// @flow strict



// Level "3" is our NEXT_VERSION_ERROR speciality:
type EslintConfigErrorLevel = 0 | 1 | 2 | 'off' | 'warn' | 'error' | 3;

type EslintRuleOption = string | { [name: string]: mixed, ...};

type EslintConfigValues =
EslintConfigErrorLevel |
[EslintConfigErrorLevel, EslintRuleOption] |
[EslintConfigErrorLevel, EslintRuleOption, EslintRuleOption];

type EslintConfig = { [string]: EslintConfigValues, ...};



module.exports = function changeNextVersionErrorLevel(
config: EslintConfig,
level: 0 | 1 | 2)
: EslintConfig {
  return Object.entries(config).reduce((acc, [ruleName, value]) => {
    if (Array.isArray(value) && value[0] === 3) {
      const [, ...config] = value;
      acc[ruleName] = [level, ...config];
    } else if (value === 3) {
      acc[ruleName] = level;
    } else {
      acc[ruleName] = value;
    }
    return acc;
  }, {});
};