"use strict"

const declarationValueIndex = require("../../utils/declarationValueIndex")
const isNumbery = require("../../utils/isNumbery")
const isStandardSyntaxValue = require("../../utils/isStandardSyntaxValue")
const isVariable = require("../../utils/isVariable")
const optionsMatches = require("../../utils/optionsMatches")
const report = require("../../utils/report")
const ruleMessages = require("../../utils/ruleMessages")
const validateOptions = require("../../utils/validateOptions")
const keywordSets = require("../../reference/keywordSets")
const _ = require("lodash")
const postcss = require("postcss")

const ruleName = "font-weight-notation"

const messages = ruleMessages(ruleName, {
  expected: type => `Expected ${type} font-weight notation`,
  invalidNamed: name => `Unexpected invalid font-weight name "${name}"`,
})

const INHERIT_KEYWORD = "inherit"
const INITIAL_KEYWORD = "initial"
const NORMAL_KEYWORD = "normal"
const WEIGHTS_WITH_KEYWORD_EQUIVALENTS = [
  "400",
  "700",
]

const rule = function (expectation, options) {
  return (root, result) => {
    const validOptions = validateOptions(result, ruleName, {
      actual: expectation,
      possible: [
        "numeric",
        "named-where-possible",
      ],
    }, {
      actual: options,
      possible: {
        ignore: ["relative"],
      },
      optional: true,
    })
    if (!validOptions) {
      return
    }

    root.walkDecls(decl => {
      if (decl.prop.toLowerCase() === "font-weight") {
        checkWeight(decl.value, decl)
      }

      if (decl.prop.toLowerCase() === "font") {
        checkFont(decl)
      }
    })

    function checkFont(decl) {
      const valueList = postcss.list.space(decl.value)
      // We do not need to more carefully distinguish font-weight
      // numbers from unitless line-heights because line-heights in
      // `font` values need to be part of a font-size/line-height pair
      const hasNumericFontWeight = valueList.some(isNumbery)

      for (const value of postcss.list.space(decl.value)) {
        if (value.toLowerCase() === NORMAL_KEYWORD && !hasNumericFontWeight || isNumbery(value) || value.toLowerCase() !== NORMAL_KEYWORD && keywordSets.fontWeightKeywords.has(value.toLowerCase())) {
          checkWeight(value, decl)
          return
        }
      }
    }

    function checkWeight(weightValue, decl) {
      if (!isStandardSyntaxValue(weightValue)) {
        return
      }
      if (isVariable(weightValue)) {
        return
      }
      if (weightValue.toLowerCase() === INHERIT_KEYWORD || weightValue.toLowerCase() === INITIAL_KEYWORD) {
        return
      }

      if (optionsMatches(options, "ignore", "relative") && keywordSets.fontWeightRelativeKeywords.has(weightValue.toLowerCase())) {
        return
      }

      const weightValueOffset = decl.value.indexOf(weightValue)

      if (expectation === "numeric") {
        if (!isNumbery(weightValue)) {
          return complain(messages.expected("numeric"))
        }
      }

      if (expectation === "named-where-possible") {
        if (isNumbery(weightValue)) {
          if (_.includes(WEIGHTS_WITH_KEYWORD_EQUIVALENTS, weightValue)) {
            complain(messages.expected("named"))
          }
          return
        }
        if (!keywordSets.fontWeightKeywords.has(weightValue.toLowerCase()) && weightValue.toLowerCase() !== NORMAL_KEYWORD) {
          return complain(messages.invalidNamed(weightValue))
        }
        return
      }

      function complain(message) {
        report({
          ruleName,
          result,
          message,
          node: decl,
          index: declarationValueIndex(decl) + weightValueOffset,
        })
      }
    }
  }
}

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