# This file is part of Tryton.  The COPYRIGHT file at the top level of
# this repository contains the full copyright notices and license terms.
from decimal import Decimal
from itertools import chain

from sql import Null
from sql.functions import CharLength

from trytond.i18n import gettext
from trytond.model import (
    ChatMixin, Index, ModelSQL, ModelView, Workflow, fields, sequence_ordered)
from trytond.model.exceptions import AccessError, RequiredValidationError
from trytond.modules.company.model import (
    employee_field, reset_employee, set_employee)
from trytond.modules.currency.fields import Monetary
from trytond.modules.product import price_digits, round_price
from trytond.pool import Pool, PoolMeta
from trytond.pyson import Bool, Eval, Id, If
from trytond.tools import firstline
from trytond.transaction import Transaction
from trytond.wizard import Wizard


class Configuration(metaclass=PoolMeta):
    __name__ = 'purchase.configuration'
    purchase_requisition_sequence = fields.MultiValue(fields.Many2One(
            'ir.sequence', "Purchase Requisition Sequence", required=True,
            domain=[
                ('company', 'in',
                    [Eval('context', {}).get('company', -1), None]),
                ('sequence_type', '=',
                    Id('purchase_requisition',
                        'sequence_type_purchase_requisition')),
                ]))

    @classmethod
    def multivalue_model(cls, field):
        pool = Pool()
        if field == 'purchase_requisition_sequence':
            return pool.get('purchase.configuration.sequence')
        return super().multivalue_model(field)

    @classmethod
    def default_purchase_requisition_sequence(cls, **pattern):
        return cls.multivalue_model('purchase_requisition_sequence'
            ).default_purchase_requisition_sequence()


class ConfigurationSequence(metaclass=PoolMeta):
    __name__ = 'purchase.configuration.sequence'
    purchase_requisition_sequence = fields.Many2One(
        'ir.sequence', "Purchase Requisition Sequence", required=True,
        domain=[
            ('company', 'in', [Eval('company', -1), None]),
            ('sequence_type', '=',
                Id('purchase_requisition',
                    'sequence_type_purchase_requisition')),
            ])

    @classmethod
    def default_purchase_requisition_sequence(cls):
        pool = Pool()
        ModelData = pool.get('ir.model.data')
        try:
            return ModelData.get_id(
                'purchase_requisition', 'sequence_purchase_requisition')
        except KeyError:
            return None


class PurchaseRequisition(Workflow, ModelSQL, ModelView, ChatMixin):
    __name__ = 'purchase.requisition'
    _rec_name = 'number'
    _states = {
        'readonly': Eval('state') != 'draft',
        }

    company = fields.Many2One(
        'company.company', "Company", required=True,
        states={
            'readonly': (Eval('state') != 'draft') | Eval('lines', [0]),
            })
    number = fields.Char('Number', readonly=True)
    description = fields.Char('Description', states=_states)
    employee = fields.Many2One(
        'company.employee', 'Employee', required=True, states=_states)
    supply_date = fields.Date(
        'Supply Date',
        states={
            'required': ~Eval('state').in_(['draft', 'cancelled']),
            'readonly': _states['readonly'],
            })
    warehouse = fields.Many2One(
        'stock.location', 'Warehouse',
        domain=[
            ('type', '=', 'warehouse'),
            ],
        states=_states)
    currency = fields.Many2One(
        'currency.currency', 'Currency',
        states={
            'readonly': (_states['readonly']
                | (Eval('lines', [0]) & Eval('currency'))),
            })
    total_amount = fields.Function(
        Monetary("Total", currency='currency', digits='currency'),
        'get_amount')
    total_amount_cache = Monetary(
        "Total Cache", currency='currency', digits='currency')
    lines = fields.One2Many(
        'purchase.requisition.line', 'requisition', 'Lines',
        states=_states)

    approved_by = employee_field(
        "Approved By", states=['approved', 'processing', 'done', 'cancelled'])
    rejected_by = employee_field(
        "Rejected By", states=['rejected', 'processing', 'done', 'cancelled'])
    state = fields.Selection([
            ('draft', "Draft"),
            ('waiting', "Waiting"),
            ('rejected', "Rejected"),
            ('approved', "Approved"),
            ('processing', "Processing"),
            ('done', "Done"),
            ('cancelled', "Cancelled"),
            ], "State", readonly=True, required=True, sort=False)

