# 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
import random
from collections import defaultdict
from decimal import Decimal
from functools import wraps

from sql.aggregate import Sum
from sql.conditionals import Coalesce

from trytond import backend
from trytond.i18n import gettext
from trytond.model import (
    ChatMixin, DeactivableMixin, Index, ModelSQL, ModelView, Workflow, fields,
    sequence_ordered, tree)
from trytond.model.exceptions import AccessError
from trytond.modules.company.model import employee_field, set_employee
from trytond.modules.product import price_digits, round_price
from trytond.pool import Pool
from trytond.pyson import Bool, Eval, If, TimeDelta
from trytond.tools import grouped_slice, reduce_ids, sqlite_apply_types
from trytond.transaction import Transaction

from .exceptions import PickerError


class WorkCenterCategory(ModelSQL, ModelView):
    __name__ = 'production.work.center.category'
    name = fields.Char('Name', required=True, translate=True)


class WorkCenter(DeactivableMixin, tree(separator=' / '), ModelSQL, ModelView):
    __name__ = 'production.work.center'
    name = fields.Char('Name', required=True, translate=True)
    parent = fields.Many2One('production.work.center', 'Parent',
        domain=[
            ('company', '=', Eval('company', -1)),
            ('warehouse', '=', Eval('warehouse', -1)),
            ])
    children = fields.One2Many('production.work.center', 'parent', 'Children',
        domain=[
            ('company', '=', Eval('company', -1)),
            ('warehouse', '=', Eval('warehouse', -1)),
            ])
    category = fields.Many2One('production.work.center.category', 'Category')
    cost_price = fields.Numeric('Cost Price', digits=price_digits,
        states={
            'required': Bool(Eval('cost_method')),
            })
    cost_method = fields.Selection([
            ('', ''),
            ('cycle', 'Per Cycle'),
            ('hour', 'Per Hour'),
            ], 'Cost Method',
        states={
            'required': Bool(Eval('cost_price')),
            })
    company = fields.Many2One('company.company', "Company", required=True)
    warehouse = fields.Many2One('stock.location', 'Warehouse', required=True,
        domain=[
            ('type', '=', 'warehouse'),
            ])

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

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

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

    @classmethod
    def get_picker(cls):
        """Return a method that picks a work center
        for the category and the parent"""
        cache = {}

        def picker(parent, category):
            key = (parent, category)
            if key not in cache:
                work_centers = cls.search([
                        ('parent', 'child_of', [parent.id]),
                        ('category', '=', category.id),
                        ])
                if not work_centers:
                    raise PickerError(
                        gettext('production_work.msg_missing_work_center',
                            category=category.rec_name,
                            parent=parent.rec_name))
                cache[key] = work_centers
            return random.choice(cache[key])
        return picker


class Work(sequence_ordered(), ModelSQL, ModelView, ChatMixin):
    __name__ = 'production.work'
    operation = fields.Many2One('production.routing.operation', 'Operation',
        required=True)
    production = fields.Many2One(
        'production', "Production", required=True, ondelete='CASCADE',
        domain=[
            ('company', '=', Eval('company', -1)),
            ])
    work_center_category = fields.Function(fields.Many2One(
            'production.work.center.category', 'Work Center Category'),
        'on_change_with_work_center_category')
    work_center = fields.Many2One('production.work.center', 'Work Center',
        domain=[
            If(~Eval('work_center_category'),
                (),
                ('category', '=', Eval('work_center_category'))),
            ('company', '=', Eval('company', -1)),
            ('warehouse', '=', Eval('warehouse', -1)),
            ],
        states={
            'required': ~Eval('state').in_(['request', 'draft']),
            })
    cycles = fields.One2Many('production.work.cycle', 'work', 'Cycles',
        states={
            'readonly': Eval('state').in_(['request', 'done']),
            })
    active_cycles = fields.One2Many(
        'production.work.cycle', 'work', "Active Cycles",
        readonly=True,
        filter=[
            ('state', '=', 'running'),
            ])
    cost = fields.Function(fields.Numeric(
        "Cost", digits=price_digits), 'get_cost')
    company = fields.Many2One('company.company', "Company", required=True)
    warehouse = fields.Function(fields.Many2One('stock.location', 'Warehouse'),
        'on_change_with_warehouse')
    state = fields.Selection([
            ('request', 'Request'),
            ('draft', 'Draft'),
            ('waiting', 'Waiting'),
            ('running', 'Running'),
            ('finished', 'Finished'),
            ('done', 'Done'),
            ], "State", readonly=True, sort=False)

