from rest_framework import serializers
import re
from django.urls import reverse
from .models import (
    Crane,
    Vehicle,
    VehicleNotification,
    WorkOrder,
    WorkOrderPhoto,
    WorkOrderInvoice,
    VehicleServiceRecord,
    VehicleServicePhoto,
    VehicleServiceAttachment,
)
from . import services


class VehicleSerializer(serializers.ModelSerializer):
    # Čitljivo ime klijenta — read-only, za prikaz u frontendu i adminu
    client_name = serializers.SerializerMethodField()

    class Meta:
        model = Vehicle
        fields = [
            'id', 'asset_type', 'registration_number', 'make', 'model', 'year', 'vin',
            'crane_serial_number',
            'superstructure_working_hours', 'chassis_working_hours',
            'current_mileage', 'service_interval_km',
            'is_company_vehicle', 'client', 'client_name',
            'assigned_servicer', 'is_active',
        ]
        read_only_fields = ['id', 'current_mileage', 'client_name']

    def get_client_name(self, obj):
        if obj.client_id:
            return obj.client.name
        return None

    def create(self, validated_data):
        validated_data.setdefault('asset_type', 'vehicle')
        return services.VehicleService.create_vehicle(validated_data)

    def update(self, instance, validated_data):
        validated_data.pop('asset_type', None)
        return services.VehicleService.update_vehicle(instance, validated_data)

    def validate_crane_serial_number(self, value):
        if value in (None, ''):
            return None
        normalized = str(value).strip()
        if not re.fullmatch(r"[0-9]{6}", normalized):
            raise serializers.ValidationError('Serijski broj dizalice mora sadržavati točno 6 znamenki.')
        return normalized

    def validate(self, attrs):
        asset_type = attrs.get('asset_type', getattr(self.instance, 'asset_type', None))
        if asset_type is None and getattr(self.Meta, 'model', None) is Crane:
            asset_type = 'crane'
        serial = attrs.get('crane_serial_number', getattr(self.instance, 'crane_serial_number', None))
        is_create = self.instance is None
        if asset_type == 'crane' and not serial and is_create:
            raise serializers.ValidationError({
                'crane_serial_number': 'Serijski broj dizalice je obavezan za dizalice.'
            })
        return attrs

class CraneSerializer(VehicleSerializer):
    display_name = serializers.SerializerMethodField()

    class Meta(VehicleSerializer.Meta):
        model = Crane
        fields = VehicleSerializer.Meta.fields + ['display_name']
        read_only_fields = VehicleSerializer.Meta.read_only_fields + ['display_name']

    def get_display_name(self, obj):
        details = " ".join(part for part in [obj.make, obj.model] if part)
        return f"{obj.registration_number} {details}".strip()

    def create(self, validated_data):
        validated_data['asset_type'] = 'crane'
        return services.VehicleService.create_vehicle(validated_data)

    def update(self, instance, validated_data):
        validated_data.pop('asset_type', None)
        return services.VehicleService.update_vehicle(instance, validated_data)

class VehicleNotificationSerializer(serializers.ModelSerializer):
    class Meta:
        model = VehicleNotification
        fields = ['id', 'title', 'message', 'metadata', 'level', 'is_sent', 'is_read', 'created_at']
        read_only_fields = ['id', 'title', 'message', 'metadata', 'level', 'is_sent', 'created_at']
        # is_read is writable via the "mark_read" action, but normally read-only in list

class WorkOrderSerializer(serializers.ModelSerializer):
    crane = serializers.SerializerMethodField()
    crane_label = serializers.SerializerMethodField()

    class Meta:
        model = WorkOrder
        fields = [
            'id', 'vehicle', 'crane', 'crane_label', 'creator', 'date',
            'start_mileage', 'end_mileage',
            'servicer_vehicle_registration', 'servicer_vehicle_make_model',
            'servicer_vehicle_start_mileage', 'servicer_vehicle_end_mileage',
            'servicer_vehicle_fuel_cost',
            'location', 'travel_start_at', 'travel_end_at',
            'purpose', 'notes', 'status'
        ]
        read_only_fields = ['id', 'date']
        extra_kwargs = {
            'vehicle': {'required': False},
            'creator': {'required': False},
            'start_mileage': {'required': False, 'allow_null': True},
            'end_mileage': {'required': False, 'allow_null': True},
            'servicer_vehicle_registration': {'required': False, 'allow_blank': True},
            'servicer_vehicle_make_model': {'required': False, 'allow_blank': True},
            'servicer_vehicle_start_mileage': {'required': False, 'allow_null': True},
            'servicer_vehicle_end_mileage': {'required': False, 'allow_null': True},
            'servicer_vehicle_fuel_cost': {'required': False, 'allow_null': True},
            'location': {'required': False, 'allow_blank': True},
            'travel_start_at': {'required': False, 'allow_null': True},
            'travel_end_at': {'required': False, 'allow_null': True},
        }

