// Minimal YAML emitter for action results (objects, arrays, scalars).
// Output only; parsing is done by the vendored yaml package (see source.mjs).

const PLAIN = /^[A-Za-z0-9_./@+-][A-Za-z0-9_ ./@+:-]*$/;
const RESERVED = /^(true|false|null|yes|no|on|off|~|-?\d+(\.\d+)?)$/i;

function scalar(value) {
  if (value === null || value === undefined) return 'null';
  if (typeof value === 'boolean' || typeof value === 'number') return String(value);
  const text = String(value);
  if (text === '' || !PLAIN.test(text) || RESERVED.test(text) || text.endsWith(':') || text.includes(': ') || text.includes(' #')) {
    return JSON.stringify(text);
  }
  return text;
}

function isEmpty(value) {
  return (Array.isArray(value) && value.length === 0) || (value && typeof value === 'object' && Object.keys(value).length === 0);
}

function emit(value, indent) {
  const pad = ' '.repeat(indent);
  if (Array.isArray(value)) {
    return value
      .map((item) => {
        if (item && typeof item === 'object' && !isEmpty(item)) {
          const body = emit(item, indent + 2);
          return `${pad}- ${body.slice(indent + 2)}`;
        }
        return `${pad}- ${isEmpty(item) ? (Array.isArray(item) ? '[]' : '{}') : scalar(item)}`;
      })
      .join('\n');
  }
  return Object.entries(value)
    .filter(([, item]) => item !== undefined)
    .map(([key, item]) => {
      if (item && typeof item === 'object' && !isEmpty(item)) return `${pad}${key}:\n${emit(item, indent + 2)}`;
      if (isEmpty(item)) return `${pad}${key}: ${Array.isArray(item) ? '[]' : '{}'}`;
      return `${pad}${key}: ${scalar(item)}`;
    })
    .join('\n');
}

export function toYaml(value) {
  return `${emit(value, 0)}\n`;
}