From d93365c684593bdf788e8a5d6962f1b51d415d0e Mon Sep 17 00:00:00 2001
From: Christopher Ormaza <cormaza@opa-consulting.com>
Date: Thu, 2 Sep 2021 14:36:01 +0000
Subject: [PATCH] [IMP] base_vat: CI and Ruc Validation for Ecuadorian Context
 - Added own implementation, for CI and RUC Validation

Part-of: odoo/odoo#75055
---
 addons/base_vat/models/res_partner.py | 61 +++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/addons/base_vat/models/res_partner.py b/addons/base_vat/models/res_partner.py
index c6dc7d5cd19..24e6d0759c7 100644
--- a/addons/base_vat/models/res_partner.py
+++ b/addons/base_vat/models/res_partner.py
@@ -7,6 +7,8 @@ import re
 import stdnum
 from stdnum.eu.vat import check_vies
 from stdnum.exceptions import InvalidComponent
+from stdnum.util import clean
+
 import logging
 
 from odoo import api, models, tools, _
@@ -258,6 +260,65 @@ class ResPartner(models.Model):
             return check == int(num[8])
         return False
 
+    def _checksum_ci_ec(self, number):
+        """Calculate a checksum over the number."""
+        fold = lambda x: x - 9 if x > 9 else x
+        return sum(fold((2, 1)[i % 2] * int(n))
+                for i, n in enumerate(number)) % 10
+
+    def _checksum_ruc_ec(self, number, weights):
+        """Calculate a checksum over the number given the weights."""
+        return sum(w * int(n) for w, n in zip(weights, number)) % 11
+
+    def is_valid_ci_ec(self, vat):
+        """Check if the number provided is a valid CI number. This checks the
+        length, formatting and check digit."""
+        if len(vat) != 10:
+            return False
+        if not vat.isdecimal():
+            return False
+        if (vat[:2] < '01' or vat[:2] > '24') and (vat[:2] not in ('30', '50')):
+            return False
+        if vat[2] > '6':
+            return False
+        if self._checksum_ci_ec(vat) != 0:
+            return False
+        return True
+
+    def is_valid_ruc_ec(self, vat):
+        """Check if the number provided is a valid RUC number. This checks the
+        length, formatting, check digit and check sum."""
+        if len(vat) != 13:
+            return False
+        if not vat.isdecimal():
+            return False
+        if (vat[:2] < '01' or vat[:2] > '24') and (vat[:2] not in ('30', '50')):
+            return False
+        if vat[2] <= '5':
+            # 0..5 = natural RUC: CI plus establishment number
+            if vat[-3:] == '000':
+                return False
+            return self.is_valid_ci_ec(vat[:10])
+        elif vat[2] == '6':
+            # 6 = public RUC
+            #if vat[-4:] == '0000':
+            #    return False
+            if self._checksum_ruc_ec(vat[:9], (3, 2, 7, 6, 5, 4, 3, 2, 1)) != 0:
+                return False
+        elif vat[2] == '9':
+            # 9 = juridical RUC
+            if vat[-3:] == '000':
+                return False
+            if self._checksum_ruc_ec(vat[:10], (4, 3, 2, 7, 6, 5, 4, 3, 2, 1)) != 0:
+                return False
+        else:
+            return False
+        return True
+
+    def check_vat_ec(self, vat):
+        vat = clean(vat, ' -.').upper().strip()
+        return self.is_valid_ruc_ec(vat)
+
     def _ie_check_char(self, vat):
         vat = vat.zfill(8)
         extra = 0