# This file is part of Tryton.  The COPYRIGHT file at the top level of
# this repository contains the full copyright notices and license terms.
import datetime
from collections import defaultdict

from trytond.model import ModelSQL, ModelView
from trytond.pool import Pool
from trytond.tools import grouped_slice
from trytond.transaction import Transaction


class ShipmentInternal(ModelSQL, ModelView):
    __name__ = 'stock.shipment.internal'

    @classmethod
    def generate_internal_shipment(cls, clean=True, warehouses=None):
        """
        Generate internal shipments to meet order points defined on
        non-warehouse location.

        If clean is set, it will remove all previous requests.
        """
        pool = Pool()
        OrderPoint = pool.get('stock.order_point')
        Location = pool.get('stock.location')
        Product = pool.get('product.product')
        Date = pool.get('ir.date')
        User = pool.get('res.user')
        Move = pool.get('stock.move')
        LeadTime = pool.get('stock.location.lead_time')
        company = User(Transaction().user).company
        if not company:
            return

        if warehouses is None:
            warehouses = Location.search([
                    ('type', '=', 'warehouse'),
                    ])

        today = Date.today()
        lead_time = LeadTime.get_max_lead_time()

        if clean:
            reqs = cls.search([
                    ('state', '=', 'request'),
                    ('company', '=', company.id),
                    ])
            cls.delete(reqs)

        # fetch quantities on order points
        order_points = OrderPoint.search([
                ('type', '=', 'internal'),
                ('company', '=', company.id)
                ])
        order_points = [
            op for op in order_points if op.location.warehouse in warehouses]
        id2product = {}
        product2op = {}
        id2location = {}
        for op in order_points:
            id2product[op.product.id] = op.product
            product2op[
                (op.storage_location.id, op.product.id)
                ] = op
            id2location[op.storage_location.id] = op.storage_location
        implicit_locations = Location.search(['OR',
                ('provisioning_location', '!=', None),
                ('overflowing_location', '!=', None),
                ])
        id2location.update({l.id: l for l in implicit_locations})
        location_ids = list(id2location.keys())

        def get_pbl(start, end, grouping_filter):
            with Transaction().set_context(
                    forecast=True, stock_date_start=start, stock_date_end=end):
                return Product.products_by_location(
                    location_ids, with_childs=True,
                    grouping_filter=grouping_filter)

        # ordered by ids to speedup reduce_ids in products_by_location
        if implicit_locations:
            products = Product.search([
                    ('type', 'in', ['goods', 'assets']),
                    ], order=[('id', 'ASC')])
            product_ids = [p.id for p in products]
            pbl = get_pbl(None, today, None)
        else:
            product_ids = list(id2product.keys())
            product_ids.sort()
            pbl = defaultdict(int)
            for sub_product_ids in grouped_slice(product_ids):
                pbl.update(get_pbl(None, today, (list(sub_product_ids),)))

        shipments = []
        date = today
        end_date = date + lead_time
        current_qties = pbl.copy()
        while date <= end_date:
            # Create a list of moves to create
            moves = {}
            for location in id2location.values():
                for product_id in product_ids:
                    qty = current_qties.get((location.id, product_id), 0)
                    op = product2op.get((location.id, product_id))
                    if op:
                        min_qty, max_qty = op.min_quantity, op.max_quantity
                        target_qty = op.target_quantity
                        prov_location = op.provisioning_location
                        over_location = op.overflowing_location
                    elif (location
                            and (location.provisioning_location
                                or location.overflowing_location)):
                        target_qty = 0
                        min_qty = 0 if location.provisioning_location else None
                        max_qty = 0 if location.overflowing_location else None
                        prov_location = location.provisioning_location
                        over_location = location.overflowing_location
                    else:
                        continue

                    change_qty = 0
                    if min_qty is not None and qty < min_qty:
                        from_loc = prov_location.id
                        to_loc = location.id
                        change_qty = target_qty - qty
                    elif max_qty is not None and qty > max_qty:
                        from_loc = location.id
                        to_loc = over_location.id
                        change_qty = qty - target_qty

                    if change_qty:
                        key = (from_loc, to_loc, product_id)
                        moves[key] = change_qty
                        current_qties[(from_loc, product_id)] -= change_qty
                        current_qties[(to_loc, product_id)] += change_qty

            # Group moves by {from,to}_location
            to_create = {}
            for key, qty in moves.items():
                from_location, to_location, product = key
                to_create.setdefault(
                    (from_location, to_location), []).append((product, qty))
            # Create shipments and moves
            for locations, moves in to_create.items():
                from_location, to_location = locations
                shipment = cls(
                    from_location=from_location,
                    to_location=to_location,
                    planned_date=date,
                    state='request',
                    )
                shipment_moves = []
                for move in moves:
                    product_id, qty = move
                    product = id2product.setdefault(
                        product_id, Product(product_id))
                    shipment_moves.append(Move(
                            from_location=from_location,
                            to_location=to_location,
                            planned_date=date,
                            product=product,
                            quantity=qty,
                            unit=product.default_uom,
                            company=company,
                            ))
                shipment.moves = shipment_moves
                shipment.planned_start_date = (
                    shipment.on_change_with_planned_start_date())
                shipments.append(shipment)
            date += datetime.timedelta(1)

            # Update quantities with next moves
            if implicit_locations:
                for key, qty in get_pbl(date, date, None).items():
                    current_qties[key] += qty
            else:
                for sub_product_ids in grouped_slice(product_ids):
                    for key, qty in get_pbl(
                            date, date, (list(sub_product_ids),)).items():
                        current_qties[key] += qty

        if shipments:
            cls.save(shipments)
            # Split moves through transit to get accurate dates
            cls._set_transit(shipments)
        return shipments
