gielfeldt/iterators

<?php

namespace Gielfeldt\Iterators;

class AtomicTempFileObject extends \SplFileObject
{
    const DISCARD = 1;
    const PERSIST = 2;
    const PERSIST_UNCHANGED = 3;

    protected $destinationRealPath;
    protected $persist = 0;
    protected $onPersistCallback;
    protected $onDiscardCallback;
    protected $onCompareCallback;

    /**
     * Constructor.
     */
    public function __construct(string $filename, $mode = 0755)
    {
        $tempDir = dirname($filename);
        if (!file_exists($tempDir)) {
            if (!@mkdir($tempDir, $mode, true)) {
                // @codeCoverageIgnoreStart
                $lastError = error_get_last();
                throw new \RuntimeException(
                    sprintf(
                        "Could create directory %s - message: %s",
                        $tempDir,
                        $lastError['message']
                    )
                );
                // @codeCoverageIgnoreEnd
            }
        }
        $tempPrefix = basename($filename) . '.AtomicTempFileObject.';
        $this->destinationRealPath = $filename;
        parent::__construct(tempnam($tempDir, $tempPrefix), "w+");
        $this->onCompare([self::class, 'compare']);
    }

    /**
     * Get the destination real path.
     *
     * @return string
     *   The real path of the destination.
     */
    public function getDestinationRealPath(): string
    {
        return $this->destinationRealPath;
    }

    /**
     * Move temp file into the destination upon object desctruction.
     */
    public function persistOnClose($persist = self::PERSIST): AtomicTempFileObject
    {
        $this->persist = $persist;
        return $this;
    }

    public function onPersist(callable $callback)
    {
        $this->onPersistCallback = \Closure::fromCallable($callback);
    }

    public function onDiscard(callable $callback)
    {
        $this->onDiscardCallback = \Closure::fromCallable($callback);
    }

    public function onCompare(callable $callback)
    {
        $this->onCompareCallback = \Closure::fromCallable($callback);
    }

    private function doPersist()
    {
        if (!@rename($this->getRealPath(), $this->destinationRealPath)) {
            // @codeCoverageIgnoreStart
            $lastError = error_get_last();
            throw new \RuntimeException(
                sprintf(
                    "Could not move %s to %s - message: %s",
                    $this->getRealPath(),
                    $this->destinationRealPath,
                    $lastError['message']
                )
            );
            // @codeCoverageIgnoreEnd
        }
        if ($this->onPersistCallback) {
            ($this->onPersistCallback)($this);
        }
    }

    private function doDiscard()
    {
        if (!@unlink($this->getRealPath())) {
            // @codeCoverageIgnoreStart
            $lastError = error_get_last();
            throw new \RuntimeException(
                sprintf(
                    "Could not remove %s - message: %s",
                    $this->getRealPath(),
                    $lastError['message']
                )
            );
            // @codeCoverageIgnoreEnd
        }
        if ($this->onDiscardCallback) {
            ($this->onDiscardCallback)($this);
        }
    }

    private function doCompare()
    {
        return ($this->onCompareCallback)($this);
    }

    /**
     * Move temp file into the destination if applicable.
     */
    public function __destruct()
    {
        $this->fflush();
        if ($this->persist == self::PERSIST || $this->persist == self::PERSIST_UNCHANGED) {
            if ($this->persist == self::PERSIST_UNCHANGED || !$this->doCompare()) {
                $this->doPersist();
            } else {
                $this->doDiscard();
            }
        } elseif ($this->persist & self::DISCARD) {
            $this->doDiscard();
        } else {
            // @codeCoverageIgnoreStart
            trigger_error("Temp file left on device: " . $this->getRealPath(), E_USER_WARNING);
            // @codeCoverageIgnoreEnd
        }
    }

    /**
     * Easy access iterator apply for processing an entire file.
     *
     * @param \Iterator $input    [description]
     * @param callable  $callback [description]
     */
    public function process(\Iterator $input, callable $callback)
    {
        $callback = \Closure::fromCallable($callback);
        $input->rewind();
        iterator_apply(
            $input,
            function (\Iterator $iterator) use ($callback) {
                $callback($iterator->current(), $iterator->key(), $iterator, $this);
                return true;
            },
            [$input]
        );
        return $this;
    }

    /**
     * Atomic file_put_contents().
     *
     * @see file_put_contents()
     */
    public static function file_put_contents($filename, $data, $flags = 0)
    {
        if ($flags & FILE_USE_INCLUDE_PATH) {
            $file = (new \SplFileInfo($filename))->openFile('r', true);
            if ($file) {
                $filename = $file->getRealPath();
            }
        }
        $tempFile = new static($filename);
        $tempFile->fwrite($data);
        $tempFile->persistOnClose();
        unset($tempFile);
    }

    /**
     * File comparison
     *
     * @return bool
     *   True if the contents of this file matches the contents of $filename.
     */
    private static function compare(AtomicTempFileObject $tempFile): bool
    {
        $filename = $tempFile->getDestinationRealPath();
        if (!file_exists($filename)) {
            return false;
        }

        // This is a temp file opened for writing and truncated to begin with,
        // so we assume that the current position is the size of the new file.
        $pos = $tempFile->ftell();

        $file = new \SplFileObject($filename, 'r');
        if ($pos <> $file->getSize()) {
            return false;
        }

        // Rewind this temp file and compare it with the specified file.
        $identical = true;
        $tempFile->fseek(0);
        while (!$file->eof()) {
            if ($file->fread(8192) != $tempFile->fread(8192)) {
                $identical = false;
                break;
            }
        }

        // Reset file pointer to end of file.
        $tempFile->fseek($pos);
        return $identical;
    }
}