import pytesseract
import subprocess
import logging

from .system import randomtempname
from PIL import Image

_logger = logging.getLogger(__name__)
ZONES = ('topleft', 'topright',
         'bottomleft', 'bottomright',
         'topcenter', 'bottomcenter')


class Zone:
    zone: str
    width: int
    height: int
    margin_top: int
    margin_bottom: int
    marign_left: int
    margin_right: int

    def __init__(self, z, w, h, mt, mr, mb, ml):
        if z not in ZONES:
            return ValueError(f'invalid zone spec: zone "{z}" is invalid')
        self.zone = z
        self.width = int(w)
        self.height = int(h)
        self.margin_top = int(mt)
        self.margin_bottom = int(mb)
        self.margin_left = int(ml)
        self.margin_right = int(mr)

    def isright(self):
        return self.zone.endswith('right')

    def isleft(self):
        return self.zone.endswith('left')

    def iscenter(self):
        return self.zone.endswith('center')

    def istop(self):
        return self.zone.startswith('top')

    def isbottom(self):
        return self.zone.startswith('bottom')

    def __repr__(self):
        return '%s,%d,%d,%d,%d,%d,%d' % (
            self.zone,
            self.
            width,
            self.height,
            self.margin_top,
            self.margin_right,
            self.margin_bottom,
            self.margin_left)

    @staticmethod
    def from_string(s):
        p = list(s.split(','))
        if len(p) != 7:
            raise ValueError(f'invalid zone spec: {s}')
        return Zone(*p)

    @staticmethod
    def getzones():
        return ZONES


def pdf2png(pdf_path, page=1):
    file = randomtempname()
    p = subprocess.run(["pdftoppm", pdf_path, file,
                        '-png',           # generate PNG instead of PPM
                        '-f', str(page),  # page number
                        '-r', '300',      # PPI
                        '-singlefile'])
    if p.returncode != 0:
        raise RuntimeError(f'pdftoppm returned {p.returncode}')
    return file+'.png'


def zonecrop(png_path, z):
    image = Image.open(png_path)
    iw, ih = image.size

    x1 = x2 = y1 = y2 = None

    if z.isleft():
        x1 = 0
    elif z.isright():
        x1 = iw-z.width
    elif z.iscenter():
        x1 = int(iw/2-z.width/2)

    if z.istop():
        y1 = 0
    elif z.isbottom():
        y1 = ih-z.height

    x1 += z.margin_left
    x1 -= z.margin_right
    y1 += z.margin_top
    y1 -= z.margin_bottom

    x2 = x1+z.width
    y2 = y1+z.height

    filename = randomtempname(suffix='.png')
    cropped = image.crop((x1, y1, x2, y2))
    cropped.save(filename)

    return filename


def img2pagenum(img_file, maxlen):
    try:
        s = pytesseract.image_to_string(img_file,
                                        timeout=10,
                                        lang='eng',
                                        config='--psm 13 -c tessedit_char_whitelist=0123456789')
    except RuntimeError as timeout_error:
        _logger.exception(timeout_error)
        return None

    for r in '_-.,—':
        s = s.replace(r, '')
    s = s.strip()
    return s if s.isnumeric() and len(s) <= maxlen else None