# -*- coding: utf-8 -*-
# Part of Odoo, Flectra. See LICENSE file for full copyright and licensing details.
from datetime import datetime, timedelta
from hashlib import sha256
from json import dumps
import pytz

from flectra import models, api, fields
from flectra.fields import Datetime
from flectra.tools.translate import _
from flectra.exceptions import UserError


def ctx_tz(record, field):
    res_lang = None
    ctx = record._context
    tz_name = pytz.timezone(ctx.get('tz') or record.env.user.tz)
    timestamp = Datetime.from_string(record[field])
    if ctx.get('lang'):
        res_lang = record.env['res.lang'].search([('code', '=', ctx['lang'])], limit=1)
    if res_lang:
        timestamp = pytz.utc.localize(timestamp, is_dst=False)
        return datetime.strftime(timestamp.astimezone(tz_name), res_lang.date_format + ' ' + res_lang.time_format)
    return Datetime.context_timestamp(record, timestamp)


class pos_config(models.Model):
    _inherit = 'pos.config'

    @api.multi
    def open_ui(self):
        for config in self.filtered(lambda c: c.company_id._is_accounting_unalterable()):
            if config.current_session_id:
                config.current_session_id._check_session_timing()
        return super(pos_config, self).open_ui()


class pos_session(models.Model):
    _inherit = 'pos.session'

    @api.multi
    def _check_session_timing(self):
        self.ensure_one()
        date_today = datetime.utcnow()
        session_start = Datetime.from_string(self.start_at)
        if not date_today - timedelta(hours=24) <= session_start:
            raise UserError(_("This session has been opened another day. To comply with the French law, you should close sessions on a daily basis. Please close session %s and open a new one.") % self.name)
        return True

    @api.multi
    def open_frontend_cb(self):
        for session in self.filtered(lambda s: s.config_id.company_id._is_accounting_unalterable()):
            session._check_session_timing()
        return super(pos_session, self).open_frontend_cb()


ORDER_FIELDS = ['date_order', 'user_id', 'lines', 'statement_ids', 'pricelist_id', 'partner_id', 'session_id', 'pos_reference', 'sale_journal', 'fiscal_position_id']
LINE_FIELDS = ['notice', 'product_id', 'qty', 'price_unit', 'discount', 'tax_ids', 'tax_ids_after_fiscal_position']
ERR_MSG = _('According to the French law, you cannot modify a %s. Forbidden fields: %s.')


class pos_order(models.Model):
    _inherit = 'pos.order'

    l10n_fr_hash = fields.Char(string="Inalteralbility Hash", readonly=True, copy=False)
    l10n_fr_secure_sequence_number = fields.Integer(string="Inalteralbility No Gap Sequence #", readonly=True, copy=False)
    l10n_fr_string_to_hash = fields.Char(compute='_compute_string_to_hash', readonly=True, store=False)

    def _get_new_hash(self, secure_seq_number):
        """ Returns the hash to write on pos orders when they get posted"""
        self.ensure_one()
        #get the only one exact previous order in the securisation sequence
        prev_order = self.search([('state', 'in', ['paid', 'done', 'invoiced']),
                                 ('company_id', '=', self.company_id.id),
                                 ('l10n_fr_secure_sequence_number', '!=', 0),
                                 ('l10n_fr_secure_sequence_number', '=', int(secure_seq_number) - 1)])
        if prev_order and len(prev_order) != 1:
            raise UserError(
               _('An error occured when computing the inalterability. Impossible to get the unique previous posted point of sale order.'))

        #build and return the hash
        return self._compute_hash(prev_order.l10n_fr_hash if prev_order else u'')

    def _compute_hash(self, previous_hash):
        """ Computes the hash of the browse_record given as self, based on the hash
        of the previous record in the company's securisation sequence given as parameter"""
        self.ensure_one()
        hash_string = sha256((previous_hash + self.l10n_fr_string_to_hash).encode('utf-8'))
        return hash_string.hexdigest()

    def _compute_string_to_hash(self):
        def _getattrstring(obj, field_str):
            field_value = obj[field_str]
            if obj._fields[field_str].type == 'many2one':
                field_value = field_value.id
            if obj._fields[field_str].type in ['many2many', 'one2many']:
                field_value = field_value.ids
            return str(field_value)

        for order in self:
            values = {}
            for field in ORDER_FIELDS:
                values[field] = _getattrstring(order, field)

            for line in order.lines:
                for field in LINE_FIELDS:
                    k = 'line_%d_%s' % (line.id, field)
                    values[k] = _getattrstring(line, field)
            #make the json serialization canonical
            #  (https://tools.ietf.org/html/draft-staykov-hu-json-canonical-form-00)
            order.l10n_fr_string_to_hash = dumps(values, sort_keys=True,
                                                ensure_ascii=True, indent=None,
                                                separators=(',',':'))

