from auto_labeling_pipeline.models import RequestModelFactory
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_framework.exceptions import ValidationError
from rest_polymorphic.serializers import PolymorphicSerializer

from .models import (DOCUMENT_CLASSIFICATION, SEQ2SEQ, SEQUENCE_LABELING,
                     SPEECH2TEXT, AutoLabelingConfig, Comment, Document,
                     DocumentAnnotation, Label, Project, Role, RoleMapping,
                     Seq2seqAnnotation, Seq2seqProject, SequenceAnnotation,
                     SequenceLabelingProject, Speech2textAnnotation,
                     Speech2textProject, Tag, TextClassificationProject)


class UserSerializer(serializers.ModelSerializer):

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


class LabelSerializer(serializers.ModelSerializer):

    def validate(self, attrs):
        prefix_key = attrs.get('prefix_key')
        suffix_key = attrs.get('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']
            label_id = context['kwargs'].get('label_id')
        except (AttributeError, KeyError):
            pass  # unit tests don't always have the correct context set up
        else:
            conflicting_labels = Label.objects.filter(
                suffix_key=suffix_key,
                prefix_key=prefix_key,
                project=project_id,
            )

            if label_id is not None:
                conflicting_labels = conflicting_labels.exclude(id=label_id)

            if conflicting_labels.exists():
                raise ValidationError('Duplicate shortcut key.')

        return super().validate(attrs)

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


class CommentSerializer(serializers.ModelSerializer):

    class Meta:
        model = Comment
        fields = ('id', 'user', 'username', 'document', 'document_text', 'text', 'created_at', )
        read_only_fields = ('user', 'document')


class TagSerializer(serializers.ModelSerializer):

    class Meta:
        model = Tag
        fields = ('id', 'project', 'text', )
        read_only_fields = ('id', 'project')


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 = get_annotation_serializer(task=project.project_type)
        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', 'comment_count')


class ApproverSerializer(DocumentSerializer):

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


class ProjectSerializer(serializers.ModelSerializer):
    current_users_role = serializers.SerializerMethodField()
    tags = TagSerializer(many=True, required=False)

    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',
                  'updated_at', 'randomize_document_order', 'collaborative_annotation', 'single_class_classification',
                  'tags')
        read_only_fields = ('updated_at', 'users', 'current_users_role', 'tags')


class TextClassificationProjectSerializer(ProjectSerializer):

    class Meta:
        model = TextClassificationProject
        fields = ProjectSerializer.Meta.fields
        read_only_fields = ProjectSerializer.Meta.read_only_fields


class SequenceLabelingProjectSerializer(ProjectSerializer):

    class Meta:
        model = SequenceLabelingProject
        fields = ProjectSerializer.Meta.fields
        read_only_fields = ProjectSerializer.Meta.read_only_fields


class Seq2seqProjectSerializer(ProjectSerializer):

    class Meta:
        model = Seq2seqProject
        fields = ProjectSerializer.Meta.fields
        read_only_fields = ProjectSerializer.Meta.read_only_fields


class Speech2textProjectSerializer(ProjectSerializer):

    class Meta:
        model = Speech2textProject
        fields = ('id', 'name', 'description', 'guideline', 'users', 'current_users_role', 'project_type',
                  'updated_at', 'randomize_document_order')
        read_only_fields = ('updated_at', 'users', 'current_users_role')


class ProjectPolymorphicSerializer(PolymorphicSerializer):
    model_serializer_mapping = {
        Project: ProjectSerializer,
        TextClassificationProject: TextClassificationProjectSerializer,
        SequenceLabelingProject: SequenceLabelingProjectSerializer,
        Seq2seqProject: Seq2seqProjectSerializer,
        Speech2textProject: Speech2textProjectSerializer,
    }


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 = serializers.PrimaryKeyRelatedField(queryset=Label.objects.all())
    document = serializers.PrimaryKeyRelatedField(queryset=Document.objects.all())

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


class SequenceAnnotationSerializer(serializers.ModelSerializer):
    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', 'created_at', 'updated_at')
        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', 'created_at', 'updated_at')
        read_only_fields = ('user',)


class Speech2textAnnotationSerializer(serializers.ModelSerializer):
    document = serializers.PrimaryKeyRelatedField(queryset=Document.objects.all())

    class Meta:
        model = Speech2textAnnotation
        fields = ('id', 'prob', 'text', 'user', 'document', 'created_at', 'updated_at')
        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')


class AutoLabelingConfigSerializer(serializers.ModelSerializer):

    class Meta:
        model = AutoLabelingConfig
        fields = ('id', 'model_name', 'model_attrs', 'template', 'label_mapping', 'default')
        read_only_fields = ('created_at', 'updated_at')

    def validate_model_name(self, value):
        try:
            RequestModelFactory.find(value)
        except NameError:
            raise serializers.ValidationError(f'The specified model name {value} does not exist.')
        return value

    def valid_label_mapping(self, value):
        if isinstance(value, dict):
            return value
        else:
            raise serializers.ValidationError(f'The {value} is not a dictionary. Please specify it as a dictionary.')

    def validate(self, data):
        try:
            RequestModelFactory.create(data['model_name'], data['model_attrs'])
        except Exception:
            model = RequestModelFactory.find(data['model_name'])
            schema = model.schema()
            required_fields = ', '.join(schema['required']) if 'required' in schema else ''
            raise serializers.ValidationError(
                'The attributes does not match the model.'
                'You need to correctly specify the required fields: {}'.format(required_fields)
            )
        return data


def get_annotation_serializer(task: str):
    mapping = {
        DOCUMENT_CLASSIFICATION: DocumentAnnotationSerializer,
        SEQUENCE_LABELING: SequenceAnnotationSerializer,
        SEQ2SEQ: Seq2seqAnnotationSerializer,
        SPEECH2TEXT: Speech2textAnnotationSerializer
    }
    try:
        return mapping[task]
    except KeyError:
        raise ValueError(f'{task} is not implemented.')