#!/usr/bin/env python3

import cairo
import math
import datetime
import calendar
import random
from utils import random_color


# dimensions of the output image
WIDTH, HEIGHT = 1920, 1080
# how much should the phases be offset?
WAVE_OFFSET = math.pi / random.choice([1, 2, 4]) #-1.9 
# amplitude of the sine wave
#AMPLITUDE = 9
# only 1 color with shades?
MONOCHROME = True
# works only if monochrome is set - uses todays date as base for the color
DATE_BASED_COLOR = True
DATE_BASED_AMPLITUDE = True
DATE_BASED_COUNT = True
# background black? White otherwise:
DARK_BG = True
# precision of the calculation
PRECISION = 10000

def days_color(date):
    import colorsys
    # a day between 1 and 365 (inclusive)
    today = date.timetuple().tm_yday
    year = date.year
    days_in_year = 365 + calendar.isleap(year)
    # between 0 and 1, how far through the year are we?
    progress = today/days_in_year
    return colorsys.hsv_to_rgb(progress, 1, 0.9)

def days_amp(date, waves):
    day = date.day
    days_in_month = calendar.monthrange(date.year, date.month)[1]
    max_amp = 1/waves/2
    return day/days_in_month * max_amp

def days_count(date):
    return date.month

def create_wpotd(output):
    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, WIDTH, HEIGHT)
    ctx = cairo.Context(surface)

    ctx.scale(WIDTH, HEIGHT)  # Normalizing the canvas
    #ctx.set_antialias(cairo.Antialias.BEST)

    step_size = 1/PRECISION
    lastpoints = [(x/PRECISION, 0) for x in range(PRECISION+1)]

    #date = datetime.datetime.strptime('2021-06-30', '%Y-%m-%d')
    date = datetime.datetime.today()
    frequency = random.randint(10, 40)
    if DATE_BASED_COUNT:
        waves = days_count(date)
    else:
        waves = 12
    if DATE_BASED_AMPLITUDE:
        amplitude = days_amp(date, waves)
    else:
        amplitude = 25
    
    if MONOCHROME:
        if DATE_BASED_COLOR:
            r, g, b = days_color(date) #datetime.datetime.now())
        else:
            r, g, b = random_color()
        alpha_step = 1/waves
    if DARK_BG:
        # make bg black
        ctx.rectangle(0, 0, 1, 1)
        ctx.set_source_rgb(0, 0, 0)
        ctx.fill()

    wave_height = 1/waves
    for num in range(waves+1):
        if not MONOCHROME:
            r, g, b = random_color()
        points = []
        x = 0
        while x < 1:
            y = amplitude * math.sin(frequency * x + (num * WAVE_OFFSET) ) 
            points.append((x, ( y + (0.5+num)*wave_height)))
            x += step_size
        #print(f'Draw {len(points)} points for curve {num}')
        if not MONOCHROME:
            ctx.set_source_rgb(r, g, b)
        else:
            ctx.set_source_rgba(r, g, b, 1 - (alpha_step * num)) # make more transparent toward bottom
        # draw waves
        ctx.move_to(*points[0])
        for p in points[1:]:
            ctx.line_to(*p)
        ctx.set_line_width(0.0004)
        ctx.stroke_preserve()
        for p in reversed(lastpoints):
            ctx.line_to(*p)
        ctx.line_to(*points[0])
        ctx.fill()
        lastpoints = points
    return surface
    #surface.write_to_png(output)  # Output to PNG

def main():
    create_wpotd('out/waves.png')

if __name__ == '__main__':
    main()