project_config.py

"""Load project configuration from ``config.json``."""

from __future__ import annotations

import json
from functools import lru_cache
from pathlib import Path
from typing import Literal

from pydantic import BaseModel, ConfigDict, Field


class StartupConfig(BaseModel):
    """Startup command planning and approval configuration."""

    model_config = ConfigDict(extra="forbid")

    approved_command: str | None = None
    approval_required: bool = False
    auto_start: bool = True
    readiness_path: str = "/openapi.json"
    readiness_timeout_seconds: float = 20.0


class ServiceConfig(BaseModel):
    """Configuration for the scanned target service and harness."""

    model_config = ConfigDict(extra="forbid")

    repo_path: str = "."
    service_url: str | None = None
    auth_token: str | None = None
    startup: StartupConfig = Field(default_factory=StartupConfig)


class LLMConfig(BaseModel):
    """Configuration for the external LLM provider."""

    model_config = ConfigDict(extra="forbid")

    provider: str | None = None
    base_url: str | None = None
    api_key: str | None = None
    model: str | None = None
    mode: Literal["auto", "responses", "chat-completions"] = "auto"


class ProjectConfig(BaseModel):
    """Top-level project configuration loaded from JSON."""

    model_config = ConfigDict(extra="forbid")

    service: ServiceConfig = Field(default_factory=ServiceConfig)
    llm: LLMConfig = Field(default_factory=LLMConfig)


def default_config_path() -> Path:
    """Return the default config file location."""

    return Path(__file__).resolve().parent / "config.json"


def load_config(path: str | Path | None = None) -> ProjectConfig:
    """Load and validate project configuration from disk."""

    config_path = Path(path) if path is not None else default_config_path()
    return _load_config_cached(str(config_path.resolve()))


@lru_cache(maxsize=8)
def _load_config_cached(path: str) -> ProjectConfig:
    config_path = Path(path)
    if not config_path.exists():
        raise FileNotFoundError(
            f"Config file not found: {config_path}. Create it from config.example.json."
        )

    payload = json.loads(config_path.read_text(encoding="utf-8"))
    if not isinstance(payload, dict):
        raise TypeError("config.json must contain a JSON object.")
    return ProjectConfig.model_validate(payload)