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

class Fish(object):
    """Object displayed on the bridge, probably a fish."""
    def __init__(self, x, y, width, height, color, step):
        """Create fish with default parameters."""
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.color = color
        self.speed = step
        self.step = step

    def update(self):
        """Swim gently to the other side of the bridge."""
        self.x += self.step
        if self.x > 200:
            self.x = 0
        self.y = 0.25 + 0.25 * math.sin(math.pi * self.x / 10)
        #theta = random.random() * math.pi / 2 - math.pi / 4
        #self.y += 0.01 * math.sin(theta)
        #print(self.y)


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, fish):
        """Change color depending on where the fish is."""
        if abs(self.transitioning_to - self.color) <= self.step:
            self.transitioning_to = pick_HSV().to_RGB()
            self.step = (random_change()
                * abs(self.color - self.transitioning_to))
        new_background = transition(
            self.color, self.transitioning_to, self.step
        )
        coverage = compute_coverage(fish, self.x, self.y)
        #coverage *= coverage
        new_color = coverage * fish.color + (1 - coverage) * new_background
        #new_color = new_background
        self.color = new_background
        if self.x == 30 and self.y == 0:
            pass
            #print(self.color.r(), self.color.g(), self.color.b())
        self.light.setRGBRaw(
            *map(lambda x: clamp(0, x, 1), new_color.components)
        )


class Bridge(object):
    """Store objects on the bridge."""
    def __init__(self, lights, fish, rig):
        """Initialize with lights and fish."""
        self.lights = lights
        self.fish = fish
        self.rig = rig

    def update(self):
        """Compute fish coverages and push lights to bridge."""
        for x, light_col in enumerate(self.lights):
            for y, light in enumerate(light_col):
                self.fish.update()
                light.update(self.fish)
        self.rig.updateOnce()


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))