"""LangSmith sandbox backend integration."""

from __future__ import annotations

import base64
import logging
import os
import time
from abc import ABC, abstractmethod
from typing import Any

import httpx
from deepagents.backends import LangSmithSandbox
from deepagents.backends.protocol import SandboxBackendProtocol
from langsmith.sandbox import SandboxClient

logger = logging.getLogger(__name__)

DEFAULT_SNAPSHOT_FS_CAPACITY_BYTES = 32 * 1024**3
DEFAULT_SANDBOX_VCPUS = 2
DEFAULT_SANDBOX_MEM_BYTES = 7936 * 1024**2  # 7936 MiB ("large" tier cap)
DEFAULT_SANDBOX_IDLE_TTL_SECONDS = 10 * 60  # 10 minutes
DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS = 24 * 60 * 60  # 24 hours
PROXY_CONFIG_MAX_ATTEMPTS = 3
PROXY_CONFIG_TIMEOUT_SECONDS = 10.0
PROXY_CONFIG_RETRY_DELAYS_SECONDS = (0.5, 1.0)
PROXY_CONFIG_RETRYABLE_STATUS_CODES = frozenset({408, 409, 425, 429, 500, 502, 503, 504, 529})


def _get_langsmith_api_key() -> str | None:
    """Get LangSmith API key from environment.

    Checks LANGSMITH_API_KEY first, then falls back to LANGSMITH_API_KEY_PROD
    for LangGraph Cloud deployments where LANGSMITH_API_KEY is reserved.
    """
    return os.environ.get("LANGSMITH_API_KEY") or os.environ.get("LANGSMITH_API_KEY_PROD")


def _parse_optional_int(name: str, default: int) -> int:
    raw = os.environ.get(name)
    if not raw:
        return default
    try:
        return int(raw)
    except ValueError as e:
        msg = f"{name} must be an integer, got {raw!r}"
        raise ValueError(msg) from e


def _get_sandbox_snapshot_config() -> tuple[str | None, int, int, int, int, int]:
    """Get sandbox snapshot configuration from environment."""
    snapshot_id = os.environ.get("DEFAULT_SANDBOX_SNAPSHOT_ID")
    fs_capacity_bytes = _parse_optional_int(
        "DEFAULT_SANDBOX_SNAPSHOT_FS_CAPACITY_BYTES", DEFAULT_SNAPSHOT_FS_CAPACITY_BYTES
    )
    vcpus = _parse_optional_int("DEFAULT_SANDBOX_VCPUS", DEFAULT_SANDBOX_VCPUS)
    mem_bytes = _parse_optional_int("DEFAULT_SANDBOX_MEM_BYTES", DEFAULT_SANDBOX_MEM_BYTES)
    idle_ttl_seconds = _parse_optional_int(
        "DEFAULT_SANDBOX_IDLE_TTL_SECONDS", DEFAULT_SANDBOX_IDLE_TTL_SECONDS
    )
    delete_after_stop_seconds = _parse_optional_int(
        "DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS",
        DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS,
    )
    return (
        snapshot_id,
        fs_capacity_bytes,
        vcpus,
        mem_bytes,
        idle_ttl_seconds,
        delete_after_stop_seconds,
    )


def _github_proxy_rules(github_token: str) -> list[dict[str, Any]]:
    basic_auth = base64.b64encode(f"x-access-token:{github_token}".encode()).decode()
    return [
        {
            "name": "github-api",
            "match_hosts": ["api.github.com"],
            "headers": [
                {
                    "name": "Authorization",
                    "type": "opaque",
                    "value": f"Bearer {github_token}",
                }
            ],
        },
        {
            "name": "github",
            "match_hosts": ["github.com", "*.github.com"],
            "headers": [
                {
                    "name": "Authorization",
                    "type": "opaque",
                    "value": f"Basic {basic_auth}",
                }
            ],
        },
    ]


def _retry_after_seconds(response: httpx.Response | None) -> float | None:
    if response is None:
        return None
    raw = response.headers.get("Retry-After")
    if not raw:
        return None
    try:
        delay = float(raw)
    except ValueError:
        return None
    return max(delay, 0.0)


def _is_retryable_proxy_config_error(exc: BaseException) -> bool:
    if isinstance(exc, httpx.HTTPStatusError):
        return exc.response.status_code in PROXY_CONFIG_RETRYABLE_STATUS_CODES
    return isinstance(exc, httpx.TransportError)


def _configure_github_proxy(sandbox_name: str, github_token: str) -> None:
    """Configure sandbox proxy to inject GitHub auth for GitHub traffic.

