Allow hook based price calculation when price pre-calculation is disabled

As discussed, I created an API function that wraps the logic required to determine which "callback" is going to be used determining the sell price calculation of a product line item.
I believe this is needed since Commerce Discount and various other contrib modules are directly invoking the "commerce_product_calculate_sell_price" event, so once this is merged, contrib modules should now use "commerce_product_pricing_invoke" instead...

I'm still unsure about the name, I also thought about "commerce_product_pricing_process", suggestions are welcome.

Thanks for the feedback, committed the patch from comment #8 (addressed your feedbacks).

Sorry, but the hook hook_commerce_product_calculate_sell_price_line_item() is not called. I believe that this is the hook to show the correct price at the add_to_cart form to correct the selling price which is seen by customers, isn't it???

What I did:
I updated commerce to Version: 7.x-1.13+25-dev (before I had the stable version of commerce). I patched the code with https://www.drupal.org/node/1541886#comment-12139654 to integrate the possibility of changing sell price per ajax.
After that, when loading a product page, I saw the correct amount. The base price is 12.00. So I had the correct calculated price, which is either 14.15 or 14.51.
After activating in admin/commerce/config/product-pricing/pre-calculation like so:

the base price is always 0 and I'm not able to revert my settings because of the set states in this form!???

So do I misunderstand anything?

Best wishes,
marc

// Edit: I forgot that I used form_alter() where I Inserted $form_state['default_product']->commerce_price['und'][0]['amount'] = 0; for testing purposes. Forget about my post and sorry!!!!

@maen: Did you implement the hook yourself in a custom module?? Because Commerce doesn't implement it by default.

@jsacksick:
Yes I did. With
drush fn-hook commerce_product_calculate_sell_price_line_item
the system shows me that it recognizes my implementation!
I'm just debugging the form from my image above, and I assume that the config from my image just above should give me in commerce_product_pricing_ui.admin in line 162:
$product_pricing_callback == 'module_invoke_all.
In fact $product_pricing_callback gives me "rules_invoke_all" and that seems to be the problem!???

So do I have to give the variable in another location???

If not, I went manually through the patch, and the code seems ok!???

And:
If I debug commerce_product_pre_calculation_settings_form_submit(...),

$values =
[commerce_product_sell_price_pre_calculation] = string "disabled";
[commerce_product_pricing_callback] = string "rules_invoke_all";

So I believe a take a deeper look at the form again!??

Sorry again, but what do I miss???

In commerce_product_pricing_ui.admin line 145:

$form['commerce_product_pricing_callback'] = array(
    '#type' => 'radios',
    '#title' => t('Price calculation process'),
    '#description' => t('You can only allow modules to directly engage in product pricing when pre-calculation is disabled.'),
    '#options' => array(
      'rules_invoke_event' => t('Evaluate pricing rules in order'),
      'rules_invoke_all' => t('Evaluate module based pricing routines then invoke pricing rules in order'),
    ),
    '#states' => array(
      'visible' => array(
        ':input[name="commerce_product_sell_price_pre_calculation"]' => array('value' => 'disabled'),
      ),
    ),
    '#default_value' => $product_pricing_callback,
  );
  // If the Product pricing callback configured is set to "module_invoke_all"
  // disable the element and update the description.
  if ($product_pricing_callback == 'module_invoke_all') {
    $form['commerce_product_pricing_callback']['#options']['module_invoke_all'] = t('Only invoke module based pricing routines');
    $form['commerce_product_pricing_callback']['#description'] .= ' ' . t("This value has been set in your site's codebase and cannot be changed via this form.");
    $form['commerce_product_pricing_callback']['#disabled'] = TRUE;
  }

In my opinion there is "show the radio button for "module_invoke_all" only then when you already selected the radio button for "module_invoke_all" which is not possible because you can't select it before!!!

@maen: The hook should be called hook_commerce_product_calculate_sell_price(), the .api.php was wrong and I just fixed it.
As for "module_invoke_all", this needs to be configured manually (either by setting

$conf['commerce_product_pricing_callback'] =
 'module_invoke_all';

or by setting the variable manually using drush (drush vset commerce_product_pricing_callback "module_invoke_all").

The reason we're not exposing this option by default is that we don't want people to accidentally select that option without being aware of the consequences (Enabling that option will completely bypass Rules).

Hope this helps!

THIS HELPS A LOT!!!! Thank you so much!