import time
import ntptime
import json
import os
from hx710b import HX710B    # Correct driver
from config import *

CALIB_FILE = "calibration.cfg"

tz_offset = 0
utc = time.localtime()
local = time.localtime(time.mktime(utc) + tz_offset * 3600)
ctime = f"{local[0]:02}-{local[1]:02}-{local[2]:02} {local[3]:02}:{local[4]:02}:{local[5]:02}"
#print("Time =", local)
print("Time =", ctime)

# ---------------------------------------------------------
# USER INPUT
# ---------------------------------------------------------
# Water depth (meters)
# KNOWN_DEPTH_M = 1.680

# Pressure created by water column (kPa)
KNOWN_PRESSURE_KPA = KNOWN_DEPTH_M * 9.81

print(
    "\nUsing depth {:.3f} m → expected pressure {:.3f} kPa".format(
        KNOWN_DEPTH_M, KNOWN_PRESSURE_KPA
    )
)

# ---------------------------------------------------------
# SAVE CALIBRATION
# ---------------------------------------------------------
def save_calibration(ctime, zero_offset, raw_at_pressure, scale_factor):
    data = {
        "zero_offset": zero_offset,
        "raw_at_pressure": raw_at_pressure,        
        "scale_factor": scale_factor,
        "Date_Time": ctime
    }

    with open(CALIB_FILE, "w") as f:
        json.dump(data, f)

    print("\n✔ Saved calibration:")
    print("   Date_Time       =", ctime)
    print("   zero_offset     =", zero_offset)
    print("   raw_at_pressure =", raw_at_pressure)
    print("   scale_factor    =", scale_factor)


# ---------------------------------------------------------
# RAW AVERAGING
# ---------------------------------------------------------
def read_average(hx, samples=30):
    total = 0
    for _ in range(samples):
        total += hx.read_raw()
        time.sleep_ms(5)
    return total / samples


# ---------------------------------------------------------
# CALIBRATION PROCESS
# ---------------------------------------------------------
print("\n=== HX710B Depth-Based Calibration ===")

hx = HX710B(dout_pin=0, sck_pin=1)

# Step 1 — ZERO PRESSURE
print("\n➡ Ensure tank is OPEN TO AIR (0 kPa)...")
time.sleep(3)

zero_offset = read_average(hx)
print("Zero offset captured:", zero_offset)

# Step 2 — APPLY KNOWN PRESSURE
print(
    "\n➡ Now apply EXACTLY {:.3f} kPa (depth {:.3f} m)...".format(
        KNOWN_PRESSURE_KPA, KNOWN_DEPTH_M
    )
)
time.sleep(10)

raw_at_pressure = read_average(hx)
print("Raw at known depth:", raw_at_pressure)

# Compute scale factor
scale_factor = KNOWN_PRESSURE_KPA / (raw_at_pressure - zero_offset)

# Save calibration (INCLUDING raw value)
save_calibration(ctime, zero_offset, raw_at_pressure, scale_factor)

print("\n=== Calibration Complete ===")

# ---------------------------------------------------------
# VERIFY
# ---------------------------------------------------------
hx.zero_offset = zero_offset
hx.scale_factor = scale_factor

test = hx.read_kpa()

print("\nVerification reading:", test, "kPa")
print("Expected:", KNOWN_PRESSURE_KPA, "kPa")
print("\nDone.\n")