"""
SCAFFOLDED MODULE — NOT YET INTEGRATED

This file is intentionally scaffolded.
Structure, interfaces, and intent are defined,
but this module is not yet wired into the active runtime.

⚠️ Do NOT assume runtime execution.
⚠️ Do NOT extend behavior without integration work.

Status: SCAFFOLDED
"""

"""
APE Type System Validator (v1.0.0 Scaffold)

This module provides type checking and inference for APE's type system.

Author: David Van Aelst
Status: Scaffold - implementation pending
"""

from typing import Optional, Dict, Any, List
from dataclasses import dataclass


@dataclass
class TypeInfo:
    """Information about a type"""
    name: str
    generic_params: List['TypeInfo'] = None
    is_nullable: bool = False
    
    def __post_init__(self):
        if self.generic_params is None:
            self.generic_params = []
    
    def __str__(self):
        if self.generic_params:
            params = ", ".join(str(p) for p in self.generic_params)
            return f"{self.name}<{params}>"
        return self.name


class TypeChecker:
    """
    Type checker and inference engine for APE.
    
    Features:
        - Generic type validation: List<Integer>, Map<String, Boolean>
        - Type inference for variables and expressions
        - Type compatibility checking
        - Constraint solving for generic parameters
    
    Example:
        checker = TypeChecker()
        list_type = checker.parse_type("List<Integer>")
        checker.validate_type(value, list_type)
    
    TODO:
        - Implement parse_type for type syntax parsing
        - Implement validate_type for runtime validation
        - Implement infer_type for expression type inference
        - Implement check_compatibility for assignment checking
        - Implement constraint solving for generics
        - Implement type unification algorithm
    
    Author: David Van Aelst
    Status: v1.0.0 scaffold - implementation pending
    """
    
    def __init__(self):
        self._type_cache: Dict[str, TypeInfo] = {}
        self._type_constraints: Dict[str, List[str]] = {}
    
    def parse_type(self, type_string: str) -> TypeInfo:
        """
        Parse a type string into TypeInfo.
        
        Example:
            parse_type("List<Integer>") -> TypeInfo(name="List", generic_params=[TypeInfo(name="Integer")])
        
        TODO: Implement parser for type syntax
        """
        raise NotImplementedError("Type parsing not yet implemented")
    
    def validate_type(self, value: Any, expected_type: TypeInfo) -> bool:
        """
        Validate that a value matches the expected type.
        
        Args:
            value: The value to check
            expected_type: The expected type
        
        Returns:
            True if value matches type, False otherwise
        
        TODO: Implement runtime type validation
        """
        raise NotImplementedError("Type validation not yet implemented")
    
    def infer_type(self, expression: Any) -> TypeInfo:
        """
        Infer the type of an expression.
        
        Args:
            expression: AST node or value to infer type for
        
        Returns:
            Inferred TypeInfo
        
        TODO: Implement type inference algorithm
        """
        raise NotImplementedError("Type inference not yet implemented")
    
    def check_compatibility(self, source_type: TypeInfo, target_type: TypeInfo) -> bool:
        """
        Check if source_type can be assigned to target_type.
        
        Examples:
            - Integer compatible with Number
            - List<Integer> compatible with List<Number> (covariance)
            - String not compatible with Integer
        
        TODO: Implement type compatibility rules
        """
        raise NotImplementedError("Type compatibility checking not yet implemented")
    
    def unify(self, type1: TypeInfo, type2: TypeInfo) -> Optional[TypeInfo]:
        """
        Attempt to unify two types, returning the most specific common type.
        
        TODO: Implement type unification algorithm
        """
        raise NotImplementedError("Type unification not yet implemented")


# Built-in type definitions
BUILT_IN_TYPES = {
    'Integer': TypeInfo(name='Integer'),
    'Number': TypeInfo(name='Number'),
    'String': TypeInfo(name='String'),
    'Boolean': TypeInfo(name='Boolean'),
    'List': TypeInfo(name='List'),
    'Map': TypeInfo(name='Map'),
    'Record': TypeInfo(name='Record'),
    'Tuple': TypeInfo(name='Tuple'),
}


__all__ = ['TypeChecker', 'TypeInfo', 'BUILT_IN_TYPES']
