"""Tool registry with @tool decorator and auto-discovery."""

from __future__ import annotations

import importlib
import inspect
import json
import logging
import pkgutil
from pathlib import Path
from typing import Any, Callable, TYPE_CHECKING

if TYPE_CHECKING:
    from ..agent import Agent
    from ..config import Config
    from ..db import Database

log = logging.getLogger(__name__)

# Global tool registry
_TOOLS: dict[str, ToolDef] = {}


class ToolDef:
    """Metadata for a registered tool."""

    def __init__(self, name: str, description: str, func: Callable, category: str = "general"):
        self.name = name
        self.description = description
        self.func = func
        self.category = category
        self.parameters = _extract_params(func)

    def to_openai_schema(self) -> dict:
        """Convert to OpenAI function-calling format."""
        return {
            "type": "function",
            "function": {
                "name": self.name,
                "description": self.description,
                "parameters": {
                    "type": "object",
                    "properties": self.parameters["properties"],
                    "required": self.parameters["required"],
                },
            },
        }


def tool(name: str, description: str, category: str = "general"):
    """Decorator to register a tool function."""

    def decorator(func: Callable) -> Callable:
        tool_def = ToolDef(name, description, func, category)
        _TOOLS[name] = tool_def
        func._tool_def = tool_def
        return func

    return decorator


def _extract_params(func: Callable) -> dict:
    """Extract parameter schema from function signature and type hints."""
    sig = inspect.signature(func)
    properties = {}
    required = []

    for param_name, param in sig.parameters.items():
        if param_name in ("self", "ctx"):
            continue

        prop: dict[str, Any] = {}
        annotation = param.annotation

        if annotation == str or annotation == inspect.Parameter.empty:
            prop["type"] = "string"
        elif annotation == int:
            prop["type"] = "integer"
        elif annotation == float:
            prop["type"] = "number"
        elif annotation == bool:
            prop["type"] = "boolean"
        elif annotation == list:
            prop["type"] = "array"
            prop["items"] = {"type": "string"}
        else:
            prop["type"] = "string"

        # Check for description in docstring (simple parsing)
        prop["description"] = f"Parameter: {param_name}"

        properties[param_name] = prop

        if param.default is inspect.Parameter.empty:
            required.append(param_name)

    return {"properties": properties, "required": required}


class ToolRegistry:
    """Runtime tool registry with execution and schema generation."""

    def __init__(self, config: "Config", db: "Database", agent: "Agent"):
        self.config = config
        self.db = db
        self.agent = agent
        self._discover_tools()

    def _discover_tools(self):
        """Auto-import all modules in the tools/ package."""
        tools_dir = Path(__file__).parent
        for _, module_name, _ in pkgutil.iter_modules([str(tools_dir)]):
            if module_name.startswith("_"):
                continue
            try:
                importlib.import_module(f".{module_name}", package=__package__)
                log.info("Loaded tool module: %s", module_name)
            except Exception as e:
                log.warning("Failed to load tool module %s: %s", module_name, e)

    def get_tools_schema(self) -> list[dict]:
        """Get all tools in OpenAI function-calling format."""
        return [t.to_openai_schema() for t in _TOOLS.values()]

    def get_tools_description(self) -> str:
        """Human-readable tool list for system prompt."""
        lines = []
        by_cat: dict[str, list[ToolDef]] = {}
        for t in _TOOLS.values():
            by_cat.setdefault(t.category, []).append(t)

        for cat, tools in sorted(by_cat.items()):
            lines.append(f"\n### {cat.title()}")
            for t in tools:
                params = ", ".join(t.parameters["required"])
                lines.append(f"- **{t.name}**({params}): {t.description}")
        return "\n".join(lines)

    def execute(self, name: str, args: dict) -> str:
        """Execute a tool by name and return the result as a string."""
        if name not in _TOOLS:
            return f"Unknown tool: {name}"

        tool_def = _TOOLS[name]
        try:
            # Inject context if the function expects it
            sig = inspect.signature(tool_def.func)
            if "ctx" in sig.parameters:
                args["ctx"] = {
                    "config": self.config,
                    "db": self.db,
                    "agent": self.agent,
                    "memory": self.agent._memory,
                }
            result = tool_def.func(**args)
            return str(result) if result is not None else "Done."
        except Exception as e:
            log.error("Tool %s failed: %s", name, e, exc_info=True)
            return f"Tool error: {e}"

    def register_external(self, tool_def: ToolDef):
        """Register a dynamically created tool."""
        _TOOLS[tool_def.name] = tool_def
        log.info("Registered external tool: %s", tool_def.name)