<?php

declare(strict_types=1);

namespace App\Cfnpp\Expression\Token;

use App\Cfnpp\Expression\Token;
use App\Cfnpp\Expression\TokenBinary;
use App\Cfnpp\Expression\ICloudformationNative;

/**
 * Basic comparison operators that take two parameters.
 *
 * @author Adam Pippin <hello@adampippin.ca>
 */
class OperatorBinary extends TokenBinary implements ICloudformationNative
{
	/**
	 * List of valid operators.
	 * @var string[]
	 */
	public const OPERATORS = [
		'and',
		'or',
		'eq',
		'concat',
		'select'
	];

	/**
	 * The operator this instance represents.
	 * @var string
	 */
	protected $operator;

	/**
	 * New binary operator.
	 *
	 * @param string $operator
	 */
	public function __construct(string $operator)
	{
		$this->operator = $operator;
	}

	/**
	 * Get the operator this instance represents.
	 *
	 * @return string
	 */
	public function getOperator(): string
	{
		return $this->operator;
	}

	public static function isToken(string $stream): bool
	{
		foreach (static::OPERATORS as $operator)
		{
			if (strlen($stream) >= strlen($operator) &&
				substr($stream, 0, strlen($operator)) == $operator)
			{
				return true;
			}
		}
		return false;
	}

	public static function getToken(string &$stream): Token
	{
		foreach (static::OPERATORS as $operator)
		{
			if (strlen($stream) >= strlen($operator) &&
				substr($stream, 0, strlen($operator)) == $operator)
			{
				$operator = substr($stream, 0, strlen($operator));
				$stream = substr($stream, strlen($operator));
				return new OperatorBinary($operator);
			}
		}
		throw new \Exception('Could not parse OperatorBinary');
	}

	/**
	 * Execute the operator.
	 *
	 * Suppressing accesses to arguments since this is guaranteed valid
	 * unless there are bugs in Expression.
	 * @suppress PhanTypeArraySuspiciousNullable
	 * @param  ?\App\Util\GraphNode[]                $arguments
	 * @return \App\Util\GraphNode|Token|scalar|null
	 */
	public function execute(?array $arguments = null)
	{
		$value1 = $arguments[0]->getValue();
		$value2 = $arguments[1]->getValue();

		switch ($this->getOperator())
		{
			case 'and':
				if (is_scalar($value1) && is_scalar($value2))
				{
					return $value1 && $value2;
				}
				elseif (is_scalar($value1))
				{
					return $value1 ? $arguments[1] : false;
				}
				elseif (is_scalar($value2))
				{
					return $value2 ? $arguments[0] : false;
				}
				elseif ($value1 instanceof Parameter && $value2 instanceof Parameter && $value1->getName() == $value2->getName())
				{
					return $value1;
				}

				return null;

			case 'or':
				if (is_scalar($value1) && is_scalar($value2))
				{
					return $value1 || $value2;
				}
				elseif (is_scalar($value1))
				{
					return $value1 ? true : $arguments[1];
				}
				elseif (is_scalar($value2))
				{
					return $value2 ? true : $arguments[0];
				}
				elseif ($value1 instanceof Parameter && $value2 instanceof Parameter && $value1->getName() == $value2->getName())
				{
					return $value1;
				}

				return null;

			case 'eq':
				if (is_scalar($value1) && is_scalar($value2))
				{
					return $arguments[0] == $arguments[1];
				}
				elseif ($value1 instanceof Parameter && $value2 instanceof Parameter && $value1->getName() == $value2->getName())
				{
					return true;
				}

				return null;

			case 'concat':
				if (is_scalar($value1) && is_scalar($value2))
				{
					return $value2.$value1;
				}
				elseif ($value1 instanceof Parameter && is_scalar($value2) && empty($value2))
				{
					return $value1;
				}
				elseif ($value2 instanceof Parameter && is_scalar($value1) && empty($value1))
				{
					return $value2;
				}

				return null;

			case 'select':
				if (is_scalar($value1) && is_array($value2))
				{
					return $value2[$value1];
				}

				return null;

			default:
				throw new \Exception('Missing implementation for binary operator: '.$this->getOperator());
		}
	}

	/**
	 * Convert this token into a CloudFormation intrinsic.
	 *
	 * Suppressing accesses to arguments since this is guaranteed valid
	 * unless there are bugs in Expression.
	 * @suppress PhanTypeArraySuspiciousNullable
	 * @param  ?\App\Util\GraphNode[] $arguments
	 * @return mixed[]
	 */
	public function toCloudformation(?array $arguments = null): array
	{
		$value1 = $arguments[0]->getValue();
		$value2 = $arguments[1]->getValue();

		switch ($this->getOperator())
		{
			case 'and':
				return ['Fn::And' => [$value1, $value2]];
			case 'or':
				return ['Fn::Or' => [$value1, $value2]];
			case 'eq':
				return ['Fn::Equals' => [$value1, $value2]];
			case 'concat':
				return ['Fn::Join' => ['', [$value2, $value1]]];
			case 'select':
				return ['Fn::Select' => [$value1, $value2]];
			default:
				throw new \Exception('Operator cannot be applied to parameters: '.$this->getOperator());
		}
	}
}