Widgets and Data Transformation

class Widget:
    def clean(self, value, row=None, **kwargs):
        """
        Transform imported value into appropriate Python object.
        
        Parameters:
        - value: Raw value from import data
        - row: dict, complete row data (optional)
        - **kwargs: Additional cleaning options
        
        Returns:
        Cleaned Python value
        """

    def render(self, value, obj=None, **kwargs):
        """
        Transform Python value into export representation.
        
        Parameters:
        - value: Python value to export
        - obj: Model instance being exported (optional)
        - **kwargs: Additional rendering options
        
        Returns:
        Serialized value for export
        """

class NumberWidget(Widget):
    """Base widget for numeric data with locale support."""
    
    def __init__(self, **kwargs):
        """
        Initialize numeric widget.
        
        Parameters:
        - **kwargs: Widget configuration options
        """

class FloatWidget(NumberWidget):
    """Widget for floating-point numbers."""

class IntegerWidget(NumberWidget):
    """Widget for integer numbers."""

class DecimalWidget(NumberWidget):
    """Widget for decimal numbers with precision control."""

class CharWidget(Widget):
    def __init__(self, allow_blank=False, **kwargs):
        """
        Widget for character/string data.
        
        Parameters:
        - allow_blank: bool, allow blank values (default: False)
        - **kwargs: Additional widget options
        """

class BooleanWidget(Widget):
    TRUE_VALUES = ['1', 1, True, 'true', 'TRUE', 'True', 'yes', 'YES', 'Yes', 'y', 'Y']
    FALSE_VALUES = ['0', 0, False, 'false', 'FALSE', 'False', 'no', 'NO', 'No', 'n', 'N']
    NULL_VALUES = ['', None]

    def __init__(self, **kwargs):
        """
        Widget for boolean data with customizable value mapping.
        
        Parameters:
        - **kwargs: Widget configuration options
        """

class DateWidget(Widget):
    def __init__(self, format='%Y-%m-%d', **kwargs):
        """
        Widget for date data.
        
        Parameters:
        - format: str, date format string (default: '%Y-%m-%d')
        - **kwargs: Additional widget options
        """

class DateTimeWidget(Widget):
    def __init__(self, format='%Y-%m-%d %H:%M:%S', **kwargs):
        """
        Widget for datetime data.
        
        Parameters:
        - format: str, datetime format string (default: '%Y-%m-%d %H:%M:%S')
        - **kwargs: Additional widget options
        """

class TimeWidget(Widget):
    def __init__(self, format='%H:%M:%S', **kwargs):
        """
        Widget for time data.
        
        Parameters:
        - format: str, time format string (default: '%H:%M:%S')
        - **kwargs: Additional widget options
        """

class DurationWidget(Widget):
    """Widget for duration/timedelta data."""

class JSONWidget(Widget):
    def __init__(self, **kwargs):
        """
        Widget for JSON data serialization/deserialization.
        
        Parameters:
        - **kwargs: JSON serialization options
        """

class SimpleArrayWidget(Widget):
    def __init__(self, separator=',', **kwargs):
        """
        Widget for simple array data.
        
        Parameters:
        - separator: str, separator character (default: ',')
        - **kwargs: Additional widget options
        """

class ForeignKeyWidget(Widget):
    def __init__(self, model, field='pk', use_natural_foreign_keys=False, key_is_id=False, **kwargs):
        """
        Widget for foreign key relationships.
        
        Parameters:
        - model: Related model class
        - field: str, field to use for lookup (default: 'pk')
        - use_natural_foreign_keys: bool, use natural keys for lookup
        - key_is_id: bool, whether key is the model ID
        - **kwargs: Additional widget options
        """

    def get_queryset(self, value, row, *args, **kwargs):
        """
        Get queryset for foreign key lookup.
        
        Parameters:
        - value: Lookup value
        - row: dict, complete row data
        - *args: Additional arguments
        - **kwargs: Additional keyword arguments
        
        Returns:
        QuerySet for lookup operations
        """

    def get_lookup_kwargs(self, value, row, **kwargs):
        """
        Get lookup kwargs for foreign key resolution.
        
        Parameters:
        - value: Lookup value
        - row: dict, complete row data
        - **kwargs: Additional options
        
        Returns:
        Dict of lookup kwargs
        """

class ManyToManyWidget(Widget):
    def __init__(self, model, separator=None, field=None, **kwargs):
        """
        Widget for many-to-many relationships.
        
        Parameters:
        - model: Related model class
        - separator: str, separator for multiple values
        - field: str, field to use for lookup
        - **kwargs: Additional widget options
        """

def format_datetime(value, datetime_format):
    """
    Format datetime value using specified format string.
    
