import { createRequire } from 'module';

const require = createRequire(import.meta.url);
const mdnAtrules = require('mdn-data/css/at-rules.json');
const mdnProperties = require('mdn-data/css/properties.json');
const mdnSyntaxes = require('mdn-data/css/syntaxes.json');
const patch = require('../data/patch.json');

const extendSyntax = /^\s*\|\s*/;

function preprocessAtrules(dict) {
    const result = Object.create(null);

    for (const atruleName in dict) {
        const atrule = dict[atruleName];
        let descriptors = null;

        if (atrule.descriptors) {
            descriptors = Object.create(null);

            for (const descriptor in atrule.descriptors) {
                descriptors[descriptor] = atrule.descriptors[descriptor].syntax;
            }
        }

        result[atruleName.substr(1)] = {
            prelude: atrule.syntax.trim().match(/^@\S+\s+([^;\{]*)/)[1].trim() || null,
            descriptors
        };
    }

    return result;
}

function patchDictionary(dict, patchDict) {
    const result = {};

    // copy all syntaxes for an original dict
    for (const key in dict) {
        result[key] = dict[key].syntax || dict[key];
    }

    // apply a patch
    for (const key in patchDict) {
        if (key in dict) {
            if (patchDict[key].syntax) {
                result[key] = extendSyntax.test(patchDict[key].syntax)
                    ? result[key] + ' ' + patchDict[key].syntax.trim()
                    : patchDict[key].syntax;
            } else {
                delete result[key];
            }
        } else {
            if (patchDict[key].syntax) {
                result[key] = patchDict[key].syntax.replace(extendSyntax, '');
            }
        }
    }

    return result;
}

function unpackSyntaxes(dict) {
    const result = {};

    for (const key in dict) {
        result[key] = dict[key].syntax;
    }

    return result;
}

function patchAtrules(dict, patchDict) {
    const result = {};

    // copy all syntaxes for an original dict
    for (const key in dict) {
        const patchDescriptors = (patchDict[key] && patchDict[key].descriptors) || null;

        result[key] = {
            prelude: key in patchDict && 'prelude' in patchDict[key]
                ? patchDict[key].prelude
                : dict[key].prelude || null,
            descriptors: dict[key].descriptors
                ? patchDictionary(dict[key].descriptors, patchDescriptors || {})
                : patchDescriptors && unpackSyntaxes(patchDescriptors)
        };
    }

    // apply a patch
    for (const key in patchDict) {
        if (!hasOwnProperty.call(dict, key)) {
            result[key] = {
                prelude: patchDict[key].prelude || null,
                descriptors: patchDict[key].descriptors && unpackSyntaxes(patchDict[key].descriptors)
            };
        }
    }

    return result;
}

export default {
    types: patchDictionary(mdnSyntaxes, patch.syntaxes),
    atrules: patchAtrules(preprocessAtrules(mdnAtrules), patch.atrules),
    properties: patchDictionary(mdnProperties, patch.properties)
};

@@ -1750,163 +1750,8 @@
 %0A%7D%0A%0A
-function unpackSyntaxes(dict) %7B%0A    const result = %7B%7D;%0A%0A    for (const key in dict) %7B%0A        result%5Bkey%5D = dict%5Bkey%5D.syntax;%0A    %7D%0A%0A    return result;%0A%7D%0A%0A
 func
@@ -1779,32 +1779,32 @@
 t, patchDict) %7B%0A
+
     const result
@@ -2185,180 +2185,75 @@
 rs: 
-dict%5Bkey%5D.descriptors%0A                ? patchDictionary(dict%5Bkey%5D.descriptors, patchDescriptors %7C%7C %7B%7D)%0A                : patchDescriptors && unpackSyntaxes(patchDescriptors
+patchDictionary(dict%5Bkey%5D.descriptors %7C%7C %7B%7D, patchDescriptors %7C%7C %7B%7D
 )%0A  
@@ -2519,23 +2519,28 @@
  && 
-unpackSyntaxes(
+patchDictionary(%7B%7D, 
 patc

Tweak patch apply for descriptors