# 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 dateutil.relativedelta import relativedelta

from trytond import backend
from trytond.i18n import gettext
from trytond.model import (
    DeactivableMixin, ModelSQL, ModelView, fields, sequence_ordered)
from trytond.modules.currency.fields import Monetary
from trytond.pool import Pool
from trytond.pyson import Eval
from trytond.transaction import Transaction
from trytond.wizard import Button, StateView, Wizard
from .exceptions import PaymentTermComputeError, PaymentTermValidationError
import logging

logger = logging.getLogger(__name__)


class PaymentTerm(DeactivableMixin, ModelSQL, ModelView):
    'Payment Term'
    __name__ = 'account.invoice.payment_term'
    name = fields.Char('Name', size=None, required=True, translate=True)
    description = fields.Text('Description', translate=True)
    lines = fields.One2Many('account.invoice.payment_term.line', 'payment',
            'Lines')

    @classmethod
    def __setup__(cls):
        super(PaymentTerm, cls).__setup__()
        cls._order.insert(0, ('name', 'ASC'))

    @classmethod
    def validate_fields(cls, terms, field_names):
        super().validate_fields(terms, field_names)
        cls.check_remainder(terms, field_names)

    @classmethod
    def check_remainder(cls, terms, field_names=None):
        if field_names and 'lines' not in field_names:
            return
        for term in terms:
            if not term.lines or not term.lines[-1].type == 'remainder':
                raise PaymentTermValidationError(gettext(
                        'account_invoice'
                        '.msg_payment_term_missing_last_remainder',
                        payment_term=term.rec_name))

    def compute(self, amount, currency, date, line_ = None):
        """Calculate payment terms and return a list of tuples
        with (date, amount) for each payment term line.

        amount must be a Decimal used for the calculation.
        """
        # TODO implement business_days
        # http://pypi.python.org/pypi/BusinessHours/
        sign = 1 if amount >= Decimal(0) else -1
        res = []
        remainder = amount
        for line in self.lines:
            value = line.get_value(remainder, amount, currency)
            value_date = line.get_date(date, line_)
            if value is None or not value_date:
                continue
            if ((remainder - value) * sign) < Decimal(0):
                res.append((value_date, remainder))
                break
            if value:
                res.append((value_date, value))
            remainder -= value
        else:
            # Enforce to have at least one term
            if not res:
                res.append((date, Decimal(0)))

        if not currency.is_zero(remainder):
            raise PaymentTermComputeError(
                gettext('account_invoice.msg_payment_term_missing_remainder',
                    payment_term=self.rec_name))
        return res


class PaymentTermLine(sequence_ordered(), ModelSQL, ModelView):
    'Payment Term Line'
    __name__ = 'account.invoice.payment_term.line'
    payment = fields.Many2One('account.invoice.payment_term', 'Payment Term',
            required=True, ondelete="CASCADE")
    type = fields.Selection([
            ('fixed', 'Fixed'),
            ('percent', 'Percentage on Remainder'),
            ('percent_on_total', 'Percentage on Total'),
            ('remainder', 'Remainder'),
            ], 'Type', required=True)
    ratio = fields.Numeric('Ratio', digits=(14, 10),
        states={
            'invisible': ~Eval('type').in_(['percent', 'percent_on_total']),
            'required': Eval('type').in_(['percent', 'percent_on_total']),
            })
    divisor = fields.Numeric('Divisor', digits=(10, 14),
        states={
            'invisible': ~Eval('type').in_(['percent', 'percent_on_total']),
            'required': Eval('type').in_(['percent', 'percent_on_total']),
            })
    amount = Monetary(
        "Amount", currency='currency', digits='currency',
        states={
            'invisible': Eval('type') != 'fixed',
            'required': Eval('type') == 'fixed',
            })
    currency = fields.Many2One('currency.currency', 'Currency',
        states={
            'invisible': Eval('type') != 'fixed',
            'required': Eval('type') == 'fixed',
            })
    relativedeltas = fields.One2Many(
        'account.invoice.payment_term.line.delta', 'line', 'Deltas')

