"""Tool base class and registry.

Following the same pattern used by the codebase this agent is modelled on,
every tool is a small subclass of :class:`ToolBase` that:

* declares a unique ``name`` and ``description`` (used by the orchestrator /
  LLM to decide which tool to call)
* exposes a JSON-schema-ish ``input_schema`` describing its arguments
* implements :meth:`run` which performs the actual work and returns a
  dictionary result

Tools register themselves automatically on import via the
``@register_tool`` decorator (or by being added to ``ALL_TOOLS`` in
``unity_tools.py``). The :class:`ToolRegistry` keeps a single global map of
``name -> tool_class``.
"""

from __future__ import annotations

import inspect
import json
import logging
from dataclasses import dataclass, field
from typing import Any, Callable, Dict, List, Optional, Type

from unity_agent.config import Settings
from unity_agent.transport.unity_transport import UnityTransport

log = logging.getLogger("unity_agent.tools")


# --------------------------------------------------------------------------- #
# Tool base
# --------------------------------------------------------------------------- #
@dataclass
class ToolResult:
    """Structured return value from :meth:`ToolBase.run`."""

    ok: bool
    tool: str
    summary: str
    files: List[str] = field(default_factory=list)
    data: Dict[str, Any] = field(default_factory=dict)
    error: Optional[str] = None

    def to_dict(self) -> dict:
        return {
            "ok": self.ok,
            "tool": self.tool,
            "summary": self.summary,
            "files": self.files,
            "data": self.data,
            "error": self.error,
        }


class ToolBase:
    """Base class for every Unity agent tool.

    Subclasses MUST override:

    * ``name`` (str)         -- unique tool name (snake_case)
    * ``description`` (str)  -- natural language description for the LLM
    * ``input_schema`` (dict)-- JSON-schema describing parameters
    * :meth:`run`            -- the actual implementation
    """

    name: str = "base_tool"
    description: str = "Override me."
    input_schema: Dict[str, Any] = {"type": "object", "properties": {}}

    def __init__(self, settings: Settings, transport: UnityTransport) -> None:
        self.settings = settings
        self.transport = transport

    # ------------------------------------------------------------------ #
    # Helpers
    # ------------------------------------------------------------------ #
    def _ensure_project(self, project_name: Optional[str] = None) -> None:
        """Open a project if one is not already open."""
        if project_name and (
            self.transport.project_name is None
            or self.transport.project_name != project_name
        ):
            self.transport.open_project(project_name)
        # If no project is open at all, default to settings.product_name.
        if self.transport._project_root is None:
            self.transport.open_project(self.settings.product_name)

    def result(
        self,
        ok: bool,
        summary: str,
        files: Optional[List[str]] = None,
        data: Optional[Dict[str, Any]] = None,
        error: Optional[str] = None,
    ) -> ToolResult:
        return ToolResult(
            ok=ok,
            tool=self.name,
            summary=summary,
            files=files or [],
            data=data or {},
            error=error,
        )

    # ------------------------------------------------------------------ #
    # Public API
    # ------------------------------------------------------------------ #
    def run(self, **kwargs: Any) -> ToolResult:  # noqa: D401 - simple
        raise NotImplementedError(f"{self.__class__.__name__}.run() not implemented")

    def schema(self) -> Dict[str, Any]:
        return {
            "name": self.name,
            "description": self.description,
            "input_schema": self.input_schema,
        }


# --------------------------------------------------------------------------- #
# Registry
# --------------------------------------------------------------------------- #
class ToolRegistry:
    """Global registry mapping tool names to tool classes."""

    def __init__(self) -> None:
        self._tools: Dict[str, Type[ToolBase]] = {}

    def register(self, tool_cls: Type[ToolBase]) -> Type[ToolBase]:
        if not issubclass(tool_cls, ToolBase):
            raise TypeError(f"{tool_cls} must subclass ToolBase")
        name = tool_cls.name
        if name in self._tools:
            log.debug("Overwriting already-registered tool %s", name)
        self._tools[name] = tool_cls
        return tool_cls

    def get(self, name: str) -> Optional[Type[ToolBase]]:
        return self._tools.get(name)

    def all_names(self) -> List[str]:
        return sorted(self._tools.keys())

    def all_schemas(self) -> List[Dict[str, Any]]:
        return [cls(None, None).schema() for cls in self._tools.values()]  # type: ignore[arg-type]

    def instantiate(
        self, name: str, settings: Settings, transport: UnityTransport
    ) -> ToolBase:
        cls = self.get(name)
        if cls is None:
            raise KeyError(f"Unknown tool: {name}")
        return cls(settings, transport)


# Single shared registry.
_GLOBAL_REGISTRY = ToolRegistry()


def get_registry() -> ToolRegistry:
    return _GLOBAL_REGISTRY


def register_tool(tool_cls: Type[ToolBase]) -> Type[ToolBase]:
    """Class decorator that registers a tool with the global registry."""
    return _GLOBAL_REGISTRY.register(tool_cls)


def instantiate_all(settings: Settings, transport: UnityTransport) -> Dict[str, ToolBase]:
    """Instantiate every registered tool with the given settings + transport."""
    return {
        name: cls(settings, transport)
        for name, cls in _GLOBAL_REGISTRY._tools.items()
    }