<?php

declare(strict_types=1);

namespace gamringer\JSONPatch;

use gamringer\JSONPointer;

use gamringer\JSONPointer\Pointer;

class Patch

{

protected $operations = [];

public static function fromJSON(string $patchContent)

{

$patch = new static();

$patchContent = self::decodePatchContent($patchContent);

foreach ($patchContent as $operationContent) {

$operation = Operation::fromDecodedJSON($operationContent);

$patch->addOperation($operation);

}

return $patch;

}

public function apply(&$target)

{

$jsonPointer = new Pointer($target);

try {

foreach ($this->operations as $i => $operation) {

$operation->apply($jsonPointer);

}

} catch (Operation\Exception $e) {

$this->revert($jsonPointer, $i);

throw new Exception('An Operation failed', 1, $e);

}

}

private function revert(Pointer $jsonPointer, $index)

{

$operations = array_reverse(array_slice($this->operations, 0, $index));

try {

foreach ($operations as $operation) {

$operation->revert($jsonPointer);

}

} catch (Operation\Exception $e) {

throw new Exception('An Operation failed and the reverting process also failed', 2, $e);

}

}

public function addOperation(Operation\Atomic $operation)

{

$this->operations[] = $operation;

}

public function __toString()

{

return '['.implode(',', $this->operations).']';

}

private static function decodePatchContent($patchContent)

{

$patchContent = json_decode($patchContent);

if (json_last_error() != JSON_ERROR_NONE) {

throw new Exception('Content of source patch file could not be decoded', 3);

}

if (!is_array($patchContent)) {

throw new Exception('Content of source patch file is not a collection', 4);

}

return $patchContent;

}

}