#format python
"""GradationEffect for BLAST expect value distribution, It uses PIL
"""
import Image, ImageDraw
import math

def yuv2rgb(Y,U,V):
    R = 1.164*(Y - 16) + 1.596*(V - 128)
    G = 1.164*(Y - 16) - 0.813*(V - 128) - 0.391*(U - 128)
    B = 1.164*(Y - 16) + 2.018*(U - 128)
    return tuple(map(int, (R,G,B)))

def rgb2yuv(R,G,B):
    Y = (0.257 * R) + (0.504 * G) + (0.098 * B) + 16
    U = -(0.148 * R) - (0.291 * G) + (0.439 * B) + 128
    V = (0.439 * R) - (0.368 * G) - (0.071 * B) + 128
    return tuple(map(int, (Y,U,V)))

def evalue2rgb(evalue):
    try:
        n = -math.log(evalue)/math.log(10)
    except OverflowError:
        n = 71
    if n > 70:
        v = 255
    elif n < 5:
        v = 0
    else:
        v = int((n-5)*255/65)
    return yuv2rgb(10,50,v)

def makeSampleImage():
    img = Image.new('RGB', (80,140), (255,255,255))
    draw = ImageDraw.Draw(img)
    for yline in range(128):
        color = yuv2rgb(10, 50, 255-yline*2)
        draw.line((5, yline+5, 35, yline+5), fill=color)
    draw.text((40, 2), '1e-70', fill='black')
    draw.text((40, 60), '1e-32', fill='black')
    draw.text((40, 126), '1e-5', fill='black')
    img.save('test.png',type='PNG')

def makeEvalueDistribution():
    img = Image.new('RGB', (80,140), (255,255,255))
    draw = ImageDraw.Draw(img)
    y = 10
    for evalue in (1e-3, 1e-5, 1e-10, 1e-34, 1e-68, 1e-70, 1e-80):
        draw.rectangle((50, y, 70, y+10),fill=evalue2rgb(evalue))
        y+=15
    img.save('test.png',type='PNG')

if __name__=='__main__':
    #makeSampleImage()
    makeEvalueDistribution()