    def get_crane(self, obj):
        return obj.vehicle_id

    def get_crane_label(self, obj):
        if not obj.vehicle_id:
            return None
        details = " ".join(part for part in [obj.vehicle.registration_number, obj.vehicle.make, obj.vehicle.model] if part)
        return details.strip()

    def create(self, validated_data):
        request = self.context.get('request')
        user = getattr(request, 'user', None)

        if not validated_data.get('vehicle'):
            raise serializers.ValidationError({
                'vehicle': 'Odaberite dizalicu za putni nalog iz servisnog konteksta.'
            })
        if getattr(validated_data['vehicle'], 'asset_type', None) != 'crane':
            raise serializers.ValidationError({
                'vehicle': 'Za putni nalog morate odabrati dizalicu (asset_type=crane).'
            })

        if user and 'creator' not in validated_data:
            validated_data['creator'] = user

        return services.VehicleService.create_work_order(validated_data)

    def update(self, instance, validated_data):
        return services.VehicleService.update_work_order(instance, validated_data)

    def validate(self, attrs):
        current = getattr(self, 'instance', None)
        travel_start_at = attrs.get('travel_start_at', getattr(current, 'travel_start_at', None))
        travel_end_at = attrs.get('travel_end_at', getattr(current, 'travel_end_at', None))
        location = attrs.get('location', getattr(current, 'location', None))

        start_mileage = attrs.get('start_mileage', getattr(current, 'start_mileage', None))
        end_mileage = attrs.get('end_mileage', getattr(current, 'end_mileage', None))
        servicer_start_mileage = attrs.get('servicer_vehicle_start_mileage', getattr(current, 'servicer_vehicle_start_mileage', None))
        servicer_end_mileage = attrs.get('servicer_vehicle_end_mileage', getattr(current, 'servicer_vehicle_end_mileage', None))
        servicer_fuel_cost = attrs.get('servicer_vehicle_fuel_cost', getattr(current, 'servicer_vehicle_fuel_cost', None))

        if (travel_start_at is None) ^ (travel_end_at is None):
            raise serializers.ValidationError({'travel_end_at': 'Unesite i početak i kraj puta, ili ostavite oba prazna.'})
        if travel_start_at is not None and not str(location or '').strip():
            raise serializers.ValidationError({'location': 'Lokacija je obavezna kada je definiran putni nalog.'})
        if travel_start_at and travel_end_at and travel_end_at < travel_start_at:
            raise serializers.ValidationError({'travel_end_at': 'Kraj puta ne može biti prije početka puta.'})
        if end_mileage is not None and start_mileage is None:
            raise serializers.ValidationError({'start_mileage': 'Početna kilometraža je obavezna ako je upisana završna.'})
        if start_mileage is not None and end_mileage is not None and end_mileage < start_mileage:
            raise serializers.ValidationError({'end_mileage': 'Završna kilometraža mora biti veća ili jednaka početnoj.'})
        if servicer_end_mileage is not None and servicer_start_mileage is None:
            raise serializers.ValidationError({'servicer_vehicle_start_mileage': 'Početna kilometraža vozila servisera je obavezna ako je upisana završna.'})
        if servicer_start_mileage is not None and servicer_end_mileage is not None and servicer_end_mileage <= servicer_start_mileage:
            raise serializers.ValidationError({'servicer_vehicle_end_mileage': 'Završna kilometraža vozila servisera mora biti veća od početne.'})
        if servicer_fuel_cost is not None and servicer_fuel_cost < 0:
            raise serializers.ValidationError({'servicer_vehicle_fuel_cost': 'Trošak goriva ne može biti negativan.'})
        return attrs


class WorkOrderInvoiceSerializer(serializers.ModelSerializer):
    image_url = serializers.SerializerMethodField()

    class Meta:
        model = WorkOrderInvoice
        fields = [
            'id',
            'work_order',
            'naziv_racuna',
            'lokacija',
            'datum',
            'opis',
            'image',
            'image_url',
            'created_by',
            'created_at',
        ]
        read_only_fields = ['id', 'created_by', 'created_at']

    def get_image_url(self, obj):
        request = self.context.get('request')
        if not obj.image:
            return None
        if request is None:
            return None
        return request.build_absolute_uri(
            reverse('work-order-invoice-image', kwargs={'pk': obj.pk})
        )


class WorkOrderPhotoSerializer(serializers.ModelSerializer):
    class Meta:
        model = WorkOrderPhoto
        fields = ['id', 'work_order', 'image', 'description', 'uploaded_by', 'created_at']
        read_only_fields = ['id', 'uploaded_by', 'created_at']
        extra_kwargs = {
            'work_order': {'required': False},
        }


