from django.conf import settings
from django.contrib.auth import get_user_model
from django.shortcuts import get_object_or_404
from rest_framework import serializers
from rest_polymorphic.serializers import PolymorphicSerializer
from rest_framework.exceptions import ValidationError


from .models import Label, Project, Document, RoleMapping, Role
from .models import TextClassificationProject, SequenceLabelingProject, Seq2seqProject
from .models import DocumentAnnotation, SequenceAnnotation, Seq2seqAnnotation


class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = get_user_model()
        fields = ('id', 'username', 'first_name', 'last_name', 'email', 'is_superuser')


class LabelSerializer(serializers.ModelSerializer):

    def validate(self, attrs):
        if 'prefix_key' not in attrs and 'suffix_key' not in attrs:
            return super().validate(attrs)

        prefix_key = attrs['prefix_key']
        suffix_key = attrs['suffix_key']

        # In the case of user don't set any shortcut key.
        if prefix_key is None and suffix_key is None:
            return super().validate(attrs)

        # Don't allow shortcut key not to have a suffix key.
        if prefix_key and not suffix_key:
            raise ValidationError('Shortcut key may not have a suffix key.')

        # Don't allow to save same shortcut key when prefix_key is null.
        try:
            context = self.context['request'].parser_context
            project_id = context['kwargs']['project_id']
        except (AttributeError, KeyError):
            pass  # unit tests don't always have the correct context set up
        else:
            if Label.objects.filter(suffix_key=suffix_key,
                                    prefix_key=prefix_key,
                                    project=project_id).exists():
                raise ValidationError('Duplicate key.')
        return super().validate(attrs)

    class Meta:
        model = Label
        fields = ('id', 'text', 'prefix_key', 'suffix_key', 'background_color', 'text_color')


class DocumentSerializer(serializers.ModelSerializer):
    annotations = serializers.SerializerMethodField()
    annotation_approver = serializers.SerializerMethodField()

    def get_annotations(self, instance):
        request = self.context.get('request')
        project = instance.project
        model = project.get_annotation_class()
        serializer = project.get_annotation_serializer()
        annotations = model.objects.filter(document=instance.id)
        if request and not project.collaborative_annotation:
            annotations = annotations.filter(user=request.user)
        serializer = serializer(annotations, many=True)
        return serializer.data

    @classmethod
    def get_annotation_approver(cls, instance):
        approver = instance.annotations_approved_by
        return approver.username if approver else None

    class Meta:
        model = Document
        fields = ('id', 'text', 'annotations', 'meta', 'annotation_approver')


class ProjectSerializer(serializers.ModelSerializer):
    current_users_role = serializers.SerializerMethodField()

    def get_current_users_role(self, instance):
        role_abstractor = {
            "is_project_admin": settings.ROLE_PROJECT_ADMIN,
            "is_annotator": settings.ROLE_ANNOTATOR,
            "is_annotation_approver": settings.ROLE_ANNOTATION_APPROVER,
        }
        queryset = RoleMapping.objects.values("role_id__name")
        if queryset:
            users_role = get_object_or_404(
                queryset, project=instance.id, user=self.context.get("request").user.id
            )
            for key, val in role_abstractor.items():
                role_abstractor[key] = users_role["role_id__name"] == val
        return role_abstractor

    class Meta:
        model = Project
        fields = ('id', 'name', 'description', 'guideline', 'users', 'current_users_role', 'project_type', 'image',
                  'updated_at', 'randomize_document_order', 'collaborative_annotation')
        read_only_fields = ('image', 'updated_at', 'current_users_role')


class TextClassificationProjectSerializer(ProjectSerializer):

    class Meta:
        model = TextClassificationProject
        fields = ('id', 'name', 'description', 'guideline', 'users', 'current_users_role', 'project_type', 'image',
                  'updated_at', 'randomize_document_order')
        read_only_fields = ('image', 'updated_at', 'users', 'current_users_role')


class SequenceLabelingProjectSerializer(ProjectSerializer):


    class Meta:
        model = SequenceLabelingProject
        fields = ('id', 'name', 'description', 'guideline', 'users', 'current_users_role', 'project_type', 'image',
                  'updated_at', 'randomize_document_order')
        read_only_fields = ('image', 'updated_at', 'users', 'current_users_role')


class Seq2seqProjectSerializer(ProjectSerializer):

    class Meta:
        model = Seq2seqProject
        fields = ('id', 'name', 'description', 'guideline', 'users', 'current_users_role', 'project_type', 'image',
                  'updated_at', 'randomize_document_order')
        read_only_fields = ('image', 'updated_at', 'users', 'current_users_role')


class ProjectPolymorphicSerializer(PolymorphicSerializer):
    model_serializer_mapping = {
        Project: ProjectSerializer,
        TextClassificationProject: TextClassificationProjectSerializer,
        SequenceLabelingProject: SequenceLabelingProjectSerializer,
        Seq2seqProject: Seq2seqProjectSerializer
    }


class ProjectFilteredPrimaryKeyRelatedField(serializers.PrimaryKeyRelatedField):

    def get_queryset(self):
        view = self.context.get('view', None)
        request = self.context.get('request', None)
        queryset = super(ProjectFilteredPrimaryKeyRelatedField, self).get_queryset()
        if not request or not queryset or not view:
            return None
        return queryset.filter(project=view.kwargs['project_id'])


class DocumentAnnotationSerializer(serializers.ModelSerializer):
    # label = ProjectFilteredPrimaryKeyRelatedField(queryset=Label.objects.all())
    label = serializers.PrimaryKeyRelatedField(queryset=Label.objects.all())
    document = serializers.PrimaryKeyRelatedField(queryset=Document.objects.all())

    class Meta:
        model = DocumentAnnotation
        fields = ('id', 'prob', 'label', 'user', 'document')
        read_only_fields = ('user', )


class SequenceAnnotationSerializer(serializers.ModelSerializer):
    #label = ProjectFilteredPrimaryKeyRelatedField(queryset=Label.objects.all())
    label = serializers.PrimaryKeyRelatedField(queryset=Label.objects.all())
    document = serializers.PrimaryKeyRelatedField(queryset=Document.objects.all())

    class Meta:
        model = SequenceAnnotation
        fields = ('id', 'prob', 'label', 'start_offset', 'end_offset', 'user', 'document')
        read_only_fields = ('user',)


class Seq2seqAnnotationSerializer(serializers.ModelSerializer):
    document = serializers.PrimaryKeyRelatedField(queryset=Document.objects.all())

    class Meta:
        model = Seq2seqAnnotation
        fields = ('id', 'text', 'user', 'document', 'prob')
        read_only_fields = ('user',)


class RoleSerializer(serializers.ModelSerializer):
    class Meta:
        model = Role
        fields = ('id', 'name')


class RoleMappingSerializer(serializers.ModelSerializer):
    username = serializers.SerializerMethodField()
    rolename = serializers.SerializerMethodField()

    @classmethod
    def get_username(cls, instance):
        user = instance.user
        return user.username if user else None

    @classmethod
    def get_rolename(cls, instance):
        role = instance.role
        return role.name if role else None

    class Meta:
        model = RoleMapping
        fields = ('id', 'user', 'role', 'username', 'rolename')