# -*- coding: utf-8 -*-

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from django.contrib.contenttypes.models import ContentType
from django.utils.encoding import force_text

from rapid.registry import registry, Action
from rapid import filters

import itertools
from django.db import models
from rapid import permissions


class InstanceData(object):
    def __init__(self, instance, request=None, excludes=None, creator=None, fields=None):
        excludes = [] if excludes is None else excludes
        self.model = ModelData(type(instance), request, excludes, creator, fields)
        self.instance = instance
        self.request = request
        self.excludes = excludes if excludes else []
        self.creator = creator
        self._fields = self.model.fields()

    def values(self):
        r = []
        o = self.instance
        for f in self.model.fields():
            if f.is_relation:
                r.append(self._value_of_field(o, f))
            else:
                r.append(self._value_of_field(o, f))
        return r

    def _value_of_field(self, instance, field):
        """
        Returns the value of the given field.
        ::return A tuple, with the actual value of the field, a boolean that is true iff
        the value is iterable, and a sequence of URLs for the viewers of the instances
        of the first element, or False if there are no viewers.
        """
        if hasattr(instance, field.accessor_name()):
            v = getattr(instance, field.accessor_name())
        else:  # Many to many relations without value may disappear
            return [], True
        if hasattr(v, '__iter__'):
            return (v, ()), True
        if hasattr(v, 'all'):
            return [(x, InstanceData(x, self.request, creator=(self, field))) for x in v.all()], True
        if isinstance(v, models.Model):
            return (v, InstanceData(v, self.request, creator=(self, field))), False
        return (v, ()), False

    def fields_and_values(self):
        r = []
        for field in self.model.fields():
            value, is_multiple = self._value_of_field(self.instance, field)
            r.append((field, value, is_multiple))
        return r

    def is_controlled(self):
        return self.model.is_controlled()

    def can_read(self):
        return self.has_permission(self.request, 'view')

    def can_write(self):
        return self.has_permission(self.request, 'edit')

    def view_url(self):
        return registry.get_url_of_action(self.model.model, "view", pk=self.instance.pk)

    def edit_url(self):
        url = registry.get_url_of_action(self.model.model, "edit", pk=self.instance.pk)
        by = self.creator
        if by:
            dt, fd = by
            if fd.one_to_one or fd.one_to_many:
                # Do not change the parent of the viewer.
                return url + "?default=" + fd.field.name + ":" + str(dt.object.pk)
            if fd.many_to_one or fd.many_to_many:
                return url
        return url

    def remove_url(self):
        return registry.get_url_of_action(self.model.model, "delete", pk=self.instance.pk)

    def create_url(self):
        return registry.get_url_of_action(self.model.model, "add")

    def list_url(self):
        return registry.get_url_of_action(self.model.model, "list")

    def select_url(self):
        return registry.get_url_of_action(self.model.model, "select")

    def actions(self):
        r = []
        acts = registry.model_entry(self.model.model)
        if self.request and acts:
            for a in acts.values():
                if self.has_permission(self.request, a.action.name) and\
                        a.action.visibility > Action.Visibility.hidden:
                    r.append((a, a.get_url(self.instance)))
        return r

    def model_actions(self):
        r = []
        for (a, u) in self.actions():
            if not a.action.query_parameters:
                r.append((a, u))
        return r

    def instance_actions(self):
        r = []
        for (a, u) in self.actions():
            if a.action.query_parameters:
                r.append((a, u))
        return r

    def list_actions(self):
        r = []
        for (a, u) in self.instance_actions():
            if a.action.visibility == Action.Visibility.list:
                r.append((a, u))
        return r

    def has_permission(self, request, action_name):
        m = registry.model_entry(self.model.model).get(action_name)
        if m:
            perm = m.permission.instances
            return permissions.has_instance(self.model, perm(request), self.instance)
        return False

    def __unicode__(self):
        return force_text(self.instance)

    def __str__(self):
        return str(self.model) + ': ' + str(self.instance.pk)


class ModelData(object):
    def __init__(self, model, request=None, excludes=None, creator=None, fields=None):
        excludes = [] if excludes is None else excludes
        self.model = model
        self.request = request
        self.excludes = excludes if excludes else []
        self.creator = creator
        self._fields = [self.field_by_name(f) for f in fields] if fields else self.all_fields()

    def model_name(self):
        # noinspection PyProtectedMember
        return force_text(self.model._meta.verbose_name)

    def model_name_plural(self):
        # noinspection PyProtectedMember
        return force_text(self.model._meta.verbose_name_plural)

    def default_manager(self):
        # noinspection PyProtectedMember
        return self.model._default_manager

    def all_fields(self):
        r = []
        relations = []
        ignore_fields = []
        for f in itertools.chain(self.local_fields(), self.related_fields()):
            if f.bare_name() in ignore_fields:
                ignore_fields.remove(f.bare_name())
                continue
            if hasattr(f.field, 'is_rapid_alternatives') and f.field.is_rapid_alternatives:
                for ff in self.rapid_alternative_data():
                    if ff[1].ct_field == f.bare_name():
                        f = FieldData(ff[1])
                        for fr in r:
                            if fr.bare_name() == ff[1].fk_field:
                                r.remove(fr)
                        ignore_fields.append(ff[1].fk_field)
                        break
            if f.is_relation():
                relations.append(f)
            else:
                if f.name not in self.excludes:
                    r.append(f)
        for f in relations:
            if f.name not in self.excludes:
                r.append(f)
        return r

    def fields(self):
        return self._fields

    def local_fields(self):
        """
        :return: FieldData for each local (not related) field of this model.
        """
        r = []
        # noinspection PyProtectedMember
        for f in self.model._meta.local_fields:
            if f.name not in self.excludes:
                r.append(FieldData(f, self.request))
        # noinspection PyProtectedMember
        for f in self.model._meta.local_many_to_many:
            if f.name not in self.excludes:
                r.append(FieldData(f, self.request))
        return r

    def rapid_alternative_data(self):
        """
        :return: Tuples of the form (name, field) with the
        AlternativeData fields of this model.

