server/scenario_loader.py

"""Scenario loader — load scenario definitions from JSON files."""

from __future__ import annotations

import json
import os
import shutil
from pathlib import Path
from typing import Optional

WORKBOOKS_DIR = os.getenv("WORKBOOKS_DIR", str(Path(__file__).resolve().parent.parent / "workbooks"))
SCENARIOS_DIR = os.getenv("SCENARIOS_DIR", str(Path(__file__).resolve().parent.parent / "scenarios"))
FIXTURES_DIR = os.path.join(WORKBOOKS_DIR, "fixtures")
TEMPLATES_DIR = os.path.join(WORKBOOKS_DIR, "templates")


def list_scenarios() -> list[dict]:
    """List all available scenario definitions."""
    if not os.path.isdir(SCENARIOS_DIR):
        return []
    scenarios = []
    for f in sorted(os.listdir(SCENARIOS_DIR)):
        if not f.endswith(".json"):
            continue
        try:
            data = load_scenario_def(f.replace(".json", ""))
            scenarios.append({
                "scenario_id": data.get("id", f.replace(".json", "")),
                "description": data.get("description", ""),
                "workbook": data.get("workbook", ""),
                "max_steps": data.get("max_steps", 50),
            })
        except Exception:
            continue
    return scenarios


def load_scenario_def(scenario_id: str) -> dict:
    """Load a single scenario definition JSON."""
    path = os.path.join(SCENARIOS_DIR, f"{scenario_id}.json")
    if not os.path.isfile(path):
        raise FileNotFoundError(f"Scenario '{scenario_id}' not found at {path}")
    with open(path) as f:
        return json.load(f)


def prepare_workbook_for_session(scenario_id: str, session_id: str) -> str:
    """Copy the template workbook to a session-specific fixture path.
    
    Returns the path to the session's workbook copy.
    """
    scenario = load_scenario_def(scenario_id)
    template_name = scenario.get("workbook", f"{scenario_id}.xlsx")
    template_path = os.path.join(TEMPLATES_DIR, template_name)

    if not os.path.isfile(template_path):
        raise FileNotFoundError(f"Template workbook not found: {template_path}")

    os.makedirs(FIXTURES_DIR, exist_ok=True)
    session_wb_path = os.path.join(FIXTURES_DIR, f"{session_id}_{template_name}")
    shutil.copy2(template_path, session_wb_path)
    return session_wb_path