#!/usr/bin/env python3
"""Analyze a captured frame: extract pulse timing structure.

Usage: .venv/bin/python tools/analyze.py captures/<name>.npz
"""
import sys

import numpy as np

path = sys.argv[1]
d = np.load(path)
volts = d["volts"]
srate = float(d["srate"])
dt_us = 1e6 / srate

# threshold midway between the two dominant plateaus
hi_level = np.median(volts)  # idle dominates the frame -> median = idle (high)
lo_level = np.percentile(volts, 10)
thr = (hi_level + lo_level) / 2
bits = (volts > thr).astype(np.int8)
print(f"levels: high~{hi_level:.2f} low~{lo_level:.2f} thr={thr:.2f} (raw units)")

# run-length encode
edges = np.flatnonzero(np.diff(bits)) + 1
starts = np.concatenate(([0], edges))
ends = np.concatenate((edges, [len(bits)]))
levels = bits[starts]
dur_us = (ends - starts) * dt_us

print(f"{len(levels)} runs total")
print("\nidx level dur_us (first/last runs are idle padding)")
for i, (lv, du) in enumerate(zip(levels, dur_us)):
    tag = "H" if lv else "L"
    print(f"{i:4d} {tag} {du:10.2f}")