<?php

namespace NoccyLabs\Ipc\Key;

class FileKey implements KeyInterface
{
    private $proj;

    private $pathname;

    /**
     * Constructor
     *
     * @param string $pathname
     * @param string $proj
     * @param boolean $create
     */
    public function __construct(string $pathname, $proj="\0", bool $create=false)
    {
        if (!file_exists($pathname)) {
            if (!$create) {
                throw new \RuntimeException("Path does not exist: {$pathname}");
            }
            if (!is_dir(dirname($pathname))) {
                throw new \RuntimeException("The directory ".dirname($pathname)." does not exist");
            }
            touch($pathname);
        }

        $this->pathname = $pathname;
        $this->proj = substr($proj,0,1);
    }

    /**
     * Get the pathname used to generate the key
     *
     * @return string
     */
    public function getPathname():string
    {
        return $this->pathname;
    }

    /**
     * Get the project identifier. Not guaranteed to be printable
     *
     * @return string
     */
    public function getProjectIdentifier():string
    {
        return $this->proj;
    }

    /**
     * Get the key value
     *
     * @return int
     */
    public function getKey():int
    {
        return ftok($this->pathname, $this->proj);
    }

    /**
     * Clone the FileKey, increasing the project identifier to create a new key for the
     * same file
     *
     * @return void
     */
    public function __clone()
    {
        $this->proj = chr(ord($this->proj) + 1);
    }

    /**
     * Create printable representation of the key
     *
     * @return string
     */
    public function __toString()
    {
        return $this->getKey();
    }
}