from PIL import Image
from matplotlib import cm

import numpy as np
import ipfml.metrics as metrics


def fig2data(fig):
    """
    @brief Convert a Matplotlib figure to a 3D numpy array with RGB channels and return it
    @param fig a matplotlib figure
    @return a numpy 3D array of RGB values
    """
    # draw the renderer
    fig.canvas.draw()
 
    # Get the RGBA buffer from the figure
    w,h = fig.canvas.get_width_height()
    buf = np.fromstring(fig.canvas.tostring_rgb(), dtype=np.uint8)
    buf.shape = (w, h, 3)
 
    # canvas.tostring_argb give pixmap in ARGB mode. Roll the ALPHA channel to have it in RGBA mode
    buf = np.roll(buf, 3, axis=2)
    return buf
    
def fig2img(fig):
    """
    @brief Convert a Matplotlib figure to a PIL Image in RGB format and return it
    @param fig a matplotlib figure
    @return a Python Imaging Library (PIL) image : default size (480,640,3)
    """
    # put the figure pixmap into a numpy array
    buf = fig2data(fig)
    w, h, d = buf.shape
    return Image.frombytes("RGB", (w, h), buf.tostring())

def get_LAB_L_SVD(image):
    """
    @brief Returns Singular values from LAB L Image information
    @param fig a matplotlib figure
    @return a Python Imaging Library (PIL) image : default size (480,640,3)
    """
    L = metrics.get_LAB_L(image)
    return metrics.get_SVD(L)

def get_LAB_L_SVD_s(image):
    """
    @brief Returns s (Singular values) SVD from L of LAB Image information
    @param PIL Image
    @return vector of singular values
    """
    L = metrics.get_LAB_L(image)
    return metrics.get_SVD_s(L)

def get_LAB_L_SVD_U(image):
    """
    @brief Returns U SVD from L of LAB Image information
    @param PIL Image
    @return vector of singular values
    """
    L = metrics.get_LAB_L(image)
    return metrics.get_SVD_U(L)

def get_LAB_L_SVD_V(image):
    """
    @brief Returns V SVD from L of LAB Image information
    @param PIL Image
    @return vector of singular values
    """
    L = metrics.get_LAB_L(image)
    return metrics.get_SVD_V(L)

def divide_in_blocks(image, block_size):
    '''
    @brief Divide image into equal size blocks
    @param img - PIL Image
    @param block - tuple (width, height) representing the size of each dimension of the block
    @return list containing all PIL Image block (in RGB)

    Usage :

    >>> import numpy as np
    >>> from PIL import Image
    >>> from ipfml import image_processing
    >>> image_values = np.random.randint(255, size=(800, 800, 3))
    >>> img = Image.fromarray(image_values.astype('uint8'), 'RGB')
    >>> blocks = divide_in_blocks(img, (20, 20))
    >>> len(blocks)
    1600
    >>> blocks[0].width
    20
    >>> blocks[0].height
    20
    '''

    blocks = []

    # check size compatibility
    width, height = block_size

    if(image.width % width != 0):
        raise "Width size issue, block size not compatible"
    
    if(image.height % height != 0):
        raise "Height size issue, block size not compatible"

    nb_block_width = image.width / width
    nb_block_height = image.height / height

    image_array = np.array(image)

    for i in range(int(nb_block_width)):

        begin_x = i * width

        for j in range(int(nb_block_height)): 

            begin_y = j * height

            # getting subblock information
            current_block = image_array[begin_x:(begin_x + width), begin_y:(begin_y + height)]
            blocks.append(Image.fromarray(current_block.astype('uint8'), 'RGB'))

    return blocks