"""
Function resolution utilities for Dana language function execution.

This module provides utilities for resolving functions in the Dana language interpreter,
including namespace resolution and function lookup logic.

Copyright © 2025 Aitomatic, Inc.
MIT License

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    1. Attribution: Please maintain attribution to Aitomatic and Dana/Dana in derivative works.
    2. Contributions: If you find Dana/Dana valuable, consider contributing improvements back rather than creating separate, similar implementations.
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Learn more: https://aitomatic.com
GitHub: https://github.com/aitomatic/dana
Discord: https://discord.gg/6jGD4PYk
"""

import logging
from enum import Enum
from typing import Any

from dana.common.exceptions import SandboxError
from dana.core.lang.interpreter.executor.function_name_utils import FunctionNameInfo
from dana.core.lang.sandbox_context import SandboxContext


class FunctionType(Enum):
    """Enumeration of supported function types."""

    DANA = "dana"  # DanaFunction
    PYTHON = "python"  # PythonFunction
    CALLABLE = "callable"  # Python callable
    REGISTRY = "registry"  # FunctionRegistry


class ResolvedFunction:
    """A resolved function with metadata about its type and source."""

    def __init__(self, func: Any, func_type: FunctionType, source: str, metadata: dict[str, Any] | None = None):
        """Initialize a resolved function.

        Args:
            func: The actual function object
            func_type: The type of function (from FunctionType enum)
            source: Where the function was found (context, registry, etc.)
            metadata: Additional metadata about the function
        """
        self.func = func
        self.func_type = func_type
        self.source = source
        self.metadata = metadata or {}

    def __str__(self) -> str:
        """String representation of the resolved function."""
        return f"ResolvedFunction(func_type={self.func_type.value}, source={self.source}, metadata={self.metadata})"


class FunctionResolver:
    """Handles function resolution and namespace lookup."""

    def __init__(self, executor):
        """Initialize function resolver.

        Args:
            executor: The function executor instance
        """
        self.executor = executor
        self.logger = logging.getLogger(__name__)

    def parse_function_name(self, func_name: str) -> FunctionNameInfo:
        """Parse a function name and determine its namespace.

        Args:
            func_name: Function name to parse (e.g., 'func', 'core.print', 'local:my_func')

        Returns:
            FunctionNameInfo with parsed components
        """
        original_name = func_name

        if ":" in func_name:
            # Handle scoped function calls (preferred format)
            parts = func_name.split(":", 1)
            namespace = parts[0]
            func_name = parts[1]
            full_key = f"{namespace}:{func_name}"
        elif "." in func_name:
            # Handle backward compatibility with dot notation
            parts = func_name.split(".", 1)
            namespace = parts[0]
            func_name = parts[1]
            full_key = f"{namespace}:{func_name}"  # Store internally as colon notation
        else:
            # Default to local namespace for unqualified names
            namespace = "local"
            full_key = f"local:{func_name}"

        return FunctionNameInfo(original_name=original_name, func_name=func_name, namespace=namespace, full_key=full_key)

    def resolve_function(self, name_info: FunctionNameInfo, context: SandboxContext, registry: Any) -> ResolvedFunction | None:
        """Resolve a function using the parsed name information.

        Resolution order (per user requirements):
        1. Function registry first (system functions)
        2. Context scope hierarchy: local → private → system → public (user functions)

        Args:
            name_info: Parsed function name information
            context: The execution context
            registry: The function registry

        Returns:
            ResolvedFunction with the resolved function and metadata, or None if not found

        Raises:
            FunctionRegistryError: If function cannot be resolved
        """
        # 1. Try registry first (system functions have highest priority)
        registry_func = self._resolve_from_registry(name_info, registry)
        if registry_func:
            return registry_func

        # 2. Try context scope hierarchy: local → private → system → public
        context_func = self._resolve_from_context_hierarchy(name_info, context)
        if context_func:
            return context_func

        return None

    def _resolve_from_context_hierarchy(self, name_info: FunctionNameInfo, context: SandboxContext) -> ResolvedFunction | None:
        """Resolve function from context using proper scope hierarchy.

