"""
Notification Serializers
"""

from rest_framework import serializers

from .models import Notification


class NotificationSerializer(serializers.ModelSerializer):
    """Serializer for Notification model"""
    
    site_name = serializers.CharField(source='site.name', read_only=True, default=None)
    
    class Meta:
        model = Notification
        fields = [
            'id',
            'notification_type',
            'title',
            'message',
            'severity',
            'site',
            'site_name',
            'action_url',
            'action_label',
            'is_read',
            'read_at',
            'metadata',
            'created_at',
        ]
        read_only_fields = ['id', 'created_at', 'read_at']


class NotificationListSerializer(serializers.ModelSerializer):
    """Lightweight serializer for notification lists"""
    
    site_name = serializers.CharField(source='site.name', read_only=True, default=None)
    time_ago = serializers.SerializerMethodField()
    
    class Meta:
        model = Notification
        fields = [
            'id',
            'notification_type',
            'title',
            'message',
            'severity',
            'site_name',
            'action_url',
            'action_label',
            'is_read',
            'created_at',
            'time_ago',
            'metadata',
        ]
    
    def get_time_ago(self, obj):
        """Return human-readable time since notification"""
        from django.utils import timezone
        from datetime import timedelta
        
        now = timezone.now()
        diff = now - obj.created_at
        
        if diff < timedelta(minutes=1):
            return 'Just now'
        elif diff < timedelta(hours=1):
            minutes = int(diff.total_seconds() / 60)
            return f'{minutes} minute{"s" if minutes != 1 else ""} ago'
        elif diff < timedelta(days=1):
            hours = int(diff.total_seconds() / 3600)
            return f'{hours} hour{"s" if hours != 1 else ""} ago'
        elif diff < timedelta(days=7):
            days = diff.days
            if days == 1:
                return 'Yesterday'
            return f'{days} days ago'
        else:
            return obj.created_at.strftime('%b %d, %Y')


class MarkReadSerializer(serializers.Serializer):
    """Serializer for marking notifications as read"""
    
    notification_ids = serializers.ListField(
        child=serializers.IntegerField(),
        required=False,
        help_text='List of notification IDs to mark as read. If empty, marks all as read.'
    )