const extensionAssetsPath = mw.config.get( 'wgExtensionAssetsPath' );
window.MathJax = {
	loader: {
		// see https://docs.mathjax.org/en/latest/input/mathml.html
		load: [ '[mml]/mml3' ],
		// see https://docs.mathjax.org/en/latest/options/startup/loader.html
		paths: {
			mathjax: extensionAssetsPath + '/Math/modules/mathjax/es5'
		}
	},
	// helper function for https://phabricator.wikimedia.org/T375932
	/* eslint-disable no-return-assign */
	remapChars( v1, v2, base, map, font ) {
		const c1 = v1.chars;
		const c2 = v2.chars;
		for ( let i = 0; i < 26; i++ ) {
			const data1 = c1[ map[ i ] || base + i ] || [];
			const data2 = c2[ 0x41 + i ];
			if ( data1.length === 0 ) {
				c1[ base + i ] = data1;
			}
			[ 0, 1, 2 ].forEach( ( j ) => data1[ j ] = data2[ j ] );
			data1[ 3 ] = Object.assign( {}, data2[ 3 ], { f: font, c: String.fromCharCode( 0x41 + i ) } );
		}
	},

	startup: {
		ready() {
			window.MathJax.startup.defaultReady();
			// See https://phabricator.wikimedia.org/T375932 and the suggested fix from
			// https://github.com/mathjax/MathJax/issues/3292#issuecomment-2383760829
			// Makes rendering of \matcal look similar to the browsers MathML rendering
			// and the old image rendering.
			// Note that \mathsrc (which is unsupported by texvc) would map to the
			// same unicode chars and thus should not be activated.
			const variant = window.MathJax.startup.document.outputJax.font.variant;
			const map = { 1: 0x212C, 4: 0x2130, 5: 0x2131, 7: 0x210B, 8: 0x2110, 11: 0x2112, 12: 0x2133, 17: 0x211B };
			window.MathJax.config.remapChars( variant.normal, variant[ '-tex-calligraphic' ], 0x1D49C, map, 'C' );
			window.MathJax.config.remapChars( variant.normal, variant[ '-tex-bold-calligraphic' ], 0x1D4D0, {}, 'CB' );
			// See https://phabricator.wikimedia.org/T375241 and the suggested startup function from
			// https://github.com/mathjax/MathJax/issues/3030#issuecomment-1490520850
			// This workaround will be included in the MathJax 4 release and no longer be
			// required when we upgrade to MathJax 4.
			const { Mml3 } = window.MathJax._.input.mathml.mml3.mml3;
			const mml3 = new Mml3( window.MathJax.startup.document );
			const adaptor = window.MathJax.startup.document.adaptor;
			const processor = new XSLTProcessor();
			const parsed = adaptor.parse( Mml3.XSLT, 'text/xml' );
			processor.importStylesheet( parsed );
			mml3.transform = ( node ) => {
				// MathJax does not support a-tags but it supports href attributes in math elements
				[].forEach.call( document.querySelectorAll( 'mi a, mo a, mtext a' ), ( aTag ) => {
					const parentElement = aTag.parentElement;
					if ( aTag.hasAttribute( 'href' ) ) {
						parentElement.setAttribute( 'href', aTag.getAttribute( 'href' ) );
						parentElement.setAttribute( 'title', aTag.getAttribute( 'title' ) );
					}
					parentElement.textContent = aTag.textContent;
				} );
				const div = adaptor.node( 'div', {}, [ adaptor.clone( node ) ] );
				const dom = adaptor.parse( adaptor.serializeXML( div ), 'text/xml' );
				const mml = processor.transformToDocument( dom );
				return ( mml ? adaptor.tags( mml, 'math' )[ 0 ] : node );
			};
			// inputJax[0] did not work as per https://github.com/mathjax/MathJax/issues/3287#issuecomment-2363843017
			const MML = window.MathJax.startup.document.inputJax[ 1 ];
			MML.mmlFilters.items.pop(); // remove old filter
			MML.mmlFilters.add( mml3.mmlFilter.bind( mml3 ) );
			// Add title attribute for popups
			window.MathJax.typesetPromise().then( () => {
				[].forEach.call( document.querySelectorAll( 'a [title]' ), ( ( child ) => {
					const parentAnchor = child.closest( 'a' );
					const title = child.getAttribute( 'title' );
					if ( parentAnchor && title ) {
						parentAnchor.setAttribute( 'title', title );
						child.removeAttribute( 'title' );
					}
				} ) );
			} );
		}
	}
};
