<?php
// $Id: ad_weight_probability.module,v 1.1.4.5 2009/03/27 19:11:50 jeremy Exp $

/**
 * @file
 * A plug in for the ad.module, allowing an admin to set the probability that
 * a given advertisement will be displayed.
 *
 * Copyright (c) 2008-2009.
 *  Jeremy Andrews <jeremy@tag1consulting.com>.
 */

define('AD_PROBABILITY_DEFAULT', 100);

/**
 * Implementation of hook_form_alter().
 * Generate a form for assigning a weight to an advertisement.
 */
function ad_weight_probability_form_alter(&$form, &$form_state, $form_id) {
  if (isset($form['type']) && $form_id == 'ad_node_form') {
    $node = $form['#node'];
    $form['weighting'] = array(
      '#type' => 'fieldset',
      '#access' => user_access('configure ad probability'),
      '#title' => t('Weight'),
      '#collapsible' => TRUE,
      '#collapsed' => FALSE,
    );
    $form['weighting']['probability'] = array(
      '#type' => 'select',
      '#access' => user_access('configure ad probability'),
      '#title' => t('Probability'),
      '#options' => _ad_weight_probability_weights(),
      '#default_value' => isset($node->probability) ? $node->probability : 100,
      '#description' => t('The greater the probability, the more frequently this advertisement will be displayed.  An advertisement with a probablity of 2 will be displayed twice as frequently as an advertisement with a probability of 1.'),
    );
    $form['weighting']['#weight'] = -1;
  }
}

/**
 * Implementation of hook_nodeapi().
 */
function ad_weight_probability_nodeapi($node, $op, $arg = 0) {
  switch ($op) {
    case 'load':
      return _ad_weight_probability_node_load($node);
    case 'insert':
    case 'update':
      if (user_access('configure ad probability')) {
        // Fully load the node object to confirm that we are working with an
        // advertisement.
        $ad = node_load($node->nid);
        if (isset($ad->adtype)) {
          return _ad_weight_probability_node_save($node, $op);
        }
      }
    case 'delete':
      return _ad_weight_probability_node_delete($node);
  }
}

/**
 * Implementation of hook_perm().
 */
function ad_weight_probability_perm() {
  return array(t('configure ad probability'));
}

/**
 * Implementation of hook_ad_build_cache().
 */
function ad_weight_probability_ad_build_cache() {
  $cache = array();
  $active = db_query("SELECT a.aid, p.probability FROM {ads} a LEFT JOIN {ad_weight_probability} p ON a.aid = p.aid WHERE adstatus = 'active'");
  while ($ad = db_fetch_object($active)) {
    $probability = $ad->probability ? $ad->probability : AD_PROBABILITY_DEFAULT;
    $ads[$ad->aid] = $probability;
  }
  $cache['weight']['probability'] = $ads;
  $cache['weight']['hook_weight'] = array(
    'weight' => 10,
    'file' => drupal_get_path('module', 'ad_weight_probability') .'/ad_weight_probability.inc',
    'function' => 'ad_weight_probability_cache_filter',
  );
  return $cache;
}

/**
 * Helper function, load the probability from the database.
 */
function _ad_weight_probability_node_load($node) {
  $probability = (int)db_result(db_query('SELECT probability FROM {ad_weight_probability} WHERE aid = %d', $node->nid));
  $output['probability'] = $probability ? $probability : AD_PROBABILITY_DEFAULT;
  return $output;
}

/**
 * Helper function, save the probability to the database.
 */
function _ad_weight_probability_node_save($node) {
  if (is_object($node) && $node->nid) {
    db_query('UPDATE {ad_weight_probability} SET probability = %d WHERE aid = %d', $node->probability, $node->nid);
    if (!db_affected_rows()) {
      db_query('INSERT INTO {ad_weight_probability} (aid, probability) VALUES(%d, %d)', $node->nid, $node->probability);
    }
  }
}

/**
 * Helper function, delete the probability from the database.
 */
function _ad_weight_probability_node_delete($node) {
  db_query('DELETE FROM {ad_weight_probability} WHERE aid = %d', $node->nid);
}

/**
 * Available weight probabilities.
 */
function _ad_weight_probability_weights() {
  return array(
    25 => t('1/4'),
    33 => t('1/3'),
    50 => t('1/2'),
    100 => t('1'),
    200 => t('2'),
    300 => t('3'),
    400 => t('4'),
  );
}