import os
import sys
import struct
import cPickle as cp
from PIL import Image
import numpy as np
import xml.etree.cElementTree as et
import xml.dom.minidom

imgSize = 32

def saveImage(fname, data, label, mapFile, pad, **key_parms):
    # data in CIFAR-10 dataset is in CHW format.
    pixData = data.reshape((3, imgSize, imgSize))
    if ('mean' in key_parms):
        key_parms['mean'] += pixData

    if pad > 0:
        pixData = np.pad(pixData, ((0, 0), (pad, pad), (pad, pad)), mode='constant', constant_values=128) # can also use mode='edge'

    img = Image.new('RGB', (imgSize + 2 * pad, imgSize + 2 * pad))
    pixels = img.load()
    for x in range(img.size[0]):
        for y in range(img.size[1]):
            pixels[x, y] = (pixData[0][y][x], pixData[1][y][x], pixData[2][y][x])
    img.save(fname)
    mapFile.write("%s\t%d\n" % (fname, label))

def saveMean(fname, data):
    root = et.Element('opencv_storage')
    et.SubElement(root, 'Channel').text = '3'
    et.SubElement(root, 'Row').text = str(imgSize)
    et.SubElement(root, 'Col').text = str(imgSize)
    meanImg = et.SubElement(root, 'MeanImg', type_id='opencv-matrix')
    et.SubElement(meanImg, 'rows').text = '1'
    et.SubElement(meanImg, 'cols').text = str(imgSize * imgSize * 3)
    et.SubElement(meanImg, 'dt').text = 'f'
    et.SubElement(meanImg, 'data').text = ' '.join(['%e' % n for n in np.reshape(data, (imgSize * imgSize * 3))])

    tree = et.ElementTree(root)
    tree.write(fname)
    x = xml.dom.minidom.parse(fname)
    with open(fname, 'w') as f:
        f.write(x.toprettyxml(indent = '  '))

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print "Usage: CifarConverter.py <path to CIFAR-10 dataset directory>\nCIFAR-10 dataset (Python version) can be downloaded from http://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz"
        sys.exit(1)
    rootDir = sys.argv[1]
    trainDir = os.path.join(rootDir, os.path.join('data', 'train'))
    if not os.path.exists(trainDir):
        os.makedirs(trainDir)
    testDir = os.path.join(rootDir, os.path.join('data', 'test'))
    if not os.path.exists(testDir):
      os.makedirs(testDir)
    data = {}
    dataMean = np.zeros((3, imgSize, imgSize)) # mean is in CHW format.
    with open(os.path.join(rootDir, 'train_map.txt'), 'w') as mapFile:
        for ifile in range(1, 6):
            with open(os.path.join(rootDir, 'data_batch_' + str(ifile)), 'rb') as f:
                data = cp.load(f)
                for i in range(10000):
                    fname = os.path.join(trainDir, ('%05d.png' % (i + (ifile - 1) * 10000)))
                    saveImage(fname, data['data'][i, :], data['labels'][i], mapFile, 4, mean=dataMean)
    dataMean = dataMean / (50 * 1000)
    saveMean(os.path.join(rootDir, 'CIFAR-10_mean.xml'), dataMean)
    with open(os.path.join(rootDir, 'test_map.txt'), 'w') as mapFile:
        with open(os.path.join(rootDir, 'test_batch'), 'rb') as f:
            data = cp.load(f)
            for i in range(10000):
                fname = os.path.join(testDir, ('%05d.png' % i))
                saveImage(fname, data['data'][i, :], data['labels'][i], mapFile, 0)