    @classmethod
    def __setup__(cls):
        super().__setup__()
        cls.__access__.add('payment')

    @staticmethod
    def default_type():
        return 'remainder'

    @classmethod
    def default_relativedeltas(cls):
        if Transaction().user == 0:
            return []
        return [{}]

    @fields.depends('type')
    def on_change_type(self):
        if self.type != 'fixed':
            self.amount = Decimal(0)
            self.currency = None
        if self.type not in ('percent', 'percent_on_total'):
            self.ratio = Decimal(0)
            self.divisor = Decimal(0)

    @fields.depends('ratio')
    def on_change_ratio(self):
        if not self.ratio:
            self.divisor = Decimal(0)
        else:
            self.divisor = self.round(1 / self.ratio,
                self.__class__.divisor.digits[1])

    @fields.depends('divisor')
    def on_change_divisor(self):
        if not self.divisor:
            self.ratio = Decimal(0)
        else:
            self.ratio = self.round(1 / self.divisor,
                self.__class__.ratio.digits[1])

    def get_date(self, date, line = None):
        #find date based on trigger:
        if line and self.trigger_event:
            trigger_date = line.get_date(self.trigger_event)
            logger.info("DATE_FROM_LINE:%s",trigger_date)
            if trigger_date:
                date = trigger_date
        
        for relativedelta_ in self.relativedeltas:
            date += relativedelta_.get()
        return date

    def get_value(self, remainder, amount, currency):
        Currency = Pool().get('currency.currency')
        if self.type == 'fixed':
            fixed = Currency.compute(self.currency, self.amount, currency)
            return fixed.copy_sign(amount)
        elif self.type == 'percent':
            return currency.round(remainder * self.ratio)
        elif self.type == 'percent_on_total':
            return currency.round(amount * self.ratio)
        elif self.type == 'remainder':
            return currency.round(remainder)
        return None

    @staticmethod
    def round(number, digits):
        quantize = Decimal(10) ** -Decimal(digits)
        return Decimal(number).quantize(quantize)

    @classmethod
    def validate_fields(cls, lines, field_names):
        super().validate_fields(lines, field_names)
        cls.check_ratio_and_divisor(lines, field_names)

    @classmethod
    def check_ratio_and_divisor(cls, lines, field_names=None):
        "Check consistency between ratio and divisor"
        if field_names and not (field_names & {'type', 'ratio', 'divisor'}):
            return
        for line in lines:
            if line.type not in ('percent', 'percent_on_total'):
                continue
            if line.ratio is None or line.divisor is None:
                raise PaymentTermValidationError(
                    gettext('account_invoice'
                        '.msg_payment_term_invalid_ratio_divisor',
                        line=line.rec_name))
            if (line.ratio != round(
                        1 / line.divisor, cls.ratio.digits[1])
                    and line.divisor != round(
                        1 / line.ratio, cls.divisor.digits[1])):
                raise PaymentTermValidationError(
                    gettext('account_invoice'
                        '.msg_payment_term_invalid_ratio_divisor',
                        line=line.rec_name))


class PaymentTermLineRelativeDelta(sequence_ordered(), ModelSQL, ModelView):
    'Payment Term Line Relative Delta'
    __name__ = 'account.invoice.payment_term.line.delta'
    line = fields.Many2One('account.invoice.payment_term.line',
        'Payment Term Line', required=True, ondelete='CASCADE')
    day = fields.Integer('Day of Month',
        domain=['OR',
            ('day', '=', None),
            [('day', '>=', 1), ('day', '<=', 31)],
            ])
    month = fields.Many2One('ir.calendar.month', "Month")
    weekday = fields.Many2One('ir.calendar.day', "Day of Week")
    months = fields.Integer('Number of Months', required=True)
    weeks = fields.Integer('Number of Weeks', required=True)
    days = fields.Integer('Number of Days', required=True)

    @classmethod
    def __setup__(cls):
        super().__setup__()
        cls.__access__.add('line')

