from machine import ADC
import time

# --- Sensor setup ---
ldr = ADC(26)          # LDR connected to GP26 (ADC0)

# --- List to store readings ---
ldr_values = []        # start with empty list

TOTAL_SAMPLES = 10     # how many readings to take
INTERVAL_SEC = 2       # time gap between readings (seconds)

print("Taking", TOTAL_SAMPLES, "LDR readings...")

# --- Collect readings into the list ---
for i in range(TOTAL_SAMPLES):
    value = ldr.read_u16()      # read sensor value
    ldr_values.append(value)    # store in the list
    
    print("Reading", i+1, "=", value)
    time.sleep(INTERVAL_SEC)

print("\nAll readings:", ldr_values)

# --- Analyse the readings using list functions ---
highest = max(ldr_values)
lowest  = min(ldr_values)
total   = sum(ldr_values)
average = total / len(ldr_values)

print("\nAnalysis of LDR readings:")
print("Maximum value :", highest)
print("Minimum value :", lowest)
print("Average value :", average)

# -------------------------------------------------
#   File Handling: save readings into CSV file
# -------------------------------------------------

FILENAME = "ldr_log.csv"

# 1) Open file in WRITE mode ("w")
f = open(FILENAME, "w")

# 2) Write header row (for Excel)
f.write("Sample,LDR_ADC\n")

# 3) Write each reading from the list as one row
for i in range(len(ldr_values)):
    sample_no = i + 1
    value = ldr_values[i]
    line = str(sample_no) + "," + str(value) + "\n"
    f.write(line)

# write analysis results at the end
f.write("\nMaximum," + str(highest) + "\n")
f.write("Minimum," + str(lowest) + "\n")
f.write("Average," + str(average) + "\n")

# 4) Close the file
f.close()

print("\nData saved to file:", FILENAME)