{
  "version": 3,
  "sources": ["../../src/assets/styles.ts"],
  "sourcesContent": ["/**\n * Internal dependencies\n */\nimport { shortestCommonSupersequence } from './scs';\n\nexport type StyleElement = HTMLLinkElement | HTMLStyleElement;\n\n/**\n * Compares the passed style or link elements to check if they can be\n * considered equal.\n *\n * @param a `<style>` or `<link>` element.\n * @param b `<style>` or `<link>` element.\n * @return Whether they are considered equal.\n */\nconst areNodesEqual = ( a: StyleElement, b: StyleElement ): boolean =>\n\ta.isEqualNode( b );\n\n/**\n * Normalizes the passed style or link element, reverting the changes\n * made by {@link prepareStylePromise|`prepareStylePromise`} to the\n * `data-original-media` and `media`.\n *\n * @example\n * The following elements should be normalized to the same element:\n * ```html\n * <link rel=\"stylesheet\" src=\"./assets/styles.css\">\n * <link rel=\"stylesheet\" src=\"./assets/styles.css\" media=\"all\">\n * <link rel=\"stylesheet\" src=\"./assets/styles.css\" media=\"preload\">\n * <link rel=\"stylesheet\" src=\"./assets/styles.css\" media=\"preload\" data-original-media=\"all\">\n * ```\n *\n * @param element `<style>` or `<link>` element.\n * @return Normalized node.\n */\nexport const normalizeMedia = ( element: StyleElement ): StyleElement => {\n\telement = element.cloneNode( true ) as StyleElement;\n\tconst media = element.media;\n\tconst { originalMedia } = element.dataset;\n\n\tif ( media === 'preload' ) {\n\t\telement.media = originalMedia || 'all';\n\t\telement.removeAttribute( 'data-original-media' );\n\t} else if ( ! element.media ) {\n\t\telement.media = 'all';\n\t}\n\treturn element;\n};\n\n/**\n * Adds the minimum style elements from Y around those in X using a\n * shortest common supersequence algorithm, returning a list of\n * promises for all the elements in Y.\n *\n * If X is empty, it appends all elements in Y to the passed parent\n * element or to `document.head` instead.\n *\n * The returned promises resolve once the corresponding style element\n * is loaded and ready. Those elements that are also in X return a\n * cached promise.\n *\n * The algorithm ensures that the final style elements present in the\n * document (or the passed `parent` element) are in the correct order\n * and they are included in either X or Y.\n *\n * @param X      Base list of style elements.\n * @param Y      List of style elements.\n * @param parent Optional parent element to append to the new style elements.\n * @return List of promises that resolve once the elements in Y are ready.\n */\nexport function updateStylesWithSCS(\n\tX: StyleElement[],\n\tY: StyleElement[],\n\tparent: Element = window.document.head\n) {\n\tif ( X.length === 0 ) {\n\t\treturn Y.map( ( element ) => {\n\t\t\tconst promise = prepareStylePromise( element );\n\t\t\tparent.appendChild( element );\n\t\t\treturn promise;\n\t\t} );\n\t}\n\n\t// Create normalized arrays for comparison.\n\tconst xNormalized = X.map( normalizeMedia );\n\tconst yNormalized = Y.map( normalizeMedia );\n\n\t// The `scs` array contains normalized elements.\n\tconst scs = shortestCommonSupersequence(\n\t\txNormalized,\n\t\tyNormalized,\n\t\tareNodesEqual\n\t);\n\tconst xLength = X.length;\n\tconst yLength = Y.length;\n\tconst promises = [];\n\tlet last = X[ xLength - 1 ];\n\tlet xIndex = 0;\n\tlet yIndex = 0;\n\n\tfor ( const scsElement of scs ) {\n\t\t// Actual elements that will end up in the DOM.\n\t\tconst xElement = X[ xIndex ];\n\t\tconst yElement = Y[ yIndex ];\n\t\t// Normalized elements for comparison.\n\t\tconst xNormEl = xNormalized[ xIndex ];\n\t\tconst yNormEl = yNormalized[ yIndex ];\n\t\tif ( xIndex < xLength && areNodesEqual( xNormEl, scsElement ) ) {\n\t\t\tif ( yIndex < yLength && areNodesEqual( yNormEl, scsElement ) ) {\n\t\t\t\tpromises.push( prepareStylePromise( xElement ) );\n\t\t\t\tyIndex++;\n\t\t\t}\n\t\t\txIndex++;\n\t\t} else {\n\t\t\tpromises.push( prepareStylePromise( yElement ) );\n\t\t\tif ( xIndex < xLength ) {\n\t\t\t\txElement.before( yElement );\n\t\t\t} else {\n\t\t\t\tlast.after( yElement );\n\t\t\t\tlast = yElement;\n\t\t\t}\n\t\t\tyIndex++;\n\t\t}\n\t}\n\n\treturn promises;\n}\n\n/**\n * Cache of promises per style elements.\n *\n * Each style element has their own associated `Promise` that resolves\n * once the element has been loaded and is ready.