# Copyright (C) 2014-2016 Andrey Antukh <niwi@niwi.nz>
# Copyright (C) 2014-2016 Jesús Espino <jespinog@gmail.com>
# Copyright (C) 2014-2016 David Barragán <bameda@dbarragan.com>
# Copyright (C) 2014-2016 Alejandro Alonso <alejandro.alonso@kaleidos.net>
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# The code is partially taken (and modified) from django rest framework
# that is licensed under the following terms:
#
# Copyright (c) 2011-2014, Tom Christie
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
# Redistributions in binary form must reproduce the above copyright notice, this
# list of conditions and the following disclaimer in the documentation and/or
# other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

"""
Serializer fields that deal with relationships.

These fields allow you to specify the style that should be used to represent
model relationships, including hyperlinks, primary keys, or slugs.
"""
from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.core.urlresolvers import resolve, get_script_prefix, NoReverseMatch
from django import forms
from django.db.models.fields import BLANK_CHOICE_DASH
from django.forms import widgets
from django.forms.models import ModelChoiceIterator
from django.utils.encoding import smart_text
from django.utils.translation import ugettext_lazy as _

from .fields import Field, WritableField, get_component, is_simple_callable
from .reverse import reverse

import warnings
from urllib import parse as urlparse




##### Relational fields #####


# Not actually Writable, but subclasses may need to be.
class RelatedField(WritableField):
    """
    Base class for related model fields.

    This represents a relationship using the unicode representation of the target.
    """
    widget = widgets.Select
    many_widget = widgets.SelectMultiple
    form_field_class = forms.ChoiceField
    many_form_field_class = forms.MultipleChoiceField
    null_values = (None, "", "None")

    cache_choices = False
    empty_label = None
    read_only = True
    many = False

    def __init__(self, *args, **kwargs):

        # "null" is to be deprecated in favor of "required"
        if "null" in kwargs:
            warnings.warn("The `null` keyword argument is deprecated. "
                          "Use the `required` keyword argument instead.",
                          DeprecationWarning, stacklevel=2)
            kwargs["required"] = not kwargs.pop("null")

        queryset = kwargs.pop("queryset", None)
        self.many = kwargs.pop("many", self.many)
        if self.many:
            self.widget = self.many_widget
            self.form_field_class = self.many_form_field_class

        kwargs["read_only"] = kwargs.pop("read_only", self.read_only)
        super(RelatedField, self).__init__(*args, **kwargs)

        if not self.required:
            self.empty_label = BLANK_CHOICE_DASH[0][1]

        self.queryset = queryset

    def initialize(self, parent, field_name):
        super(RelatedField, self).initialize(parent, field_name)
        if self.queryset is None and not self.read_only:
            manager = getattr(self.parent.opts.model, self.source or field_name)
            if hasattr(manager, "related"):  # Forward
                self.queryset = manager.related.model._default_manager.all()
            else:  # Reverse
                self.queryset = manager.field.rel.to._default_manager.all()

    ### We need this stuff to make form choices work...

    def prepare_value(self, obj):
        return self.to_native(obj)

    def label_from_instance(self, obj):
        """
        Return a readable representation for use with eg. select widgets.
        """
        desc = smart_text(obj)
        ident = smart_text(self.to_native(obj))
        if desc == ident:
            return desc
        return "%s - %s" % (desc, ident)

    def _get_queryset(self):
        return self._queryset

    def _set_queryset(self, queryset):
        self._queryset = queryset
        self.widget.choices = self.choices

    queryset = property(_get_queryset, _set_queryset)

    def _get_choices(self):
        # If self._choices is set, then somebody must have manually set
        # the property self.choices. In this case, just return self._choices.
        if hasattr(self, "_choices"):
            return self._choices