    @api.multi
    def write(self, vals):
        has_been_posted = False
        for order in self:
            if order.company_id._is_accounting_unalterable():
                # write the hash and the secure_sequence_number when posting or invoicing an pos.order
                if vals.get('state') in ['paid', 'done', 'invoiced']:
                    has_been_posted = True

                # restrict the operation in case we are trying to write a forbidden field
                if (order.state in ['paid', 'done', 'invoiced'] and set(vals).intersection(ORDER_FIELDS)):
                    raise UserError(_('According to the French law, you cannot modify a point of sale order. Forbidden fields: %s.') % ', '.join(ORDER_FIELDS))
                # restrict the operation in case we are trying to overwrite existing hash
                if (order.l10n_fr_hash and 'l10n_fr_hash' in vals) or (order.l10n_fr_secure_sequence_number and 'l10n_fr_secure_sequence_number' in vals):
                    raise UserError(_('You cannot overwrite the values ensuring the inalterability of the point of sale.'))
        res = super(pos_order, self).write(vals)
        # write the hash and the secure_sequence_number when posting or invoicing a pos order
        if has_been_posted:
            for order in self.filtered(lambda o: o.company_id._is_accounting_unalterable() and
                                                not (o.l10n_fr_secure_sequence_number or o.l10n_fr_hash)):
                new_number = order.company_id.l10n_fr_pos_cert_sequence_id.next_by_id()
                vals_hashing = {'l10n_fr_secure_sequence_number': new_number,
                                'l10n_fr_hash': order._get_new_hash(new_number)}
                res |= super(pos_order, order).write(vals_hashing)
        return res

    @api.model
    def _check_hash_integrity(self, company_id):
        """Checks that all posted or invoiced pos orders have still the same data as when they were posted
        and raises an error with the result.
        """
        def build_order_info(order):
            entry_reference = _('(Receipt ref.: %s)')
            order_reference_string = order.pos_reference and entry_reference % order.pos_reference or ''
            return [ctx_tz(order, 'date_order'), order.l10n_fr_secure_sequence_number, order.name, order_reference_string, ctx_tz(order, 'write_date')]

        orders = self.search([('state', 'in', ['paid', 'done', 'invoiced']),
                             ('company_id', '=', company_id),
                             ('l10n_fr_secure_sequence_number', '!=', 0)],
                            order="l10n_fr_secure_sequence_number ASC")

        if not orders:
            raise UserError(_('There isn\'t any order flagged for data inalterability yet for the company %s. This mechanism only runs for point of sale orders generated after the installation of the module France - Certification CGI 286 I-3 bis. - POS') % self.env.user.company_id.name)
        previous_hash = u''
        start_order_info = []
        for order in orders:
            if order.l10n_fr_hash != order._compute_hash(previous_hash=previous_hash):
                raise UserError(_('Corrupted data on point of sale order with id %s.') % order.id)
            previous_hash = order.l10n_fr_hash

        orders_sorted_date = orders.sorted(lambda o: o.date_order)
        start_order_info = build_order_info(orders_sorted_date[0])
        end_order_info = build_order_info(orders_sorted_date[-1])

        report_dict = {'start_order_name': start_order_info[2],
                       'start_order_ref': start_order_info[3],
                       'start_order_date': start_order_info[0],
                       'end_order_name': end_order_info[2],
                       'end_order_ref': end_order_info[3],
                       'end_order_date': end_order_info[0]}

        # Raise on success
        raise UserError(_('''Successful test !

                         The point of sale orders are guaranteed to be in their original and inalterable state
                         From: %(start_order_name)s %(start_order_ref)s recorded on %(start_order_date)s
                         To: %(end_order_name)s %(end_order_ref)s recorded on %(end_order_date)s

                         For this report to be legally meaningful, please 
                         download your certification from your customer 
                         account on flectrahq.com (Only for Flectra 
                         Enterprise users).'''
                         ) % report_dict)


class PosOrderLine(models.Model):
    _inherit = "pos.order.line"

    @api.multi
    def write(self, vals):
        # restrict the operation in case we are trying to write a forbidden field
        if set(vals).intersection(LINE_FIELDS):
            if any(l.company_id._is_accounting_unalterable() and l.order_id.state in ['done', 'invoiced'] for l in self):
                raise UserError(_('According to the French law, you cannot modify a point of sale order line. Forbidden fields: %s.') % ', '.join(LINE_FIELDS))
        return super(PosOrderLine, self).write(vals)