        Scope resolution order: local → private → system → public

        Args:
            name_info: Parsed function name information
            context: The execution context

        Returns:
            Resolved function from context, or None if not found
        """
        # Define scope hierarchy (order matters!)
        scope_hierarchy = ["local", "private", "system", "public"]

        # If the function name specifies a scope (e.g., "private:my_func"), only check that scope
        if name_info.namespace is not None:
            try:
                func_data = context.get(name_info.full_key)
                if func_data is not None:
                    return self._create_resolved_function_from_context(func_data, name_info)
            except Exception:
                pass
            return None

        # For unscoped function names, try each scope in hierarchy order
        for scope in scope_hierarchy:
            try:
                scoped_key = f"{scope}:{name_info.func_name}"
                func_data = context.get(scoped_key)
                if func_data is not None:
                    # Found function in this scope, create resolved function
                    resolved_info = FunctionNameInfo(
                        original_name=name_info.original_name, func_name=name_info.func_name, namespace=scope, full_key=scoped_key
                    )
                    return self._create_resolved_function_from_context(func_data, resolved_info)
            except Exception:
                # Continue to next scope if this one fails
                continue

        return None

    def _create_resolved_function_from_context(self, func_data: Any, name_info: FunctionNameInfo) -> ResolvedFunction:
        """Create a ResolvedFunction from context data."""
        from dana.core.lang.interpreter.functions.dana_function import DanaFunction
        from dana.core.lang.interpreter.functions.python_function import PythonFunction
        from dana.core.lang.interpreter.functions.sandbox_function import SandboxFunction

        # Check if this is a decorated function (has __wrapped__ attribute)
        if hasattr(func_data, "__wrapped__"):
            # Decorated functions should be treated as CALLABLE since the decorator
            # has transformed them into regular Python callables, regardless of the
            # original wrapped function type
            func_type = FunctionType.CALLABLE
        else:
            # Not decorated, check type directly
            if isinstance(func_data, (DanaFunction | SandboxFunction)):
                func_type = FunctionType.DANA
            elif isinstance(func_data, PythonFunction):
                func_type = FunctionType.PYTHON
            elif callable(func_data):
                func_type = FunctionType.CALLABLE
            else:
                # This should never happen for functions - raise an error instead of using invalid type
                self.logger.error(f"ERROR: Function '{name_info.full_key}' has unknown type '{type(func_data)}' and is not callable")
                raise SandboxError(f"Invalid function type '{type(func_data)}' for function '{name_info.full_key}'")

        return ResolvedFunction(
            func=func_data,
            func_type=func_type,
            source="context",
            metadata={"resolved_name": name_info.full_key, "original_name": name_info.original_name, "scope": name_info.namespace},
        )

    def _resolve_from_context(self, name_info: FunctionNameInfo, context: SandboxContext) -> ResolvedFunction | None:
        """Resolve function from all scoped context.

        Args:
            name_info: Parsed function name information
            context: The execution context

        Returns:
            Resolved function from all scoped context, or None if not found
        """
        try:
            func_data = context.get(name_info.full_key)
        except Exception:
            return None

        if func_data is None:
            return None

        # Determine function type and create resolved function
        from dana.core.lang.interpreter.functions.dana_function import DanaFunction
        from dana.core.lang.interpreter.functions.python_function import PythonFunction
        from dana.core.lang.interpreter.functions.sandbox_function import SandboxFunction

        if isinstance(func_data, (DanaFunction | SandboxFunction)):
            return ResolvedFunction(func_data, FunctionType.DANA, "scoped_context")
        elif isinstance(func_data, PythonFunction):
            return ResolvedFunction(func_data, FunctionType.PYTHON, "scoped_context")
        elif callable(func_data):
            # Regular callable (Python function, bound method, etc.)
            return ResolvedFunction(func_data, FunctionType.CALLABLE, "scoped_context")
        else:
            self.logger.warning(f"Found non-callable object '{type(func_data)}' for function '{name_info.full_key}'")
            return None

    def _resolve_from_registry(self, name_info: FunctionNameInfo, registry: Any) -> ResolvedFunction | None:
        """Resolve function from function registry.