        # Otherwise, execute the QuerySet in self.queryset to determine the
        # choices dynamically. Return a fresh ModelChoiceIterator that has not been
        # consumed. Note that we"re instantiating a new ModelChoiceIterator *each*
        # time _get_choices() is called (and, thus, each time self.choices is
        # accessed) so that we can ensure the QuerySet has not been consumed. This
        # construct might look complicated but it allows for lazy evaluation of
        # the queryset.
        return ModelChoiceIterator(self)

    def _set_choices(self, value):
        # Setting choices also sets the choices on the widget.
        # choices can be any iterable, but we call list() on it because
        # it will be consumed more than once.
        self._choices = self.widget.choices = list(value)

    choices = property(_get_choices, _set_choices)

    ### Default value handling

    def get_default_value(self):
        default = super(RelatedField, self).get_default_value()
        if self.many and default is None:
            return []
        return default

    ### Regular serializer stuff...

    def field_to_native(self, obj, field_name):
        try:
            if self.source == "*":
                return self.to_native(obj)

            source = self.source or field_name
            value = obj

            for component in source.split("."):
                if value is None:
                    break
                value = get_component(value, component)
        except ObjectDoesNotExist:
            return None

        if value is None:
            return None

        if self.many:
            if is_simple_callable(getattr(value, "all", None)):
                return [self.to_native(item) for item in value.all()]
            else:
                # Also support non-queryset iterables.
                # This allows us to also support plain lists of related items.
                return [self.to_native(item) for item in value]
        return self.to_native(value)

    def field_from_native(self, data, files, field_name, into):
        if self.read_only:
            return

        try:
            if self.many:
                try:
                    # Form data
                    value = data.getlist(field_name)
                    if value == [""] or value == []:
                        raise KeyError
                except AttributeError:
                    # Non-form data
                    value = data[field_name]
            else:
                value = data[field_name]
        except KeyError:
            if self.partial:
                return
            value = self.get_default_value()

        if value in self.null_values:
            if self.required:
                raise ValidationError(self.error_messages["required"])
            into[(self.source or field_name)] = None
        elif self.many:
            into[(self.source or field_name)] = [self.from_native(item) for item in value]
        else:
            into[(self.source or field_name)] = self.from_native(value)


### PrimaryKey relationships

class PrimaryKeyRelatedField(RelatedField):
    """
    Represents a relationship as a pk value.
    """
    read_only = False

    default_error_messages = {
        "does_not_exist": _("Invalid pk '%s' - object does not exist."),
        "incorrect_type": _("Incorrect type. Expected pk value, received %s."),
    }

    # TODO: Remove these field hacks...
    def prepare_value(self, obj):
        return self.to_native(obj.pk)

    def label_from_instance(self, obj):
        """
        Return a readable representation for use with eg. select widgets.
        """
        desc = smart_text(obj)
        ident = smart_text(self.to_native(obj.pk))
        if desc == ident:
            return desc
        return "%s - %s" % (desc, ident)

    # TODO: Possibly change this to just take `obj`, through prob less performant
    def to_native(self, pk):
        return pk

    def from_native(self, data):
        if self.queryset is None:
            raise Exception("Writable related fields must include a `queryset` argument")

        try:
            return self.queryset.get(pk=data)
        except ObjectDoesNotExist:
            msg = self.error_messages["does_not_exist"] % smart_text(data)
            raise ValidationError(msg)
        except (TypeError, ValueError):
            received = type(data).__name__
            msg = self.error_messages["incorrect_type"] % received
            raise ValidationError(msg)

    def field_to_native(self, obj, field_name):
        if self.many:
            # To-many relationship

            queryset = None
            if not self.source:
                # Prefer obj.serializable_value for performance reasons
                try:
                    queryset = obj.serializable_value(field_name)
                except AttributeError:
                    pass
            if queryset is None:
                # RelatedManager (reverse relationship)
                source = self.source or field_name
                queryset = obj
                for component in source.split("."):
                    if queryset is None:
                        return []
                    queryset = get_component(queryset, component)

