor: isDragging ? 'grabbing' : 'default' }}
      >
        <div
          className="absolute inset-0 flex items-center justify-center"
          style={{
            transform: `translate(${position.x}px, ${position.y}px) scale(${zoom})`,
            transformOrigin: 'center center',
            transition: isDragging ? 'none' : 'transform 0.2s ease-out',
          }}
        >
          {/* Document Image/PDF */}
          <div className="relative">
            {fileType === 'image' ? (
              <img
                src={fileUrl}
                alt="Schuelerarbeit"
                className="max-w-full max-h-full object-contain shadow-2xl"
                draggable={false}
              />
            ) : (
              <iframe
                src={`${fileUrl}#page=${currentPage}`}
                className="w-[800px] h-[1000px] bg-white shadow-2xl"
                title="PDF Dokument"
              />
            )}

            {/* Annotation Overlay */}
            {children && (
              <div className="absolute inset-0 pointer-events-none">
                {children}
              </div>
            )}
          </div>
        </div>
      </div>

      {/* Page Thumbnails (for multi-page) */}
      {totalPages > 1 && (
        <div className="flex gap-2 p-3 bg-white/5 border-t border-white/10 overflow-x-auto">
          {Array.from({ length: totalPages }, (_, i) => i + 1).map((page) => (
            <button
              key={page}
              onClick={() => onPageChange(page)}
              className={`flex-shrink-0 w-12 h-16 rounded-lg border-2 flex items-center justify-center text-sm font-medium transition-all ${
                page === currentPage
                  ? 'border-purple-500 bg-purple-500/20 text-white'
                  : 'border-white/10 bg-white/5 text-white/60 hover:border-white/30'
              }`}
            >
              {page}
            </button>
          ))}
        </div>
      )}
    </div>
  )
}