"""
Miscellaneous Routines.
"""
import io
import pathlib
import struct
from html import escape
from typing import (Any, BinaryIO, Callable, Dict, Generic, Iterable, Iterator,
                    List, Optional, Set, TextIO, Tuple, TypeVar, Union,
                    TYPE_CHECKING, cast)

if TYPE_CHECKING:
    from .layout import LTComponent

import chardet  # For str encoding detection

# from sys import maxint as INF doesn't work anymore under Python3, but PDF
# still uses 32 bits ints
INF = (1 << 31) - 1


FileOrName = Union[pathlib.PurePath, str, io.IOBase]
AnyIO = Union[TextIO, BinaryIO]


class open_filename(object):
    """
    Context manager that allows opening a filename
    (str or pathlib.PurePath type is supported) and closes it on exit,
    (just like `open`), but does nothing for file-like objects.
    """
    def __init__(
        self,
        filename: FileOrName,
        *args: Any,
        **kwargs: Any
    ) -> None:
        if isinstance(filename, pathlib.PurePath):
            filename = str(filename)
        if isinstance(filename, str):
            self.file_handler: AnyIO = open(filename, *args, **kwargs)
            self.closing = True
        elif isinstance(filename, io.IOBase):
            self.file_handler = cast(AnyIO, filename)
            self.closing = False
        else:
            raise TypeError('Unsupported input type: %s' % type(filename))

    def __enter__(self) -> AnyIO:
        return self.file_handler

    def __exit__(
        self,
        exc_type: object,
        exc_val: object,
        exc_tb: object
    ) -> None:
        if self.closing:
            self.file_handler.close()


def make_compat_bytes(in_str: str) -> bytes:
    "Converts to bytes, encoding to unicode."
    assert isinstance(in_str, str), str(type(in_str))
    return in_str.encode()


def make_compat_str(o: object) -> str:
    """Converts everything to string, if bytes guessing the encoding."""
    if isinstance(o, bytes):
        enc = chardet.detect(o)
        return o.decode(enc['encoding'])
    else:
        return str(o)


def shorten_str(s: str, size: int) -> str:
    if size < 7:
        return s[:size]
    if len(s) > size:
        length = (size - 5) // 2
        return '{} ... {}'.format(s[:length], s[-length:])
    else:
        return s


def compatible_encode_method(
    bytesorstring: Union[bytes, str],
    encoding: str = 'utf-8',
    erraction: str = 'ignore'
) -> str:
    """When Py2 str.encode is called, it often means bytes.encode in Py3.

     This does either.
     """
    if isinstance(bytesorstring, str):
        return bytesorstring
    assert isinstance(bytesorstring, bytes), str(type(bytesorstring))
    return bytesorstring.decode(encoding, erraction)


def paeth_predictor(left: int, above: int, upper_left: int) -> int:
    # From http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
    # Initial estimate
    p = left + above - upper_left
    # Distances to a,b,c
    pa = abs(p - left)
    pb = abs(p - above)
    pc = abs(p - upper_left)

    # Return nearest of a,b,c breaking ties in order a,b,c
    if pa <= pb and pa <= pc:
        return left
    elif pb <= pc:
        return above
    else:
        return upper_left


def apply_png_predictor(
    pred: int,
    colors: int,
    columns: int,
    bitspercomponent: int,
    data: bytes
) -> bytes:
    """Reverse the effect of the PNG predictor

    Documentation: http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
    """
    if bitspercomponent != 8:
        msg = "Unsupported `bitspercomponent': %d" % bitspercomponent
        raise ValueError(msg)

    nbytes = colors * columns * bitspercomponent // 8
    bpp = colors * bitspercomponent // 8  # number of bytes per complete pixel
    buf = b''
    line_above = b'\x00' * columns
    for scanline_i in range(0, len(data), nbytes + 1):
        filter_type = data[scanline_i]
        line_encoded = data[scanline_i + 1:scanline_i + 1 + nbytes]
        raw = b''

        if filter_type == 0:
            # Filter type 0: None
            raw += line_encoded

        elif filter_type == 1:
            # Filter type 1: Sub
            # To reverse the effect of the Sub() filter after decompression,
            # output the following value:
            #   Raw(x) = Sub(x) + Raw(x - bpp)
            # (computed mod 256), where Raw() refers to the bytes already
            #  decoded.
            for j, sub_x in enumerate(line_encoded):
                if j - bpp < 0:
                    raw_x_bpp = 0
                else:
                    raw_x_bpp = int(raw[j - bpp])
                raw_x = (sub_x + raw_x_bpp) & 255
                raw += bytes((raw_x,))