    @classmethod
    def __setup__(cls):
        super().__setup__()
        t = cls.__table__()
        cls._sql_indexes.add(
            Index(
                t, (t.state, Index.Equality(cardinality='low')),
                where=t.state.in_(['request', 'draft', 'waiting', 'running'])))
        cls._buttons.update({
                'start': {
                    'invisible': Bool(Eval('active_cycles', [])),
                    'readonly': Eval('state').in_(['request', 'done']),
                    'depends': ['active_cycles'],
                    },
                'stop': {
                    'invisible': ~Bool(Eval('active_cycles', [])),
                    'depends': ['active_cycles'],
                    },
                })

    @fields.depends('operation')
    def on_change_with_work_center_category(self, name=None):
        return self.operation.work_center_category if self.operation else None

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

    @fields.depends('production', '_parent_production.warehouse')
    def on_change_with_warehouse(self, name=None):
        return self.production.warehouse if self.production else None

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

    @classmethod
    @ModelView.button
    def start(cls, works):
        pool = Pool()
        Cycle = pool.get('production.work.cycle')
        cycles = [Cycle(work=w) for w in works]
        Cycle.save(cycles)
        Cycle.run(cycles)

    @classmethod
    @ModelView.button
    def stop(cls, works):
        pool = Pool()
        Cycle = pool.get('production.work.cycle')

        to_do = []
        for work in works:
            for cycle in work.active_cycles:
                to_do.append(cycle)
        Cycle.do(to_do)

    @property
    def _state(self):
        if self.production.state == 'waiting' and not self.cycles:
            return 'request'
        elif self.production.state == 'done':
            return 'done'
        elif (not self.cycles
                or all(c.state == 'cancelled' for c in self.cycles)):
            return 'draft'
        elif all(c.state in ['done', 'cancelled'] for c in self.cycles):
            return 'finished'
        elif any(c.state == 'running' for c in self.cycles):
            return 'running'
        else:
            return 'waiting'

    @classmethod
    def set_state(cls, works):
        for work in works:
            state = work._state
            if work.state != state:
                work.state = state
        cls.save(works)

    def get_rec_name(self, name):
        return '%s @ %s' % (self.operation.rec_name, self.production.rec_name)

    @classmethod
    def search_rec_name(cls, name, clause):
        if clause[1].startswith('!') or clause[1].startswith('not '):
            bool_op = 'AND'
        else:
            bool_op = 'OR'
        return [bool_op,
            ('operation.rec_name',) + tuple(clause[1:]),
            ('production.rec_name',) + tuple(clause[1:]),
            ]

    @classmethod
    def get_cost(cls, works, name):
        pool = Pool()
        Cycle = pool.get('production.work.cycle')
        cycle = Cycle.__table__()
        cursor = Transaction().connection.cursor()
        costs = defaultdict(Decimal)

        for sub_works in grouped_slice(works):
            red_sql = reduce_ids(cycle.work, [w.id for w in sub_works])
            query = cycle.select(
                cycle.work, Sum(Coalesce(cycle.cost, 0)).as_('cost'),
                where=red_sql & (cycle.state == 'done'),
                group_by=cycle.work)
            if backend.name == 'sqlite':
                sqlite_apply_types(query, [None, 'NUMERIC'])
            cursor.execute(*query)
            costs.update(cursor)
        for cost in costs:
            costs[cost] = round_price(costs[cost])
        return costs

    @classmethod
    def on_modification(cls, mode, works, field_names=None):
        super().on_modification(mode, works, field_names=field_names)
        if mode in {'create', 'write'}:
            cls.set_state(works)

