import framebuf
import network
import ntptime
import time
from machine import Pin, I2C
import ssd1306

# --- Configuration ---
try:
    import config as Config
except ImportError:
    print("ERROR: config.py not found.")
    print("Create config.py on the device with your Wi-Fi and NTP settings.")
    while True:
        time.sleep(2)

# --- Hardware Setup ---
i2c = I2C(0, sda=Pin(16), scl=Pin(17), freq=400000)
oled = ssd1306.SSD1306_I2C(128, 64, i2c)


def display_message(line1, line2=""):
    oled.fill(0)
    oled.text(line1, 0, 16)
    oled.text(line2, 0, 32)
    oled.show()


# --- Wi-Fi Connection ---
display_message("Connecting to", "Wi-Fi...")
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(Config.WIFI_SSID, Config.WIFI_PASSWORD)

timeout = 20
while not wlan.isconnected() and timeout > 0:
    time.sleep(1)
    timeout -= 1

if not wlan.isconnected():
    display_message("Wi-Fi Error", "Check settings")
    raise RuntimeError("Failed to connect to Wi-Fi")

# --- NTP Synchronization ---
display_message("Syncing time...", "NTP server")
try:
    ntptime.settime()  # Sets the Pico internal RTC to UTC
except Exception as e:
    display_message("NTP Failed", str(e))
    time.sleep(3)

# Disconnect Wi-Fi to conserve power once time is synchronized
wlan.active(False)


def draw_scaled_text(display, text, x, y, scale=2):
    """
    Renders text scaled up by an integer factor (scale=2 -> 16x16, scale=3 -> 24x24).
    Uses a temporary 1-bit FrameBuffer to capture the default 8x8 font.
    """
    width = len(text) * 8
    height = 8

    # 1-bit MONO_HLSB buffer: (width * height) / 8 bytes
    buf = bytearray((width * height) // 8)
    fb = framebuf.FrameBuffer(buf, width, height, framebuf.MONO_HLSB)

    # Render string with built-in font into the scratch buffer
    fb.fill(0)
    fb.text(text, 0, 0, 1)

    # Read each pixel and draw a (scale x scale) block on the OLED
    for r in range(height):
        for c in range(width):
            if fb.pixel(c, r):
                display.fill_rect(x + (c * scale), y + (r * scale), scale, scale, 1)


def calculate_x_spacing(text, scale=1):
    """
    Calculates the amount of horizontal (x) spacing is needed to center a string.
    """
    scaled_text = len(text) * scale
    return (128 - (scaled_text * 8)) // 2


def is_dst(year, month, day, hour_utc, weekday):
    """
    Returns True if UTC time falls within US/Canada Daylight Saving Time:
    - Starts: 2nd Sunday in March at 02:00 local (07:00 UTC for UTC-5)
    - Ends:   1st Sunday in November at 02:00 local (06:00 UTC for UTC-4)
    Note: weekday is 0=Monday ... 6=Sunday.
    """
    if not Config.DST_OBSERVED:
        return False

    # 1. Months completely inside or outside DST
    if month < 3 or month > 11:
        return False
    if 3 < month < 11:
        return True

    # 2. March (Starts 2nd Sunday)
    # The 2nd Sunday always falls between March 8 and March 14
    if month == 3:
        # Find the day of the 2nd Sunday
        second_sunday = 14 - ((weekday - day + 14) % 7)
        if day < second_sunday:
            return False
        elif day > second_sunday:
            return True
        else:
            # On the transition day itself, 02:00 EST is 07:00 UTC
            return hour_utc >= 7

    # 3. November (Ends 1st Sunday)
    # The 1st Sunday always falls between Nov 1 and Nov 7
    if month == 11:
        first_sunday = 7 - ((weekday - day + 7) % 7)
        if day < first_sunday:
            return True
        elif day > first_sunday:
            return False
        else:
            # On the transition day itself, 02:00 EDT (01:00 EST) is 06:00 UTC
            return hour_utc < 6

    return False


# --- Main Loop ---
DAYS = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
TIME_Y = 12  # Keep vertical placement consistent

last_second = -1

while True:
    # 1. Fast, single-integer read from RTC
    current_sec = time.time()

    # 2. Gate everything behind the 1-second boundary
    if current_sec != last_second:
        last_second = current_sec

        # Unpack UTC once per second
        utc_year, utc_month, utc_day, utc_hour, _, _, utc_weekday, _ = time.gmtime(current_sec)

        # Run DST check
        dst_offset = 1 if is_dst(utc_year, utc_month, utc_day, utc_hour, utc_weekday) else 0
        total_offset = Config.UTC_OFFSET + dst_offset

        # Compute local wall-clock components
        local_epoch = current_sec + (total_offset * 3600)
        year, month, day, hour_24, minute, second, weekday, _ = time.localtime(local_epoch)

        # --- String formatting and OLED rendering ---
        sep = ":" if second % 2 == 0 else " "

        if Config.USE_24_HOUR:
            time_str = f"{hour_24:02d}{sep}{minute:02d}"
            period = None
        else:
            hour_12 = hour_24 % 12 or 12
            time_str = f"{hour_12}{sep}{minute:02d}"
            period = "AM" if hour_24 < 12 else "PM"

        oled.fill(0)
        time_x = calculate_x_spacing(time_str, scale=2)
        draw_scaled_text(oled, time_str, x=time_x, y=TIME_Y, scale=2)

        if period:
            oled.text(period, time_x + (len(time_str) * 16) + 4, TIME_Y + 8)

        date_str = f"{DAYS[weekday]} {year}-{month:02d}-{day:02d}"
        oled.text(date_str, calculate_x_spacing(date_str), 42)

        oled.show()

    # Fast poll to catch the next second boundary immediately
    time.sleep_ms(25)