        Those are not returned by fields()
        """
        for k, v in self.model.__dict__.items():
            if hasattr(v, 'is_rapid_alternatives') and v.is_rapid_alternatives:
                yield (k, v)

    def related_fields(self):
        """
        :return: A FieldData for each related manager for this model.
        """
        # noinspection PyProtectedMember
        return [FieldData(f, self.request) for f in self.model._meta.get_all_related_objects()]

    def is_controlled(self):
        """
        :return: True if this model is already controlled by the rapid registry.
        """
        return registry.is_controlled(self.model)

    def can_read(self):
        if self.can_write():
            return True
        vw = registry.model_entry(self.model)['view'].permission(self.request)
        if vw:
            return vw.exists()
        return False

    def can_write(self):
        ed = registry.model_entry(self.model)['edit'].permission(self.request)
        if ed:
            return ed.exists()
        return False

    def create_url(self):
        """
        :return: URL of the "add" action.
        """
        return registry.get_url_of_action(self.model, "add")

    def list_url(self):
        """
        :return: URL of the "list" action.
        """
        return registry.get_url_of_action(self.model, "list")

    def select_url(self):
        """
        :return: URL of the "select" action.
        """
        return registry.get_url_of_action(self.model, "select")

    def actions(self):
        """
        :return: All actions available for this model (with the object's request).
        """
        r = []
        acts = registry.model_entry(self.model)
        if self.request and acts:
            for a in acts.values():
                if self.has_permission(self.request, a.action.name) and\
                        not a.action.query_parameters and\
                        a.action.visibility > Action.Visibility.hidden:
                    r.append((a, a.get_url()))
        return r

    def has_permission(self, request, action_name):
        m = registry.model_entry(self.model)
        if m:
            a = m.get(action_name)
            if a:
                return bool(a.permission.model(request))
        return False

    def field_by_name(self, field_name):
        """
        :return: A FieldData with the field of this model that has the given name.
        """
        # noinspection PyProtectedMember
        return FieldData(self.model._meta.get_field(field_name), self.request)

    def content_type(self):
        """
        :return: The Django registry ContentType for this model.
        """
        return ContentType.objects.get_for_model(self.model)

    def __unicode__(self):
        return force_text(self.model)

    def __str__(self):
        return 'Model: ' + str(self.model)


class FieldData(object):
    def __init__(self, field, request=None):
        self.field = field
        self.request = request

    @classmethod
    def from_model(cls, model, field_name):
        ff = ModelData(model).fields()
        for f in ff:
            if f.bare_name() == force_text(field_name):
                return f
        return None

    def bare_name(self):
        return force_text(self.field.name)

    def accessor_name(self):
        if hasattr(self.field, 'get_accessor_name'):
            return force_text(self.field.get_accessor_name())
        return force_text(self.field.name)

    def name(self):
        if self.is_auto() and self.is_relation():
            return self.related_model().model_name_plural() + ' - ' + self.related_field().name()
        if hasattr(self.field, "verbose_name"):
            return force_text(self.field.verbose_name)
        return force_text(self.field.name)

    def name_plural(self):
        if self.is_auto() and self.is_relation():
            return self.related_model().model_name_plural() + ' - ' + self.related_field().name_plural()
        if hasattr(self.field, "verbose_name_plural"):
            return force_text(self.field.verbose_name_plural)
        return self.name() + "s"

    def is_relation(self):
        return self.field.is_relation

    def is_multiple(self):
        if not self.is_relation():
            return False
        if self.field.one_to_many:
            return True
        if self.field.many_to_many:
            return True
        return False

    def related_model(self):
        if hasattr(self.field, "related_model"):
            return ModelData(self.field.related_model)
        if hasattr(self.field, "to"):
            return ModelData(self.field.to)
        return None

    def related_field(self):
        if hasattr(self.field, "field"):
            return FieldData(self.field.field, self.request)
        return None

    def is_auto(self):
        return self.field.auto_created

    def is_existential_dependency(self):
        """
        :return: True if this field determine an existential dependency relation between this model
        and another one.

        That is, returns true if, because of this field, one element of this model can only exist if
        there is one element of one other model.

        Example: A required ForeignKey.
        """
        if not self.is_relation():
            return False
        f = self.field
        if hasattr(f, "many_to_many") and f.many_to_many:
            return False
        if hasattr(f, "many_to_one") and self.field.many_to_one:
            return False
        if hasattr(self.field, "required"):
            return self.field.required
        return True

    def filter_html(self):
        return filters.Filter.selection_type_html(self, self.request)

    def __str__(self):
        return self.bare_name()


class ValueData(object):
    def __init__(self, value, field):
        self.value = value
        self.field = field

    def can_view(self):
        if self.field.is_relation():
            o = self.field.related_model()
            return registry.is_controlled(o)
        return False

    def is_multiple(self):
        return self.field.is_multiple()

    def __str__(self):
        return str(self.field) + ': ' + str(self.value)