The strange thing, is that I tryed to adapt the code of commerce_line_item_unit_price_amount() found in commerce/modules/line_item/commerce_line_item.rules.inc, so my code liiks like:
<?php
global $user;
$product = commerce_product_load(4); // my commerce product for test
$line_item = commerce_product_line_item_new(
$product,
1,
0,
array(
),
'cover' // I do have this line_items type
);
// manually set amount and component name
$amount = 1234;
$component_name = 'base_price'; // tryed with discount, nothing change
$wrapper = entity_metadata_wrapper('commerce_line_item', $line_item);
$unit_price = commerce_price_wrapper_value($wrapper, 'commerce_unit_price', TRUE);
// Calculate the updated amount and create a price array representing the
// difference between it and the current amount.
$current_amount = $unit_price['amount'];
$updated_amount = commerce_round(COMMERCE_ROUND_HALF_UP, $amount);
$difference = array(
'amount' => $updated_amount - $current_amount,
'currency_code' => $unit_price['currency_code'],
'data' => array(),
);
// Set the amount of the unit price and add the difference as a component.
$wrapper->commerce_unit_price->amount = $updated_amount;
$wrapper->commerce_unit_price->data = commerce_price_component_add(
$wrapper->commerce_unit_price->value(),
$component_name,
$difference,
TRUE
);
$insert_line_item = commerce_cart_product_add($user->uid, $line_item, FALSE);
?>
