<?php
// $Id: uc_bulk_discount.module,v 1.1.2.1 2009/12/14 21:25:40 awebb Exp $

/**
 * uc_bulk_discount.module
 * ------------------------------------
 *  
 * This module provides users with the 'manage discounts' role the ability to 
 * specify quantity discounts ( percentage ) for specific users and all users 
 * of specified roles on products.
 * 
 * > When a site visitor logs in, special discounts goes into effect.
 * 
 * > Discounts are specified with quantity tiers.
 * 
 * > User discounts override role discounts.
 * 
 * > If user has multiple roles with special discounts, then the greatest 
 *   discount is used.
 * 
 * > Display discount tiers for this user on the product page.
 *   Got to encourage those sales :-)
 * 
 * > Discounts apply to all product types ( attribute combinations ).
 * 
 */

//------------------------------------------------------------------------------
// Constants
//------------------------------------------------------------------------------

/**
 * Module permissions.
 */
define( 'UCBD_PERM_MANAGE_DISCOUNTS', 'manage discounts' );

/**
 * Pricing rule types.
 */
define( 'UCBD_TYPE_USER', 'user' );
define( 'UCBD_TYPE_ROLE', 'role' );

//------------------------------------------------------------------------------
// Drupal hooks
//------------------------------------------------------------------------------

/**
 * Implementation of hook_perm().
 *
 * @see http://api.drupal.org/api/function/hook_perm/6
 */
function uc_bulk_discount_perm( ) {

  return array ( 
    UCBD_PERM_MANAGE_DISCOUNTS 
  );
}

//------------------------------------------------------------------------------

/**
 * Implementation of hook_menu().
 * 
 * Implemented pages:
 * 
 * 	node/{nid}/edit/discounts/add            ( local task )
 *  node/{nid}/edit/discounts/edit/{pdid}    ( local task )
 *  node/{nid}/edit/discounts/delete/{pdid}  ( local task )
 * 
 *  where {nid} is a product node.
 * 
 * @see http://api.drupal.org/api/function/hook_menu/6
 */
function uc_bulk_discount_menu( ) {
  $items = array();
    
  $items['node/%node/edit/discounts'] = array(
    'title' => 'Discounts',
  	'page callback' => 'uc_bulk_discount_list_discounts',
    'page arguments' => array(1),
    'access callback' => 'uc_bulk_discount_admin_access',
    'access arguments' => array(1),
    'weight' => -6,
    'type' => MENU_LOCAL_TASK,
    'file' => 'uc_bulk_discount.admin.inc',
  );
    
  $items['node/%node/edit/discounts/add'] = array(
    'title' => 'Add product discount rule',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('uc_bulk_discount_add_discount_form', 1),
    'access callback' => 'uc_bulk_discount_admin_access',
    'access arguments' => array(1),
    'weight' => -8,
    'type' => MENU_LOCAL_TASK,
    'file' => 'uc_bulk_discount.admin.inc',
  );
  
  $items['node/%node/edit/discounts/edit/%discount_rule'] = array(
    'title' => 'Edit product discount rule',
    'page callback' => 'drupal_get_form', 
    'page arguments' => array('uc_bulk_discount_edit_discount_form', 1, 5),
    'access callback' => 'uc_bulk_discount_admin_access',
    'access arguments' => array(1),
    'weight' => -6,
    'type' => MENU_LOCAL_TASK,
    'file' => 'uc_bulk_discount.admin.inc',
  );
    
  $items['node/%node/edit/discounts/delete/%discount_rule'] = array(
    'title' => 'Delete product discount rule',
    'page callback' => 'drupal_get_form', 
    'page arguments' => array('uc_bulk_discount_delete_discount_form', 1, 5),
    'access callback' => 'uc_bulk_discount_admin_access',
    'access arguments' => array(1),
    'weight' => -4,
    'type' => MENU_LOCAL_TASK,
    'file' => 'uc_bulk_discount.admin.inc',
  );
  
  return $items;
}

//------------------------------------------------------------------------------

/**
 * Implementation of hook_theme().
 *
 * @see http://api.drupal.org/api/function/hook_theme/6
 */
function uc_bulk_discount_theme( ) {  
  return array(
    'uc_bulk_discount_rule_listing' => array(
      'arguments' => array( 'node' => NULL, 'discount_rules' => NULL ),
      'file'      => 'uc_bulk_discount.admin.inc',
    ),
    'uc_bulk_discount_product_discounts' => array(
      'arguments' => array( 'form' => NULL ),
    )  
  );  
}