        Args:
            name_info: Parsed function name information
            registry: The function registry

        Returns:
            Resolved function from registry, or None if not found
        """
        if not registry:
            return None

        try:
            # Try original name first
            if registry.has(name_info.original_name):
                return ResolvedFunction(
                    func=None,  # Registry functions don't expose the actual function object
                    func_type=FunctionType.REGISTRY,
                    source="registry",
                    metadata={"resolved_name": name_info.original_name, "original_name": name_info.original_name},
                )

            # Try base function name
            if registry.has(name_info.func_name):
                return ResolvedFunction(
                    func=None,  # Registry functions don't expose the actual function object
                    func_type=FunctionType.REGISTRY,
                    source="registry",
                    metadata={"resolved_name": name_info.func_name, "original_name": name_info.original_name},
                )

        except Exception as e:
            self.logger.debug(f"Registry lookup failed for '{name_info.original_name}': {e}")

        return None

    def execute_resolved_function(
        self, resolved_func: ResolvedFunction, context: SandboxContext, evaluated_args: list, evaluated_kwargs: dict, func_name: str
    ) -> Any:
        if resolved_func.source == "registry":
            # Registry function - delegate to the registry's call method which handles context injection properly
            registry = self.executor.function_registry
            if registry:
                # Use the resolved name (which worked) rather than the original name (which might not work)
                resolved_name = str(resolved_func.metadata.get("resolved_name") or resolved_func.metadata.get("original_name") or func_name)
                raw_result = registry.call(resolved_name, context, "", *evaluated_args, **evaluated_kwargs)
            else:
                raise SandboxError(f"No function registry available to execute function '{func_name}'")
            return self.executor._assign_and_coerce_result(raw_result, func_name)

        elif resolved_func.func_type == FunctionType.DANA:
            # DanaFunction - use execute method with context
            raw_result = resolved_func.func.execute(context, *evaluated_args, **evaluated_kwargs)
            return self.executor._assign_and_coerce_result(raw_result, func_name)

        elif resolved_func.func_type == FunctionType.PYTHON:
            # PythonFunction or other Python-backed SandboxFunction - use execute method
            raw_result = resolved_func.func.execute(context, *evaluated_args, **evaluated_kwargs)
            return self.executor._assign_and_coerce_result(raw_result, func_name)

        elif resolved_func.func_type == FunctionType.CALLABLE:
            # Regular callable
            raw_result = resolved_func.func(*evaluated_args, **evaluated_kwargs)
            return self.executor._assign_and_coerce_result(raw_result, func_name)

        else:
            raise SandboxError(f"Unknown function type '{resolved_func.func_type.value}' for function '{func_name}'")

    def list_available_functions(self, namespace: str | None = None) -> list[str]:
        """List available functions in the given namespace.

        Args:
            namespace: Optional namespace to filter by

        Returns:
            List of available function names
        """
        available = []

        # Get functions from context
        for var_name in self.context.list_variables():
            if "." in var_name:
                ns, func_name = var_name.split(".", 1)
                if namespace is None or ns == namespace:
                    available.append(var_name)

        # Get functions from registry
        try:
            from dana.registry.function_registry import FunctionRegistry

            for func_name in FunctionRegistry.list_functions():
                if namespace is None or namespace == "registry":
                    available.append(f"registry.{func_name}")
        except ImportError:
            # FunctionRegistry not available, skip registry functions
            pass

        return sorted(available)
