import frappe
from frappe import _
from frappe.utils import flt, cint
from collections import defaultdict
from erpnext.stock.doctype.serial_no.serial_no import get_serial_nos

class Subcontracting():
	def set_materials_for_subcontracted_items(self, raw_material_table):
		if self.doctype == 'Purchase Invoice' and not self.update_stock:
			return

		self.raw_material_table = raw_material_table
		self.__identify_change_in_item_table()
		self.__prepare_supplied_items()
		self.__validate_consumed_qty()

	def __prepare_supplied_items(self):
		self.initialized_fields()
		self.__get_purchase_orders()
		self.__get_pending_qty_to_receive()
		self.get_available_materials()
		self.__remove_changed_rows()
		self.__set_supplied_items()

	def initialized_fields(self):
		self.available_materials = frappe._dict()
		self.alternative_item_details = frappe._dict()
		self.__get_backflush_based_on()

	def __get_backflush_based_on(self):
		self.backflush_based_on = frappe.db.get_single_value("Buying Settings",
			"backflush_raw_materials_of_subcontract_based_on")

	def __get_purchase_orders(self):
		self.purchase_orders = []

		if self.doctype == 'Purchase Order':
			return

		self.purchase_orders = [d.purchase_order for d in self.items if d.purchase_order]

	def __identify_change_in_item_table(self):
		self.__changed_name = []
		self.__reference_name = []

		if self.doctype == 'Purchase Order' or self.is_new():
			self.set(self.raw_material_table, [])
			return

		item_dict = self.__get_data_before_save()
		if not item_dict:
			return True

		for n_row in self.items:
			self.__reference_name.append(n_row.name)
			if (n_row.name not in item_dict) or (n_row.item_code, n_row.qty) != item_dict[n_row.name]:
				self.__changed_name.append(n_row.name)

			if item_dict.get(n_row.name):
				del item_dict[n_row.name]

		self.__changed_name.extend(item_dict.keys())

	def __get_data_before_save(self):
		item_dict = {}
		if self.doctype in ['Purchase Receipt', 'Purchase Invoice'] and self._doc_before_save:
			for row in self._doc_before_save.get('items'):
				item_dict[row.name] = (row.item_code, row.qty)

		return item_dict

	def get_available_materials(self):
		''' Get the available raw materials which has been transferred to the supplier.
			available_materials = {
				(item_code, subcontracted_item, purchase_order): {
					'qty': 1, 'serial_no': [ABC], 'batch_no': {'batch1': 1}, 'data': item_details
				}
			}
		'''
		if not self.purchase_orders:
			return

		for row in self.__get_transferred_items():
			key = (row.rm_item_code, row.main_item_code, row.purchase_order)

			if key not in self.available_materials:
				self.available_materials.setdefault(key, frappe._dict({'qty': 0, 'serial_no': [],
					'batch_no': defaultdict(float), 'item_details': row, 'po_details': []})
				)

			details = self.available_materials[key]
			details.qty += row.qty
			details.po_details.append(row.po_detail)

			if row.serial_no:
				details.serial_no.extend(get_serial_nos(row.serial_no))

			if row.batch_no:
				details.batch_no[row.batch_no] += row.qty

			self.__set_alternative_item_details(row)

		for doctype in ['Purchase Receipt', 'Purchase Invoice']:
			self.__update_consumed_materials(doctype)

	def __update_consumed_materials(self, doctype, return_consumed_items=False):
		'''Deduct the consumed materials from the available materials.'''

		pr_items = self.__get_received_items(doctype)
		if not pr_items:
			return ([], {}) if return_consumed_items else None

		pr_items = {d.name: d.get(self.get('po_field') or 'purchase_order') for d in pr_items}
		consumed_materials = self.__get_consumed_items(doctype, pr_items.keys())

		if return_consumed_items:
			return (consumed_materials, pr_items)

		for row in consumed_materials:
			key = (row.rm_item_code, row.main_item_code, pr_items.get(row.reference_name))
			if not self.available_materials.get(key):
				continue

			self.available_materials[key]['qty'] -= row.consumed_qty
			if row.serial_no:
				self.available_materials[key]['serial_no'] = list(
					set(self.available_materials[key]['serial_no']) - set(get_serial_nos(row.serial_no))
				)

			if row.batch_no:
				self.available_materials[key]['batch_no'][row.batch_no] -= row.consumed_qty

	def __get_transferred_items(self):
		fields = ['`tabStock Entry`.`purchase_order`']
		alias_dict = {'item_code': 'rm_item_code', 'subcontracted_item': 'main_item_code', 'basic_rate': 'rate'}

		child_table_fields = ['item_code', 'item_name', 'description', 'qty', 'basic_rate', 'amount',
			'serial_no', 'uom', 'subcontracted_item', 'stock_uom', 'batch_no', 'conversion_factor',
			's_warehouse', 't_warehouse', 'item_group', 'po_detail']

		if self.backflush_based_on == 'BOM':
			child_table_fields.append('original_item')

