import os
import csv
from datetime import datetime, timezone
import threading

# A lock to prevent race conditions when multiple strategies might log at once in the future
log_lock = threading.Lock()

def log_trade(strategy: str, coin: str, action: str, price: float, size: float, signal: str, pnl: float = 0.0):
    """
    Appends a record of a trade action to a persistent CSV log file.

    Args:
        strategy (str): The name of the strategy that triggered the action.
        coin (str): The coin being traded (e.g., 'BTC').
        action (str): The action taken (e.g., 'OPEN_LONG', 'CLOSE_LONG').
        price (float): The execution price of the trade.
        size (float): The size of the trade.
        signal (str): The signal that triggered the trade (e.g., 'BUY', 'SELL').
        pnl (float, optional): The realized profit and loss for closing trades. Defaults to 0.0.
    """
    log_dir = "_logs"
    file_path = os.path.join(log_dir, "trade_history.csv")
    
    # Ensure the logs directory exists
    if not os.path.exists(log_dir):
        os.makedirs(log_dir)

    # Define the headers for the CSV file
    headers = ["timestamp_utc", "strategy", "coin", "action", "price", "size", "signal", "pnl"]
    
    # Check if the file needs a header
    file_exists = os.path.isfile(file_path)

    with log_lock:
        try:
            with open(file_path, 'a', newline='', encoding='utf-8') as f:
                writer = csv.DictWriter(f, fieldnames=headers)
                
                if not file_exists:
                    writer.writeheader()
                
                writer.writerow({
                    "timestamp_utc": datetime.now(timezone.utc).isoformat(),
                    "strategy": strategy,
                    "coin": coin,
                    "action": action,
                    "price": price,
                    "size": size,
                    "signal": signal,
                    "pnl": pnl
                })
        except IOError as e:
            # If logging fails, print an error to the main console as a fallback.
            print(f"CRITICAL: Failed to write to trade log file: {e}")