    Parameters:
    - value: datetime object or string
    - datetime_format: str, format string
    
    Returns:
    Formatted datetime string
    """

from import_export import fields, widgets

class BookResource(resources.ModelResource):
    # Use date widget with custom format
    published_date = fields.Field(
        attribute='published_date',
        widget=widgets.DateWidget(format='%d/%m/%Y')
    )
    
    # Use boolean widget for active status
    is_active = fields.Field(
        attribute='is_active',
        widget=widgets.BooleanWidget()
    )
    
    # Use JSON widget for metadata
    metadata = fields.Field(
        attribute='metadata',
        widget=widgets.JSONWidget()
    )

class UpperCaseWidget(widgets.CharWidget):
    """Custom widget that converts text to uppercase."""
    
    def clean(self, value, row=None, **kwargs):
        value = super().clean(value, row, **kwargs)
        return value.upper() if value else value
    
    def render(self, value, obj=None, **kwargs):
        return value.upper() if value else value

class BookResource(resources.ModelResource):
    title = fields.Field(
        attribute='title',
        widget=UpperCaseWidget()
    )

class AuthorWidget(widgets.ForeignKeyWidget):
    """Custom foreign key widget for author lookup."""
    
    def __init__(self, **kwargs):
        super().__init__(Author, field='name', **kwargs)
    
    def get_queryset(self, value, row, *args, **kwargs):
        # Custom queryset filtering
        return Author.objects.filter(active=True)
    
    def get_lookup_kwargs(self, value, row, **kwargs):
        # Custom lookup logic
        return {'name__iexact': value.strip()}

class BookResource(resources.ModelResource):
    author = fields.Field(
        attribute='author',
        widget=AuthorWidget()
    )

class TagWidget(widgets.ManyToManyWidget):
    """Custom M2M widget for tags."""
    
    def __init__(self, **kwargs):
        super().__init__(Tag, separator='|', field='name', **kwargs)
    
    def clean(self, value, row=None, **kwargs):
        if not value:
            return []
        
        # Split by separator and clean each tag
        tag_names = [name.strip() for name in value.split(self.separator)]
        tags = []
        
        for name in tag_names:
            if name:
                tag, created = Tag.objects.get_or_create(name=name)
                tags.append(tag)
        
        return tags

class BookResource(resources.ModelResource):
    tags = fields.Field(
        attribute='tags',
        widget=TagWidget()
    )

class FlexibleDateWidget(widgets.DateWidget):
    """Date widget that accepts multiple input formats."""
    
    FORMATS = ['%Y-%m-%d', '%d/%m/%Y', '%m/%d/%Y', '%Y%m%d']
    
    def clean(self, value, row=None, **kwargs):
        if not value:
            return None
        
        if isinstance(value, date):
            return value
        
        # Try multiple formats
        for fmt in self.FORMATS:
            try:
                return datetime.strptime(str(value), fmt).date()
            except ValueError:
                continue
        
        raise ValueError(f"Unable to parse date: {value}")

class BookResource(resources.ModelResource):
    published_date = fields.Field(
        attribute='published_date',
        widget=FlexibleDateWidget()
    )

class ConditionalWidget(widgets.CharWidget):
    """Widget that behaves differently based on row data."""
    
    def clean(self, value, row=None, **kwargs):
        value = super().clean(value, row, **kwargs)
        
        # Modify value based on other row data
        if row and row.get('category') == 'special':
            return f"SPECIAL: {value}"
        
        return value

class BookResource(resources.ModelResource):
    title = fields.Field(
        attribute='title',
        widget=ConditionalWidget()
    )

class PriceWidget(widgets.Widget):
    """Widget for handling price data with currency conversion."""
    
    def __init__(self, currency='USD', **kwargs):
        self.currency = currency
        super().__init__(**kwargs)
    
    def clean(self, value, row=None, **kwargs):
        if not value:
            return None
        
        # Handle different price formats
        if isinstance(value, str):
            # Remove currency symbols and convert
            value = value.replace('$', '').replace(',', '').strip()
        
        try:
            price = Decimal(str(value))
            
            # Convert currency if needed
            if row and row.get('currency') != self.currency:
                price = self.convert_currency(
                    price, row.get('currency'), self.currency
                )
            
            return price
        except (ValueError, TypeError):
            raise ValueError(f"Invalid price format: {value}")
    
    def render(self, value, obj=None, **kwargs):
        if value is None:
            return ''
        return f"${value:.2f}"
    
    def convert_currency(self, amount, from_currency, to_currency):
        # Mock currency conversion
        rates = {'USD': 1.0, 'EUR': 0.85, 'GBP': 0.75}
        return amount * rates.get(to_currency, 1.0) / rates.get(from_currency, 1.0)

class BookResource(resources.ModelResource):
    price = fields.Field(
        attribute='price',
        widget=PriceWidget(currency='USD')
    )

class ISBNWidget(widgets.CharWidget):
    """Widget for ISBN validation and formatting."""
    
    def clean(self, value, row=None, **kwargs):
        value = super().clean(value, row, **kwargs)
        
        if not value:
            return value
        
        # Clean ISBN format
        isbn = ''.join(c for c in value if c.isdigit() or c.upper() == 'X')
        
        # Validate ISBN length
        if len(isbn) not in [10, 13]:
            raise ValueError(f"Invalid ISBN length: {isbn}")
        
        # Add hyphens for readability
        if len(isbn) == 13:
            return f"{isbn[:3]}-{isbn[3:4]}-{isbn[4:6]}-{isbn[6:12]}-{isbn[12]}"
        else:
            return f"{isbn[:1]}-{isbn[1:4]}-{isbn[4:9]}-{isbn[9]}"
    
    def render(self, value, obj=None, **kwargs):
        # Remove hyphens for export
        return ''.join(c for c in (value or '') if c.isdigit() or c.upper() == 'X')

class BookResource(resources.ModelResource):
    isbn = fields.Field(
        attribute='isbn',
        widget=ISBNWidget()
    )

class BookResource(resources.ModelResource):
    class Meta:
        model = Book
        widgets = {
            'published_date': {'format': '%d/%m/%Y'},
            'price': {'currency': 'EUR'},
            'is_active': {'true_values': ['yes', 'y', '1']},
            'tags': {'separator': ';'},
        }