\n */\nconst stylePromiseCache = new WeakMap<\n\tStyleElement,\n\tPromise< StyleElement >\n>();\n\n/**\n * Prepares and returns the corresponding `Promise` for the passed style\n * element.\n *\n * It returns the cached promise if it exists. Otherwise, constructs\n * a `Promise` that resolves once the element has finished loading.\n *\n * For those elements that are not in the DOM yet, this function\n * injects a `media=\"preload\"` attribute to the passed element so the\n * style is loaded without applying any styles to the document.\n *\n * @param element Style element.\n * @return The associated `Promise` to the passed element.\n */\nconst prepareStylePromise = (\n\telement: StyleElement\n): Promise< StyleElement > => {\n\tif ( stylePromiseCache.has( element ) ) {\n\t\treturn stylePromiseCache.get( element );\n\t}\n\n\t// When the element exists in the main document and its media attribute\n\t// is not \"preload\", that means the element comes from the initial page.\n\t// The `media` attribute doesn't need to be handled in this case.\n\tif ( window.document.contains( element ) && element.media !== 'preload' ) {\n\t\tconst promise = Promise.resolve( element );\n\t\tstylePromiseCache.set( element, promise );\n\t\treturn promise;\n\t}\n\n\tif ( element.hasAttribute( 'media' ) && element.media !== 'all' ) {\n\t\telement.dataset.originalMedia = element.media;\n\t}\n\n\telement.media = 'preload';\n\n\tif ( element instanceof HTMLStyleElement ) {\n\t\tconst promise = Promise.resolve( element );\n\t\tstylePromiseCache.set( element, promise );\n\t\treturn promise;\n\t}\n\n\tconst promise = new Promise< HTMLLinkElement >( ( resolve, reject ) => {\n\t\telement.addEventListener( 'load', () => resolve( element ) );\n\t\telement.addEventListener( 'error', ( event ) => {\n\t\t\tconst { href } = event.target as HTMLLinkElement;\n\t\t\treject(\n\t\t\t\tError(\n\t\t\t\t\t`The style sheet with the following URL failed to load: ${ href }`\n\t\t\t\t)\n\t\t\t);\n\t\t} );\n\t} );\n\n\tstylePromiseCache.set( element, promise );\n\treturn promise;\n};\n\n/**\n * Prepares all style elements contained in the passed document.\n *\n * This function calls {@link updateStylesWithSCS|`updateStylesWithSCS`}\n * to insert only the minimum amount of style elements into the DOM, so\n * those present in the passed document end up in the DOM while the order\n * is respected.\n *\n * New appended style elements contain a `media=preload` attribute to\n * make them effectively disabled until they are applied with the\n * {@link applyStyles|`applyStyles`} function.\n *\n * Note that this function alters the passed document, as it can transfer\n * nodes from it to the global document.\n *\n * @param doc Document instance.\n * @return A list of promises for each style element in the passed document.\n */\nexport const preloadStyles = ( doc: Document ): Promise< StyleElement >[] => {\n\tconst currentStyleElements = Array.from(\n\t\twindow.document.querySelectorAll< StyleElement >(\n\t\t\t'style,link[rel=stylesheet]'\n\t\t)\n\t);\n\tconst newStyleElements = Array.from(\n\t\tdoc.querySelectorAll< StyleElement >( 'style,link[rel=stylesheet]' )\n\t);\n\n\t// Set styles in order.\n\treturn updateStylesWithSCS( currentStyleElements, newStyleElements );\n};\n\n/**\n * Traverses all style elements in the DOM, enabling only those included\n * in the passed list and disabling the others.\n *\n * If the style element has the `data-original-media` attribute, the\n * original `media` value is restored.\n *\n * @param styles List of style elements to apply.\n */\nexport const applyStyles = ( styles: StyleElement[] ) => {\n\twindow.document\n\t\t.querySelectorAll( 'style,link[rel=stylesheet]' )\n\t\t.forEach( ( el: HTMLLinkElement | HTMLStyleElement ) => {\n\t\t\tif ( el.sheet ) {\n\t\t\t\tif ( styles.includes( el ) ) {\n\t\t\t\t\t// Only update mediaText when necessary.\n\t\t\t\t\tif ( el.sheet.media.mediaText === 'preload' ) {\n\t\t\t\t\t\tconst { originalMedia = 'all' } = el.dataset;\n\t\t\t\t\t\tel.sheet.media.mediaText = originalMedia;\n\t\t\t\t\t}\n\t\t\t\t\tel.sheet.disabled = false;\n\t\t\t\t} else {\n\t\t\t\t\tel.sheet.disabled = true;\n\t\t\t\t}\n\t\t\t}\n\t\t} );\n};\n"],
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