"""
HermesAgentLoop -- Reusable Multi-Turn Agent Engine

Runs the hermes-agent tool-calling loop using standard OpenAI-spec tool calling.
Works with any server that returns ChatCompletion objects with tool_calls:
    - Phase 1: OpenAI server type (VLLM, SGLang, OpenRouter, OpenAI API)
    - Phase 2: ManagedServer with client-side tool call parser

The loop passes tools= and checks response.choices[0].message.tool_calls,
identical to hermes-agent's run_agent.py. Tool execution is dispatched via
handle_function_call() from model_tools.py.
"""

import asyncio
import concurrent.futures
import json
import logging
import os
import uuid
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional, Set

from model_tools import handle_function_call

# Thread pool for running sync tool calls that internally use asyncio.run()
# (e.g., the Modal/Docker/Daytona terminal backends). Running them in a separate
# thread gives them a clean event loop so they don't deadlock inside Atropos's loop.
# Size must be large enough for concurrent eval tasks (e.g., 89 TB2 tasks all
# making tool calls). Too small = thread pool starvation, tasks queue for minutes.
# Resized at runtime by HermesAgentBaseEnv.__init__ via resize_tool_pool().
_tool_executor = concurrent.futures.ThreadPoolExecutor(max_workers=128)


def resize_tool_pool(max_workers: int):
    """
    Replace the global tool executor with a new one of the given size.

    Called by HermesAgentBaseEnv.__init__ based on config.tool_pool_size.
    Safe to call before any tasks are submitted.
    """
    global _tool_executor
    old_executor = _tool_executor
    _tool_executor = concurrent.futures.ThreadPoolExecutor(max_workers=max_workers)
    old_executor.shutdown(wait=False)
    logger.info("Tool thread pool resized to %d workers", max_workers)

logger = logging.getLogger(__name__)


@dataclass
class ToolError:
    """Record of a tool execution error during the agent loop."""

    turn: int                  # Which turn the error occurred on
    tool_name: str             # Which tool was called
    arguments: str             # The arguments passed (truncated)
    error: str                 # The error message
    tool_result: str           # The raw result returned to the model


@dataclass
class AgentResult:
    """Result of running the agent loop."""

    # Full conversation history in OpenAI message format
    messages: List[Dict[str, Any]]
    # ManagedServer.get_state() if available (Phase 2), None otherwise
    managed_state: Optional[Dict[str, Any]] = None
    # How many LLM calls were made
    turns_used: int = 0
    # True if model stopped calling tools naturally (vs hitting max_turns)
    finished_naturally: bool = False
    # Extracted reasoning content per turn (from PR #297 helpers)
    reasoning_per_turn: List[Optional[str]] = field(default_factory=list)
    # Tool errors encountered during the loop
    tool_errors: List[ToolError] = field(default_factory=list)


def _extract_reasoning_from_message(message) -> Optional[str]:
    """
    Extract reasoning content from a ChatCompletion message.

    Handles multiple provider formats:
    1. message.reasoning_content field (some providers)
    2. message.reasoning field (some providers)
    3. message.reasoning_details[].text (OpenRouter style)

    Note: <think> block extraction from content is NOT done here -- that's
    handled by the response already in Phase 1 (server does it) or by
    ManagedServer's patch in Phase 2.

    Args:
        message: The assistant message from ChatCompletion response

    Returns:
        Extracted reasoning text, or None if not found
    """
    # Check reasoning_content field (common across providers)
    if hasattr(message, "reasoning_content") and message.reasoning_content:
        return message.reasoning_content

    # Check reasoning field
    if hasattr(message, "reasoning") and message.reasoning:
        return message.reasoning

    # Check reasoning_details (OpenRouter style)
    if hasattr(message, "reasoning_details") and message.reasoning_details:
        for detail in message.reasoning_details:
            if hasattr(detail, "text") and detail.text:
                return detail.text
            if isinstance(detail, dict) and detail.get("text"):
                return detail["text"]

    return None


class HermesAgentLoop:
    """
    Runs hermes-agent's tool-calling loop using standard OpenAI-spec tool calling.

    Same pattern as run_agent.py:
    - Pass tools= to the API
    - Check response.choices[0].message.tool_calls
    - Dispatch via handle_function_call()

    Works identically with any server type -- OpenAI, VLLM, SGLang, OpenRouter,
    or ManagedServer with a parser. The server determines how tool_calls get
    populated on the response.
    """

    def __init__(
        self,
        server,
        tool_schemas: List[Dict[str, Any]],
        valid_tool_names: Set[str],
        max_turns: int = 30,
        task_id: Optional[str] = None,
        temperature: float = 1.0,
        max_tokens: Optional[int] = None,
        extra_body: Optional[Dict[str, Any]] = None,
    ):
        """
        Initialize the agent loop.

