'use strict';

module.exports = function defFunc(ajv) {
  if (!ajv._opts.v5) console.warn('keywords if/then/else require v5 option');

  defFunc.definition = {
    macro: function (schema, parentSchema) {
      if (parentSchema.then === undefined)
        throw new Error('keyword "then" is absent');
      var cases = [ { 'if': schema, 'then': parentSchema.then } ];
      if (parentSchema.else !== undefined)
        cases[1] = { 'then': parentSchema.else };
      return { switch: cases };
    }
  };

  ajv.addKeyword('if', defFunc.definition);
  ajv.addKeyword('then');
  ajv.addKeyword('else');
  return ajv;
};