            # Forward relationship
            if is_simple_callable(getattr(queryset, "all", None)):
                return [self.to_native(item.pk) for item in queryset.all()]
            else:
                # Also support non-queryset iterables.
                # This allows us to also support plain lists of related items.
                return [self.to_native(item.pk) for item in queryset]

        # To-one relationship
        try:
            # Prefer obj.serializable_value for performance reasons
            pk = obj.serializable_value(self.source or field_name)
        except AttributeError:
            # RelatedObject (reverse relationship)
            try:
                pk = getattr(obj, self.source or field_name).pk
            except (ObjectDoesNotExist, AttributeError):
                return None

        # Forward relationship
        return self.to_native(pk)


### Slug relationships


class SlugRelatedField(RelatedField):
    """
    Represents a relationship using a unique field on the target.
    """
    read_only = False

    default_error_messages = {
        "does_not_exist": _("Object with %s=%s does not exist."),
        "invalid": _("Invalid value."),
    }

    def __init__(self, *args, **kwargs):
        self.slug_field = kwargs.pop("slug_field", None)
        assert self.slug_field, "slug_field is required"
        super(SlugRelatedField, self).__init__(*args, **kwargs)

    def to_native(self, obj):
        return getattr(obj, self.slug_field)

    def from_native(self, data):
        if self.queryset is None:
            raise Exception("Writable related fields must include a `queryset` argument")

        try:
            return self.queryset.get(**{self.slug_field: data})
        except ObjectDoesNotExist:
            raise ValidationError(self.error_messages["does_not_exist"] %
                                  (self.slug_field, smart_text(data)))
        except (TypeError, ValueError):
            msg = self.error_messages["invalid"]
            raise ValidationError(msg)


### Hyperlinked relationships

class HyperlinkedRelatedField(RelatedField):
    """
    Represents a relationship using hyperlinking.
    """
    read_only = False
    lookup_field = "pk"

    default_error_messages = {
        "no_match": _("Invalid hyperlink - No URL match"),
        "incorrect_match": _("Invalid hyperlink - Incorrect URL match"),
        "configuration_error": _("Invalid hyperlink due to configuration error"),
        "does_not_exist": _("Invalid hyperlink - object does not exist."),
        "incorrect_type": _("Incorrect type.  Expected url string, received %s."),
    }

    # These are all pending deprecation
    pk_url_kwarg = "pk"
    slug_field = "slug"
    slug_url_kwarg = None  # Defaults to same as `slug_field` unless overridden

    def __init__(self, *args, **kwargs):
        try:
            self.view_name = kwargs.pop("view_name")
        except KeyError:
            raise ValueError("Hyperlinked field requires \"view_name\" kwarg")

        self.lookup_field = kwargs.pop("lookup_field", self.lookup_field)
        self.format = kwargs.pop("format", None)

        # These are pending deprecation
        if "pk_url_kwarg" in kwargs:
            msg = "pk_url_kwarg is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
        if "slug_url_kwarg" in kwargs:
            msg = "slug_url_kwarg is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
        if "slug_field" in kwargs:
            msg = "slug_field is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)

        self.pk_url_kwarg = kwargs.pop("pk_url_kwarg", self.pk_url_kwarg)
        self.slug_field = kwargs.pop("slug_field", self.slug_field)
        default_slug_kwarg = self.slug_url_kwarg or self.slug_field
        self.slug_url_kwarg = kwargs.pop("slug_url_kwarg", default_slug_kwarg)

        super(HyperlinkedRelatedField, self).__init__(*args, **kwargs)

    def get_url(self, obj, view_name, request, format):
        """
        Given an object, return the URL that hyperlinks to the object.

