'''imports'''
import machine
import math
import time

'''
Pin and constant definitions
'''

sevseg_pins = 8 # including DP
sevseg_dig = 4
SEVEN_SEGMENT_START_PIN = 0
DISPLAY_COUNT = 4
DECIMAL_PRECISION = 3

'''HEX values for 7 segment display values'''
digit_list_hex = [
    0x40,  # 0
    0x79,  # 1
    0x24,  # 2
    0x30,  # 3
    0x19,  # 4
    0x12,  # 5
    0x02,  # 6
    0x78,  # 7
    0x00,  # 8
    0x10,  # 9
    0x08,  # A
    0x03,  # B
    0x46,  # C
    0x21,  # D
    0x06,  # E
    0x0E,  # F
    0x7F   # Empty
]

'''
Global variables
'''
display_value = 0
segment_pins = []
display_select_pins = []
current_display_index = DISPLAY_COUNT -1  # to keep track of which digit is currently being displayed
display_timer = None
counter_timer = None

last_button_time_click = 0
button_click = "no"

'''
Function definitions
'''

def interrupt_callback(pin):
    global last_button_time_click, button_click

    program_start = time.ticks_ms()
    time_between_buttons = program_start - last_button_time_click
    if time_between_buttons > 250: #I made the debouncing to 250 because it still bounced at 200
        last_button_time_click = program_start
        button_click = "yes"

'''Function to read the ADC pin and
   to convert the digital value to a voltage level in the 0-3.3V range
   This function updates the value of the display_value global variable'''
def read_analogue_voltage():
    global display_value, analog_val

    digital_val = anal_signal.read_u16()
    '''Calculate analog value'''
    analog_val = round(float((digital_val/(2**16-1)) * 3.3), 3)
    print(analog_val, "Volts")

    display_value = int(analog_val * 1000)

'''Function to disable timer that triggers scanning 7 segment displays'''
def disable_display_timer():
    global display_timer
    display_timer.deinit()

'''Function to enable timer that triggers scanning 7 segment displays'''
def enable_display_timer():
    global display_timer
    display_timer.init(period=30, mode=machine.Timer.PERIODIC, callback=scan_display)

'''Function to handle scanning 7 segment displays
   Display the value stored in the display_value global variable
   on available 7-segment displays'''
def scan_display(timer_int):
    global current_display_index, display_value

    '''Extract the digit corresponding to the current display index'''
    digit = int((display_value // math.pow(10, current_display_index))) % 10

    '''Display the digit,
       enable the decimal point if the current digit index equals to the set decimal precision'''
    display_digit(digit, current_display_index, 
        current_display_index == DECIMAL_PRECISION and 0 != DECIMAL_PRECISION)

    '''Move to the next display'''
    current_display_index = (current_display_index - 1)
    if current_display_index < 0:
        current_display_index = DISPLAY_COUNT -1

'''Function display the given value on the display with the specified index
 dp_enable specifies if the decimal point should be on or off'''
def display_digit(digit_value, digit_index, dp_enable=False):
    '''Ensure the value is valid'''
    if digit_value < 0 or digit_value > len(digit_list_hex):
        return

    '''Deselect all display select pins'''
    for pin in display_select_pins:
        pin.value(0)

    '''Set the segments according to the digit value'''
    mask = digit_list_hex[digit_value]
    for i in range(7):  # 7 segments from A to G
        segment_pins[i].value((mask >> i) & 1)

    '''Set the DP if it's enabled'''
    segment_pins[7].value(1 if dp_enable == False else 0)

    '''If digit_index is -1, activate all display select pins'''
    if digit_index == -1:
        for pin in display_select_pins:
            pin.value(1)

    # Otherwise, ensure the index is valid and activate the relevant display select pin
    elif 0 <= digit_index < DISPLAY_COUNT:
        display_select_pins[digit_index].value(1)
    

'''Function to test avaiable 7-segment displays'''
def display_value_test():
    global display_value

    disable_display_timer()
    current_display_index = 0

    for i in range(0, len(digit_list_hex)):
        display_digit(i, -1, i % 2 != 0)
        time.sleep(0.5)

    for i in range(0, len(digit_list_hex)):
        display_digit(i, DISPLAY_COUNT - 1 - (i % DISPLAY_COUNT), True)
        time.sleep(0.5)        

    display_digit(16, -1, False)
    enable_display_timer()

'''Function to setup GPIO/ADC pins, timers and interrupts'''
def setup():
    global anal_signal
    global segment_pins, display_select_pins
    global display_timer, counter_timer

    button = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)
    button.irq(trigger=machine.Pin.IRQ_FALLING, handler=interrupt_callback)

    anal_signal = machine.ADC(26)


    '''Set up display select pins'''
    for i in range(SEVEN_SEGMENT_START_PIN + 8, SEVEN_SEGMENT_START_PIN + 8 + DISPLAY_COUNT):
        pin = machine.Pin(i, machine.Pin.OUT)
        pin.value(0)
        display_select_pins.append(pin)
    
    '''Set up seven segment pins'''
    for i in range(SEVEN_SEGMENT_START_PIN, SEVEN_SEGMENT_START_PIN + 8):
        pin = machine.Pin(i, machine.Pin.OUT)
        pin.value(1)
        segment_pins.append(pin)

    '''Start the timer interrupt for scanning'''
    display_timer = machine.Timer()
    enable_display_timer()


def main():
    time.sleep(.05)
    global button_click, analog_val
    print("Program starting")
    print("Note: the value shown in the Seven-Segment display is in Volts")
    while True:
        if button_click == "yes":
            button_click = "no"
            read_analogue_voltage()
            time.sleep(.5)


        time.sleep(.05)

if __name__ == "__main__":
    setup()
    # display_value_test()
    main()