"use strict";

const isWhitespace = require("../../utils/isWhitespace");
const report = require("../../utils/report");
const ruleMessages = require("../../utils/ruleMessages");
const styleSearch = require("style-search");
const validateOptions = require("../../utils/validateOptions");

const ruleName = "function-whitespace-after";

const messages = ruleMessages(ruleName, {
  expected: 'Expected whitespace after ")"',
  rejected: 'Unexpected whitespace after ")"'
});

const ACCEPTABLE_AFTER_CLOSING_PAREN = new Set([")", ",", "}", ":", undefined]);

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

    root.walkDecls(decl => {
      const declString = decl.toString();

      styleSearch(
        {
          source: declString,
          target: ")",
          functionArguments: "only"
        },
        match => {
          checkClosingParen(declString, match.startIndex, decl);
        }
      );
    });

    function checkClosingParen(source, index, node) {
      const nextChar = source[index + 1];
      if (expectation === "always") {
        // Allow for the next character to be a single empty space,
        // another closing parenthesis, a comma, or the end of the value
        if (nextChar === " ") {
          return;
        }
        if (nextChar === "\n") {
          return;
        }
        if (source.substr(index + 1, 2) === "\r\n") {
          return;
        }
        if (ACCEPTABLE_AFTER_CLOSING_PAREN.has(nextChar)) {
          return;
        }
        report({
          message: messages.expected,
          node,
          index: index + 1,
          result,
          ruleName
        });
      } else if (expectation === "never") {
        if (isWhitespace(nextChar)) {
          report({
            message: messages.rejected,
            node,
            index: index + 1,
            result,
            ruleName
          });
        }
      }
    }
  };
};

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