        elif filter_type == 2:
            # Filter type 2: Up
            # To reverse the effect of the Up() filter after decompression,
            # output the following value:
            #   Raw(x) = Up(x) + Prior(x)
            # (computed mod 256), where Prior() refers to the decoded bytes of
            # the prior scanline.
            for (up_x, prior_x) in zip(line_encoded, line_above):
                raw_x = (up_x + prior_x) & 255
                raw += bytes((raw_x,))

        elif filter_type == 3:
            # Filter type 3: Average
            # To reverse the effect of the Average() filter after
            # decompression, output the following value:
            #    Raw(x) = Average(x) + floor((Raw(x-bpp)+Prior(x))/2)
            # where the result is computed mod 256, but the prediction is
            # calculated in the same way as for encoding. Raw() refers to the
            # bytes already decoded, and Prior() refers to the decoded bytes of
            # the prior scanline.
            for j, average_x in enumerate(line_encoded):
                if j - bpp < 0:
                    raw_x_bpp = 0
                else:
                    raw_x_bpp = int(raw[j - bpp])
                prior_x = int(line_above[j])
                raw_x = (average_x + (raw_x_bpp + prior_x) // 2) & 255
                raw += bytes((raw_x,))

        elif filter_type == 4:
            # Filter type 4: Paeth
            # To reverse the effect of the Paeth() filter after decompression,
            # output the following value:
            #    Raw(x) = Paeth(x)
            #             + PaethPredictor(Raw(x-bpp), Prior(x), Prior(x-bpp))
            # (computed mod 256), where Raw() and Prior() refer to bytes
            # already decoded. Exactly the same PaethPredictor() function is
            # used by both encoder and decoder.
            for j, paeth_x in enumerate(line_encoded):
                if j - bpp < 0:
                    raw_x_bpp = 0
                    prior_x_bpp = 0
                else:
                    raw_x_bpp = int(raw[j - bpp])
                    prior_x_bpp = int(line_above[j - bpp])
                prior_x = int(line_above[j])
                paeth = paeth_predictor(raw_x_bpp, prior_x, prior_x_bpp)
                raw_x = (paeth_x + paeth) & 255
                raw += bytes((raw_x,))

        else:
            raise ValueError("Unsupported predictor value: %d" % filter_type)

        buf += raw
        line_above = raw
    return buf


Point = Tuple[float, float]
Rect = Tuple[float, float, float, float]
Matrix = Tuple[float, float, float, float, float, float]
PathSegment = Union[
    Tuple[str],                                             # Literal['h']
    Tuple[str, float, float],                               # Literal['m', 'l']
    Tuple[str, float, float, float, float],                 # Literal['v', 'y']
    Tuple[str, float, float, float, float, float, float]]   # Literal['c']

#  Matrix operations
MATRIX_IDENTITY: Matrix = (1, 0, 0, 1, 0, 0)


def mult_matrix(m1: Matrix, m0: Matrix) -> Matrix:
    (a1, b1, c1, d1, e1, f1) = m1
    (a0, b0, c0, d0, e0, f0) = m0
    """Returns the multiplication of two matrices."""
    return (a0 * a1 + c0 * b1, b0 * a1 + d0 * b1,
            a0 * c1 + c0 * d1, b0 * c1 + d0 * d1,
            a0 * e1 + c0 * f1 + e0, b0 * e1 + d0 * f1 + f0)


def translate_matrix(m: Matrix, v: Point) -> Matrix:
    """Translates a matrix by (x, y)."""
    (a, b, c, d, e, f) = m
    (x, y) = v
    return a, b, c, d, x * a + y * c + e, x * b + y * d + f


def apply_matrix_pt(m: Matrix, v: Point) -> Point:
    (a, b, c, d, e, f) = m
    (x, y) = v
    """Applies a matrix to a point."""
    return a * x + c * y + e, b * x + d * y + f


def apply_matrix_norm(m: Matrix, v: Point) -> Point:
    """Equivalent to apply_matrix_pt(M, (p,q)) - apply_matrix_pt(M, (0,0))"""
    (a, b, c, d, e, f) = m
    (p, q) = v
    return a * p + c * q, b * p + d * q


#  Utility functions

def isnumber(x: object) -> bool:
    return isinstance(x, (int, float))


