"use strict"

const atRuleParamIndex = require("../../utils/atRuleParamIndex")
const report = require("../../utils/report")
const ruleMessages = require("../../utils/ruleMessages")
const validateOptions = require("../../utils/validateOptions")
const whitespaceChecker = require("../../utils/whitespaceChecker")
const findMediaOperator = require("../findMediaOperator")

const ruleName = "media-feature-range-operator-space-before"

const messages = ruleMessages(ruleName, {
  expectedBefore: () => "Expected single space before range operator",
  rejectedBefore: () => "Unexpected whitespace before range operator",
})

const rule = function (expectation) {
  const checker = whitespaceChecker("space", expectation, messages)
  return (root, result) => {
    const validOptions = validateOptions(result, ruleName, {
      actual: expectation,
      possible: [
        "always",
        "never",
      ],
    })
    if (!validOptions) {
      return
    }

    root.walkAtRules(/^media$/i, atRule => {
      findMediaOperator(atRule, checkBeforeOperator)
    })

    function checkBeforeOperator(match, params, node) {
      // The extra `+ 1` is because the match itself contains
      // the character before the operator
      checker.before({
        source: params,
        index: match.index + 1,
        err: m => {
          report({
            message: m,
            node,
            index: match.index + atRuleParamIndex(node),
            result,
            ruleName,
          })
        },
      })
    }
  }
}

rule.ruleName = ruleName
rule.messages = messages
module.exports = rule