transition: implement extension of a loan

invenio_circulation/config.py

@@ -15,11 +15,13 @@
 from .search import LoansSearch
 from .transitions.transitions import CreatedToItemOnLoan, CreatedToPending, \
     ItemAtDeskToItemOnLoan, ItemInTransitHouseToItemReturned, \
-    ItemOnLoanToItemInTransitHouse, ItemOnLoanToItemReturned, \
-    PendingToItemAtDesk, PendingToItemInTransitPickup
-from .utils import get_default_loan_duration, is_item_available, \
-    is_loan_duration_valid, item_exists, item_location_retriever, \
-    patron_exists
+    ItemOnLoanToItemInTransitHouse, ItemOnLoanToItemOnLoan, \
+    ItemOnLoanToItemReturned, PendingToItemAtDesk, \
+    PendingToItemInTransitPickup
+from .utils import get_default_extension_duration, \
+    get_default_extension_max_count, get_default_loan_duration, \
+    is_item_available, is_loan_duration_valid, item_exists, \
+    item_location_retriever, patron_exists
 
 _CIRCULATION_LOAN_PID_TYPE = 'loan_pid'
 """."""
@@ -72,6 +74,8 @@
         dict(dest='ITEM_RETURNED', transition=ItemOnLoanToItemReturned),
         dict(dest='ITEM_IN_TRANSIT_TO_HOUSE',
              transition=ItemOnLoanToItemInTransitHouse),
+        dict(dest='ITEM_ON_LOAN', transition=ItemOnLoanToItemOnLoan,
+             trigger='extend'),
         dict(dest='CANCELLED', trigger='cancel')
     ],
     'ITEM_IN_TRANSIT_TO_HOUSE': [
@@ -102,6 +106,11 @@
         duration_validate=is_loan_duration_valid,
         item_available=is_item_available
     ),
+    extension=dict(
+        from_end_date=True,
+        duration_default=get_default_extension_duration,
+        max_count=get_default_extension_max_count
+    ),
 )
 """."""
 

invenio_circulation/transitions/transitions.py

@@ -8,7 +8,7 @@
 
 """Invenio Circulation custom transitions."""
 
-from datetime import timedelta
+from datetime import datetime, timedelta
 
 from flask import current_app
 from invenio_db import db
@@ -59,6 +59,34 @@ def _update_document_pending_request_for_item(item_pid):
         # TODO: index loan again?
 
 
+def _ensure_valid_extension(loan):
+    """Validate end dates for a extended loan."""
+    get_extension_max_count = current_app.config['CIRCULATION_POLICIES'][
+        'extension']['max_count']
+    extension_max_count = get_extension_max_count(loan)
+
+    extension_count = loan.get('extension_count', 0)
+    extension_count += 1
+    if extension_count > extension_max_count + 1:
+        msg = 'Max extension count reached `{0}`'.format(extension_max_count)
+        raise TransitionConstraintsViolation(msg=msg)
+
+    loan['extension_count'] = extension_count
+
+    get_extension_duration = current_app.config['CIRCULATION_POLICIES'][
+        'extension']['duration_default']
+    number_of_days = get_extension_duration(loan)
+    get_extension_from_end_date = current_app.config[
+        'CIRCULATION_POLICIES']['extension']['from_end_date']
+
+    end_date = parse_date(loan['end_date'])
+    if not get_extension_from_end_date:
+        end_date = loan.get('transaction_date')
+
+    end_date += timedelta(days=number_of_days)
+    loan['end_date'] = end_date.isoformat()
+
+
 class CreatedToPending(Transition):
     """Action to request to loan an item."""
 
@@ -165,6 +193,20 @@ def after(self, loan):
         super(ItemAtDeskToItemOnLoan, self).after(loan)
 
 
+class ItemOnLoanToItemOnLoan(Transition):
+    """Extend action to perform a item loan extension."""
+
+    def before(self, loan, **kwargs):
+        """Validate extension action."""
+        super(ItemOnLoanToItemOnLoan, self).before(loan, **kwargs)
+
+        _ensure_valid_extension(loan)
+
+    def after(self, loan):
+        """."""
+        super(ItemOnLoanToItemOnLoan, self).after(loan)
+
+
 class ItemOnLoanToItemInTransitHouse(Transition):
     """Check-in action when returning an item not to its belonging location."""
 

invenio_circulation/utils.py

@@ -38,6 +38,16 @@ def get_default_loan_duration(loan):
     return 30
 
 
+def get_default_extension_duration(loan):
+    """Return a default extension duration in number of days."""
+    return 30
+
+
+def get_default_extension_max_count(loan):
+    """Return a default extensions max count."""
+    return float("inf")
+
+
 def is_loan_duration_valid(loan):
     """Validate the loan duration."""
     return loan['end_date'] > loan['start_date'] and \

tests/test_loan_transitions.py

@@ -12,6 +12,7 @@
 
 import mock
 import pytest
+from flask import current_app
 from helpers import SwappedConfig, SwappedNestedConfig
 
 from invenio_circulation.api import Loan, is_item_available
@@ -60,6 +61,61 @@ def test_loan_request(loan_created, db, params):
     assert loan['state'] == 'PENDING'
 
 
+def test_loan_extend(loan_created, db, params,
+                     mock_is_item_available):
+    """Test loan extend action."""
+
+    def get_max_count_1(loan):
+        return 1
+
+    loan = current_circulation.circulation.trigger(
+        loan_created, **dict(params, trigger='checkout')
+    )
+    db.session.commit()
+    end_date = parse_date(loan['end_date'])
+
+    loan = current_circulation.circulation.trigger(
+        loan, **dict(params, trigger='extend')
+    )
+    db.session.commit()
+    new_end_date = parse_date(loan['end_date'])
+    assert new_end_date == end_date + timedelta(days=30)
+    assert loan['extension_count'] == 1
+    loan = current_circulation.circulation.trigger(
+        loan, **dict(params, trigger='extend')
+    )
+    db.session.commit()
+
+    # test to manny extensions
+    current_app.config['CIRCULATION_POLICIES']['extension'][
+        'max_count'] = get_max_count_1
+    with pytest.raises(TransitionConstraintsViolation):
+        loan = current_circulation.circulation.trigger(
+            loan, **dict(params, trigger='extend')
+        )
+
+
+def test_loan_extend_from_enddate(loan_created, db, params,
+                                  mock_is_item_available):
+    """Test loan extend action from transaction date."""
+
+    loan = current_circulation.circulation.trigger(
+        loan_created, **dict(params, trigger='checkout')
+    )
+    db.session.commit()
+    extension_date = parse_date(loan.get('transaction_date'))
+    current_app.config['CIRCULATION_POLICIES']['extension'][
+        'from_end_date'] = False
+
+    loan = current_circulation.circulation.trigger(
+        loan, **dict(params, trigger='extend')
+    )
+    db.session.commit()
+    new_end_date = parse_date(loan['end_date'])
+    assert new_end_date == extension_date + timedelta(days=30)
+    assert loan['extension_count'] == 1
+
+
 def test_cancel_action(loan_created, db, params,
                        mock_is_item_available):
     """Test should pass when calling `cancel` from `ITEM_ON_LOAN`."""