_T = TypeVar('_T')


def uniq(objs: Iterable[_T]) -> Iterator[_T]:
    """Eliminates duplicated elements."""
    done = set()
    for obj in objs:
        if obj in done:
            continue
        done.add(obj)
        yield obj
    return


def fsplit(
    pred: Callable[[_T], bool],
    objs: Iterable[_T]
) -> Tuple[List[_T], List[_T]]:
    """Split a list into two classes according to the predicate."""
    t = []
    f = []
    for obj in objs:
        if pred(obj):
            t.append(obj)
        else:
            f.append(obj)
    return t, f


def drange(v0: float, v1: float, d: int) -> range:
    """Returns a discrete range."""
    return range(int(v0) // d, int(v1 + d) // d)


def get_bound(pts: Iterable[Point]) -> Rect:
    """Compute a minimal rectangle that covers all the points."""
    limit: Rect = (INF, INF, -INF, -INF)
    (x0, y0, x1, y1) = limit
    for (x, y) in pts:
        x0 = min(x0, x)
        y0 = min(y0, y)
        x1 = max(x1, x)
        y1 = max(y1, y)
    return x0, y0, x1, y1


def pick(
    seq: Iterable[_T],
    func: Callable[[_T], float],
    maxobj: Optional[_T] = None
) -> Optional[_T]:
    """Picks the object obj where func(obj) has the highest value."""
    maxscore = None
    for obj in seq:
        score = func(obj)
        if maxscore is None or maxscore < score:
            (maxscore, maxobj) = (score, obj)
    return maxobj


def choplist(n: int, seq: Iterable[_T]) -> Iterator[Tuple[_T, ...]]:
    """Groups every n elements of the list."""
    r = []
    for x in seq:
        r.append(x)
        if len(r) == n:
            yield tuple(r)
            r = []
    return


def nunpack(s: bytes, default: int = 0) -> int:
    """Unpacks 1 to 4 or 8 byte integers (big endian)."""
    length = len(s)
    if not length:
        return default
    elif length == 1:
        return ord(s)
    elif length == 2:
        return cast(int, struct.unpack('>H', s)[0])
    elif length == 3:
        return cast(int, struct.unpack('>L', b'\x00' + s)[0])
    elif length == 4:
        return cast(int, struct.unpack('>L', s)[0])
    elif length == 8:
        return cast(int, struct.unpack('>Q', s)[0])
    else:
        raise TypeError('invalid length: %d' % length)


PDFDocEncoding = ''.join(chr(x) for x in (
    0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,
    0x0008, 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f,
    0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0017, 0x0017,
    0x02d8, 0x02c7, 0x02c6, 0x02d9, 0x02dd, 0x02db, 0x02da, 0x02dc,
    0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
    0x0028, 0x0029, 0x002a, 0x002b, 0x002c, 0x002d, 0x002e, 0x002f,
    0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
    0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e, 0x003f,
    0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
    0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f,
    0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
    0x0058, 0x0059, 0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f,
    0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
    0x0068, 0x0069, 0x006a, 0x006b, 0x006c, 0x006d, 0x006e, 0x006f,
    0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
    0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d, 0x007e, 0x0000,
    0x2022, 0x2020, 0x2021, 0x2026, 0x2014, 0x2013, 0x0192, 0x2044,
    0x2039, 0x203a, 0x2212, 0x2030, 0x201e, 0x201c, 0x201d, 0x2018,
    0x2019, 0x201a, 0x2122, 0xfb01, 0xfb02, 0x0141, 0x0152, 0x0160,
    0x0178, 0x017d, 0x0131, 0x0142, 0x0153, 0x0161, 0x017e, 0x0000,
    0x20ac, 0x00a1, 0x00a2, 0x00a3, 0x00a4, 0x00a5, 0x00a6, 0x00a7,
    0x00a8, 0x00a9, 0x00aa, 0x00ab, 0x00ac, 0x0000, 0x00ae, 0x00af,
    0x00b0, 0x00b1, 0x00b2, 0x00b3, 0x00b4, 0x00b5, 0x00b6, 0x00b7,
    0x00b8, 0x00b9, 0x00ba, 0x00bb, 0x00bc, 0x00bd, 0x00be, 0x00bf,
    0x00c0, 0x00c1, 0x00c2, 0x00c3, 0x00c4, 0x00c5, 0x00c6, 0x00c7,
    0x00c8, 0x00c9, 0x00ca, 0x00cb, 0x00cc, 0x00cd, 0x00ce, 0x00cf,
    0x00d0, 0x00d1, 0x00d2, 0x00d3, 0x00d4, 0x00d5, 0x00d6, 0x00d7,
    0x00d8, 0x00d9, 0x00da, 0x00db, 0x00dc, 0x00dd, 0x00de, 0x00df,
    0x00e0, 0x00e1, 0x00e2, 0x00e3, 0x00e4, 0x00e5, 0x00e6, 0x00e7,
    0x00e8, 0x00e9, 0x00ea, 0x00eb, 0x00ec, 0x00ed, 0x00ee, 0x00ef,
    0x00f0, 0x00f1, 0x00f2, 0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7,
    0x00f8, 0x00f9, 0x00fa, 0x00fb, 0x00fc, 0x00fd, 0x00fe, 0x00ff,
))