//------------------------------------------------------------------------------

/**
 * Implementation of hook_nodeapi(). 
 *
 * @see http://api.drupal.org/api/function/hook_nodeapi/6
 */
function uc_bulk_discount_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  
  switch ($op) {
    case 'delete':
      // Clear all existing product rules when a node is deleted.
      module_load_include( 'inc', 'uc_bulk_discount', 'uc_bulk_discount.api' );
      
      $discount_rules = uc_bulk_discount_select_rules(
        array(
        	'nid' => $node->nid,
        ),
        TRUE
      );
      
      foreach ($discount_rules as $rule) {
        uc_bulk_discount_remove_rule($rule);
      }      
      break;    
  }  
}

//------------------------------------------------------------------------------

/**
 * Implementation of hook_user(). 
 *
 * @see http://api.drupal.org/api/function/hook_user/6
 */
function uc_bulk_discount_user($op, &$edit, &$account, $category = NULL) {
  
  switch ($op) {
    case 'delete':
      // Clear all user rules when the corresponding user is deleted.
      module_load_include( 'inc', 'uc_bulk_discount', 'uc_bulk_discount.api' );
      
      $discount_rules = uc_bulk_discount_select_rules(
        array(
          'type' => UCBD_TYPE_USER,
        	'xid'  => $account->uid,
        ),
        TRUE
      );
      
      foreach ($discount_rules as $rule) {
        uc_bulk_discount_remove_rule($rule);
      }      
      break;     
  }
}

//------------------------------------------------------------------------------

/**
 * Implementation of hook_form_alter(). 
 *
 * @see http://api.drupal.org/api/function/hook_form_alter/6
 */
function uc_bulk_discount_form_alter(&$form, $form_state, $form_id) {
	
	if ($form_id == 'user_admin_role') {
	  // Delete relevant rules when role is deleted.
		$form['#submit'][] = 'uc_bulk_discount_user_admin_role_submit';		
	}
	elseif (variable_get('uc_bulk_discount_show_discounts', TRUE)
	        && preg_match('/^uc_product_add_to_cart_form(_\d+)?/', $form_id)) {
	  
	  module_load_include('inc', 'uc_bulk_discount', 'uc_bulk_discount.api');
	  
	  // Append discount information to cart form.
	  $form['discounts'] = array(
	    '#type'  => 'markup',
	    '#value' => theme('uc_bulk_discount_product_discounts', $form['nid']['#value']),
	    '#weight' => 10,
	  );
	  $form['submit']['#weight'] = 15;
	}
}

//------------------------------------------------------------------------------
// Ubercart hooks
//------------------------------------------------------------------------------

/**
 * Implementation of hook_line_item().
 */
function uc_bulk_discount_line_item() {
  
	$items[] = array(
    'id' => 'uc_bulk_discount',
    'title' => t('Group upgrade discount'),
    'callback' => 'uc_bulk_discount_line_item_discount',
    'weight' => 5,
    'stored' => TRUE,
    'default' => FALSE,
    'calculated' => TRUE,
    'display_only' => FALSE,
  );

  return $items;
}

//------------------------------------------------------------------------------
// Menu access handlers
//------------------------------------------------------------------------------

function uc_bulk_discount_admin_access( $node ) {
  if ( uc_product_is_product( $node ) && user_access( UCBD_PERM_MANAGE_DISCOUNTS ) ) {
    return TRUE;
  }
  return FALSE;
}

