import React, { useEffect, useRef } from 'react';
import type { PdfFile } from '../pdf/pdfTypes';
import * as pdfjsLib from 'pdfjs-dist';
import pdfjsWorker from 'pdfjs-dist/build/pdf.worker?worker&url';

// pdf.js worker setup
// eslint-disable-next-line @typescript-eslint/no-explicit-any
(pdfjsLib as any).GlobalWorkerOptions.workerSrc = pdfjsWorker;

interface PagePreviewModalProps {
  isOpen: boolean;
  pdf: PdfFile | null;
  pageIndex: number | null;        // original page index, 0-based
  rotation: number;                // degrees

  visualIndex: number | null;      // current position in order, 0-based
  totalPages: number;

  canGoPrevious: boolean;
  canGoNext: boolean;
  onPrevious: () => void;
  onNext: () => void;

  onClose: () => void;
}

const PagePreviewModal: React.FC<PagePreviewModalProps> = ({
  isOpen,
  pdf,
  pageIndex,
  rotation,
  visualIndex,
  totalPages,
  canGoPrevious,
  canGoNext,
  onPrevious,
  onNext,
  onClose,
}) => {
  const canvasRef = useRef<HTMLCanvasElement | null>(null);

  useEffect(() => {
    if (!isOpen) return;

    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key === 'Escape') {
        e.preventDefault();
        onClose();
        return;
      }

      if (e.key === 'ArrowLeft' && canGoPrevious) {
        e.preventDefault();
        onPrevious();
        return;
      }

      if (e.key === 'ArrowRight' && canGoNext) {
        e.preventDefault();
        onNext();
      }
    };

    window.addEventListener('keydown', handleKeyDown);

    return () => {
      window.removeEventListener('keydown', handleKeyDown);
    };
  }, [isOpen, canGoPrevious, canGoNext, onPrevious, onNext, onClose]);

  useEffect(() => {
    if (!isOpen || !pdf || pageIndex == null) return;

    let cancelled = false;

    (async () => {
      try {
        const canvas = canvasRef.current;
        if (canvas) {
          const ctx = canvas.getContext('2d');
          if (ctx) {
            ctx.clearRect(0, 0, canvas.width, canvas.height);
          }
        }

        // copy data for pdf.js (avoid detaching original ArrayBuffer)
        const src = new Uint8Array(pdf.arrayBuffer);
        const copy = new Uint8Array(src.byteLength);
        copy.set(src);

        const loadingTask = pdfjsLib.getDocument({ data: copy });
        const doc = await loadingTask.promise;
        if (cancelled) return;

        const page = await doc.getPage(pageIndex + 1);
        if (cancelled) return;

        const viewport = page.getViewport({ scale: 1 });

        const maxWidth = Math.min(window.innerWidth * 0.9, 800);
        const maxHeight = window.innerHeight * 0.75;

        const scale = Math.min(
          maxWidth / viewport.width,
          maxHeight / viewport.height
        );

        const scaledViewport = page.getViewport({ scale });

        const visibleCanvas = canvasRef.current;
        if (!visibleCanvas) return;

        const visibleCtx = visibleCanvas.getContext('2d');
        if (!visibleCtx) return;

        let canvasWidth = scaledViewport.width;
        let canvasHeight = scaledViewport.height;

        const angle = ((rotation % 360) + 360) % 360;

        if (angle === 90 || angle === 270) {
          canvasWidth = scaledViewport.height;
          canvasHeight = scaledViewport.width;
        }

        visibleCanvas.width = canvasWidth;
        visibleCanvas.height = canvasHeight;

        const baseCanvas = document.createElement('canvas');
        const baseCtx = baseCanvas.getContext('2d');
        if (!baseCtx) return;

        baseCanvas.width = scaledViewport.width;
        baseCanvas.height = scaledViewport.height;

        const renderTask = page.render({
          canvasContext: baseCtx,
          viewport: scaledViewport,
        });

        await renderTask.promise;
        if (cancelled) return;

        visibleCtx.save();