        Args:
            server: Server object with chat_completion() method (OpenAIServer,
                    ManagedServer, ServerManager, etc.)
            tool_schemas: OpenAI-format tool definitions from get_tool_definitions()
            valid_tool_names: Set of tool names the model is allowed to call
            max_turns: Maximum number of LLM calls before stopping
            task_id: Unique ID for terminal/browser session isolation
            temperature: Sampling temperature for generation
            max_tokens: Max tokens per generation (None for server default)
            extra_body: Extra parameters passed to the OpenAI client's create() call.
                        Used for OpenRouter provider preferences, transforms, etc.
                        e.g. {"provider": {"ignore": ["DeepInfra"]}}
        """
        self.server = server
        self.tool_schemas = tool_schemas
        self.valid_tool_names = valid_tool_names
        self.max_turns = max_turns
        self.task_id = task_id or str(uuid.uuid4())
        self.temperature = temperature
        self.max_tokens = max_tokens
        self.extra_body = extra_body

    async def run(self, messages: List[Dict[str, Any]]) -> AgentResult:
        """
        Execute the full agent loop using standard OpenAI tool calling.

        Args:
            messages: Initial conversation messages (system + user).
                      Modified in-place as the conversation progresses.

        Returns:
            AgentResult with full conversation history, managed state, and metadata
        """
        reasoning_per_turn = []
        tool_errors: List[ToolError] = []

        # Per-loop TodoStore for the todo tool (ephemeral, dies with the loop)
        from tools.todo_tool import TodoStore, todo_tool as _todo_tool
        _todo_store = TodoStore()

        # Extract user task from first user message for browser_snapshot context
        _user_task = None
        for msg in messages:
            if msg.get("role") == "user":
                content = msg.get("content", "")
                if isinstance(content, str) and content.strip():
                    _user_task = content.strip()[:500]  # Cap to avoid huge strings
                break

        import time as _time

        for turn in range(self.max_turns):
            turn_start = _time.monotonic()

            # Build the chat_completion kwargs
            chat_kwargs = {
                "messages": messages,
                "n": 1,
                "temperature": self.temperature,
            }

            # Only pass tools if we have them
            if self.tool_schemas:
                chat_kwargs["tools"] = self.tool_schemas

            # Only pass max_tokens if explicitly set
            if self.max_tokens is not None:
                chat_kwargs["max_tokens"] = self.max_tokens

            # Inject extra_body for provider-specific params (e.g., OpenRouter
            # provider preferences like banned/preferred providers, transforms)
            if self.extra_body:
                chat_kwargs["extra_body"] = self.extra_body

            # Make the API call -- standard OpenAI spec
            api_start = _time.monotonic()
            try:
                response = await self.server.chat_completion(**chat_kwargs)
            except Exception as e:
                api_elapsed = _time.monotonic() - api_start
                logger.error("API call failed on turn %d (%.1fs): %s", turn + 1, api_elapsed, e)
                return AgentResult(
                    messages=messages,
                    managed_state=self._get_managed_state(),
                    turns_used=turn + 1,
                    finished_naturally=False,
                    reasoning_per_turn=reasoning_per_turn,
                    tool_errors=tool_errors,
                )

            api_elapsed = _time.monotonic() - api_start

            if not response or not response.choices:
                logger.warning("Empty response on turn %d (api=%.1fs)", turn + 1, api_elapsed)
                return AgentResult(
                    messages=messages,
                    managed_state=self._get_managed_state(),
                    turns_used=turn + 1,
                    finished_naturally=False,
                    reasoning_per_turn=reasoning_per_turn,
                    tool_errors=tool_errors,
                )

            assistant_msg = response.choices[0].message

            # Extract reasoning content from the response (all provider formats)
            reasoning = _extract_reasoning_from_message(assistant_msg)
            reasoning_per_turn.append(reasoning)

