import { useEffect, useRef, useState } from '@wordpress/element';
import { __ } from '@wordpress/i18n';
import { Lang, Theme } from 'shiki';
import { useTheme } from '../../hooks/useTheme';

type ThemePreviewProps = {
    id: string;
    theme: Theme;
    lang: Lang;
    code: string;
    fontSize: string;
    lineHeight: string;
    fontFamily: string;
    onClick: () => void;
};
export const ThemePreview = ({
    id,
    theme,
    lang,
    onClick,
    code,
    fontSize,
    lineHeight,
    fontFamily,
}: ThemePreviewProps) => {
    const [inView, setInView] = useState(false);
    const { highlighter, error, loading } = useTheme({
        theme,
        // If no code is written yet, show a classic Carmack snippet
        lang: code ? lang : 'c',
        ready: inView,
    });
    const [codeRendered, setCode] = useState('');
    const [backgroundColor, setBg] = useState('#ffffff');
    const observer = useRef<IntersectionObserver>(
        new IntersectionObserver(([entry]) => {
            if (entry.isIntersecting) {
                setInView(true);
                observer.current.disconnect();
            }
        }),
    );
    const codeSnippet = `
float Q_rsqrt( float number )
{
    long i;
    float x2, y;
    const float threehalfs = 1.5F;

    x2 = number * 0.5F;
    y  = number;
    i  = * ( long * ) &y;                       // evil floating point bit level hacking
    i  = 0x5f3759df - ( i >> 1 );               // what the frack?
    y  = * ( float * ) &i;
    y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
//  y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}`.trim();

    useEffect(() => {
        if (!highlighter) return;
        const hl = code
            ? highlighter.codeToHtml(code, { lang })
            : highlighter.codeToHtml(codeSnippet, { lang: 'c' });
        setCode(hl);
        setBg(highlighter.getBackgroundColor());
    }, [highlighter, lang, code, codeSnippet]);

    return (
        <button
            id={id}
            type="button"
            onClick={onClick}
            className="p-4 px-3 border flex items-start w-full text-left outline-none cursor-pointer no-underline ring-offset-2 ring-offset-white focus:shadow-none focus:ring-wp overflow-x-auto max-h-80 overflow-y-hidden"
            style={{ backgroundColor, minHeight: '50px' }}>
            {loading || error || !inView ? (
                <span
                    id={id}
                    ref={(el) => {
                        if (!el) return;
                        observer.current.observe(el);
                    }}
                    style={{ minHeight: '200px' }}
                    className="flex items-center justify-center p-6 w-full">
                    {error?.message || __('Loading...', 'code-block-pro')}
                </span>
            ) : (
                <span
                    className="pointer-events-none"
                    style={{
                        fontSize: fontSize,
                        // Tiny check to avoid block invalidation error
                        fontFamily: fontFamily,
                        lineHeight: lineHeight,
                    }}
                    dangerouslySetInnerHTML={{ __html: codeRendered }}
                />
            )}
        </button>
    );
};