# Account Invoice Triple Discount Readonly

## Description

This module fixes a bug in `account_invoice_triple_discount` when combined with `purchase_triple_discount`.

### Original Problem

In purchase orders, when configuring a discount in the `discount2` or `discount3` columns, upon saving:
- All discounts were accumulated in the `discount1` column
- The `discount2` and `discount3` fields were reset to zero

This occurred because the original mixin's `write` method always reset `discount2` and `discount3` to 0 when the computed `discount` field was included in the write (which happens when any discount is modified).

### Solution

The module overrides the `write` method of `triple.discount.mixin` to:
1. Detect if `discount1`, `discount2` or `discount3` are being explicitly modified
2. If there are explicit discounts, ignore the computed `discount` field
3. If only the `discount` field comes, maintain legacy behavior (map to `discount1` and reset the rest)

Additionally, it makes the `discount` field (total discount) **readonly** in:
- Partner form view (`res.partner`)
- Supplier info in product form (`product.supplierinfo`)
- Base mixin (`triple.discount.mixin`)

This forces users to work only with the `discount1`, `discount2` and `discount3` columns, avoiding confusion.

## Installation

1. Make sure `account_invoice_triple_discount` and `purchase_triple_discount` are installed
2. Update the module list
3. Install `account_invoice_triple_discount_readonly`

## Usage

After installation:
- The total discount field will be readonly and automatically calculated
- Users must use discount1, discount2, and discount3 fields to set discounts
- When saving, the individual discount values will be preserved correctly

## Bug Tracker

Bugs are tracked on [GitHub Issues](https://github.com/OCA/account-invoicing/issues).
In case of trouble, please check there if your issue has already been reported.

## Credits

### Contributors

* Coop Makers

### Maintainers

This module is maintained by the OCA.

## Compatibility

- Odoo 16.0
- account_invoice_triple_discount
- purchase_triple_discount