		for field in child_table_fields:
			fields.append(f'`tabStock Entry Detail`.`{field}` As {alias_dict.get(field, field)}')

		filters = [['Stock Entry', 'docstatus', '=', 1], ['Stock Entry', 'purpose', '=', 'Send to Subcontractor'],
			['Stock Entry', 'purchase_order', 'in', self.purchase_orders]]

		return frappe.get_all('Stock Entry', fields = fields, filters=filters)

	def __get_received_items(self, doctype):
		fields = []
		self.po_field = 'purchase_order'

		for field in ['name', self.po_field, 'parent']:
			fields.append(f'`tab{doctype} Item`.`{field}`')

		filters = [[doctype, 'docstatus', '=', 1], [f'{doctype} Item', self.po_field, 'in', self.purchase_orders]]
		if doctype == 'Purchase Invoice':
			filters.append(['Purchase Invoice', 'update_stock', "=", 1])

		return frappe.get_all(f'{doctype}', fields = fields, filters = filters)

	def __get_consumed_items(self, doctype, pr_items):
		return frappe.get_all('Purchase Receipt Item Supplied',
			fields = ['serial_no', 'rm_item_code', 'reference_name', 'batch_no', 'consumed_qty', 'main_item_code'],
			filters = {'docstatus': 1, 'reference_name': ('in', list(pr_items)), 'parenttype': doctype})

	def __set_alternative_item_details(self, row):
		if row.get('original_item'):
			self.alternative_item_details[row.get('original_item')] = row

	def __get_pending_qty_to_receive(self):
		'''Get qty to be received against the purchase order.'''

		self.qty_to_be_received = defaultdict(float)

		if self.doctype != 'Purchase Order' and self.backflush_based_on != 'BOM' and self.purchase_orders:
			for row in frappe.get_all('Purchase Order Item',
				fields = ['item_code', '(qty - received_qty) as qty', 'parent', 'name'],
				filters = {'docstatus': 1, 'parent': ('in', self.purchase_orders)}):

				self.qty_to_be_received[(row.item_code, row.parent)] += row.qty

	def __get_materials_from_bom(self, item_code, bom_no, exploded_item=0):
		doctype = 'BOM Item' if not exploded_item else 'BOM Explosion Item'
		fields = [f'`tab{doctype}`.`stock_qty` / `tabBOM`.`quantity` as qty_consumed_per_unit']

		alias_dict = {'item_code': 'rm_item_code', 'name': 'bom_detail_no', 'source_warehouse': 'reserve_warehouse'}
		for field in ['item_code', 'name', 'rate', 'stock_uom',
			'source_warehouse', 'description', 'item_name', 'stock_uom']:
			fields.append(f'`tab{doctype}`.`{field}` As {alias_dict.get(field, field)}')

		filters = [[doctype, 'parent', '=', bom_no], [doctype, 'docstatus', '=', 1],
			['BOM', 'item', '=', item_code], [doctype, 'sourced_by_supplier', '=', 0]]

		return frappe.get_all('BOM', fields = fields, filters=filters, order_by = f'`tab{doctype}`.`idx`') or []

	def __remove_changed_rows(self):
		if not self.__changed_name:
			return

		i=1
		self.set(self.raw_material_table, [])
		for d in self._doc_before_save.supplied_items:
			if d.reference_name in self.__changed_name:
				continue

			if (d.reference_name not in self.__reference_name):
				continue

			d.idx = i
			self.append('supplied_items', d)

			i += 1

	def __set_supplied_items(self):
		self.bom_items = {}

		has_supplied_items = True if self.get(self.raw_material_table) else False
		for row in self.items:
			if (self.doctype != 'Purchase Order' and ((self.__changed_name and row.name not in self.__changed_name)
				or (has_supplied_items and not self.__changed_name))):
				continue

			if self.doctype == 'Purchase Order' or self.backflush_based_on == 'BOM':
				for bom_item in self.__get_materials_from_bom(row.item_code, row.bom, row.get('include_exploded_items')):
					qty = (flt(bom_item.qty_consumed_per_unit) * flt(row.qty) * row.conversion_factor)
					bom_item.main_item_code = row.item_code
					self.__update_reserve_warehouse(bom_item, row)
					self.__set_alternative_item(bom_item)
					self.__add_supplied_item(row, bom_item, qty)

			elif self.backflush_based_on != 'BOM':
				for key, transfer_item in self.available_materials.items():
					if (key[1], key[2]) == (row.item_code, row.purchase_order) and transfer_item.qty > 0:
						qty = self.__get_qty_based_on_material_transfer(row, transfer_item) or 0
						transfer_item.qty -= qty
						self.__add_supplied_item(row, transfer_item.get('item_details'), qty)

				if self.qty_to_be_received:
					self.qty_to_be_received[(row.item_code, row.purchase_order)] -= row.qty

