"""
Context management for conversation history
"""

import logging
import os
import zoneinfo
from datetime import datetime
from pathlib import Path
from typing import Any

import yaml
from jinja2 import Template
from litellm import Message, acompletion

logger = logging.getLogger(__name__)

# Module-level cache for HF username — avoids repeating the slow whoami() call
_hf_username_cache: str | None = None

_HF_WHOAMI_URL = "https://huggingface.co/api/whoami-v2"
_HF_WHOAMI_TIMEOUT = 5  # seconds


def _get_hf_username() -> str:
    """Return the HF username, cached after the first call.

    Uses subprocess + curl to avoid Python HTTP client IPv6 issues that
    cause 40+ second hangs (httpx/urllib try IPv6 first which times out
    at OS level before falling back to IPv4 — the "Happy Eyeballs" problem).
    """
    import json
    import subprocess
    import time as _t

    global _hf_username_cache
    if _hf_username_cache is not None:
        return _hf_username_cache

    hf_token = os.environ.get("HF_TOKEN") or os.environ.get("HUGGINGFACE_HUB_TOKEN")
    if not hf_token:
        logger.warning("No HF_TOKEN set, using 'unknown' as username")
        _hf_username_cache = "unknown"
        return _hf_username_cache

    t0 = _t.monotonic()
    try:
        result = subprocess.run(
            [
                "curl",
                "-s",
                "-4",  # force IPv4
                "-m",
                str(_HF_WHOAMI_TIMEOUT),  # max time
                "-H",
                f"Authorization: Bearer {hf_token}",
                _HF_WHOAMI_URL,
            ],
            capture_output=True,
            text=True,
            timeout=_HF_WHOAMI_TIMEOUT + 2,
        )
        t1 = _t.monotonic()
        if result.returncode == 0 and result.stdout:
            data = json.loads(result.stdout)
            _hf_username_cache = data.get("name", "unknown")
            logger.info(
                f"HF username resolved to '{_hf_username_cache}' in {t1 - t0:.2f}s"
            )
        else:
            logger.warning(
                f"curl whoami failed (rc={result.returncode}) in {t1 - t0:.2f}s"
            )
            _hf_username_cache = "unknown"
    except Exception as e:
        t1 = _t.monotonic()
        logger.warning(f"HF whoami failed in {t1 - t0:.2f}s: {e}")
        _hf_username_cache = "unknown"

    return _hf_username_cache


class ContextManager:
    """Manages conversation context and message history for the agent"""

    def __init__(
        self,
        max_context: int = 180_000,
        compact_size: float = 0.1,
        untouched_messages: int = 5,
        tool_specs: list[dict[str, Any]] | None = None,
        prompt_file_suffix: str = "system_prompt_v2.yaml",
    ):
        self.system_prompt = self._load_system_prompt(
            tool_specs or [],
            prompt_file_suffix="system_prompt_v2.yaml",
        )
        self.max_context = max_context
        self.compact_size = int(max_context * compact_size)
        self.context_length = len(self.system_prompt) // 4
        self.untouched_messages = untouched_messages
        self.items: list[Message] = [Message(role="system", content=self.system_prompt)]

    def _load_system_prompt(
        self,
        tool_specs: list[dict[str, Any]],
        prompt_file_suffix: str = "system_prompt.yaml",
    ):
        """Load and render the system prompt from YAML file with Jinja2"""
        prompt_file = Path(__file__).parent.parent / "prompts" / f"{prompt_file_suffix}"

        with open(prompt_file, "r") as f:
            prompt_data = yaml.safe_load(f)
            template_str = prompt_data.get("system_prompt", "")

        # Get current date and time
        tz = zoneinfo.ZoneInfo("Europe/Paris")
        now = datetime.now(tz)
        current_date = now.strftime("%d-%m-%Y")
        current_time = now.strftime("%H:%M:%S.%f")[:-3]
        current_timezone = f"{now.strftime('%Z')} (UTC{now.strftime('%z')[:3]}:{now.strftime('%z')[3:]})"

        # Get HF user info (cached after the first call)
        hf_user_info = _get_hf_username()

        template = Template(template_str)
        return template.render(
            tools=tool_specs,
            num_tools=len(tool_specs),
            current_date=current_date,
            current_time=current_time,
            current_timezone=current_timezone,
            hf_user_info=hf_user_info,
        )

    def add_message(self, message: Message, token_count: int = None) -> None:
        """Add a message to the history"""
        if token_count:
            self.context_length = token_count
        self.items.append(message)

    def get_messages(self) -> list[Message]:
        """Get all messages for sending to LLM"""
        return self.items

    async def compact(self, model_name: str) -> None:
        """Remove old messages to keep history under target size"""
        if (self.context_length <= self.max_context) or not self.items:
            return

        system_msg = (
            self.items[0] if self.items and self.items[0].role == "system" else None
        )

        # Don't summarize a certain number of just-preceding messages
        # Walk back to find a user message to make sure we keep an assistant -> user ->
        # assistant general conversation structure
        idx = len(self.items) - self.untouched_messages
        while idx > 1 and self.items[idx].role != "user":
            idx -= 1

        recent_messages = self.items[idx:]
        messages_to_summarize = self.items[1:idx]

        # improbable, messages would have to very long
        if not messages_to_summarize:
            return

        messages_to_summarize.append(
            Message(
                role="user",
                content="Please provide a concise summary of the conversation above, focusing on key decisions, code changes, problems solved, and important context needed for future turns.",
            )
        )

        hf_key = os.environ.get("INFERENCE_TOKEN")
        response = await acompletion(
            model=model_name,
            messages=messages_to_summarize,
            max_completion_tokens=self.compact_size,
            api_key=hf_key
            if hf_key and model_name.startswith("huggingface/")
            else None,
        )
        summarized_message = Message(
            role="assistant", content=response.choices[0].message.content
        )

        # Reconstruct: system + summary + recent messages (includes tools)
        if system_msg:
            self.items = [system_msg, summarized_message] + recent_messages
        else:
            self.items = [summarized_message] + recent_messages

        self.context_length = (
            len(self.system_prompt) // 4 + response.usage.completion_tokens
        )