#!/usr/bin/env python3
"""Parse ALSA status log file and plot avail value over time."""

import sys
import re
import os
from datetime import datetime

import matplotlib.pyplot as plt


TIMESTAMP_RE = re.compile(r"^===== (\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d+) =====")
AVAIL_RE = re.compile(r"^avail\s*:\s*(\d+)")


def parse_log(log_path):
    timestamps = []
    avail_values = []

    with open(log_path, "r") as f:
        current_timestamp = None
        for line in f:
            line = line.strip()
            
            # Check for timestamp line
            ts_match = TIMESTAMP_RE.match(line)
            if ts_match:
                current_timestamp = datetime.strptime(ts_match.group(1), "%Y-%m-%d %H:%M:%S.%f")
                continue
            
            # Check for avail line (only if we have a timestamp)
            if current_timestamp:
                avail_match = AVAIL_RE.match(line)
                if avail_match:
                    timestamps.append(current_timestamp)
                    avail_values.append(int(avail_match.group(1)))
                    current_timestamp = None  # Reset until next timestamp

    if not timestamps:
        print("No valid timestamp/avail pairs found in the log file.", file=sys.stderr)
        sys.exit(1)

    # Convert to relative seconds from first timestamp
    t0 = timestamps[0]
    seconds = [(t - t0).total_seconds() for t in timestamps]
    return seconds, avail_values


def plot(seconds, avail_values, out_path):
    plt.figure(figsize=(12, 6))
    plt.plot(seconds, avail_values, label="avail", linewidth=1, alpha=0.7)
    
    # Add moving average (windowed mean)
    if len(avail_values) >= 10:  # Only if we have enough data points
        window_size = min(50, len(avail_values) // 10)  # Adaptive window size
        import numpy as np
        moving_avg = np.convolve(avail_values, np.ones(window_size)/window_size, mode='valid')
        # Adjust timestamps for the moving average (they align with window centers)
        ma_seconds = seconds[window_size-1:]
        plt.plot(ma_seconds, moving_avg, label=f"moving mean (window={window_size})", linewidth=2)
    
    plt.xlabel("Time (s)")
    plt.ylabel("Available samples")
    plt.title("ALSA Available Samples Over Time")
    plt.legend()
    plt.grid(True)
    plt.tight_layout()
    plt.savefig(out_path, dpi=150)
    print(f"Plot saved to {out_path}")


def main():
    if len(sys.argv) != 2:
        print(f"Usage: {sys.argv[0]} <path_to_alsa_status_log>", file=sys.stderr)
        sys.exit(1)

    log_path = sys.argv[1]
    if not os.path.isfile(log_path):
        print(f"File not found: {log_path}", file=sys.stderr)
        sys.exit(1)

    seconds, avail_values = parse_log(log_path)

    log_dir = os.path.dirname(os.path.abspath(log_path))
    log_base = os.path.splitext(os.path.basename(log_path))[0]
    out_path = os.path.join(log_dir, f"{log_base}_avail_plot.png")

    plot(seconds, avail_values, out_path)


if __name__ == "__main__":
    main()