	def __update_reserve_warehouse(self, row, item):
		if self.doctype == 'Purchase Order':
			row.reserve_warehouse = (self.set_reserve_warehouse or item.warehouse)

	def __get_qty_based_on_material_transfer(self, item_row, transfer_item):
		key = (item_row.item_code, item_row.purchase_order)

		if self.qty_to_be_received == item_row.qty:
			return transfer_item.qty

		if self.qty_to_be_received:
			qty = (flt(item_row.qty) * flt(transfer_item.qty)) / flt(self.qty_to_be_received.get(key, 0))
			if (transfer_item.serial_no or frappe.get_cached_value('UOM',
				transfer_item.item_details.stock_uom, 'must_be_whole_number')):
				return frappe.utils.ceil(qty)

			return qty

	def __set_alternative_item(self, bom_item):
		if self.alternative_item_details.get(bom_item.rm_item_code):
			bom_item.update(self.alternative_item_details[bom_item.rm_item_code])

	def __add_supplied_item(self, item_row, bom_item, qty):
		bom_item.conversion_factor = item_row.conversion_factor
		rm_obj = self.append(self.raw_material_table, bom_item)
		rm_obj.reference_name = item_row.name

		if self.doctype == 'Purchase Order':
			rm_obj.required_qty = qty
		else:
			self.__set_batch_nos(bom_item, item_row, rm_obj, qty)

	def __set_batch_nos(self, bom_item, item_row, rm_obj, qty):
		key = (rm_obj.rm_item_code, item_row.item_code, item_row.purchase_order)

		if (self.available_materials.get(key) and self.available_materials[key]['batch_no']):
			for batch_no, batch_qty in self.available_materials[key]['batch_no'].items():
				if batch_qty >= qty:
					self.__set_batch_no_as_per_qty(item_row, rm_obj, batch_no, qty)
					self.available_materials[key]['batch_no'][batch_no] -= qty
					return

				elif qty > 0 and batch_qty > 0:
					qty -= batch_qty
					new_rm_obj = self.append(self.raw_material_table, bom_item)
					new_rm_obj.reference_name = item_row.name
					self.__set_batch_no_as_per_qty(item_row, new_rm_obj, batch_no, batch_qty)
					self.available_materials[key]['batch_no'][batch_no] = 0
		else:
			rm_obj.required_qty = qty
			rm_obj.consumed_qty = qty
			self.__set_serial_nos(item_row, rm_obj)

	def __set_batch_no_as_per_qty(self, item_row, rm_obj, batch_no, qty):
		rm_obj.update({'consumed_qty': qty, 'batch_no': batch_no, 'required_qty': qty})
		self.__set_serial_nos(item_row, rm_obj)

	def __set_serial_nos(self, item_row, rm_obj):
		key = (rm_obj.rm_item_code, item_row.item_code, item_row.purchase_order)
		if (self.available_materials.get(key) and self.available_materials[key]['serial_no']):
			used_serial_nos = self.available_materials[key]['serial_no'][0: cint(rm_obj.consumed_qty)]
			rm_obj.serial_no = '\n'.join(used_serial_nos)

			# Removed the used serial nos from the list
			for sn in used_serial_nos:
				self.available_materials[key]['serial_no'].remove(sn)

	def set_consumed_qty_in_po(self):
		# Update consumed qty back in the purchase order
		if self.is_subcontracted != 'Yes':
			return

		self.__get_purchase_orders()
		itemwise_consumed_qty = defaultdict(float)
		for doctype in ['Purchase Receipt', 'Purchase Invoice']:
			consumed_items, pr_items = self.__update_consumed_materials(doctype, return_consumed_items=True)

			for row in consumed_items:
				key = (row.rm_item_code, row.main_item_code, pr_items.get(row.reference_name))
				itemwise_consumed_qty[key] += row.consumed_qty

		self.__update_consumed_qty_in_po(itemwise_consumed_qty)

	def __update_consumed_qty_in_po(self, itemwise_consumed_qty):
		fields = ['main_item_code', 'rm_item_code', 'parent', 'supplied_qty', 'name']
		filters = {'docstatus': 1, 'parent': ('in', self.purchase_orders)}

		for row in frappe.get_all('Purchase Order Item Supplied', fields = fields, filters=filters, order_by='idx'):
			key = (row.rm_item_code, row.main_item_code, row.parent)
			consumed_qty = itemwise_consumed_qty.get(key, 0)

			if row.supplied_qty < consumed_qty:
				consumed_qty = row.supplied_qty

			itemwise_consumed_qty[key] -= consumed_qty
			frappe.db.set_value('Purchase Order Item Supplied', row.name, 'consumed_qty', consumed_qty)

	def __validate_consumed_qty(self):
		for row in self.get(self.raw_material_table):
			if flt(row.consumed_qty) == 0.0 and row.get('serial_no'):
				msg = f'Row {row.idx}: the consumed qty cannot be zero for the item {frappe.bold(row.rm_item_code)}'

				frappe.throw(_(msg),title=_('Consumed Items Qty Check'))