    @classmethod
    def __register__(cls, module_name):
        transaction = Transaction()
        cursor = transaction.connection.cursor()
        pool = Pool()
        Month = pool.get('ir.calendar.month')
        Day = pool.get('ir.calendar.day')
        sql_table = cls.__table__()
        month = Month.__table__()
        day = Day.__table__()
        table_h = cls.__table_handler__(module_name)

        # Migration from 5.0: use ir.calendar
        migrate_calendar = False
        if (backend.TableHandler.table_exist(cls._table)
                and table_h.column_exist('month')
                and table_h.column_exist('weekday')):
            migrate_calendar = (
                table_h.column_is_type('month', 'VARCHAR')
                or table_h.column_is_type('weekday', 'VARCHAR'))
            if migrate_calendar:
                table_h.column_rename('month', '_temp_month')
                table_h.column_rename('weekday', '_temp_weekday')

        super(PaymentTermLineRelativeDelta, cls).__register__(module_name)

        table_h = cls.__table_handler__(module_name)

        # Migration from 5.0: use ir.calendar
        if migrate_calendar:
            update = transaction.connection.cursor()
            cursor.execute(*month.select(month.id, month.index))
            for month_id, index in cursor:
                update.execute(*sql_table.update(
                        [sql_table.month], [month_id],
                        where=sql_table._temp_month == str(index)))
            table_h.drop_column('_temp_month')
            cursor.execute(*day.select(day.id, day.index))
            for day_id, index in cursor:
                update.execute(*sql_table.update(
                        [sql_table.weekday], [day_id],
                        where=sql_table._temp_weekday == str(index)))
            table_h.drop_column('_temp_weekday')

    @staticmethod
    def default_months():
        return 0

    @staticmethod
    def default_weeks():
        return 0

    @staticmethod
    def default_days():
        return 0

    def get(self):
        "Return the relativedelta"
        return relativedelta(
            day=self.day,
            month=int(self.month.index) if self.month else None,
            days=self.days,
            weeks=self.weeks,
            months=self.months,
            weekday=int(self.weekday.index) if self.weekday else None,
            )


class TestPaymentTerm(Wizard):
    'Test Payment Term'
    __name__ = 'account.invoice.payment_term.test'
    start_state = 'test'
    test = StateView('account.invoice.payment_term.test',
        'account_invoice.payment_term_test_view_form',
        [Button('Close', 'end', 'tryton-close', default=True)])

    def default_test(self, fields):
        default = {}
        if (self.model
                and self.model.__name__ == 'account.invoice.payment_term'):
            default['payment_term'] = self.record.id if self.record else None
        return default


class TestPaymentTermView(ModelView):
    'Test Payment Term'
    __name__ = 'account.invoice.payment_term.test'
    payment_term = fields.Many2One('account.invoice.payment_term',
        'Payment Term', required=True)
    date = fields.Date("Date", required=True)
    amount = Monetary(
        "Amount", currency='currency', digits='currency', required=True)
    currency = fields.Many2One('currency.currency', 'Currency', required=True)
    result = fields.One2Many('account.invoice.payment_term.test.result',
        None, 'Result', readonly=True)

    @classmethod
    def default_date(cls):
        return Pool().get('ir.date').today()

    @staticmethod
    def default_currency():
        pool = Pool()
        Company = pool.get('company.company')
        company = Transaction().context.get('company')
        if company:
            return Company(company).currency.id

    @fields.depends('payment_term', 'date', 'amount', 'currency', 'result')
    def on_change_with_result(self):
        pool = Pool()
        Result = pool.get('account.invoice.payment_term.test.result')
        result = []
        if (self.payment_term and self.amount and self.currency and self.date):
            for date, amount in self.payment_term.compute(
                    self.amount, self.currency, self.date):
                result.append(Result(
                        date=date,
                        amount=amount,
                        currency=self.currency))
        return result


class TestPaymentTermViewResult(ModelView):
    'Test Payment Term'
    __name__ = 'account.invoice.payment_term.test.result'
    date = fields.Date('Date', readonly=True)
    amount = Monetary(
        "Amount", currency='currency', digits='currency', readonly=True)
    currency = fields.Many2One('currency.currency', "Currency")