<?php

require_once ("domframework/queue.php");
require_once ("domframework/file.php");

/** 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);
    $res = array ();
    if (count ($entries) > 0)
    {
      for ($i = $start ; $i < $start + $number ; $i++)
      {
        if (! key_exists ($i, $entries))
        {
          $file->lockUN ($this->queue);
          throw new \Exception ("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;
  }
  // }}}
}