# 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 warnings
from itertools import chain

from sql.conditionals import Case

from trytond.pool import Pool
from trytond.rpc import RPC
from trytond.tools import is_instance_method
from trytond.tools.string_ import LazyString
from trytond.transaction import Transaction

from .field import Field, order_method


class SelectionMixin(Field):
    translate_selection = True
    sort = True

    def translated(self, name=None):
        "Return a descriptor for the translated value of the field"
        if name is None:
            name = self.name
        if name is None:
            raise ValueError('Missing name argument')
        return TranslatedSelection(name)

    def definition(self, model, language):
        pool = Pool()
        Translation = pool.get('ir.translation')
        definition = super().definition(model, language)
        if not isinstance(self.selection, str) and self.translate_selection:
            name = '%s,%s' % (model.__name__, self.name)
            selection = []
            for key, source in self.selection:
                if not isinstance(source, LazyString):
                    source = Translation.get_source(
                        name, 'selection', language, source) or source
                selection.append((key, str(source)))
        elif hasattr(self.selection, 'copy'):
            selection = self.selection.copy()
        else:
            selection = self.selection
        if self.help_selection:
            help_selection = {}
            for key, source in self.help_selection.items():
                if not isinstance(source, LazyString):
                    source = Translation.get_source(
                        name, 'selection', language, source) or source
                help_selection[key] = str(source)
        else:
            help_selection = None
        definition['selection'] = selection
        definition['selection_change_with'] = list(self.selection_change_with)
        definition['sort'] = self.sort
        definition['help_selection'] = help_selection
        return definition

    def definition_translations(self, model, language):
        name = '%s,%s' % (model.__name__, self.name)
        selection = []
        sources = []
        if not isinstance(self.selection, str) and self.translate_selection:
            sources.append(self.selection)
        if self.help_selection:
            sources.append(self.help_selection.items())
        for key, source in chain(*sources):
            if not isinstance(source, LazyString):
                selection.append(
                    (name, 'selection', language, source))
        return super().definition_translations(model, language) + selection

    @classmethod
    def get_selection(cls, model, name, inst):
        selection = model.fields_get([name])[name]['selection']
        if isinstance(selection, str):
            sel_func = getattr(model, selection)
            if not is_instance_method(model, selection):
                selection = sel_func()
            else:
                selection = sel_func(inst)
        return dict(selection)

    @classmethod
    def get_selection_string(cls, selection, value):
        # None and '' are equivalent
        if value is None or value == '':
            if value not in selection:
                switch_value = {None: '', '': None}[value]
                if switch_value in selection:
                    value = switch_value
        return selection.get(value, value)


class Selection(SelectionMixin, Field):
    '''
    Define a selection field (``str``).
    '''
    _type = 'selection'
    _sql_type = 'VARCHAR'
    _py_type = str

    def __init__(self, selection, string='', sort=True,
            selection_change_with=None, translate=True, help='',
            help_selection=None, required=False, readonly=False, domain=None,
            states=None, on_change=None, on_change_with=None,
            depends=None, context=None, loading='eager'):
        '''
        :param selection: A list or a function name that returns a list.
            The list must be a list of tuples. First member is the value
            to store and the second is the value to display.
        :param sort: A boolean to sort or not the selections.
        '''
        super(Selection, self).__init__(string=string, help=help,
            required=required, readonly=readonly, domain=domain, states=states,
            on_change=on_change, on_change_with=on_change_with,
            depends=depends, context=context, loading=loading)
        if hasattr(selection, 'copy'):
            self.selection = selection.copy()
        else:
            self.selection = selection
        self.selection_change_with = set()
        if selection_change_with:
            warnings.warn('selection_change_with argument is deprecated, '
                'use the depends decorator',
                DeprecationWarning, stacklevel=2)
            self.selection_change_with.update(selection_change_with)
        self.sort = sort
        self.translate_selection = translate
        self.help_selection = help_selection
    __init__.__doc__ += Field.__init__.__doc__

    def set_rpc(self, model):
        super(Selection, self).set_rpc(model)
        if not isinstance(self.selection, (list, tuple)):
            assert hasattr(model, self.selection), \
                'Missing %s on model %s' % (self.selection, model.__name__)
            instantiate = 0 if self.selection_change_with else None
            cache = dict(days=1) if instantiate is None else None
            model.__rpc__.setdefault(
                self.selection, RPC(instantiate=instantiate, cache=cache))

    @order_method
    def convert_order(self, name, tables, Model):
        table, _ = tables[None]
        selections = Model.fields_get([name])[name]['selection']
        if not isinstance(selections, (tuple, list)):
            if not is_instance_method(Model, selections):
                selections = getattr(Model, selections)()
            else:
                selections = []
        column = self.sql_column(table)
        if not self.sort:
            else_ = len(selections) + 1
            selections = ((k, i) for i, (k, v) in enumerate(selections))
        else:
            else_ = column
        whens = []
        for key, value in selections:
            whens.append((column == key, value))
        if whens:
            return [Case(*whens, else_=else_)]
        else:
            return [column]


class TranslatedSelection(object):
    'A descriptor for translated value of Selection field'

    def __init__(self, name):
        self.name = name

    def __get__(self, inst, cls):
        from ..model import Model
        if inst is None:
            return self
        field = cls._fields[self.name]
        with Transaction().set_context(getattr(inst, '_context', {})):
            selection = field.get_selection(cls, self.name, inst)
        value = getattr(inst, self.name)
        # Use Model __name__ for Reference field
        if isinstance(value, Model):
            value = value.__name__
        if isinstance(value, (list, tuple)):
            values = []
            for item in value:
                values.append(field.get_selection_string(selection, item))
            return values
        else:
            return field.get_selection_string(selection, value)
