import os
import numpy as np
import matplotlib.pyplot as plt

DATA_DIR = "data"

# find newest summary file
files = [f for f in os.listdir(DATA_DIR)
         if f.startswith("summary_") and f.endswith(".csv")]
if not files:
    raise FileNotFoundError("No summary files found in 'data/'")

latest = max(files, key=lambda f: os.path.getmtime(os.path.join(DATA_DIR, f)))
path = os.path.join(DATA_DIR, latest)

print(f"Using {path}")

starts = []
ends = []

with open(path, "r") as f:
    next(f)  # skip header
    for line in f:
        parts = line.strip().split(",")
        if len(parts) < 2:
            continue
        start_ms = float(parts[0])
        end_ms = float(parts[1])
        starts.append(start_ms)
        ends.append(end_ms)

starts = np.array(starts)
ends   = np.array(ends)

# measurement durations
measurement = ends - starts

# gap durations (between batches)
# drop last batch because there is no next-start to compute gap against
gaps = starts[1:] - ends[:-1]

# align measurement durations to gaps dimension
# (both arrays indexed by batch interval "between measurements")
measurement = measurement[:-1]

# percentages
total = measurement + gaps
measurement_pct = (measurement / total) * 100.0
downtime_pct = (gaps / total) * 100.0

# time axis: batch index (no absolute time in summaries)
x = np.arange(len(measurement_pct))

# plot
plt.figure(figsize=(12, 6))
plt.plot(x, measurement_pct, label="measurement time (%)")
plt.plot(x, downtime_pct, label="downtime (%)")

plt.xlabel("Batch index")
plt.ylabel("Percentage of interval")
plt.title(f"Measurement vs. Downtime Percentage ({latest})")
plt.grid(True)
plt.legend()

plt.tight_layout()
plt.show()