Added Customers Not Buying Since Long Time against Sales Invoice
diff --git a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.js b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.js
index e975e9f..6d00b82 100644
--- a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.js
+++ b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.js
@@ -8,6 +8,13 @@
 			"label": __("Days Since Last Order"),
 			"fieldtype": "Int",
 			"default": 60
+		},
+		{
+			"fieldname":"doctype",
+			"label": __("Doctype"),
+			"fieldtype": "Select",
+			"default": "Sales Order",
+			"options": "Sales Order\nSales Invoice"
 		}
 	]
 }
\ No newline at end of file
diff --git a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
index de4c655..86186aa 100644
--- a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
+++ b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
@@ -10,41 +10,51 @@
 	if not filters: filters ={}
 
 	days_since_last_order = filters.get("days_since_last_order")
+	doctype = filters.get("doctype")
+	
 	if cint(days_since_last_order) <= 0:
 		frappe.throw(_("'Days Since Last Order' must be greater than or equal to zero"))
 
 	columns = get_columns()
-	customers = get_so_details()
+	customers = get_sales_details(doctype)
 
 	data = []
 	for cust in customers:
 		if cint(cust[8]) >= cint(days_since_last_order):
-			cust.insert(7,get_last_so_amt(cust[0]))
+			cust.insert(7,get_last_sales_amt(cust[0], doctype))
 			data.append(cust)
 	return columns, data
 
-def get_so_details():
+def get_sales_details(doctype):
+	cond = """sum(so.base_net_total) as 'total_order_considered',
+			max(so.posting_date) as 'last_order_date',
+			DATEDIFF(CURDATE(), max(so.posting_date)) as 'days_since_last_order' """
+	if doctype == "Sales Order":
+		cond = """sum(if(so.status = "Stopped",
+				so.base_net_total * so.per_delivered/100,
+				so.base_net_total)) as 'total_order_considered',
+			max(so.transaction_date) as 'last_order_date',
+			DATEDIFF(CURDATE(), max(so.transaction_date)) as 'days_since_last_order'"""
+	
 	return frappe.db.sql("""select
 			cust.name,
 			cust.customer_name,
 			cust.territory,
 			cust.customer_group,
 			count(distinct(so.name)) as 'num_of_order',
-			sum(base_net_total) as 'total_order_value',
-			sum(if(so.status = "Stopped",
-				so.base_net_total * so.per_delivered/100,
-				so.base_net_total)) as 'total_order_considered',
-			max(so.transaction_date) as 'last_sales_order_date',
-			DATEDIFF(CURDATE(), max(so.transaction_date)) as 'days_since_last_order'
-		from `tabCustomer` cust, `tabSales Order` so
+			sum(base_net_total) as 'total_order_value', {0}
+		from `tabCustomer` cust, `tab{1}` so
 		where cust.name = so.customer and so.docstatus = 1
 		group by cust.name
-		order by 'days_since_last_order' desc """,as_list=1)
+		order by 'days_since_last_order' desc """.format(cond, doctype), as_list=1)
 
-def get_last_so_amt(customer):
-	res =  frappe.db.sql("""select base_net_total from `tabSales Order`
-		where customer = %s and docstatus = 1 order by transaction_date desc
-		limit 1""", customer)
+def get_last_sales_amt(customer, doctype):
+	cond = "posting_date"
+	if doctype =="Sales Order":
+		cond = "transaction_date"
+	res =  frappe.db.sql("""select base_net_total from `tab{0}`
+		where customer = %s and docstatus = 1 order by {1} desc
+		limit 1""".format(doctype, cond), customer)
 
 	return res and res[0][0] or 0
 
@@ -58,6 +68,6 @@
 		_("Total Order Value") + ":Currency:120",
 		_("Total Order Considered") + ":Currency:160",
 		_("Last Order Amount") + ":Currency:160",
-		_("Last Sales Order Date") + ":Date:160",
+		_("Last Order Date") + ":Date:160",
 		_("Days Since Last Order") + "::160"
 	]