import time

from gradients import Gradient

class Pattern:
    def __init__(self, gradient, cycle_length, cycle_time_s=None, reverse=False, march=False):
        self.gradient = gradient
        self.cycle_length = cycle_length
        self.cycle_time_s = cycle_time_s or (cycle_length / 2 if march else cycle_length)
        self.reverse = reverse
        self.march = march
        self.last = None
        self.offset = 0

    def step(self, length):
        now = time.time()
        duration = 0 if self.last is None else now - self.last
        self.last = now

        offset_delta = self.cycle_length * duration / self.cycle_time_s
        self.offset = (self.offset + (offset_delta if self.reverse else -offset_delta)) % self.cycle_length

        offset = self.offset if not self.march else int(self.offset)
        return (self.gradient.at(((i + offset) / self.cycle_length + 1) % 1) for i in range(0, length))

    def from_dict(dict):
        return Pattern(
            Gradient.from_dict(dict['gradient']),
            dict['cycle_length'],
            cycle_time_s = dict.get('cycle_time_s'),
            reverse = not not dict.get('reverse', False),
            march = not not dict.get('march', False)
        )