    Uses the LangSmith proxy-config API to set up header injection so that
    git operations (clone, pull, push) authenticate via the proxy rather than
    writing credentials to disk in the sandbox.

    Args:
        sandbox_name: The sandbox name/ID returned by the LangSmith API.
        github_token: GitHub token to inject as Authorization header.
    """
    api_key = _get_langsmith_api_key()
    if not api_key:
        logger.warning("No LangSmith API key found, skipping GitHub proxy configuration")
        return
    langsmith_endpoint = os.environ.get("LANGSMITH_ENDPOINT", "https://api.smith.langchain.com")
    url = f"{langsmith_endpoint}/v2/sandboxes/boxes/{sandbox_name}"
    payload = {"proxy_config": {"rules": _github_proxy_rules(github_token)}}
    with httpx.Client(timeout=PROXY_CONFIG_TIMEOUT_SECONDS) as client:
        for attempt in range(PROXY_CONFIG_MAX_ATTEMPTS):
            try:
                response = client.patch(
                    url,
                    json=payload,
                    headers={"X-API-Key": api_key},
                )
                response.raise_for_status()
                break
            except Exception as exc:
                if attempt == PROXY_CONFIG_MAX_ATTEMPTS - 1 or not _is_retryable_proxy_config_error(
                    exc
                ):
                    raise
                retry_after = (
                    _retry_after_seconds(exc.response)
                    if isinstance(exc, httpx.HTTPStatusError)
                    else None
                )
                delay = (
                    retry_after
                    or PROXY_CONFIG_RETRY_DELAYS_SECONDS[
                        min(attempt, len(PROXY_CONFIG_RETRY_DELAYS_SECONDS) - 1)
                    ]
                )
                logger.warning(
                    "Failed to configure GitHub proxy for sandbox %s (%s); retrying in %.1fs",
                    sandbox_name,
                    type(exc).__name__,
                    delay,
                )
                time.sleep(delay)
    logger.info("Configured GitHub proxy for sandbox %s", sandbox_name)


def create_langsmith_sandbox(
    sandbox_id: str | None = None,
    github_token: str | None = None,
) -> SandboxBackendProtocol:
    """Create or connect to a LangSmith sandbox without automatic cleanup.

    This function directly uses the LangSmithProvider to create/connect to sandboxes
    without the context manager cleanup, allowing sandboxes to persist across
    multiple agent invocations.

    Args:
        sandbox_id: Optional existing sandbox ID to connect to.
                   If None, creates a new sandbox.
        github_token: Optional GitHub token. Used to configure proxy auth on
                      new sandboxes. Ignored when connecting to an existing sandbox.

    Returns:
        SandboxBackendProtocol instance
    """
    api_key = _get_langsmith_api_key()
    (
        snapshot_id,
        fs_capacity_bytes,
        vcpus,
        mem_bytes,
        idle_ttl_seconds,
        delete_after_stop_seconds,
    ) = _get_sandbox_snapshot_config()

    provider = LangSmithProvider(api_key=api_key)
    backend = provider.get_or_create(
        sandbox_id=sandbox_id,
        snapshot_id=snapshot_id,
        fs_capacity_bytes=fs_capacity_bytes,
        vcpus=vcpus,
        mem_bytes=mem_bytes,
        idle_ttl_seconds=idle_ttl_seconds,
        delete_after_stop_seconds=delete_after_stop_seconds,
    )
    _update_thread_sandbox_metadata(backend.id)

    if sandbox_id is None and github_token:
        _configure_github_proxy(backend.id, github_token)

    return backend


def _update_thread_sandbox_metadata(sandbox_id: str) -> None:
    """Update thread metadata with sandbox_id."""
    try:
        import asyncio

        from langgraph.config import get_config
        from langgraph_sdk import get_client

        config = get_config()
        thread_id = config.get("configurable", {}).get("thread_id")
        if not thread_id:
            return
        client = get_client()

        async def _update() -> None:
            await client.threads.update(
                thread_id=thread_id,
                metadata={"sandbox_id": sandbox_id},
            )

        try:
            loop = asyncio.get_running_loop()
        except RuntimeError:
            asyncio.run(_update())
        else:
            loop.create_task(_update())
    except Exception:
        pass


class SandboxProvider(ABC):
    """Interface for creating and deleting sandbox backends."""

