<?php declare(strict_types = 1);

namespace MailPoet\Validator;

use MailPoet\InvalidStateException;

use function json_encode;

abstract class Schema {
  protected $schema = [];

  /** @return static */
  public function nullable() {
    $type = $this->schema['type'] ?? ['null'];
    return $this->updateSchemaProperty('type', is_array($type) ? $type : [$type, 'null']);
  }

  /** @return static */
  public function nonNullable() {
    $type = $this->schema['type'] ?? null;
    return $type === null
      ? $this->unsetSchemaProperty('type')
      : $this->updateSchemaProperty('type', is_array($type) ? $type[0] : $type);
  }

  /** @return static */
  public function required() {
    return $this->updateSchemaProperty('required', true);
  }

  /** @return static */
  public function optional() {
    return $this->unsetSchemaProperty('required');
  }

  public function toArray(): array {
    return $this->schema;
  }

  public function toString(): string {
    $json = json_encode($this->schema, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_PRESERVE_ZERO_FRACTION);
    $error = json_last_error();
    if ($error || $json === false) {
      throw new InvalidStateException(json_last_error_msg(), (string)$error);
    }
    return $json;
  }

  /** @return static */
  protected function updateSchemaProperty(string $name, $value) {
    $clone = clone $this;
    $clone->schema[$name] = $value;
    return $clone;
  }

  /** @return static */
  protected function unsetSchemaProperty(string $name) {
    $clone = clone $this;
    unset($clone->schema[$name]);
    return $clone;
  }
}