eslint-plugin-comment-length/src/rules/limit-single-line-comments/util.format-block.ts

An ESLint plugin that provides rules that limit the line length of your comments

import type { TSESTree } from "@typescript-eslint/utils";

import type { Context } from "../../typings.context.js";
import { isAnotherWrapPointComing } from "../../utils/is-another-wrap-point-coming.js";
import { isPunctuation } from "../../utils/is-punctuation.js";
import { isURL } from "../../utils/is-url.js";

import { SINGLE_LINE_COMMENT_BOILERPLATE_SIZE } from "./const.boilerplate-size.js";

export function formatBlock(
  block: TSESTree.LineComment,
  context: Context,
): string {
  const lineStartSize =
    context.whitespace.size + SINGLE_LINE_COMMENT_BOILERPLATE_SIZE;
  const words = block.value.trim().split(" ");
  const newValue = words.reduce(
    (acc, curr, index) => {
      const currentWordIsURL = isURL(curr);
      const lengthIfAdded = acc.currentLineLength + curr.length + 1;

      // We can safely split to a new line in case we are reaching and
      // overflowing line AND if there is at least one word on the current line.
      const splitToNewline =
        lengthIfAdded >= context.maxLength &&
        acc.currentLineLength !== lineStartSize &&
        (!context.ignoreUrls || !currentWordIsURL);

      const previousWord = words[index - 1];

      const splitEarly =
        context.logicalWrap &&
        acc.currentLineLength >= context.maxLength / 2 &&
        previousWord &&
        isPunctuation(previousWord.at(-1)) &&
        previousWord.length > 1 &&
        !isAnotherWrapPointComing(
          acc.currentLineLength,
          context.maxLength,
          words.slice(index),
        );

      if (splitToNewline || splitEarly) {
        return {
          value: `${acc.value}\n${context.whitespace.string}// ${curr}`,
          currentLineLength: lineStartSize + curr.length,
        };
      } else {
        return {
          value: `${acc.value} ${curr}`,
          currentLineLength: lengthIfAdded,
        };
      }
    },
    { value: "//", currentLineLength: lineStartSize },
  );
  return newValue.value;
}