from rest_framework import serializers
from django.contrib.auth import get_user_model
from .models import Skill, Event, TaskArea, Shift, ShiftSignup, EventTemplate
from apps.users.serializers import UserSerializer

User = get_user_model()

class SkillSerializer(serializers.ModelSerializer):
    class Meta:
        model = Skill
        fields = ['id', 'name', 'description', 'color', 'created_at']

class ShiftSignupSerializer(serializers.ModelSerializer):
    display_name = serializers.SerializerMethodField()
    is_guest = serializers.SerializerMethodField()
    is_self = serializers.SerializerMethodField()

    class Meta:
        model = ShiftSignup
        fields = ['id', 'display_name', 'is_guest', 'is_self', 'created_at']

    def get_is_guest(self, obj):
        return obj.user is None

    def _is_own_signup(self, obj, request):
        if not request:
            return False
        if request.user and request.user.is_authenticated:
            return obj.user_id == request.user.id
        
        # Check session key for guest user
        session_key = getattr(request.session, 'session_key', None)
        if session_key and obj.guest_session_key and obj.guest_session_key == session_key:
            return True
            
        return False

    def get_is_self(self, obj):
        request = self.context.get('request')
        return self._is_own_signup(obj, request)

    def get_display_name(self, obj):
        request = self.context.get('request')
        
        # Authenticated users see real names of all participants
        if request and request.user and request.user.is_authenticated:
            if obj.user:
                return obj.user.get_display_name()
            return obj.guest_name or "Gast"

        # Guest users see their own real name for their own signups
        if request and self._is_own_signup(obj, request):
            return obj.guest_name or "Gast"

        # Other participants are anonymized for privacy
        return "Belegt (Anonym)"

class ShiftSerializer(serializers.ModelSerializer):
    required_skills = SkillSerializer(many=True, read_only=True)
    required_skill_ids = serializers.PrimaryKeyRelatedField(
        queryset=Skill.objects.all(), many=True, write_only=True, required=False, source='required_skills'
    )
    signups = serializers.SerializerMethodField()
    signups_count = serializers.SerializerMethodField()
    is_full = serializers.SerializerMethodField()

    class Meta:
        model = Shift
        fields = [
            'id', 'task_area', 'title', 'date', 'start_time', 'end_time',
            'max_participants', 'required_skills', 'required_skill_ids',
            'signups', 'signups_count', 'is_full'
        ]

    def get_signups(self, obj):
        signups_qs = obj.signups.all()
        serializer = ShiftSignupSerializer(signups_qs, many=True, context=self.context)
        return serializer.data

    def get_signups_count(self, obj):
        return obj.signups.count()

    def get_is_full(self, obj):
        return obj.signups.count() >= obj.max_participants

class TaskAreaSerializer(serializers.ModelSerializer):
    shifts = ShiftSerializer(many=True, read_only=True)

    class Meta:
        model = TaskArea
        fields = ['id', 'event', 'name', 'description', 'order', 'shifts']

class EventSerializer(serializers.ModelSerializer):
    task_areas = TaskAreaSerializer(many=True, read_only=True)
    created_by_name = serializers.SerializerMethodField()
    co_managers = UserSerializer(many=True, read_only=True)
    co_manager_ids = serializers.PrimaryKeyRelatedField(
        queryset=User.objects.all(), many=True, write_only=True, required=False, source='co_managers'
    )

    class Meta:
        model = Event
        fields = [
            'id', 'title', 'description', 'location',
            'start_date', 'end_date', 'is_active', 'created_by', 'created_by_name',
            'co_managers', 'co_manager_ids',
            'task_areas', 'created_at', 'updated_at'
        ]
        read_only_fields = ['created_by', 'created_at', 'updated_at']

    def get_created_by_name(self, obj):
        return obj.created_by.get_display_name() if obj.created_by else "Unbekannt"

class EventTemplateSerializer(serializers.ModelSerializer):
    created_by_name = serializers.SerializerMethodField()

    class Meta:
        model = EventTemplate
        fields = ['id', 'name', 'description', 'template_data', 'created_by', 'created_by_name', 'created_at']
        read_only_fields = ['created_by', 'created_at']

    def get_created_by_name(self, obj):
        return obj.created_by.get_display_name() if obj.created_by else "System"