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import Block from "https://deno.land/x/stylecow_core/css/block.js";import Rule from "https://deno.land/x/stylecow_core/css/rule.js";import MediaQueries from "https://deno.land/x/stylecow_core/css/media-queries.js";import Keyword from "https://deno.land/x/stylecow_core/css/keyword.js";import ConditionalExpression from "https://deno.land/x/stylecow_core/css/conditional-expression.js";import Selectors from "https://deno.land/x/stylecow_core/css/selectors.js";import Combinator from "https://deno.land/x/stylecow_core/css/combinator.js";
export default function (tasks) {  //Merge nested rules  tasks.addTask({    filter: "Rule",    fn: resolveNested,  });
  //Merge nested @nest  tasks.addTask({    filter: {      type: "AtRule",      name: "nest",    },    fn: resolveNested,  });
  //Merge nested @media  tasks.addTask({    filter: {      type: "AtRule",      name: "media",    },    fn: function (parentMedia) {      const index = parentMedia.index(), offset = 1;
      parentMedia        .getChild("Block")        .getChildren({          type: "AtRule",          name: "media",        })        .forEach((child) => nestedMedia(parentMedia, child, index + offset));    },  });}
function resolveNested(parentRule) {  const index = parentRule.index();  let offset = 1;
  parentRule    .getChild("Block")    .getChildren()    .forEach(function (child) {      if (child.type === "AtRule") {        // resolve nested @media        if (child.name === "media") {          nestedRuleMedia(parentRule, child, index + offset);          ++offset;        } // resolve @nested at-rules        else if (child.name === "nest") {          nestedRule(parentRule, child, index + offset);          ++offset;        }      } // resolve nested rules      else if (child.type === "Rule") {        nestedRule(parentRule, child, index + offset);        ++offset;      }    });
  //remove the rule if it's empty  if (!parentRule.getChild("Block").length) {    parentRule.remove();  }}
function nestedRuleMedia(parentRule, media, parentRuleIndex) {  const rule = new Rule();
  rule.push(parentRule.getChild("Selectors").clone());  rule.push(media.getChild("Block"));
  const block = new Block();  block.push(rule);  media.push(block);
  const index = rule.index();  let offset = 1;
  rule    .getChild("Block")    .getChildren("Rule")    .forEach(function (child) {      nestedRule(rule, child, index + offset);      ++offset;    });
  if (rule.getChild("Block").length === 0) {    rule.remove();  }
  parentRule.getParent().splice(parentRuleIndex, 0, media);}
function nestedMedia(parentMedia, media, parentMediaIndex) {  const mediaQueries = media.getChild("MediaQueries");  const mergedMediaQueries = new MediaQueries();
  parentMedia    .getChild("MediaQueries")    .forEach(function (parentMediaQuery) {      mediaQueries.forEach(function (mediaQuery) {        mergedMediaQueries.push(          mergeMediaQuery(parentMediaQuery.clone(), mediaQuery.clone()),        );      });    });
  mediaQueries.replaceWith(mergedMediaQueries);  parentMedia.getParent().splice(parentMediaIndex, 0, media);}
function nestedRule(parentRule, rule, parentRuleIndex) {  const selectors = rule.getChild("Selectors");  const mergedSelectors = new Selectors();
  parentRule    .getChild("Selectors")    .forEach(function (parentSelector) {      selectors.forEach(function (selector) {        mergedSelectors.push(          mergeSelector(parentSelector.clone(), selector.clone()),        );      });    });
  selectors.replaceWith(mergedSelectors);
  //@nest  if (rule.type === "AtRule") {    const tmpRule = new Rule();
    while (rule.length) {      tmpRule.push(rule.shift());    }
    rule.remove();    rule = tmpRule;  }
  parentRule.getParent().splice(parentRuleIndex, 0, rule);}
function mergeSelector(selector, appendedSelector) {  let joinCombinator = appendedSelector.get({    type: "Combinator",    name: "&",  });
  if (!joinCombinator) {    if (appendedSelector[0].type !== "Combinator") {      appendedSelector.unshift(new Combinator().setName(" "));    }
    joinCombinator = new Combinator().setName("&");    appendedSelector.unshift(joinCombinator);  }
  //resolve .foo&html => html.foo  const next = joinCombinator.next();
  if (next && next.is("TypeSelector")) {    const combinators = selector.getChildren("Combinator");
    if (combinators.length) {      combinators.pop().after(next);    } else {      selector.unshift(next);    }  }
  while (selector[0]) {    joinCombinator.before(selector.shift());  }
  joinCombinator.remove();
  return appendedSelector;}
function mergeMediaQuery(mediaQueries, appendedMediaQuery) {  mediaQueries.push(new Keyword().setName("and"));
  if (    (appendedMediaQuery.length === 1) &&    (appendedMediaQuery[0].type === "ConditionalExpression")  ) {    mediaQueries.push(appendedMediaQuery[0]);
    return mediaQueries;  }
  const expression = new ConditionalExpression();
  while (appendedMediaQuery[0]) {    expression.push(appendedMediaQuery.shift());  }
  mediaQueries.push(expression);
  return mediaQueries;}