Enhance Type Safety and Value Validation

[oasaph]

Description

Improve type safety and add comprehensive validation for flag values and operations to catch errors early and provide better developer experience.

Goals

• Complete type annotations coverage
• Runtime value validation
• Enhanced IDE support
• Custom type definitions
• Validation error handling

Proposed Implementation

1. Type Annotations

from typing import TypeVar, Generic, Union, Optional
from datetime import datetime

T = TypeVar('T')

class Flag(Generic[T]):
    def __init__(
        self,
        name: str,
        value: T,
        operation: Optional[str] = None,
        description: Optional[str] = None
    ) -> None: ...
    
    def is_enabled(self, compare_value: Optional[T] = None) -> bool: ...

class Flaggle:
    def __init__(
        self,
        url: str,
        interval: int = 60,
        default_flags: Optional[dict[str, Flag[Any]]] = None,
        timeout: int = 10,
        verify_ssl: bool = True
    ) -> None: ...

2. Value Validation

class FlagValue(Generic[T]):
    """Validated flag value container."""
    def __init__(self, value: T) -> None:
        self.validate(value)
        self._value = value
    
    @staticmethod
    def validate(value: T) -> None:
        # Type-specific validation
        pass

class Flag(Generic[T]):
    def __init__(self, name: str, value: T) -> None:
        self.value = FlagValue[T](value)

Acceptance Criteria

• Complete type annotations for all public APIs
• Runtime value validation
• Custom type definitions for flag values
• Validation error handling
• Type checking in CI pipeline
• Updated documentation with type information
• Migration guide for existing users

Additional Benefits

1. Better IDE support (autocomplete, type checking)
2. Early error detection
3. Improved code maintainability
4. Better developer experience