//------------------------------------------------------------------------------
// Form handlers
//------------------------------------------------------------------------------

function uc_bulk_discount_user_admin_role_submit($form, &$form_state) {

	if ($form_state['values']['op'] == t('Delete role')) {
		// Clear all role based rules when the corresponding role is deleted.
    module_load_include('inc', 'uc_bulk_discount', 'uc_bulk_discount.api');
      
    $discount_rules = uc_bulk_discount_select_rules(
      array(
        'type' => UCBD_TYPE_ROLE,
      	'xid'  => $form_state['values']['rid'],
      ),
      TRUE
    );
      
    foreach ($discount_rules as $rule) {
      uc_bulk_discount_remove_rule($rule);
    }
	}
}

//------------------------------------------------------------------------------
// Line item handlers
//------------------------------------------------------------------------------

/**
 * Handle the discount line item.
 */
function uc_bulk_discount_line_item_discount($op, $arg1) {
  module_load_include( 'inc', 'uc_bulk_discount', 'uc_bulk_discount.api' );
	
	switch ($op) {
  	case 'cart-preview':
  		$discounts = uc_bulk_discount_get_discounts($arg1);
  		
  		if (count($discounts)) {
  			$js = 'if (Drupal.jsEnabled) { $(document).ready(function() { '
        	   . ' if (window.set_line_item) { ';
  			
        foreach ($discounts as $discount) {
        	$js .= "set_line_item('uc_bulk_discount', '". $discount->name ."', ". $discount->amount .", ". variable_get('uc_bulk_discount_discount_weight', 5) ."); ";
      	}
  			
      	$js .= '} }) };';
  		
  			drupal_add_js($js, 'inline');
  		}
      break;
      
    case 'load':
      $lines = array();
      	
      foreach (uc_bulk_discount_get_discounts($arg1->products) as $discount) {
       	$lines[] = array(
         	'id'     => 'uc_bulk_discount',
         	'title'  => $discount->name,
         	'amount' => $discount->amount,
         	'weight' => variable_get('uc_bulk_discount_discount_weight', 5),
         	'data'   => $discount->data,
       	);
      }
      return $lines;
  }
}

//------------------------------------------------------------------------------
// Theme functions
//------------------------------------------------------------------------------

function theme_uc_bulk_discount_product_discounts($product_nid) {
  								
  $discount_tiers = uc_bulk_discount_get_discount_tiers($product_nid);
  
  $header = array(t('Low quantity'), t('High quantity'), t('Discount'));
  $rows   = array();
  
  foreach ($discount_tiers as $tier) {
    
    $row = array(
      $tier['low_qty'],
      $tier['high_qty'],
      sprintf( '%.2f', $tier['discount']) . '% off'
    );
        
    $rows[] = $row;    
  }  
  if (count($rows)) {
    return '<div class="discount-table">'
  	  . '<div class="table-message">' . t('Get a discount when you purchase more of this product.') . '</div>' 
      . theme('table', $header, $rows)
      . '</div>';
  }
  return '';
}

//------------------------------------------------------------------------------
// Internal utilities
//------------------------------------------------------------------------------

function discount_rule_load( $pdid ) {
  module_load_include( 'inc', 'uc_bulk_discount', 'uc_bulk_discount.api' );
  return uc_bulk_discount_select_rules( array( 'pdid' => $pdid ) );  
}

//------------------------------------------------------------------------------

function uc_bulk_discount_get_discounts($products) {
	
  $discounts    = array();
  $product_data = array();
			
	foreach ($products as $product) {
	  
	  $price = ($product->price * $product->qty);
	  
	  if (!array_key_exists($product->nid, $product_data)) {
	    $product_data[$product->nid] = array(
	      'nid'   => $product->nid,
	    	'title' => $product->title,
	      'qty'   => $product->qty,
	      'price' => $price,
	    );
	  }
	  else {
	    $product_data[$product->nid]['qty'] += $product->qty;
	    $product_data[$product->nid]['price'] += $price;  
	  }	  
	}
	
	foreach ($product_data as $nid => $data) {
		$amount = _uc_bulk_discount_get_discount_amount($data);
			
		if ($amount) {
			$discount = new stdClass();
			
