import Image, ImageDraw, ImageFont
import ImageEnhance, ImageOps, ImageStat

def annotate(image, text, destination, font=None):
    """ Annotate an image with some text and save it to destination.

        - `image`: full path of source image, as a string
        - `text` : the string to paste on the image
        - `destination` : full path of image to save, as a string
        - `font` : full path of .pil bitmap font to use

                     w
        <--------------------------->
      ^ +---------------------------+
      | |                           |
      | |                           |
      | |                           |
    h | |     (w0,h0)               |
      | |        +---------+        |
      | |        |some text|        | |-> hb
      | |        +---------+(w1,h1) | |-> fromBottomPixels
      v +---------------------------+
            l                   l
         <------>           <------->
                 <--------->
                     wb
    """
    fromBottomPixels = 5
    borderSize = 2

    # Try to load a nice font (from pilfonts package)
    if font:
        font = ImageFont.load(font)
    else:
        font = ImageFont.load_default()

    img = Image.open(image)
    draw = ImageDraw.Draw(img)

    # calculate the textBox corners coordinates
    # text will be wrapped in that box
    wb, hb = font.getsize(text)
    w, h = img.size
    w0 = int((w-wb) / 2.)
    h0 = h - hb - fromBottomPixels
    w1 = w0 + wb
    h1 = h0 + hb

    box = (w0-borderSize, h0, w1+borderSize, h1)
    textBox = img.crop(box)

    inboundBox = Image.new('RGB', textBox.size, (136,213,123))
    inboundBox = Image.blend(inboundBox, textBox, 0.5) 


    # build the borders of the box
    size = inboundBox.size
    colour = (0, 0, 0)
    inboundBox = ImageOps.crop(inboundBox, border=borderSize)
    bordered = Image.new('RGBA', size, colour)
    bordered.paste(inboundBox, (borderSize, borderSize))

    # paste the bordered box back to the image
    img.paste(bordered, box)
    # heh annotate the image, finally :)
    draw.text((w0,h0), text, font=font, fill=colour)
    img.save(destination)

if __name__ == '__main__':
    import sys
    args = sys.argv[1:]
    if len(args) < 3:
        sys.exit(-1)
    if len(args) <= 4:
        image, text, destination = args[0:3]
        font = None
    if len(args) == 4:
        font = args[-1]
    annotate(image, text, destination, font)