    del _states

    @classmethod
    def __setup__(cls):
        cls.number.search_unaccented = False
        super().__setup__()
        t = cls.__table__()
        cls._sql_indexes.add(
            Index(
                t,
                (t.state, Index.Equality(cardinality='low')),
                where=t.state.in_([
                        'draft', 'waiting', 'approved', 'processing'])))
        cls._transitions |= set((
                ('cancelled', 'draft'),
                ('rejected', 'draft'),
                ('draft', 'cancelled'),
                ('draft', 'waiting'),
                ('waiting', 'draft'),
                ('waiting', 'rejected'),
                ('waiting', 'approved'),
                ('approved', 'processing'),
                ('approved', 'draft'),
                ('processing', 'done'),
                ('done', 'processing'),
                ))
        cls._buttons.update({
                'cancel': {
                    'invisible': Eval('state') != 'draft',
                    'depends': ['state'],
                    },
                'draft': {
                    'invisible': ~Eval('state').in_(
                        ['cancelled', 'waiting', 'approved', 'rejected']),
                    'icon': If(Eval('state').in_(['cancelled', 'rejected']),
                        'tryton-undo',
                        'tryton-back'),
                    'depends': ['state'],
                    },
                'wait': {
                    'pre_validate': [('supply_date', '!=', None)],
                    'invisible': ((Eval('state') != 'draft')
                        | ~Eval('lines', [])),
                    'readonly': ~Eval('lines', []),
                    'depends': ['state'],
                    },
                'approve': {
                    'invisible': Eval('state') != 'waiting',
                    'depends': ['state'],
                    },
                'process': {
                    'invisible': ~Eval('state').in_(
                        ['approved', 'processing']),
                    'icon': If(Eval('state') == 'approved',
                        'tryton-forward', 'tryton-refresh'),
                    'depends': ['state'],
                    },
                'reject': {
                    'invisible': Eval('state') != 'waiting',
                    'depends': ['state'],
                    },
                })
        # The states where amounts are cached
        cls._states_cached = ['approved', 'done', 'rejected',
            'processing', 'cancelled']

    @classmethod
    def order_number(cls, tables):
        table, _ = tables[None]
        return [
            ~((table.state == 'cancelled') & (table.number == Null)),
            CharLength(table.number), table.number]

    @classmethod
    def default_state(cls):
        return 'draft'

    @classmethod
    def default_company(cls):
        return Transaction().context.get('company')

    @classmethod
    def default_employee(cls):
        return Transaction().context.get('employee')

    @classmethod
    def default_warehouse(cls):
        Location = Pool().get('stock.location')
        return Location.get_default_warehouse()

    @classmethod
    def default_currency(cls):
        Company = Pool().get('company.company')
        company = Transaction().context.get('company')
        if company is not None and company >= 0:
            return Company(company).currency.id

    @fields.depends('lines', 'currency')
    def on_change_with_total_amount(self):
        self.total_amount = Decimal(0)
        if self.lines:
            for line in self.lines:
                self.total_amount += getattr(line, 'amount', None) or 0
        if self.currency:
            self.total_amount = self.currency.round(self.total_amount)
        return self.total_amount

    @classmethod
    def store_cache(cls, requisitions):
        requisitions = list(requisitions)
        cls.write(requisitions, {
                'total_amount_cache': None,
                })
        for requisition in requisitions:
            requisition.total_amount_cache = requisition.total_amount
        cls.save(requisitions)

    @classmethod
    def get_amount(cls, requisitions, name):
        total_amount = {}

        # Browse separately not cached to limit number of lines read
        cached, not_cached = [], []
        for requisition in requisitions:
            if requisition.state in cls._states_cached:
                cached.append(requisition)
            else:
                not_cached.append(requisition)
        for requisition in chain(cached, cls.browse(not_cached)):
            if (requisition.state in cls._states_cached
                    and requisition.total_amount_cache is not None):
                total_amount[requisition.id] = requisition.total_amount_cache
            else:
                total_amount[requisition.id] = (
                    requisition.on_change_with_total_amount())
        return total_amount

    @classmethod
    def create_requests(cls, requisitions):
        pool = Pool()
        Request = pool.get('purchase.request')
        requests = []
        for requisition in requisitions:
            for line in requisition.lines:
                request = line.compute_request()
                if request:
                    requests.append(request)
        if requests:
            Request.save(requests)

