"""训练日志CSV记录器"""
import csv
import os


class TrainingLogger:
    def __init__(self, log_dir, model_name, resume=False):
        self.log_path = os.path.join(log_dir, f"{model_name}_training_log.csv")
        self.fieldnames = [
            "episode", "reward", "throughput", "mean_speed",
            "policy_loss", "value_loss", "entropy"
        ]

        if not resume or not os.path.exists(self.log_path):
            with open(self.log_path, "w", newline="", encoding="utf-8") as f:
                writer = csv.DictWriter(f, fieldnames=self.fieldnames)
                writer.writeheader()

    def log(self, episode, reward, throughput, mean_speed,
            policy_loss=None, value_loss=None, entropy=None):
        with open(self.log_path, "a", newline="", encoding="utf-8") as f:
            writer = csv.DictWriter(f, fieldnames=self.fieldnames)
            writer.writerow({
                "episode": episode,
                "reward": f"{reward:.4f}",
                "throughput": f"{throughput:.2f}",
                "mean_speed": f"{mean_speed:.2f}",
                "policy_loss": f"{policy_loss:.6f}" if policy_loss is not None else "",
                "value_loss": f"{value_loss:.6f}" if value_loss is not None else "",
                "entropy": f"{entropy:.6f}" if entropy is not None else ""
            })