import time
from collections import deque
import Adafruit_ADS1x15

# ---- Config ----
CHANNEL = 0          # A0
GAIN = 1             # +/-4.096V
SAMPLE_HZ = 50       # 50 samples/sec is enough for breathing
WINDOW_SEC = 6       # normalise over last N seconds
REFRACTORY_SEC = 1.0 # minimum time between detected breaths

adc = Adafruit_ADS1x15.ADS1115()
LSB = 4.096 / 32768.0

N = int(SAMPLE_HZ * WINDOW_SEC)
buf = deque(maxlen=N)

baseline = 0.0
alpha = 0.02  # baseline tracking speed (lower = slower drift removal)

last_cross = 0.0
breath_times = deque(maxlen=8)
armed = True

def read_v():
    raw = adc.read_adc(CHANNEL, gain=GAIN)
    return raw * LSB

def clamp(x, lo, hi):
    return lo if x < lo else hi if x > hi else x

print("Breath scope: Ctrl+C to stop")
print("Tip: put belt on, breathe slowly for 10s to let it settle.\n")

while True:
    v = read_v()

    # Remove slow drift (piezo/belt baseline wander)
    baseline = (1 - alpha) * baseline + alpha * v
    x = v - baseline  # "AC" part (what we care about)

    buf.append(x)

    # Normalise based on recent window
    if len(buf) > 20:
        mn = min(buf)
        mx = max(buf)
        span = (mx - mn) if (mx - mn) > 1e-6 else 1e-6
        norm = (x - mn) / span  # 0..1
    else:
        norm = 0.5

    # Draw a bar (0..50 chars)
    width = 50
    pos = int(clamp(norm, 0.0, 1.0) * width)
    bar = (" " * pos) + "|" + (" " * (width - pos))

    # Simple breath detection: threshold crossing on normalised signal
    now = time.time()
    thr = 0.75  # adjust if needed
    if len(buf) > 20:
        if armed and norm > thr and (now - last_cross) > REFRACTORY_SEC:
            breath_times.append(now)
            last_cross = now
            armed = False
        if norm < 0.55:
            armed = True

    bpm = None
    if len(breath_times) >= 3:
        periods = [breath_times[i] - breath_times[i-1] for i in range(1, len(breath_times))]
        avg_p = sum(periods) / len(periods)
        if avg_p > 0:
            bpm = 60.0 / avg_p

    # Print one line, overwrite in place
    if bpm is None:
        line = "V={:0.3f}  AC={:+0.3f}  [{}]".format(v, x, bar)
    else:
        line = "V={:0.3f}  AC={:+0.3f}  BPM={:0.1f}  [{}]".format(v, x, bpm, bar)

    print("\r" + line + "   ", end="")
    time.sleep(1.0 / SAMPLE_HZ)