    @classmethod
    def view_attributes(cls):
        return super().view_attributes() + [
            ('/tree', 'visual',
                If(Eval('state') == 'cancelled', 'muted', '')),
            ]

    @classmethod
    def preprocess_values(cls, mode, values):
        pool = Pool()
        Configuration = pool.get('purchase.configuration')
        values = super().preprocess_values(mode, values)
        if mode == 'create' and not values.get('number'):
            company_id = values.get('company', cls.default_company())
            if company_id is not None:
                configuration = Configuration(1)
                if sequence := configuration.get_multivalue(
                        'purchase_requisition_sequence',
                        company=company_id):
                    values['number'] = sequence.get()
        return values

    @classmethod
    def check_modification(
            cls, mode, requisitions, values=None, external=False):
        super().check_modification(
            mode, requisitions, values=values, external=external)
        if mode == 'delete':
            for requisition in requisitions:
                if requisition.state not in {'cancelled', 'draft'}:
                    raise AccessError(gettext(
                            'purchase_requisition.msg_delete_cancel',
                            requisition=requisition.rec_name))

    def check_for_waiting(self):
        if not self.warehouse:
            for line in self.lines:
                if line.product and line.product.type in {'goods', 'assets'}:
                    raise RequiredValidationError(
                        gettext('purchase_requisition.msg_warehouse_required',
                            requisition=self.rec_name))

    @classmethod
    def copy(cls, requisitions, default=None):
        if default is None:
            default = {}
        else:
            default = default.copy()
        default.setdefault('number', None)
        default.setdefault('supply_date', None)
        default.setdefault('approved_by')
        default.setdefault('rejected_by')
        default.setdefault('total_amount_cache')
        return super().copy(
            requisitions, default=default)

    @classmethod
    @ModelView.button
    @Workflow.transition('cancelled')
    def cancel(cls, requisitions):
        cls.store_cache(requisitions)

    @classmethod
    @ModelView.button
    @Workflow.transition('draft')
    @reset_employee('approved_by', 'rejected_by')
    def draft(cls, requisitions):
        cls.write(requisitions, {
                'total_amount_cache': None,
                })

    @classmethod
    @ModelView.button
    @Workflow.transition('waiting')
    def wait(cls, requisitions):
        for requisition in requisitions:
            requisition.check_for_waiting()

    @classmethod
    @ModelView.button
    @Workflow.transition('rejected')
    @set_employee('rejected_by')
    def reject(cls, requisitions):
        pass

    @classmethod
    @ModelView.button
    @Workflow.transition('approved')
    @set_employee('approved_by')
    def approve(cls, requisitions):
        pool = Pool()
        Configuration = pool.get('purchase.configuration')
        transaction = Transaction()
        context = transaction.context
        cls.store_cache(requisitions)
        config = Configuration(1)
        with transaction.set_context(
                queue_scheduled_at=config.purchase_process_after,
                queue_batch=context.get('queue_batch', True)):
            cls.__queue__.process(requisitions)

    @classmethod
    @Workflow.transition('processing')
    def proceed(cls, requisitions):
        pass

    @classmethod
    @Workflow.transition('done')
    def do(cls, requisitions):
        pass

    @classmethod
    @ModelView.button
    def process(cls, requisitions):
        done = []
        process = []
        requisitions = [r for r in requisitions
            if r.state in {'approved', 'processing', 'done'}]
        cls.create_requests(requisitions)
        for requisition in requisitions:
            if requisition.is_done():
                if requisition.state != 'done':
                    done.append(requisition)
            elif requisition.state != 'processing':
                process.append(requisition)
        if process:
            cls.proceed(process)
        if done:
            cls.do(done)

    def is_done(self):
        return all(
            r.state in {'purchased', 'done', 'cancelled'}
            for l in self.lines for r in l.purchase_requests)


class PurchaseRequisitionLine(sequence_ordered(), ModelSQL, ModelView):
    __name__ = 'purchase.requisition.line'
    _states = {
        'readonly': Eval('purchase_requisition_state') != 'draft',
        }