        May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
        attributes are not configured to correctly match the URL conf.
        """
        lookup_field = getattr(obj, self.lookup_field)
        kwargs = {self.lookup_field: lookup_field}
        try:
            return reverse(view_name, kwargs=kwargs, request=request, format=format)
        except NoReverseMatch:
            pass

        if self.pk_url_kwarg != "pk":
            # Only try pk if it has been explicitly set.
            # Otherwise, the default `lookup_field = "pk"` has us covered.
            pk = obj.pk
            kwargs = {self.pk_url_kwarg: pk}
            try:
                return reverse(view_name, kwargs=kwargs, request=request, format=format)
            except NoReverseMatch:
                pass

        slug = getattr(obj, self.slug_field, None)
        if slug is not None:
            # Only try slug if it corresponds to an attribute on the object.
            kwargs = {self.slug_url_kwarg: slug}
            try:
                ret = reverse(view_name, kwargs=kwargs, request=request, format=format)
                if self.slug_field == "slug" and self.slug_url_kwarg == "slug":
                    # If the lookup succeeds using the default slug params,
                    # then `slug_field` is being used implicitly, and we
                    # we need to warn about the pending deprecation.
                    msg = "Implicit slug field hyperlinked fields are pending deprecation." \
                          "You should set `lookup_field=slug` on the HyperlinkedRelatedField."
                    warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
                return ret
            except NoReverseMatch:
                pass

        raise NoReverseMatch()

    def get_object(self, queryset, view_name, view_args, view_kwargs):
        """
        Return the object corresponding to a matched URL.

        Takes the matched URL conf arguments, and the queryset, and should
        return an object instance, or raise an `ObjectDoesNotExist` exception.
        """
        lookup = view_kwargs.get(self.lookup_field, None)
        pk = view_kwargs.get(self.pk_url_kwarg, None)
        slug = view_kwargs.get(self.slug_url_kwarg, None)

        if lookup is not None:
            filter_kwargs = {self.lookup_field: lookup}
        elif pk is not None:
            filter_kwargs = {"pk": pk}
        elif slug is not None:
            filter_kwargs = {self.slug_field: slug}
        else:
            raise ObjectDoesNotExist()

        return queryset.get(**filter_kwargs)

    def to_native(self, obj):
        view_name = self.view_name
        request = self.context.get("request", None)
        format = self.format or self.context.get("format", None)

        if request is None:
            msg = (
                "Using `HyperlinkedRelatedField` without including the request "
                "in the serializer context is deprecated. "
                "Add `context={'request': request}` when instantiating "
                "the serializer."
            )
            warnings.warn(msg, DeprecationWarning, stacklevel=4)

        # If the object has not yet been saved then we cannot hyperlink to it.
        if getattr(obj, "pk", None) is None:
            return

        # Return the hyperlink, or error if incorrectly configured.
        try:
            return self.get_url(obj, view_name, request, format)
        except NoReverseMatch:
            msg = (
                "Could not resolve URL for hyperlinked relationship using "
                "view name '%s'. You may have failed to include the related "
                "model in your API, or incorrectly configured the "
                "`lookup_field` attribute on this field."
            )
            raise Exception(msg % view_name)

    def from_native(self, value):
        # Convert URL -> model instance pk
        # TODO: Use values_list
        queryset = self.queryset
        if queryset is None:
            raise Exception("Writable related fields must include a `queryset` argument")

        try:
            http_prefix = value.startswith(("http:", "https:"))
        except AttributeError:
            msg = self.error_messages["incorrect_type"]
            raise ValidationError(msg % type(value).__name__)

        if http_prefix:
            # If needed convert absolute URLs to relative path
            value = urlparse.urlparse(value).path
            prefix = get_script_prefix()
            if value.startswith(prefix):
                value = "/" + value[len(prefix):]

        try:
            match = resolve(value)
        except Exception:
            raise ValidationError(self.error_messages["no_match"])

        if match.view_name != self.view_name:
            raise ValidationError(self.error_messages["incorrect_match"])

        try:
            return self.get_object(queryset, match.view_name,
                                   match.args, match.kwargs)
        except (ObjectDoesNotExist, TypeError, ValueError):
            raise ValidationError(self.error_messages["does_not_exist"])


class HyperlinkedIdentityField(Field):
    """
    Represents the instance, or a property on the instance, using hyperlinking.
    """
    lookup_field = "pk"
    read_only = True