            # Check for tool calls -- standard OpenAI spec.
            # Fallback: if response has no structured tool_calls but content
            # contains raw tool call tags (e.g. <tool_call>), parse them using
            # hermes-agent's standalone parsers. This handles the case where
            # ManagedServer's ToolCallTranslator couldn't parse because vLLM
            # isn't installed.
            if (
                not assistant_msg.tool_calls
                and assistant_msg.content
                and self.tool_schemas
                and "<tool_call>" in (assistant_msg.content or "")
            ):
                try:
                    from environments.tool_call_parsers import get_parser
                    fallback_parser = get_parser("hermes")
                    parsed_content, parsed_calls = fallback_parser.parse(
                        assistant_msg.content
                    )
                    if parsed_calls:
                        assistant_msg.tool_calls = parsed_calls
                        if parsed_content is not None:
                            assistant_msg.content = parsed_content
                        logger.debug(
                            "Fallback parser extracted %d tool calls from raw content",
                            len(parsed_calls),
                        )
                except Exception:
                    pass  # Fall through to no tool calls

            if assistant_msg.tool_calls:
                # Normalize tool calls to dicts — they may come as objects
                # (OpenAI API) or dicts (vLLM ToolCallTranslator).
                def _tc_to_dict(tc):
                    if isinstance(tc, dict):
                        return {
                            "id": tc.get("id", f"call_{uuid.uuid4().hex[:8]}"),
                            "type": "function",
                            "function": {
                                "name": tc.get("function", {}).get("name", tc.get("name", "")),
                                "arguments": tc.get("function", {}).get("arguments", tc.get("arguments", "{}")),
                            },
                        }
                    return {
                        "id": tc.id,
                        "type": "function",
                        "function": {
                            "name": tc.function.name,
                            "arguments": tc.function.arguments,
                        },
                    }

                # Build the assistant message dict for conversation history
                msg_dict: Dict[str, Any] = {
                    "role": "assistant",
                    "content": assistant_msg.content or "",
                    "tool_calls": [_tc_to_dict(tc) for tc in assistant_msg.tool_calls],
                }

                # Preserve reasoning_content for multi-turn chat template handling
                # (e.g., Kimi-K2's template renders <think> blocks differently
                # for history vs. the latest turn based on this field)
                if reasoning:
                    msg_dict["reasoning_content"] = reasoning

                messages.append(msg_dict)

                # Execute each tool call via hermes-agent's dispatch
                for tc in assistant_msg.tool_calls:
                    # Handle both object (OpenAI) and dict (vLLM) formats
                    if isinstance(tc, dict):
                        tool_name = tc.get("function", {}).get("name", tc.get("name", ""))
                        tool_args_raw = tc.get("function", {}).get("arguments", tc.get("arguments", "{}"))
                    else:
                        tool_name = tc.function.name
                        tool_args_raw = tc.function.arguments

                    # Validate tool name
                    if tool_name not in self.valid_tool_names:
                        tool_result = json.dumps(
                            {
                                "error": f"Unknown tool '{tool_name}'. "
                                f"Available tools: {sorted(self.valid_tool_names)}"
                            }
                        )
                        tool_errors.append(ToolError(
                            turn=turn + 1, tool_name=tool_name,
                            arguments=tool_args_raw[:200],
                            error=f"Unknown tool '{tool_name}'",
                            tool_result=tool_result,
                        ))
                        logger.warning(
                            "Model called unknown tool '%s' on turn %d",
                            tool_name, turn + 1,
                        )
                    else:
                        # Parse arguments
                        try:
                            args = json.loads(tool_args_raw)
                        except json.JSONDecodeError as e:
                            args = None
                            tool_result = json.dumps(
                                {"error": f"Invalid JSON in tool arguments: {e}. Please retry with valid JSON."}
                            )
                            tool_errors.append(ToolError(
                                turn=turn + 1, tool_name=tool_name,
                                arguments=tool_args_raw[:200],
                                error=f"Invalid JSON: {e}",
                                tool_result=tool_result,
                            ))
                            logger.warning(
                                "Invalid JSON in tool call arguments for '%s': %s",
                                tool_name, tool_args_raw[:200],
                            )

                        # Dispatch tool only if arguments parsed successfully
                        if args is not None:
                            try:
                                if tool_name == "terminal":
                                    backend = os.getenv("TERMINAL_ENV", "local")
                                    cmd_preview = args.get("command", "")[:80]
                                    logger.info(
                                        "[%s] $ %s", self.task_id[:8], cmd_preview,
                                    )

                                tool_submit_time = _time.monotonic()

