--- /dev/null
+"use strict";
+
+const atRuleParamIndex = require("../../utils/atRuleParamIndex");
+const isCustomMediaQuery = require("../../utils/isCustomMediaQuery");
+const isRangeContextMediaFeature = require("../../utils/isRangeContextMediaFeature");
+const isStandardSyntaxMediaFeatureName = require("../../utils/isStandardSyntaxMediaFeatureName");
+const mediaParser = require("postcss-media-query-parser").default;
+const report = require("../../utils/report");
+const ruleMessages = require("../../utils/ruleMessages");
+const validateOptions = require("../../utils/validateOptions");
+
+const ruleName = "media-feature-name-case";
+
+const messages = ruleMessages(ruleName, {
+ expected: (actual, expected) => `Expected "${actual}" to be "${expected}"`
+});
+
+const rule = function(expectation) {
+ return (root, result) => {
+ const validOptions = validateOptions(result, ruleName, {
+ actual: expectation,
+ possible: ["lower", "upper"]
+ });
+ if (!validOptions) {
+ return;
+ }
+
+ root.walkAtRules(/^media$/i, atRule => {
+ mediaParser(atRule.params).walk(/^media-feature$/i, mediaFeatureNode => {
+ const parent = mediaFeatureNode.parent,
+ sourceIndex = mediaFeatureNode.sourceIndex,
+ value = mediaFeatureNode.value;
+
+ if (
+ isRangeContextMediaFeature(parent.value) ||
+ !isStandardSyntaxMediaFeatureName(value) ||
+ isCustomMediaQuery(value)
+ ) {
+ return;
+ }
+
+ const expectedFeatureName =
+ expectation === "lower" ? value.toLowerCase() : value.toUpperCase();
+
+ if (value === expectedFeatureName) {
+ return;
+ }
+
+ report({
+ index: atRuleParamIndex(atRule) + sourceIndex,
+ message: messages.expected(value, expectedFeatureName),
+ node: atRule,
+ ruleName,
+ result
+ });
+ });
+ });
+ };
+};
+
+rule.ruleName = ruleName;
+rule.messages = messages;
+module.exports = rule;