    requisition = fields.Many2One(
        'purchase.requisition', 'Requisition',
        ondelete='CASCADE', required=True)
    supplier = fields.Many2One('party.party', 'Supplier', states=_states)
    product = fields.Many2One(
        'product.product', 'Product',
        ondelete='RESTRICT',
        domain=[
            If((Eval('purchase_requisition_state') == 'draft')
                & ~(Eval('quantity', 0) < 0),
                ('purchasable', '=', True),
                ()),
            ],
        states=_states)
    product_uom_category = fields.Function(
        fields.Many2One(
            'product.uom.category', "Product UoM Category",
            help="The category of Unit of Measure for the product."),
        'on_change_with_product_uom_category')
    description = fields.Text("Description", states=_states)
    summary = fields.Function(
        fields.Char('Summary'), 'on_change_with_summary',
        searcher='search_summary')
    quantity = fields.Float(
        "Quantity", digits='unit', required=True, states=_states)
    unit = fields.Many2One(
        'product.uom', 'Unit', ondelete='RESTRICT',
        states={
            'required': Bool(Eval('product')),
            'readonly': _states['readonly'],
            })
    unit_price = Monetary(
        'Unit Price', currency='currency', digits=price_digits, states=_states)
    currency = fields.Function(fields.Many2One('currency.currency',
        'Currency'), 'on_change_with_currency')
    amount = fields.Function(Monetary(
            "Amount", currency='currency', digits='currency'),
        'on_change_with_amount')
    purchase_requests = fields.One2Many(
        'purchase.request', 'origin', 'Purchase Request', readonly=True)
    purchase_requisition_state = fields.Function(fields.Selection(
            'get_purchase_requisition_states', "Purchase Requisition State"),
        'on_change_with_purchase_requisition_state')

    del _states

    @classmethod
    def __setup__(cls):
        super().__setup__()
        cls.__access__.add('requisition')
        unit_categories = cls._unit_categories()
        cls.unit.domain = [
            If(Bool(Eval('product_uom_category')),
                ('category', 'in', [Eval(c) for c in unit_categories]),
                ('category', '!=', -1)),
            ]

    @classmethod
    def _unit_categories(cls):
        return ['product_uom_category']

    @fields.depends('product')
    def on_change_with_product_uom_category(self, name=None):
        return self.product.default_uom_category if self.product else None

    @fields.depends('requisition', '_parent_requisition.currency')
    def on_change_with_currency(self, name=None):
        return self.requisition.currency if self.requisition else None

    @classmethod
    def get_purchase_requisition_states(cls):
        pool = Pool()
        Requisition = pool.get('purchase.requisition')
        return Requisition.fields_get(['state'])['state']['selection']

    @fields.depends('requisition', '_parent_requisition.state')
    def on_change_with_purchase_requisition_state(self, name=None):
        if self.requisition:
            return self.requisition.state

    @fields.depends('product', 'unit', 'quantity', 'supplier')
    def on_change_product(self):
        if not self.product:
            return

        category = self.product.purchase_uom.category
        if not self.unit or self.unit.category != category:
            self.unit = self.product.purchase_uom

    @fields.depends('description')
    def on_change_with_summary(self, name=None):
        return firstline(self.description or '')

    @classmethod
    def search_summary(cls, name, clause):
        return [('description', *clause[1:])]

    @fields.depends(
        'quantity', 'unit_price',
        'requisition', '_parent_requisition.currency')
    def on_change_with_amount(self, name=None):
        if (self.unit_price is None) or (self.quantity is None):
            return None
        amount = Decimal(str(self.quantity)) * self.unit_price
        if self.requisition.currency:
            amount = self.requisition.currency.round(amount)
        return amount

    def get_rec_name(self, name):
        pool = Pool()
        Lang = pool.get('ir.lang')
        if self.product:
            lang = Lang.get()
            return (lang.format_number_symbol(
                    self.quantity or 0, self.unit, digits=self.unit.digits)
                + ' %s @ %s' % (
                    self.product.rec_name, self.requisition.rec_name))
        else:
            return self.requisition.rec_name

    def _get_purchase_request_product_supplier_pattern(self):
        pattern = {
            'company': self.requisition.company.id,
            }
        if self.supplier:
            pattern['party'] = self.supplier.id
        return pattern

    @property
    def request_unit(self):
        unit = self.unit
        if (self.product
                and self.product.purchase_uom.category == self.unit.category):
            unit = self.product.purchase_uom
        return unit

