# backend/modules/task_management/serializers.py

from rest_framework import serializers
from .models import Task, TaskTemplate, TaskTemplateEntry, TaskWorkEntry, TaskWorkHoursTable


WORK_HOURS_ROW_FIELDS = [
    'day',
    'date',
    'work_time_from',
    'work_time_to',
    'travel_time_from',
    'travel_time_to',
    'break_hours',
    'work_hours',
    'travel_hours',
    'departure_place',
    'arrival_place',
    'vehicle_km',
]


class TaskWorkHoursTableSerializer(serializers.ModelSerializer):
    class Meta:
        model = TaskWorkHoursTable
        fields = ['id', 'task', 'data', 'created_at', 'updated_at']
        read_only_fields = ['id', 'created_at', 'updated_at']

    def _normalize_row(self, row):
        normalized = {}
        for field in WORK_HOURS_ROW_FIELDS:
            value = row.get(field, '')
            normalized[field] = '' if value is None else str(value).strip()
        return normalized

    def validate_data(self, value):
        if value is None:
            return None
        if not isinstance(value, dict):
            raise serializers.ValidationError("Podaci tablice moraju biti JSON objekt ili null.")

        rows = value.get('rows', [])
        if not isinstance(rows, list):
            raise serializers.ValidationError({"rows": "Polje 'rows' mora biti lista redaka."})

        normalized_rows = []
        for row in rows[:30]:
            if not isinstance(row, dict):
                raise serializers.ValidationError({"rows": "Svaki redak mora biti JSON objekt."})
            normalized_rows.append(self._normalize_row(row))

        return {'rows': normalized_rows}


class TaskWorkEntrySerializer(serializers.ModelSerializer):
    class Meta:
        model = TaskWorkEntry
        fields = [
            'id', 'task', 'template_entry', 'sort_order', 'title',
            'work_description', 'active_faults', 'explanation_hr',
            'created_at',
        ]
        read_only_fields = ['id', 'created_at']


class TaskTemplateEntrySerializer(serializers.ModelSerializer):
    class Meta:
        model = TaskTemplateEntry
        fields = [
            'id', 'sort_order', 'title', 'work_description',
            'active_faults', 'explanation_hr',
        ]
        read_only_fields = ['id']


class TaskTemplateSerializer(serializers.ModelSerializer):
    entries = TaskTemplateEntrySerializer(many=True, read_only=True)

    class Meta:
        model = TaskTemplate
        fields = ['id', 'code', 'title', 'description', 'status', 'entries']
        read_only_fields = ['id']


class TaskSerializer(serializers.ModelSerializer):
    assigned_to_name = serializers.SerializerMethodField()
    work_order_label = serializers.SerializerMethodField()
    vehicle_registration = serializers.SerializerMethodField()
    vehicle_make = serializers.SerializerMethodField()
    vehicle_model = serializers.SerializerMethodField()
    vehicle_owner_name = serializers.SerializerMethodField()
    vehicle_asset_type = serializers.SerializerMethodField()
    crane_serial_number = serializers.SerializerMethodField()
    template_id = serializers.UUIDField(write_only=True, required=False, allow_null=True)
    auto_close_work_order = serializers.BooleanField(write_only=True, required=False)

    class Meta:
        model = Task
        fields = [
            'id', 'title', 'description', 'status',
            'assigned_to', 'assigned_to_name',
            'vehicle', 'vehicle_registration', 'vehicle_make', 'vehicle_model',
            'vehicle_owner_name', 'vehicle_asset_type', 'crane_serial_number',
            'work_order', 'work_order_label',
            'scheduled_date',
            'service_report_note',
            'template_id', 'auto_close_work_order',
            'created_at',
        ]
        read_only_fields = ['id', 'created_at']
        extra_kwargs = {
            'title': {'required': False, 'allow_blank': True},
            'description': {'required': False, 'allow_blank': True},
            'status': {'required': False},
            'work_order': {'required': False, 'allow_null': True},
            'vehicle': {'required': False, 'allow_null': True},
            'scheduled_date': {'required': False, 'allow_null': True},
            'service_report_note': {'required': False, 'allow_blank': True},
        }

    def validate_title(self, value):
        if not value:
            return value
        if len(value) < 3:
            raise serializers.ValidationError("Naslov zadatka mora imati barem 3 znaka.")
        return value

    def validate(self, attrs):
        current = getattr(self, 'instance', None)
        template_id = attrs.get('template_id')
        status_value = attrs.get('status', getattr(current, 'status', 'aktivan'))
        work_order = attrs.get('work_order', getattr(current, 'work_order', None))
        vehicle = attrs.get('vehicle', getattr(current, 'vehicle', None))
        title = (attrs.get('title', getattr(current, 'title', '')) or '').strip()

        if template_id:
            template = TaskTemplate.objects.filter(id=template_id, is_active=True).first()
            if not template:
                raise serializers.ValidationError({'template_id': 'Odabrani template ne postoji ili nije aktivan.'})

        if current is None and not vehicle:
            raise serializers.ValidationError({
                'vehicle': "Dizalica je obavezna pri kreiranju taska."
            })

        if current is None and not template_id and not title:
            raise serializers.ValidationError({
                'title': "Naslov zadatka je obavezan ako se task ne kreira iz templatea."
            })

        # If task has no crane yet, auto-derive it from the work order's crane (backward compat).
        # Cross-crane assignment is intentionally allowed: a servicer can share one work order
        # across tasks for multiple cranes on the same day.
        if work_order and not vehicle:
            vehicle = work_order.vehicle
            attrs['vehicle'] = vehicle

        if status_value in {'neaktivan', 'zavrsen'} and not work_order:
            raise serializers.ValidationError({
                'work_order': "Putni nalog je obavezan prije zatvaranja zadatka."
            })
        return attrs

    def get_work_order_label(self, obj):
        if not obj.work_order_id:
            return None
        display_code = str(getattr(obj.work_order, 'display_code', '') or '').strip().upper()
        if display_code:
            return display_code
        return None

    def get_assigned_to_name(self, obj):
        if not obj.assigned_to_id:
            return None
        full_name = obj.assigned_to.get_full_name()
        if full_name:
            return full_name
        email = getattr(obj.assigned_to, 'email', None)
        if email:
            return email
        username = getattr(obj.assigned_to, 'username', None)
        if username:
            return username
        return str(obj.assigned_to_id)

    def get_vehicle_registration(self, obj):
        if not obj.vehicle_id:
            return None
        return obj.vehicle.registration_number

    def get_vehicle_make(self, obj):
        if not obj.vehicle_id:
            return None
        return obj.vehicle.make or None

    def get_vehicle_model(self, obj):
        if not obj.vehicle_id:
            return None
        return obj.vehicle.model or None

    def get_vehicle_owner_name(self, obj):
        if not obj.vehicle_id or not obj.vehicle.client_id:
            return None
        return obj.vehicle.client.name

    def get_vehicle_asset_type(self, obj):
        if not obj.vehicle_id:
            return None
        return obj.vehicle.asset_type

    def get_crane_serial_number(self, obj):
        if not obj.vehicle_id:
            return None
        return obj.vehicle.crane_serial_number or None