        switch (angle) {
          case 90:
            visibleCtx.translate(canvasWidth, 0);
            visibleCtx.rotate((angle * Math.PI) / 180);
            break;
          case 180:
            visibleCtx.translate(canvasWidth, canvasHeight);
            visibleCtx.rotate((angle * Math.PI) / 180);
            break;
          case 270:
            visibleCtx.translate(0, canvasHeight);
            visibleCtx.rotate((angle * Math.PI) / 180);
            break;
        }

        visibleCtx.drawImage(baseCanvas, 0, 0);
        visibleCtx.restore();
      } catch (e) {
        console.error('Error rendering preview', e);
      }
    })();

    return () => {
      cancelled = true;
    };
  }, [isOpen, pdf, pageIndex, rotation]);

  if (!isOpen || !pdf || pageIndex == null) return null;

  const positionLabel =
    visualIndex != null && visualIndex >= 0
      ? `${visualIndex + 1} / ${totalPages}`
      : `Page ${pageIndex + 1}`;

  return (
    <div
      onClick={onClose}
      style={{
        position: 'fixed',
        inset: 0,
        background: 'rgba(15, 23, 42, 0.8)',
        zIndex: 50,
        display: 'flex',
        justifyContent: 'center',
        alignItems: 'center',
        padding: '1rem',
      }}
    >
      <div
        onClick={(e) => e.stopPropagation()}
        style={{
          position: 'relative',
          background: '#111827',
          borderRadius: '0.75rem',
          padding: '0.75rem',
          maxWidth: '90vw',
          maxHeight: '90vh',
          display: 'flex',
          flexDirection: 'column',
          alignItems: 'center',
          gap: '0.5rem',
          overflow: 'visible',
        }}
      >
        {/* Previous page */}
        <button
          type="button"
          onClick={(e) => {
            e.stopPropagation();
            onPrevious();
          }}
          disabled={!canGoPrevious}
          style={{
            position: 'absolute',
            left: 0,
            top: '50%',
            transform: 'translate(-50%, -50%)',
            width: '2.5rem',
            height: '2.5rem',
            borderRadius: '999px',
            border: 'none',
            background: canGoPrevious ? '#374151' : '#1f2937',
            color: canGoPrevious ? '#e5e7eb' : '#6b7280',
            cursor: canGoPrevious ? 'pointer' : 'default',
            fontSize: '1.35rem',
            lineHeight: 1,
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center',
            zIndex: 2,
          }}
          title="Previous page (←)"
          aria-label="Previous page"
        >
          ◀
        </button>

        {/* Next page */}
        <button
          type="button"
          onClick={(e) => {
            e.stopPropagation();
            onNext();
          }}
          disabled={!canGoNext}
          style={{
            position: 'absolute',
            right: 0,
            top: '50%',
            transform: 'translate(50%, -50%)',
            width: '2.5rem',
            height: '2.5rem',
            borderRadius: '999px',
            border: 'none',
            background: canGoNext ? '#374151' : '#1f2937',
            color: canGoNext ? '#e5e7eb' : '#6b7280',
            cursor: canGoNext ? 'pointer' : 'default',
            fontSize: '1.35rem',
            lineHeight: 1,
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center',
            zIndex: 2,
          }}
          title="Next page (→)"
          aria-label="Next page"
        >
          ▶
        </button>

        {/* Close */}
        <button
          type="button"
          onClick={(e) => {
            e.stopPropagation();
            onClose();
          }}
          style={{
            position: 'absolute',
            top: 0,
            right: 0,
            transform: 'translate(50%, -50%)',
            width: '2.25rem',
            height: '2.25rem',
            borderRadius: '999px',
            border: 'none',
            background: '#374151',
            color: '#e5e7eb',
            cursor: 'pointer',
            fontSize: '1.2rem',
            lineHeight: 1,
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center',
            zIndex: 3,
          }}
          title="Close preview (Esc)"
          aria-label="Close preview"
        >
          ×
        </button>

        <canvas
          ref={canvasRef}
          style={{
            maxWidth: '100%',
            maxHeight: '75vh',
            background: 'white',
            borderRadius: '0.5rem',
          }}
        />

        <div style={{ color: '#e5e7eb', fontSize: '0.85rem' }}>
          {positionLabel} · Original page {pageIndex + 1} · Rot {rotation}°
        </div>
      </div>
    </div>
  );
};

export default PagePreviewModal;