class VehicleServiceRecordSerializer(serializers.ModelSerializer):
    crane = serializers.SerializerMethodField()
    crane_registration = serializers.SerializerMethodField()
    photos_count = serializers.SerializerMethodField()
    attachments_count = serializers.SerializerMethodField()
    files_count = serializers.SerializerMethodField()
    performed_by_name = serializers.SerializerMethodField()
    vehicle_registration = serializers.SerializerMethodField()
    task_label = serializers.SerializerMethodField()
    crane_serial_number = serializers.SerializerMethodField()

    class Meta:
        model = VehicleServiceRecord
        fields = [
            'id', 'vehicle', 'crane', 'vehicle_registration', 'crane_registration',
            'task', 'task_label', 'crane_serial_number',
            'performed_by', 'performed_by_name',
            'service_title', 'description', 'parts', 'cost',
            'service_date', 'mileage', 'next_service_due_at',
            'photos_count', 'attachments_count', 'files_count',
        ]
        read_only_fields = [
            'id', 'service_date', 'next_service_due_at',
            'photos_count', 'attachments_count', 'files_count',
            'performed_by_name', 'vehicle_registration', 'crane', 'crane_registration',
            'task_label',
        ]
        extra_kwargs = {
            'performed_by': {'required': False},
            'vehicle': {'required': False},
            'mileage': {'required': False, 'allow_null': True},
        }

    def get_photos_count(self, obj):
        # prefetch_related('photos') u viewsetu sprječava N+1
        return obj.photos.count()

    def get_crane(self, obj):
        return obj.vehicle_id

    def get_attachments_count(self, obj):
        return obj.attachments.count()

    def get_files_count(self, obj):
        return self.get_photos_count(obj) + self.get_attachments_count(obj)

    def get_performed_by_name(self, obj):
        if obj.performed_by_id:
            return obj.performed_by.get_full_name() or obj.performed_by.username
        return None

    def get_vehicle_registration(self, obj):
        if obj.vehicle_id:
            return obj.vehicle.registration_number
        return None

    def get_crane_registration(self, obj):
        return self.get_vehicle_registration(obj)

    def get_task_label(self, obj):
        if not obj.task_id:
            return None
        return obj.task.title

    def get_crane_serial_number(self, obj):
        # Provjeri je li povezano vozilo/dizalica postoji i vrati serijski broj
        if hasattr(obj, 'vehicle') and obj.vehicle:
            return getattr(obj.vehicle, 'crane_serial_number', None)
        return None

    def create(self, validated_data):
        request = self.context.get('request')
        user = getattr(request, 'user', None)
        task = validated_data.get('task')
        if not task:
            raise serializers.ValidationError({
                'task': 'Odaberite radni zadatak prije kreiranja servisnog zapisa.'
            })
        if not task.vehicle_id:
            raise serializers.ValidationError({
                'task': 'Odabrani radni zadatak nema dodijeljenu dizalicu.'
            })
        validated_data['vehicle'] = task.vehicle

        if user and not getattr(user, 'is_staff', False):
            validated_data['performed_by'] = user
        elif user and 'performed_by' not in validated_data:
            validated_data['performed_by'] = user
        return services.VehicleService.create_service_record(validated_data)

class VehicleServicePhotoSerializer(serializers.ModelSerializer):
    image = serializers.ImageField(required=True)

    class Meta:
        model = VehicleServicePhoto
        fields = ['id', 'service_record', 'image', 'description', 'uploaded_by', 'created_at']
        read_only_fields = ['id', 'created_at', 'uploaded_by']

    def create(self, validated_data):
        # Ako postoji request user, postavi uploaded_by
        request = self.context.get('request') if self.context else None
        user = getattr(request, 'user', None)
        if user and 'uploaded_by' not in validated_data:
            validated_data['uploaded_by'] = user
        # Kreiranje direktno kroz model je ok; može se delegirati u services ako želiš dodatnu logiku
        return VehicleServicePhoto.objects.create(**validated_data)

class VehicleServiceAttachmentSerializer(serializers.ModelSerializer):
    file = serializers.FileField(required=True)

    class Meta:
        model = VehicleServiceAttachment
        fields = ['id', 'service_record', 'file', 'description', 'uploaded_by', 'created_at']
        read_only_fields = ['id', 'created_at', 'uploaded_by']

    def create(self, validated_data):
        request = self.context.get('request') if self.context else None
        user = getattr(request, 'user', None)
        if user and 'uploaded_by' not in validated_data:
            validated_data['uploaded_by'] = user
        return VehicleServiceAttachment.objects.create(**validated_data)