    @property
    def request_quantity(self):
        pool = Pool()
        Uom = pool.get('product.uom')
        quantity = self.quantity
        request_unit = self.request_unit
        if (self.product
                and request_unit
                and request_unit.category == self.unit.category):
            quantity = Uom.compute_qty(
                self.unit, self.quantity, request_unit, round=True)
        return quantity

    @property
    def request_unit_price(self):
        return self.unit_price

    def compute_request(self):
        """
        Return the value of the purchase request which will answer to
        the needed quantity at the given date.
        """
        pool = Pool()
        Uom = pool.get('product.uom')
        Request = pool.get('purchase.request')

        if self.purchase_requests:
            return

        supply_date = self.requisition.supply_date
        supplier = None
        purchase_date = None

        if self.product:
            supplier, purchase_date = Request.find_best_supplier(
                self.product, supply_date,
                **self._get_purchase_request_product_supplier_pattern())
        elif self.supplier:
            lead_time = self.supplier.get_multivalue(
                'supplier_lead_time', company=self.requisition.company.id)
            if lead_time is not None:
                purchase_date = supply_date - lead_time

        unit = self.request_unit
        quantity = self.request_quantity
        if (self.product
                and self.product.purchase_uom.category == self.unit.category):
            unit = self.product.purchase_uom
            quantity = Uom.compute_qty(
                self.unit, self.quantity, unit, round=True)

        return Request(
            product=self.product,
            description=self.description,
            party=supplier or self.supplier,
            quantity=quantity,
            unit=unit,
            computed_quantity=self.quantity,
            computed_unit=self.unit,
            purchase_date=purchase_date,
            supply_date=supply_date,
            company=self.requisition.company,
            warehouse=self.requisition.warehouse,
            origin=self,
            )

    @classmethod
    def copy(cls, lines, default=None):
        if default is None:
            default = {}
        else:
            default = default.copy()
        default.setdefault('purchase_requests')
        return super().copy(lines, default=default)


class PurchaseRequest(metaclass=PoolMeta):
    __name__ = 'purchase.request'

    @classmethod
    def _get_origin(cls):
        return (super()._get_origin()
            | {'purchase.requisition.line'})

    @property
    def currency(self):
        pool = Pool()
        RequisitionLine = pool.get('purchase.requisition.line')
        currency = super().currency
        if (isinstance(self.origin, RequisitionLine)
                and self.origin.requisition.currency):
            return self.origin.requisition.currency
        return currency

    @classmethod
    def update_state(cls, requests):
        pool = Pool()
        Requisition = pool.get('purchase.requisition')
        RequisitionLine = pool.get('purchase.requisition.line')

        super().update_state(requests)

        if requisitions := {
                r.origin.requisition for r in requests
                if isinstance(r.origin, RequisitionLine) and r.origin.id >= 0}:
            requisitions = Requisition.browse(requisitions)
            Requisition.__queue__.process(requisitions)


class HandlePurchaseCancellationException(metaclass=PoolMeta):
    __name__ = 'purchase.request.handle.purchase.cancellation'

    def transition_reset(self):
        pool = Pool()
        Requisition = pool.get('purchase.requisition')
        RequisitionLine = pool.get('purchase.requisition.line')

        state = super(
            HandlePurchaseCancellationException, self).transition_reset()

        requests = self.records
        requisition_ids = list({r.origin.requisition.id for r in requests
                if isinstance(r.origin, RequisitionLine)})
        Requisition.process(Requisition.browse(requisition_ids))
        return state


class CreatePurchase(Wizard):
    __name__ = 'purchase.request.create_purchase'

    def _group_purchase_line_key(self, request):
        pool = Pool()
        RequisitionLine = pool.get('purchase.requisition.line')
        key = super()._group_purchase_line_key(request)
        if isinstance(request.origin, RequisitionLine):
            unit_price = request.origin.request_unit_price
            if unit_price:
                key += (('unit_price', unit_price),)
        return key

    @classmethod
    def compute_purchase_line(cls, key, requests, purchase):
        pool = Pool()
        RequisitionLine = pool.get('purchase.requisition.line')
        Uom = pool.get('product.uom')

        line = super().compute_purchase_line(key, requests, purchase)

        key_values = dict(key)
        if (key_values.get('unit_price') is not None
                and any(
                    isinstance(r.origin, RequisitionLine) for r in requests)):
            line.unit_price = round_price(
                Uom.compute_price(
                    key_values.get('unit', line.unit),
                    key_values['unit_price'],
                    line.unit))
        return line