from __future__ import annotations

from dataclasses import dataclass, field, replace
from typing import Any, Optional
from uuid import uuid4

from fastapi import Request


CONTRACT_VERSION = "v1alpha1"
DEFAULT_EXECUTOR_TYPE = "legacy_subprocess"


@dataclass(frozen=True)
class RequestContext:
    """Minimal request-scoped metadata passed into application services."""

    request_id: str
    contract_version: str = CONTRACT_VERSION
    executor_type: str = DEFAULT_EXECUTOR_TYPE
    auth_key: Optional[str] = None
    provider_api_key: Optional[str] = None
    llm_provider: Optional[str] = None
    backend_url: Optional[str] = None
    deep_think_llm: Optional[str] = None
    quick_think_llm: Optional[str] = None
    selected_analysts: tuple[str, ...] = ()
    analysis_prompt_style: Optional[str] = None
    llm_timeout: Optional[float] = None
    llm_max_retries: Optional[int] = None
    client_host: Optional[str] = None
    is_local: bool = False
    metadata: dict[str, Any] = field(default_factory=dict)


def build_request_context(
    request: Optional[Request] = None,
    *,
    auth_key: Optional[str] = None,
    provider_api_key: Optional[str] = None,
    llm_provider: Optional[str] = None,
    backend_url: Optional[str] = None,
    deep_think_llm: Optional[str] = None,
    quick_think_llm: Optional[str] = None,
    selected_analysts: Optional[list[str] | tuple[str, ...]] = None,
    analysis_prompt_style: Optional[str] = None,
    llm_timeout: Optional[float] = None,
    llm_max_retries: Optional[int] = None,
    request_id: Optional[str] = None,
    contract_version: str = CONTRACT_VERSION,
    executor_type: str = DEFAULT_EXECUTOR_TYPE,
    metadata: Optional[dict[str, Any]] = None,
) -> RequestContext:
    """Create a stable request context without leaking FastAPI internals into services."""
    client_host = request.client.host if request and request.client else None
    is_local = client_host in {"127.0.0.1", "::1", "localhost", "testclient"}
    return RequestContext(
        request_id=request_id or uuid4().hex,
        contract_version=contract_version,
        executor_type=executor_type,
        auth_key=auth_key,
        provider_api_key=provider_api_key,
        llm_provider=llm_provider,
        backend_url=backend_url,
        deep_think_llm=deep_think_llm,
        quick_think_llm=quick_think_llm,
        selected_analysts=tuple(selected_analysts or ()),
        analysis_prompt_style=analysis_prompt_style,
        llm_timeout=llm_timeout,
        llm_max_retries=llm_max_retries,
        client_host=client_host,
        is_local=is_local,
        metadata=dict(metadata or {}),
    )


def clone_request_context(
    context: RequestContext,
    *,
    metadata_updates: Optional[dict[str, Any]] = None,
    **overrides: Any,
) -> RequestContext:
    metadata = dict(context.metadata)
    metadata.update(metadata_updates or {})
    return replace(context, metadata=metadata, **overrides)