<?php

namespace Qs\ImageFs;

use Exception;
use Qs_Options;

class SizeRegistry
{
    /** @var  String */
    protected $_file;

    /** @var String */
    protected $_sizes;

    public function __construct(array $options = [])
    {
        Qs_Options::setConstructorOptions($this, $options);
    }

    public function getFile()
    {
        if (null === $this->_file) {
            $this->setFile(realpath(__DIR__ . '/../../tmp/cache') . '/image-size-registry.txt');
        }
        return $this->_file;
    }

    public function setFile($file)
    {
        if (!$file || !($dir = dirname($file)) || !file_exists($dir)) {
            throw new Exception('Invalid file path');
        }
        $this->_file = $file;
        return $this;
    }

    public function getSizes()
    {
        if (null === $this->_sizes) {
            $this->_sizes = $this->readSizes();
        }
        return $this->_sizes;
    }

    public function isRegistered($width, $height)
    {
        return !empty($this->getSizes()) && false !== strpos($this->getSizes(), $this->createSize($width, $height));
    }

    private function createSize($width, $height)
    {
        return $width . 'x' . $height . PHP_EOL;
    }

    public function register($width, $height)
    {
        $file = $this->getFile();
        if (false === ($handle = fopen($file, 'a+'))) {
            throw new Exception('Failed to open file: ' . $file);
        }
        if (false === flock($handle, LOCK_EX)) {
            throw new Exception('Failed to lock file: ' . $file);
        }

        // force file re-read after writer lock to ensure we have fresh data which possibly updated by parallel process
        $this->_sizes = null;

        if (!$this->isRegistered($width, $height)) {
            $size = $this->createSize($width, $height);
            fwrite($handle, $size);
            $this->_sizes .= $size;
        }
        flock($handle, LOCK_UN);
        fclose($handle);
        return $this;
    }

    private function readSizes()
    {
        $file = $this->getFile();
        if (!file_exists($file)) {
            return '';
        }
        if (false === ($content = file_get_contents($file))) {
            throw new Exception('Failed to read file ' . $file);
        }
        return $content;
    }
}