                                # Todo tool -- handle locally (needs per-loop TodoStore)
                                if tool_name == "todo":
                                    tool_result = _todo_tool(
                                        todos=args.get("todos"),
                                        merge=args.get("merge", False),
                                        store=_todo_store,
                                    )
                                    tool_elapsed = _time.monotonic() - tool_submit_time
                                elif tool_name == "memory":
                                    tool_result = json.dumps({"error": "Memory is not available in RL environments."})
                                    tool_elapsed = _time.monotonic() - tool_submit_time
                                elif tool_name == "session_search":
                                    tool_result = json.dumps({"error": "Session search is not available in RL environments."})
                                    tool_elapsed = _time.monotonic() - tool_submit_time
                                else:
                                    # Run tool calls in a thread pool so backends that
                                    # use asyncio.run() internally (modal, docker, daytona) get
                                    # a clean event loop instead of deadlocking.
                                    loop = asyncio.get_event_loop()
                                    # Capture current tool_name/args for the lambda
                                    _tn, _ta, _tid = tool_name, args, self.task_id
                                    tool_result = await loop.run_in_executor(
                                        _tool_executor,
                                        lambda: handle_function_call(
                                            _tn, _ta, task_id=_tid,
                                            user_task=_user_task,
                                        ),
                                    )
                                    tool_elapsed = _time.monotonic() - tool_submit_time

                                # Log slow tools and thread pool stats for debugging
                                pool_active = _tool_executor._work_queue.qsize()
                                if tool_elapsed > 30:
                                    logger.warning(
                                        "[%s] turn %d: %s took %.1fs (pool queue=%d)",
                                        self.task_id[:8], turn + 1, tool_name,
                                        tool_elapsed, pool_active,
                                    )
                            except Exception as e:
                                tool_result = json.dumps(
                                    {"error": f"Tool execution failed: {type(e).__name__}: {str(e)}"}
                                )
                                tool_errors.append(ToolError(
                                    turn=turn + 1, tool_name=tool_name,
                                    arguments=tool_args_raw[:200],
                                    error=f"{type(e).__name__}: {str(e)}",
                                    tool_result=tool_result,
                                ))
                                logger.error(
                                    "Tool '%s' execution failed on turn %d: %s",
                                    tool_name, turn + 1, e,
                                )

                        # Also check if the tool returned an error in its JSON result
                        try:
                            result_data = json.loads(tool_result)
                            if isinstance(result_data, dict):
                                err = result_data.get("error")
                                exit_code = result_data.get("exit_code")
                                if err and exit_code and exit_code < 0:
                                    tool_errors.append(ToolError(
                                        turn=turn + 1, tool_name=tool_name,
                                        arguments=tool_args_raw[:200],
                                        error=str(err),
                                        tool_result=tool_result[:500],
                                    ))
                        except (json.JSONDecodeError, TypeError):
                            pass

                    # Add tool response to conversation
                    tc_id = tc.get("id", "") if isinstance(tc, dict) else tc.id
                    messages.append(
                        {
                            "role": "tool",
                            "tool_call_id": tc_id,
                            "content": tool_result,
                        }
                    )

                turn_elapsed = _time.monotonic() - turn_start
                logger.info(
                    "[%s] turn %d: api=%.1fs, %d tools, turn_total=%.1fs",
                    self.task_id[:8], turn + 1, api_elapsed,
                    len(assistant_msg.tool_calls), turn_elapsed,
                )

            else:
                # No tool calls -- model is done
                msg_dict = {
                    "role": "assistant",
                    "content": assistant_msg.content or "",
                }
                if reasoning:
                    msg_dict["reasoning_content"] = reasoning
                messages.append(msg_dict)

                turn_elapsed = _time.monotonic() - turn_start
                logger.info(
                    "[%s] turn %d: api=%.1fs, no tools (finished), turn_total=%.1fs",
                    self.task_id[:8], turn + 1, api_elapsed, turn_elapsed,
                )

                return AgentResult(
                    messages=messages,
                    managed_state=self._get_managed_state(),
                    turns_used=turn + 1,
                    finished_naturally=True,
                    reasoning_per_turn=reasoning_per_turn,
                    tool_errors=tool_errors,
                )

        # Hit max turns without the model stopping
        logger.info("Agent hit max_turns (%d) without finishing", self.max_turns)
        return AgentResult(
            messages=messages,
            managed_state=self._get_managed_state(),
            turns_used=self.max_turns,
            finished_naturally=False,
            reasoning_per_turn=reasoning_per_turn,
            tool_errors=tool_errors,
        )

    def _get_managed_state(self) -> Optional[Dict[str, Any]]:
        """
        Get ManagedServer state if the server supports it.

        Returns state dict with SequenceNodes containing tokens/logprobs/masks,
        or None if the server doesn't support get_state() (e.g., regular OpenAI server).
        """
        if hasattr(self.server, "get_state"):
            return self.server.get_state()
        return None