    @classmethod
    def check_modification(cls, mode, works, values=None, external=False):
        super().check_modification(
            mode, works, values=values, external=external)
        if mode == 'delete':
            for work in works:
                if work.state not in {'request', 'draft'}:
                    raise AccessError(
                        gettext('production_work.msg_delete_request',
                            work=work.rec_name))


def set_work_state(func):
    @wraps(func)
    def wrapper(cls, cycles):
        pool = Pool()
        Work = pool.get('production.work')
        result = func(cls, cycles)
        Work.set_state(Work.browse({c.work.id for c in cycles}))
        return result
    return wrapper


class WorkCycle(Workflow, ModelSQL, ModelView):
    __name__ = 'production.work.cycle'
    work = fields.Many2One(
        'production.work', "Work", required=True, ondelete='CASCADE')
    duration = fields.TimeDelta(
        "Duration",
        domain=['OR',
            ('duration', '=', None),
            ('duration', '>=', TimeDelta()),
            ],
        states={
            'required': Eval('state') == 'done',
            'readonly': Eval('state').in_(['done', 'draft', 'cancelled']),
            })
    cost = fields.Numeric('Cost', digits=price_digits, readonly=True)
    company = fields.Function(
        fields.Many2One('company.company', "Company"),
        'on_change_with_company', searcher='search_company')
    run_by = employee_field("Run By", states={
        'readonly': Eval('state') != 'draft',
        })
    done_by = employee_field("Done By", states={
        'readonly': Eval('state').in_(['draft', 'running']),
        })
    cancelled_by = employee_field("Cancelled By", states={
        'readonly': Eval('state').in_(['draft', 'running']),
        })
    state = fields.Selection([
            ('draft', 'Draft'),
            ('running', 'Running'),
            ('done', 'Done'),
            ('cancelled', 'Cancelled'),
            ], "State", required=True, readonly=True, sort=False)

    @classmethod
    def __setup__(cls):
        super().__setup__()
        t = cls.__table__()
        cls._sql_indexes.add(
            Index(
                t, (t.state, Index.Equality(cardinality='low')),
                where=t.state.in_(['draft', 'running'])))
        cls._transitions |= set((
                ('draft', 'running'),
                ('running', 'done'),
                ('draft', 'cancelled'),
                ('running', 'cancelled'),
                ))
        cls._buttons.update({
                'cancel': {
                    'invisible': Eval('state').in_(['done', 'cancelled']),
                    'depends': ['state'],
                    },
                'run': {
                    'invisible': Eval('state') != 'draft',
                    'depends': ['state'],
                    },
                'do': {
                    'invisible': Eval('state') != 'running',
                    'depends': ['state'],
                    },
                })

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

    @fields.depends('work', '_parent_work.company')
    def on_change_with_company(self, name=None):
        if self.work and self.work.company:
            return self.work.company.id

    @classmethod
    def search_company(cls, name, clause):
        return [('work.' + clause[0], *clause[1:])]

    @classmethod
    def copy(cls, cycles, default=None):
        default = default.copy() if default is not None else {}
        default.setdefault('run_by')
        default.setdefault('done_by')
        default.setdefault('cancelled_by')
        return super().copy(cycles, default=default)

    @classmethod
    @ModelView.button
    @set_work_state
    @Workflow.transition('cancelled')
    @set_employee('cancelled_by')
    def cancel(cls, cycles):
        pass

    @classmethod
    @ModelView.button
    @set_work_state
    @Workflow.transition('running')
    @set_employee('run_by')
    def run(cls, cycles):
        pass

    @classmethod
    @ModelView.button
    @set_work_state
    @Workflow.transition('done')
    @set_employee('done_by')
    def do(cls, cycles):
        now = datetime.datetime.now()
        for cycle in cycles:
            cycle.set_duration(now)
            cycle.set_cost()
        cls.save(cycles)

    def set_duration(self, now):
        if self.duration is None:
            self.duration = now - (self.write_date or self.create_date)

    def set_cost(self):
        if self.cost is None:
            center = self.work.work_center
            if center.cost_method == 'cycle':
                self.cost = center.cost_price
            elif center.cost_method == 'hour':
                hours = self.duration.total_seconds() / (60 * 60)
                self.cost = center.cost_price * Decimal(str(hours))
                self.cost = round_price(self.cost)