query params. experiment in something a little different

query-params.php

<?php

namespace param {
  class QueryParam {
    const SINGLE = 'single';
    const MANY = 'many';
    const MANY_CSV = 'csv';

    public $queryField;
    private $nullable = false;
    private $type = self::SINGLE;

    private $eachLimitations = [];

    function __construct($queryField) {
      $this->queryField = $queryField;
    }

    function int() {
      $this->eachLimitations[] = new IntParam;
      return $this;
    }

    function many() {
      $this->type = static::MANY;
      return $this;
    }

    function many_csv() {
      $this->type = static::MANY_CSV;
      return $this;
    }

    function nullable() {
      $this->nullable = true;
      return $this;
    }

    function only($only) {
      $this->eachLimitations[] = new OneOfParam($only);
      return $this;
    }

    function __invoke($input) {
      $input = $this->runType($input);

      if (is_array($input)) {
        $input = array_map(function($in) { return $this->runLimitations($in); }, $input);

        if ( ! $this->nullable) {
          $input = array_filter($input, function($in) {
            return ! is_null($in) && $in !== Param::NOPE;
          });
        }

        $input = array_values($input);

        return $input;
      }
      else {
        $input = $this->runLimitations($input);

        if ( ! $this->nullable && is_null($input)) {
          $input = Param::NOPE;
        }

        return $input;
      }
    }

    private function runLimitations($input) {
      return array_reduce($this->eachLimitations, function($carry, $limitation) {
        return call_user_func($limitation, $carry);
      }, $input);
    }

    private function runType($input) {
      if ($this->type === static::SINGLE) {
        return is_array($input) ? reset($input) : $input;
      }

      if ($this->type === static::MANY) {
        return is_array($input) ? $input : [$input];
      }

      if ($this->type === static::MANY_CSV && ! is_array($input)) {
        return explode(',', $input);
      }
      
      return $input;
    }

  }

  abstract class Param {
    const NOPE = 'n9qughouy(&YU@H97t2uoehjdOUYGHPifj0qo9272)_+_=';
  }

  class IntParam extends Param {
    function __invoke($input) {
      return is_numeric($input) ? intval($input) : static::NOPE;
    }
  }

  class StringParam extends Param {
    function __invoke($input) {
      return (string) $input;
    }
  }

  class OneOfParam extends Param {
    function __construct($oneOf) {
      $this->oneOf = $oneOf;
    }
    function __invoke($input) {
      return in_array($input, $this->oneOf) ? $input : static::NOPE;
    }
  }

  function to($queryField) {
    return new QueryParam($queryField);
  }

  function run($inputs, $map, $queryObject) {
    foreach ($map as $inputField => $param) {
      $result = call_user_func($param, $inputs[$inputField]);
      if ($result !== Param::NOPE) {
        $queryField = $param->queryField;
        $queryObject->$queryField = $result;
      }
    }
    return $queryObject;
  }

}

namespace {
  class InspectionState { const STATES = [100,200,300,400,500,900]; }

  $map = [
    'state_id' => param\to('stateId')->int()->many_csv()->only(InspectionState::STATES),
    'clerk_id' => param\to('clerkId')->int()->nullable(),
  ];

  $input = [
    'state_id' => '100,foo,200,0',
    'clerk_id' => ['22'],
  ];

  $queryObject = (object) [];

  $queryObject = param\run($input, $map, $queryObject);

  print_r($queryObject);
}