"""Rendering classes and helper functions."""
from __future__ import division
import color
import random
import constants
from constants import *
import math
from show import Show

class Sun(object):
    """Object displayed on the bridge, probably a fish."""
    def __init__(self):
        """Create fish with default parameters."""
        self.center_x = 140
        self.center_y = -5
        self.width = 30
        self.height = 5
        self.wait = 0

    def update(self):
        """Swim gently to the other side of the bridge."""
        self.center_y += 0.005
        if self.center_y >= 1:
            self.center_y = 1
            self.wait += 1
            if self.wait >= 200:
                self.wait = 0
                self.center_y = -5

    def color_at(self, x, y):
        ball_width = 15
        if abs(x - self.center_x) < ball_width:
            return color.RGB(1, 1, 1)
        distance = abs(self.center_x - x)
        start_hue = 58 / 360
        end_hue = 41 / 360
        start_sat = 0
        end_sat = 0.92
        sat = scale_with_clamp(distance, ball_width, 60, start_sat, end_sat)
        hue = scale_with_clamp(distance, ball_width, 100, start_hue, end_hue)
        return color.HSV(hue, sat, 1).to_RGB()


def scale_with_clamp(inp, min_inp, max_inp, min_out, max_out):
    return (clamp(min_inp, inp, max_inp) - min_inp) / (max_inp - min_inp) * (max_out - min_out) + min_out


class Light(object):
    """Represent a bridge light and its state."""
    def __init__(self, x, y, light):
        """Store all facts about a light."""
        self.light = light
        self.color = color.black
        self.transitioning_to = self.color
        self.step = 0
        self.x = x
        self.y = y

    def update(self, sun):
        """Change color depending on where the fish is."""
        self.light.setRGBRaw(*sun.color_at(self.x, self.y).components)


class SunriseShow(Show):
    def init(self):
        self.lights = [Light(x, y, self.bridge.get_light(x, y))
                       for y in xrange(self.bridge.HEIGHT)
                       for x in xrange(self.bridge.WIDTH)]
        self.sun = Sun()


    def update(self):
        self.sun.update()
        for light in self.lights:
            light.update(self.sun)


def compute_coverage(fish, x, y):
    """Calculate the coverage of a fish over a box."""
    middle_of_fish = fish.x + fish.width / 2
    middle_of_panel = x + 0.5
    diff = abs(middle_of_fish - middle_of_panel) / (fish.width / 2)
    scale = 1 - diff
    min_x = min(max(x, fish.x), x + 1)
    max_x = max(min(x+1, fish.x + fish.width), x)
    min_y = min(max(y, fish.y), y + 1)
    max_y = max(min(y+1, fish.y + fish.height), y)
    coverage = (max_x - min_x) * (max_y - min_y)
    return coverage * scale


def pick_HSV():
    """Return a random color in an appropriate interval."""
    hue = random.random() * (constants.MAX_HUE - constants.MIN_HUE) + constants.MIN_HUE
    saturation = random.random() * (MAX_SATURATION - MIN_SATURATION) + MIN_SATURATION
    value = random.random() * (MAX_VALUE - MIN_VALUE) + MIN_VALUE
    return color.HSV(hue, saturation, value)


def transition(start, end, step):
    """Return a vector equal to (end - start) * step + start."""
    if start == end:
        return start
    diff_vector = end - start
    step_vector = diff_vector / abs(diff_vector) * step
    result = step_vector + start
    return result


def random_change():
    """Return a random amount that a light should change each frame."""
    min_time = int(constants.MIN_TIME * FRAME_RATE)
    max_time = int(MAX_TIME * FRAME_RATE)
    return 1 / random.randint(min_time, max_time)


def clamp(low, x, high):
    """Return v such that low <= v <= high and |x - v| is minimal."""
    return max(low, min(x, high))