import React, { useState, useCallback } from 'react';

import { IAttachmentHasId } from '@growi/core';
import { Property } from 'csstype';
import Carousel, { Modal, ModalGateway } from 'react-images';

import { RefsContext } from './util/refs-context';

type Props = {
  attachments: IAttachmentHasId[],
  refsContext: RefsContext,
};

/**
 *  1. when 'fileFormat' is image, render Attachment as an image
 *  2. when 'fileFormat' is not image, render Attachment as an Attachment component
 */
export const ExtractedAttachments = React.memo(({
  attachments,
  refsContext,
}: Props): JSX.Element => {

  const [showCarousel, setShowCarousel] = useState(false);
  const [currentIndex, setCurrentIndex] = useState<number | null>(null);

  const imageClickedHandler = useCallback((index: number) => {
    setShowCarousel(true);
    setCurrentIndex(index);
  }, []);

  const getAttachmentsFilteredByFormat = useCallback(() => {
    return attachments
      .filter(attachment => attachment.fileFormat.startsWith('image/'));
  }, []);

  const getClassesAndStylesForNonGrid = useCallback(() => {
    const { options } = refsContext;

    const width = options?.width;
    const height = options?.height;
    const maxWidth = options?.maxWidth;
    const maxHeight = options?.maxHeight;
    const display = options?.display || 'block';

    const containerStyles = {
      width, height, maxWidth, maxHeight, display,
    };

    const imageClasses = [];
    const imageStyles = {
      width, height, maxWidth, maxHeight,
    };

    return {
      containerStyles,
      imageClasses,
      imageStyles,
    };
  }, []);

  const getClassesAndStylesForGrid = useCallback(() => {
    const { options } = refsContext;

    const maxWidth = options?.maxWidth;
    const maxHeight = options?.maxHeight;

    const containerStyles = {
      width: refsContext.getOptGridWidth(),
      height: refsContext.getOptGridHeight(),
      maxWidth,
      maxHeight,
    };

    const imageClasses = ['w-100', 'h-100'];
    const imageStyles = {
      objectFit: 'cover' as Property.ObjectFit,
      maxWidth,
      maxHeight,
    };

    return {
      containerStyles,
      imageClasses,
      imageStyles,
    };
  }, []);

  /**
   * wrapper method for getClassesAndStylesForGrid/getClassesAndStylesForNonGrid
   */
  const getClassesAndStyles = useCallback(() => {
    const { options } = refsContext;

    return (options?.grid != null)
      ? getClassesAndStylesForGrid()
      : getClassesAndStylesForNonGrid();
  }, []);

  const renderExtractedImage = useCallback((attachment: IAttachmentHasId, index: number) => {
    const { options } = refsContext;

    // determine alt
    let alt = refsContext.isSingle ? options?.alt : undefined; // use only when single mode
    alt = alt || attachment.originalName; //                     use 'originalName' if options.alt is not specified

    // get styles
    const {
      containerStyles, imageClasses, imageStyles,
    } = getClassesAndStyles();

    // carousel settings
    let onClick;
    if (options?.noCarousel == null) {
      // pointer cursor
      Object.assign(containerStyles, { cursor: 'pointer' });
      // set click handler
      onClick = () => {
        imageClickedHandler(index);
      };
    }

    return (
      <div key={attachment._id} style={containerStyles} onClick={onClick}>
        <img src={attachment.filePathProxied} alt={alt} className={imageClasses.join(' ')} style={imageStyles} />
      </div>
    );
  }, []);

  const renderCarousel = useCallback(() => {
    const { options } = refsContext;
    const withCarousel = options?.noCarousel == null;

    const images = getAttachmentsFilteredByFormat()
      .map((attachment) => {
        return { src: attachment.filePathProxied };
      });

    // overwrite react-images modal styles
    const zIndex = 1030; // > grw-navbar
    const modalStyles = {
      blanket: (styleObj) => {
        return Object.assign(styleObj, { zIndex });
      },
      positioner: (styleObj) => {
        return Object.assign(styleObj, { zIndex });
      },
    };

    return (
      <ModalGateway>
        { withCarousel && showCarousel && (
          <Modal styles={modalStyles} onClose={() => { setShowCarousel(false) }}>
            <Carousel views={images} currentIndex={currentIndex} />
          </Modal>
        ) }
      </ModalGateway>
    );
  }, []);

  const { options } = refsContext;
  const grid = options?.grid;
  const gridGap = options?.gridGap;

  const styles = {};

  // Grid mode
  if (grid != null) {

    const gridTemplateColumns = (refsContext.isOptGridColumnEnabled())
      ? `repeat(${refsContext.getOptGridColumnsNum()}, 1fr)`
      : `repeat(auto-fill, ${refsContext.getOptGridWidth()})`;

    Object.assign(styles, {
      display: 'grid',
      gridTemplateColumns,
      gridAutoRows: '1fr',
      gridGap,
    });

  }

  const contents = getAttachmentsFilteredByFormat()
    .map((attachment, index) => renderExtractedImage(attachment, index));

  return (
    <React.Fragment>
      <div style={styles}>
        {contents}
      </div>

      { renderCarousel() }
    </React.Fragment>
  );
});