async function addComments()

in packages/flow-dev-tools/src/comment/add-commentsRunner.js [69:134]
49 lines of code
8 McCabe index (conditional complexity)

async function addComments(args: Args, errors: Array<FlowError>) {
  const seen = new Set();
  let filenameToLineToLocsMap: Map<
    string,
    Map<number, Suppression>,
  > = new Map();
  // Filter out errors without a main location
  let errorCount = 0;
  for (const error of errors) {
    const loc = mainSourceLocOfError(error);
    const error_codes = error.error_codes;
    if (loc != null && loc.source != null) {
      const source = loc.source;
      const lineToLocsMap = filenameToLineToLocsMap.get(source) || new Map();
      const isError = error.kind !== 'lint';
      let lints = new Set();
      if (error.kind === 'lint') {
        // \u0060 is `. using the escape to avoid a syntax highlighting bug in vscode-language-babel
        const match = /\(\u0060([^\u0060]+)\u0060\)$/.exec(
          error.message[0].descr,
        );
        if (match) {
          lints.add(match[1]);
        }
      }
      function joinSuppression(
        prevValue: ?Suppression,
        newValue: Suppression,
      ): Suppression {
        if (!prevValue) {
          return newValue;
        }
        return {
          loc: newValue.loc,
          isError: newValue.isError || prevValue.isError,
          lints: new Set([...newValue.lints, ...prevValue.lints]),
          error_codes: [...newValue.error_codes, ...prevValue.error_codes],
        };
      }
      const prevValue: ?Suppression = lineToLocsMap.get(loc.start.line);
      const value = joinSuppression(prevValue, {
        loc,
        isError,
        lints,
        error_codes,
      });
      lineToLocsMap.set(loc.start.line, value);
      filenameToLineToLocsMap.set(source, lineToLocsMap);
      errorCount++;
    }
  }

  const promises = [];
  for (const [source, lineToLocsMap] of filenameToLineToLocsMap.entries()) {
    promises.push(
      addCommentsToSource(args, source, Array.from(lineToLocsMap.values())),
    );
  }
  const counts = await Promise.all(promises);
  const commentCount = counts.reduce((c1, c2) => c1 + c2, 0);
  console.log(
    'Added %d comments to suppress %d errors',
    commentCount,
    errorCount,
  );
}