<?php

/**
 * DomFramework
 * @package domframework
 * @author Dominique Fournier <dominique@fournier38.fr>
 * @license BSD
 */

namespace Domframework;

/**
 * Manage a queue in file
 * A process can add entries to the end of a queue
 * A process can get all the entries in a queue
 * A process can clear all the entries in a queue
 * A process can get the first entry in the queue (FIFO), with optional
 * removing of the entry
 * A process can get the last entry in the queue (LIFO), with optional
 * removing of the entry
 * A process can get X entries starting at position Y
 */
class Queuefile extends Queue
{
    /**
     * The queue connected object
     */
    private $queue = null;

    /**
     * Connect to the queue. Create it if not exists
     * @param string $dsn The DSN to connect to queue
     * @return $this;
     */
    public function connect($dsn)
    {
        // The DSN format must be file:///tmp/queuefile.txt
        if (substr($dsn, 0, 7) !== "file://") {
            throw new \Exception("Invalid DSN provided to queuefile : not starting " .
            "by file://", 500);
        }
        $this->queue = substr($dsn, 7);
        $file = new File();
        if (! $file->file_exists(dirname($this->queue))) {
            $file->mkdir(dirname($this->queue), 0777, true);
        }
        if (! $file->file_exists($this->queue)) {
            $file->touch($this->queue);
        }
        return $this;
    }

    /**
     * Add a new entry to the end of the queue
     * @param mixed $entry The entry to add
     * @return $this;
     */
    public function add($entry)
    {
        $file = new File();
        $file->lockEX($this->queue);
        $file->file_put_contents(
            $this->queue,
            json_encode($entry) . "\n",
            FILE_APPEND
        );
        $file->lockUN($this->queue);
        return $this;
    }

    /**
     * Get all the entries of the queue
     * @param boolean|null $delete If true, delete the read entry
     * @return array
     */
    public function getAll($delete = false)
    {
        $file = new File();
        if ($delete) {
            $file->lockEX($this->queue);
        } else {
            $file->lockSH($this->queue);
        }
        $content = $file->file_get_contents($this->queue);
        $entries = explode("\n", $content);
        // Explode return always one empty entry at end. Remove it
        array_pop($entries);
        foreach ($entries as $key => $val) {
            $entries[$key] = json_decode($val);
        }
        if ($delete) {
            $file->file_put_contents($this->queue, "");
        }
        $file->lockUN($this->queue);
        return $entries;
    }

    /**
     * Get the number of entries in the queue
     */
    public function count()
    {
        $file = new File();
        $file->lockSH($this->queue);
        $content = $file->file_get_contents($this->queue);
        $count = substr_count($content, "\n");
        $file->lockUN($this->queue);
        return $count;
    }

    /**
     * Clear all the entries of the queue
     * @return $this;
     */
    public function clear()
    {
        $file = new File();
        $file->lockEX($this->queue);
        $file->file_put_contents($this->queue, "");
        $file->lockUN($this->queue);
        return $this;
    }

    /**
     * Get the first entry in the queue with optional removing of the entry
     * @param boolean|null $delete If true, delete the read entry
     * @return mixed Return null if there is no entry, or the first entry in the
     * queue (FIFO)
     */
    public function getFirst($delete = false)
    {
        $file = new File();
        if ($delete) {
            $file->lockEX($this->queue);
        } else {
            $file->lockSH($this->queue);
        }
        $content = $file->file_get_contents($this->queue);
        $entries = explode("\n", $content);
        // Explode return always one empty entry at end. Remove it
        array_pop($entries);
        if (count($entries) === 0) {
            $res = null;
        } else {
            $json = array_shift($entries);
            $res =  json_decode($json);
            if ($delete) {
                $file->file_put_contents(
                    $this->queue,
                    implode("\n", $entries)
                );
            }
        }
        $file->lockUN($this->queue);
        return $res;
    }

    /**
     * Get the last entry in the queue with optional removing of the entry
     * @param boolean|null $delete If true, delete the read entry
     * @return mixed Return null if there is no entry, or the last entry in the
     * queue (LIFO)
     */
    public function getLast($delete = false)
    {
        $file = new File();
        if ($delete) {
            $file->lockEX($this->queue);
        } else {
            $file->lockSH($this->queue);
        }
        $content = $file->file_get_contents($this->queue);
        $entries = explode("\n", $content);
        // Explode return always one empty entry at end. Remove it
        array_pop($entries);
        if (count($entries) === 0) {
            $res = null;
        } else {
            $json = array_pop($entries);
            $res =  json_decode($json);
            if ($delete) {
                $file->file_put_contents(
                    $this->queue,
                    implode("\n", $entries)
                );
            }
        }
        $file->lockUN($this->queue);
        return $res;
    }

    /**
     * Get X entries starting at position Y
     * @param integer $start the starting position (the entries start at position
     * zero)
     * @param integer $number The number of entries to get
     * @param boolean|null $delete If true, delete the read entries
     * @return array An array of mixed entries
     */
    public function getRange($start, $number, $delete = false)
    {
        $file = new File();
        if ($delete) {
            $file->lockEX($this->queue);
        } else {
            $file->lockSH($this->queue);
        }
        $content = $file->file_get_contents($this->queue);
        $entries = explode("\n", $content);
        // Explode return always one empty entry at end. Remove it
        array_pop($entries);
        $res = [];
        if (count($entries) > 0) {
            for ($i = $start; $i < $start + $number; $i++) {
                if (! key_exists($i, $entries)) {
                    $file->lockUN($this->queue);
                    throw new \Exception(dgettext(
                        "domframework",
                        "Invalid entry requested"
                    ), 406);
                }
                $json = $entries[$i];
                $content = json_decode($json, true);
                if (json_last_error() === JSON_ERROR_NONE) {
                    $res[] =  $content;
                } else {
                    $res[] =  $json;
                }
            }
            if ($delete) {
                $file->file_put_contents(
                    $this->queue,
                    implode("\n", $entries)
                );
            }
        }
        $file->lockUN($this->queue);
        return $res;
    }
}