			$discount->name   = t('!title quantity discount', array('!title' => $data['title']));
			$discount->amount = $amount;
			$discount->data   = array();		
			
			$discounts[] = $discount;
		}
	}
	
	return $discounts;	
}

//------------------------------------------------------------------------------

function _uc_bulk_discount_get_discount_amount($product_data) {
    
  $amount = 0;
    
  $discount_map = uc_bulk_discount_map_discounts($product_data['nid']);
  $product_qty  = $product_data['qty'];
  
  if (array_key_exists($product_qty, $discount_map)) {
    $amount = uc_bulk_discount_calculate_discount($product_data['price'], $discount_map[$product_qty]);  
  }
  return min($amount, 0);
}

//------------------------------------------------------------------------------

function uc_bulk_discount_map_discounts($product_nid, $account = NULL) {
    
  $rules = uc_bulk_discount_applicable_rules($product_nid, $account);
  $map   = array();  
  
  // Higher discount role rules override lower discount rules.
  foreach ($rules['role'] as $rule) {
  	for ($qty = $rule['low_qty']; $qty <= $rule['high_qty']; $qty++) {
  	  if (!$map[$qty] || $rule['discount'] > $map[$qty]) {
  	    $map[$qty] = $rule['discount'];
  	  }
  	}
  }
  // User rules override all role rules, even if they are lower discount.
  foreach ($rules['user'] as $rule) {
    for ($qty = $rule['low_qty']; $qty <= $rule['high_qty']; $qty++) {
  	  $map[$qty] = $rule['discount'];
  	}	 
  }
  return $map;
}

//------------------------------------------------------------------------------

function uc_bulk_discount_applicable_rules($nid, $account = NULL) {
	global $user;
	
	if (is_null($account)) {
		$account = $user;
	}
	
	$rules = uc_bulk_discount_select_rules(array('nid' => $nid), TRUE);
	
	$user_rules = array( );
	$role_rules = array( );
	
	$results = array();
	
  // Separate into type sections.
  foreach ($rules as $rule) {
    switch ($rule['type']) {
      case UCBD_TYPE_USER:
        $user_rules[$rule['xid']][] = $rule;
        break;  
          
  	 	case UCBD_TYPE_ROLE:
        $role_rules[$rule['xid']][] = $rule;
        break;                   
    }
  }	      

  // First see if there are any user rules available.
  $results['user'] = array();
  if (array_key_exists($account->uid, $user_rules)) {
  	$results['user'] = $user_rules[$account->uid];
  }
  
  // Check for role based rules.
  $results['role'] = array();  
  foreach ($account->roles as $rid => $name) {
  	if (array_key_exists($rid, $role_rules)) {
  	  $results['role'] = array_merge($results['role'], $role_rules[$rid]);  
  	}
  }  
  return $results;
}

//------------------------------------------------------------------------------

function uc_bulk_discount_get_discount_tiers($product_nid, $account = NULL) {
  
  $discount_map = uc_bulk_discount_map_discounts($product_nid, $account);
  $tiers        = array();
  
  $tier = NULL;
  foreach ($discount_map as $qty => $discount) {
    
    if (is_null($tier)
        || ($qty > ($tier['high_qty'] + 1)) 
        || ($discount != $tier['discount'])) {
          
      if (!is_null($tier)) {
        $tiers[] = $tier;
      }      
      // Start new tier.
      $tier = array(
        'low_qty' => $qty,
        'high_qty' => $qty,
        'discount' => $discount,
      );
    }
    else {
      // Continue old tier.
      $tier['high_qty'] = $qty;
    }
  }
  if (!is_null($tier)) {
    $tiers[] = $tier;  
  }
  return $tiers;
}

//------------------------------------------------------------------------------

function uc_bulk_discount_calculate_discount($price, $discount_amount) {
  return (-1 * ($price * ($discount_amount / 100)));
}

//------------------------------------------------------------------------------