import json
import os
from datetime import datetime

def load_config():
    """Loads config.json and ensures directories exist."""
    try:
        with open("config.json", "r") as f:
            config = json.load(f)
            
        os.makedirs(config.get("DataDirectory", "./"), exist_ok=True)
        os.makedirs(config.get("PDFOutputDirectory", "./"), exist_ok=True)
        return config
    except FileNotFoundError:
        print("Error: config.json is missing. Please create it.")
        exit(1)
    except Exception as e:
        print(f"Error reading config: {e}")
        exit(1)

def load_json(filepath, default_structure):
    """Loads a JSON file or creates it with a default structure if missing."""
    if not os.path.exists(filepath):
        save_json(filepath, default_structure)
        return default_structure
    try:
        with open(filepath, "r") as f:
            return json.load(f)
    except json.JSONDecodeError:
        print(f"Warning: {filepath} is corrupted. Returning default structure.")
        return default_structure

def save_json(filepath, data):
    """Saves data to a JSON file."""
    try:
        with open(filepath, "w") as f:
            json.dump(data, f, indent=2)
    except Exception as e:
        print(f"File write failure for {filepath}: {e}")

def get_next_id(prefix, current_records, id_field):
    """Generates the next sequential ID (e.g., CLT-001)."""
    if not current_records:
        return f"{prefix}-001"
    ids = [int(r[id_field].split("-")[1]) for r in current_records if r[id_field].startswith(prefix)]
    next_num = max(ids) + 1 if ids else 1
    return f"{prefix}-{next_num:03d}"