    @abstractmethod
    def get_or_create(
        self,
        *,
        sandbox_id: str | None = None,
        **kwargs: Any,
    ) -> SandboxBackendProtocol:
        """Get an existing sandbox, or create one if needed."""
        raise NotImplementedError

    @abstractmethod
    def delete(
        self,
        *,
        sandbox_id: str,
        **kwargs: Any,
    ) -> None:
        """Delete a sandbox by id."""
        raise NotImplementedError


class LangSmithProvider(SandboxProvider):
    """LangSmith sandbox provider implementation."""

    def __init__(self, api_key: str | None = None) -> None:
        from langsmith import sandbox

        self._api_key = api_key or _get_langsmith_api_key()
        if not self._api_key:
            msg = "LANGSMITH_API_KEY (or LANGSMITH_API_KEY_PROD) not set"
            raise ValueError(msg)
        self._client: SandboxClient = sandbox.SandboxClient(api_key=self._api_key)

    @classmethod
    def validate_startup_config(cls) -> None:
        """Validate env-var configuration at server startup. Raises ValueError if invalid."""
        if not os.environ.get("DEFAULT_SANDBOX_SNAPSHOT_ID"):
            msg = "DEFAULT_SANDBOX_SNAPSHOT_ID must be set when SANDBOX_TYPE=langsmith"
            raise ValueError(msg)
        for name in (
            "DEFAULT_SANDBOX_SNAPSHOT_FS_CAPACITY_BYTES",
            "DEFAULT_SANDBOX_VCPUS",
            "DEFAULT_SANDBOX_MEM_BYTES",
            "DEFAULT_SANDBOX_IDLE_TTL_SECONDS",
            "DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS",
        ):
            raw = os.environ.get(name)
            if raw is None or raw == "":
                continue
            try:
                value = int(raw)
            except ValueError as e:
                msg = f"{name} must be an integer, got {raw!r}"
                raise ValueError(msg) from e
            if (
                name
                in {
                    "DEFAULT_SANDBOX_IDLE_TTL_SECONDS",
                    "DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS",
                }
                and value < 0
            ):
                msg = f"{name} must be >= 0, got {value}"
                raise ValueError(msg)

    def get_or_create(
        self,
        *,
        sandbox_id: str | None = None,
        timeout: int = 180,
        snapshot_id: str | None = None,
        fs_capacity_bytes: int | None = None,
        vcpus: int | None = None,
        mem_bytes: int | None = None,
        idle_ttl_seconds: int | None = None,
        delete_after_stop_seconds: int | None = None,
        **kwargs: Any,
    ) -> SandboxBackendProtocol:
        """Get existing or create new LangSmith sandbox."""
        if kwargs:
            msg = f"Received unsupported arguments: {list(kwargs.keys())}"
            raise TypeError(msg)
        if sandbox_id:
            try:
                sandbox = self._client.get_sandbox(name=sandbox_id)
            except Exception as e:
                msg = f"Failed to connect to existing sandbox '{sandbox_id}': {e}"
                raise RuntimeError(msg) from e
            return LangSmithSandbox(sandbox)

        if not snapshot_id:
            msg = "DEFAULT_SANDBOX_SNAPSHOT_ID must be set when SANDBOX_TYPE=langsmith"
            raise ValueError(msg)

        try:
            sandbox = self._client.create_sandbox(
                snapshot_id=snapshot_id,
                fs_capacity_bytes=fs_capacity_bytes,
                vcpus=vcpus,
                mem_bytes=mem_bytes,
                idle_ttl_seconds=idle_ttl_seconds,
                delete_after_stop_seconds=delete_after_stop_seconds,
                timeout=timeout,
            )
        except Exception as e:
            msg = f"Failed to create sandbox from snapshot '{snapshot_id}': {e}"
            raise RuntimeError(msg) from e

        return LangSmithSandbox(sandbox)

    def delete(self, *, sandbox_id: str, **kwargs: Any) -> None:
        """Delete a LangSmith sandbox."""
        self._client.delete_sandbox(sandbox_id)