from django.contrib.auth import get_user_model
from rest_framework import serializers
from drf_spectacular.utils import extend_schema_field

from apps.projects.models.project import (
    Project,
    KanbanColumn,
    KanbanTask,
    ProjectDocument,
)
from apps.profiles.models.institution import Institution

User = get_user_model()


class ProjectUserMiniSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ['id', 'email', 'fullname', 'avatar']
        read_only_fields = fields


class ProjectInstitutionMiniSerializer(serializers.ModelSerializer):
    type_display = serializers.CharField(source='get_type_display', read_only=True)

    class Meta:
        model = Institution
        fields = ['id', 'name', 'slug', 'type', 'type_display', 'avatar', 'city', 'country']
        read_only_fields = fields


class KanbanTaskSerializer(serializers.ModelSerializer):
    priority_display = serializers.CharField(source='get_priority_display', read_only=True)
    column_name = serializers.CharField(source='column.name', read_only=True)
    column_code = serializers.CharField(source='column.code', read_only=True)
    assignee = ProjectUserMiniSerializer(read_only=True)

    class Meta:
        model = KanbanTask
        fields = [
            'id',
            'project',
            'column',
            'column_name',
            'column_code',
            'title',
            'description',
            'priority',
            'priority_display',
            'assignee',
            'due_date',
            'labels',
            'order',
            'created_at',
            'updated_at',
        ]
        read_only_fields = ['id', 'project', 'priority_display', 'column_name', 'column_code', 'created_at', 'updated_at']


class KanbanTaskCreateUpdateSerializer(serializers.ModelSerializer):
    class Meta:
        model = KanbanTask
        fields = [
            'column',
            'title',
            'description',
            'priority',
            'assignee',
            'due_date',
            'labels',
            'order',
        ]

    def validate(self, attrs):
        project = self.context.get('project')
        column = attrs.get('column')
        if project and column and column.project != project:
            raise serializers.ValidationError({"column": "Selected column does not belong to this project."})
        return attrs


class KanbanColumnSerializer(serializers.ModelSerializer):
    tasks = serializers.SerializerMethodField()

    class Meta:
        model = KanbanColumn
        fields = [
            'id',
            'project',
            'name',
            'code',
            'order',
            'color',
            'tasks',
        ]
        read_only_fields = ['id', 'project']

    @extend_schema_field(KanbanTaskSerializer(many=True))
    def get_tasks(self, obj):
        tasks = obj.tasks.all().select_related('assignee').order_by('order', 'id')
        return KanbanTaskSerializer(tasks, many=True).data


class ProjectDocumentSerializer(serializers.ModelSerializer):
    doc_type_display = serializers.CharField(source='get_doc_type_display', read_only=True)
    uploaded_by_email = serializers.EmailField(source='uploaded_by.email', read_only=True, allow_null=True)

    class Meta:
        model = ProjectDocument
        fields = [
            'id',
            'project',
            'title',
            'file',
            'doc_type',
            'doc_type_display',
            'uploaded_by_email',
            'uploaded_at',
        ]
        read_only_fields = ['id', 'project', 'doc_type_display', 'uploaded_by_email', 'uploaded_at']

    def create(self, validated_data):
        request = self.context.get('request')
        if request and request.user.is_authenticated:
            validated_data['uploaded_by'] = request.user
        return super().create(validated_data)


class ProjectListSerializer(serializers.ModelSerializer):
    status_display = serializers.CharField(source='get_status_display', read_only=True)
    owner_institution = ProjectInstitutionMiniSerializer(read_only=True)
    collaborating_institutions_count = serializers.SerializerMethodField()
    tasks_count = serializers.SerializerMethodField()
    completed_tasks_count = serializers.SerializerMethodField()

    class Meta:
        model = Project
        fields = [
            'id',
            'title',
            'slug',
            'owner_institution',
            'collaborating_institutions_count',
            'category',
            'status',
            'status_display',
            'progress_percentage',
            'budget',
            'team_size',
            'cover_image',
            'start_date',
            'estimated_end_date',
            'tasks_count',
            'completed_tasks_count',
            'created_at',
        ]
        read_only_fields = fields

    @extend_schema_field(serializers.IntegerField)
    def get_collaborating_institutions_count(self, obj) -> int:
        return obj.collaborating_institutions.count()

    @extend_schema_field(serializers.IntegerField)
    def get_tasks_count(self, obj) -> int:
        return obj.tasks.count()

    @extend_schema_field(serializers.IntegerField)
    def get_completed_tasks_count(self, obj) -> int:
        return obj.tasks.filter(column__code='done').count()


class ProjectDetailSerializer(serializers.ModelSerializer):
    status_display = serializers.CharField(source='get_status_display', read_only=True)
    owner_institution = ProjectInstitutionMiniSerializer(read_only=True)
    collaborating_institutions = ProjectInstitutionMiniSerializer(many=True, read_only=True)
    columns = KanbanColumnSerializer(many=True, read_only=True)
    documents = ProjectDocumentSerializer(many=True, read_only=True)
    can_edit = serializers.SerializerMethodField()
    created_by_email = serializers.EmailField(source='created_by.email', read_only=True, allow_null=True)

    class Meta:
        model = Project
        fields = [
            'id',
            'title',
            'slug',
            'description',
            'owner_institution',
            'collaborating_institutions',
            'category',
            'status',
            'status_display',
            'progress_percentage',
            'budget',
            'team_size',
            'cover_image',
            'start_date',
            'estimated_end_date',
            'actual_end_date',
            'columns',
            'documents',
            'can_edit',
            'created_by_email',
            'created_at',
            'updated_at',
        ]
        read_only_fields = [
            'id',
            'slug',
            'columns',
            'documents',
            'can_edit',
            'created_by_email',
            'created_at',
            'updated_at',
        ]

    @extend_schema_field(serializers.BooleanField)
    def get_can_edit(self, obj) -> bool:
        request = self.context.get('request')
        if not request or not request.user.is_authenticated:
            return False
        return obj.can_user_edit(request.user)


class ProjectCreateUpdateSerializer(serializers.ModelSerializer):
    class Meta:
        model = Project
        fields = [
            'title',
            'description',
            'owner_institution',
            'collaborating_institutions',
            'category',
            'status',
            'progress_percentage',
            'budget',
            'team_size',
            'cover_image',
            'start_date',
            'estimated_end_date',
            'actual_end_date',
        ]

    def create(self, validated_data):
        request = self.context.get('request')
        collaborating = validated_data.pop('collaborating_institutions', [])
        if request and request.user.is_authenticated:
            validated_data['created_by'] = request.user

        project = super().create(validated_data)
        if collaborating:
            project.collaborating_institutions.set(collaborating)
        return project