    # These are all pending deprecation
    pk_url_kwarg = "pk"
    slug_field = "slug"
    slug_url_kwarg = None  # Defaults to same as `slug_field` unless overridden

    def __init__(self, *args, **kwargs):
        try:
            self.view_name = kwargs.pop("view_name")
        except KeyError:
            msg = "HyperlinkedIdentityField requires \"view_name\" argument"
            raise ValueError(msg)

        self.format = kwargs.pop("format", None)
        lookup_field = kwargs.pop("lookup_field", None)
        self.lookup_field = lookup_field or self.lookup_field

        # These are pending deprecation
        if "pk_url_kwarg" in kwargs:
            msg = "pk_url_kwarg is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
        if "slug_url_kwarg" in kwargs:
            msg = "slug_url_kwarg is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
        if "slug_field" in kwargs:
            msg = "slug_field is pending deprecation. Use lookup_field instead."
            warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)

        self.slug_field = kwargs.pop("slug_field", self.slug_field)
        default_slug_kwarg = self.slug_url_kwarg or self.slug_field
        self.pk_url_kwarg = kwargs.pop("pk_url_kwarg", self.pk_url_kwarg)
        self.slug_url_kwarg = kwargs.pop("slug_url_kwarg", default_slug_kwarg)

        super(HyperlinkedIdentityField, self).__init__(*args, **kwargs)

    def field_to_native(self, obj, field_name):
        request = self.context.get("request", None)
        format = self.context.get("format", None)
        view_name = self.view_name

        if request is None:
            warnings.warn("Using `HyperlinkedIdentityField` without including the "
                          "request in the serializer context is deprecated. "
                          "Add `context={'request': request}` when instantiating the serializer.",
                          DeprecationWarning, stacklevel=4)

        # By default use whatever format is given for the current context
        # unless the target is a different type to the source.
        #
        # Eg. Consider a HyperlinkedIdentityField pointing from a json
        # representation to an html property of that representation...
        #
        # "/snippets/1/" should link to "/snippets/1/highlight/"
        # ...but...
        # "/snippets/1/.json" should link to "/snippets/1/highlight/.html"
        if format and self.format and self.format != format:
            format = self.format

        # Return the hyperlink, or error if incorrectly configured.
        try:
            return self.get_url(obj, view_name, request, format)
        except NoReverseMatch:
            msg = (
                "Could not resolve URL for hyperlinked relationship using "
                "view name '%s'. You may have failed to include the related "
                "model in your API, or incorrectly configured the "
                "`lookup_field` attribute on this field."
            )
            raise Exception(msg % view_name)

    def get_url(self, obj, view_name, request, format):
        """
        Given an object, return the URL that hyperlinks to the object.

        May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
        attributes are not configured to correctly match the URL conf.
        """
        lookup_field = getattr(obj, self.lookup_field, None)
        kwargs = {self.lookup_field: lookup_field}

        # Handle unsaved object case
        if lookup_field is None:
            return None

        try:
            return reverse(view_name, kwargs=kwargs, request=request, format=format)
        except NoReverseMatch:
            pass

        if self.pk_url_kwarg != "pk":
            # Only try pk lookup if it has been explicitly set.
            # Otherwise, the default `lookup_field = "pk"` has us covered.
            kwargs = {self.pk_url_kwarg: obj.pk}
            try:
                return reverse(view_name, kwargs=kwargs, request=request, format=format)
            except NoReverseMatch:
                pass

        slug = getattr(obj, self.slug_field, None)
        if slug:
            # Only use slug lookup if a slug field exists on the model
            kwargs = {self.slug_url_kwarg: slug}
            try:
                return reverse(view_name, kwargs=kwargs, request=request, format=format)
            except NoReverseMatch:
                pass

        raise NoReverseMatch()
