FlatDB.php

<?php

class FlatDB {

  public $storageFileLocation = __DIR__ . "/../storage/flatdb";
  public $storageFolderLocation = __DIR__ . "/../storage";

  public $errors;
  public $cacheFile;
  public $cacheChanged = false;


  /**
   * FlatDb
   * A small flat file driven database using PHP operations to store and
   * access data of string format.
   */

  public function __construct() {

    // check for storage directory
    if ( !file_exists( $this->storageFolderLocation ) ) {
      // directory does not exist, try and create it
      $makeDirectory = mkdir( $this->storageFolderLocation, 0600 );
      if ( $makeDirectory !== true) {
        throw new \Exception("FlatDB is unable to create the storage location");
      }
    }

    if ( !file_exists( $this->storageFileLocation ) ) {
      try {
        file_put_contents( $this->storageFileLocation , '' );
      } catch (\Exception $e) {
        $this->errors = $e->getMessage();
      }
    }

    // get a cached version upon instantiation
    $this->cacheFile = file_get_contents( $this->storageFileLocation );

    if ( $this->cacheFile === false ) {
      throw new \Exception("FlatDB is unable to load from storage location");
    }

  }

  public function insert($key, $value) {


    $key = str_replace(";;", "&#59;&#59;", $key);
    $value = str_replace(";;", "&#59;&#59;", $value);

    $this->cacheFile .= ";;{$key};;" . $value;

    $put = file_put_contents( $this->storageFileLocation , $this->cacheFile );

    if ( $put === false ) {
      throw new \Exception("Unable to load from storage location");
    }

    $this->cacheChanged = true;

    return $value;

  }

  public function select($key) {

    $valuesFound = array();

    if ( $this->cacheChanged ) {
      $this->reloadCache();
    }

    $numTimesKeyWasFound = substr_count ( $this->cacheFile , ";;{$key};;" );
    $currentOffset = 0;

    for ($x = 0; $x < $numTimesKeyWasFound; $x++) {

      $occurance = strpos($this->cacheFile, ";;{$key};;", $currentOffset);

      if ( $occurance !== false ) {

        // key was found at $occrance;
        $keyPosAtEnd = ($occurance + (4 + strlen($key))) ;

        $endingPositionOfValue = strpos($this->cacheFile, ";;", $keyPosAtEnd);

        $endingPositionOfValue = ( $endingPositionOfValue === 0 ) ? null : $endingPositionOfValue;

        $lengthOfValue = (($endingPositionOfValue - $keyPosAtEnd) > 0) ? ($endingPositionOfValue - $keyPosAtEnd) : strlen($this->cacheFile);

        $value = str_replace("&#59;&#59;", ";;", substr($this->cacheFile, $keyPosAtEnd, $lengthOfValue));

        array_push($valuesFound, $value);

        $currentOffset = $keyPosAtEnd;

      }

    }

    if ( sizeof($valuesFound) === 0 ) {
      return null;
    }

    if ( sizeof($valuesFound) === 1 ) {
      return $valuesFound[0];
    }

    // return an array of objects
    return $valuesFound;

  }

  private function reloadCache() {

    $getCache = file_get_contents( $this->storageFileLocation );

    if ( $getCache === false ) {
      throw new \Exception("Unable to load from storage location");
    }

    $this->cacheFile = $getCache;
    $this->cacheChanged = false;

    return true;
  }

}