"use strict";

const declarationValueIndex = require("../../utils/declarationValueIndex");
const isSingleLineString = require("../../utils/isSingleLineString");
const isStandardSyntaxFunction = require("../../utils/isStandardSyntaxFunction");
const report = require("../../utils/report");
const ruleMessages = require("../../utils/ruleMessages");
const validateOptions = require("../../utils/validateOptions");
const valueParser = require("postcss-value-parser");

const ruleName = "function-parentheses-newline-inside";

const messages = ruleMessages(ruleName, {
  expectedOpening: 'Expected newline after "("',
  expectedClosing: 'Expected newline before ")"',
  expectedOpeningMultiLine:
    'Expected newline after "(" in a multi-line function',
  rejectedOpeningMultiLine:
    'Unexpected whitespace after "(" in a multi-line function',
  expectedClosingMultiLine:
    'Expected newline before ")" in a multi-line function',
  rejectedClosingMultiLine:
    'Unexpected whitespace before ")" in a multi-line function'
});

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

    root.walkDecls(decl => {
      if (decl.value.indexOf("(") === -1) {
        return;
      }

      valueParser(decl.value).walk(valueNode => {
        if (valueNode.type !== "function") {
          return;
        }

        if (!isStandardSyntaxFunction(valueNode)) {
          return;
        }

        const functionString = valueParser.stringify(valueNode);
        const isMultiLine = !isSingleLineString(functionString);
        function containsNewline(str) {
          return str.indexOf("\n") !== -1;
        }

        // Check opening ...

        const openingIndex = valueNode.sourceIndex + valueNode.value.length + 1;

        if (expectation === "always" && !containsNewline(valueNode.before)) {
          complain(messages.expectedOpening, openingIndex);
        }

        if (
          isMultiLine &&
          expectation === "always-multi-line" &&
          !containsNewline(valueNode.before)
        ) {
          complain(messages.expectedOpeningMultiLine, openingIndex);
        }

        if (
          isMultiLine &&
          expectation === "never-multi-line" &&
          valueNode.before !== ""
        ) {
          complain(messages.rejectedOpeningMultiLine, openingIndex);
        }

        // Check closing ...

        const closingIndex = valueNode.sourceIndex + functionString.length - 2;

        if (expectation === "always" && !containsNewline(valueNode.after)) {
          complain(messages.expectedClosing, closingIndex);
        }

        if (
          isMultiLine &&
          expectation === "always-multi-line" &&
          !containsNewline(valueNode.after)
        ) {
          complain(messages.expectedClosingMultiLine, closingIndex);
        }

        if (
          isMultiLine &&
          expectation === "never-multi-line" &&
          valueNode.after !== ""
        ) {
          complain(messages.rejectedClosingMultiLine, closingIndex);
        }
      });

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

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