def decode_text(s: bytes) -> str:
    """Decodes a PDFDocEncoding string to Unicode."""
    if s.startswith(b'\xfe\xff'):
        return str(s[2:], 'utf-16be', 'ignore')
    else:
        return ''.join(PDFDocEncoding[c] for c in s)


def enc(x: str) -> str:
    """Encodes a string for SGML/XML/HTML"""
    if isinstance(x, bytes):
        return ''
    return escape(x)


def bbox2str(bbox: Rect) -> str:
    (x0, y0, x1, y1) = bbox
    return '{:.3f},{:.3f},{:.3f},{:.3f}'.format(x0, y0, x1, y1)


def matrix2str(m: Matrix) -> str:
    (a, b, c, d, e, f) = m
    return '[{:.2f},{:.2f},{:.2f},{:.2f}, ({:.2f},{:.2f})]'\
        .format(a, b, c, d, e, f)


def vecBetweenBoxes(obj1: "LTComponent", obj2: "LTComponent") -> Point:
    """A distance function between two TextBoxes.

    Consider the bounding rectangle for obj1 and obj2.
    Return vector between 2 boxes boundaries if they don't overlap, otherwise
    returns vector betweeen boxes centers

             +------+..........+ (x1, y1)
             | obj1 |          :
             +------+www+------+
             :          | obj2 |
    (x0, y0) +..........+------+
    """
    (x0, y0) = (min(obj1.x0, obj2.x0), min(obj1.y0, obj2.y0))
    (x1, y1) = (max(obj1.x1, obj2.x1), max(obj1.y1, obj2.y1))
    (ow, oh) = (x1 - x0, y1 - y0)
    (iw, ih) = (ow - obj1.width - obj2.width, oh - obj1.height - obj2.height)
    if iw < 0 and ih < 0:
        # if one is inside another we compute euclidean distance
        (xc1, yc1) = ((obj1.x0 + obj1.x1) / 2, (obj1.y0 + obj1.y1) / 2)
        (xc2, yc2) = ((obj2.x0 + obj2.x1) / 2, (obj2.y0 + obj2.y1) / 2)
        return xc1 - xc2, yc1 - yc2
    else:
        return max(0, iw), max(0, ih)


LTComponentT = TypeVar('LTComponentT', bound='LTComponent')


class Plane(Generic[LTComponentT]):
    """A set-like data structure for objects placed on a plane.

    Can efficiently find objects in a certain rectangular area.
    It maintains two parallel lists of objects, each of
    which is sorted by its x or y coordinate.
    """

    def __init__(self, bbox: Rect, gridsize: int = 50) -> None:
        self._seq: List[LTComponentT] = []  # preserve the object order.
        self._objs: Set[LTComponentT] = set()
        self._grid: Dict[Point, List[LTComponentT]] = {}
        self.gridsize = gridsize
        (self.x0, self.y0, self.x1, self.y1) = bbox

    def __repr__(self) -> str:
        return '<Plane objs=%r>' % list(self)

    def __iter__(self) -> Iterator[LTComponentT]:
        return (obj for obj in self._seq if obj in self._objs)

    def __len__(self) -> int:
        return len(self._objs)

    def __contains__(self, obj: object) -> bool:
        return obj in self._objs

    def _getrange(self, bbox: Rect) -> Iterator[Point]:
        (x0, y0, x1, y1) = bbox
        if x1 <= self.x0 or self.x1 <= x0 or y1 <= self.y0 or self.y1 <= y0:
            return
        x0 = max(self.x0, x0)
        y0 = max(self.y0, y0)
        x1 = min(self.x1, x1)
        y1 = min(self.y1, y1)
        for grid_y in drange(y0, y1, self.gridsize):
            for grid_x in drange(x0, x1, self.gridsize):
                yield (grid_x, grid_y)

    def extend(self, objs: Iterable[LTComponentT]) -> None:
        for obj in objs:
            self.add(obj)

    def add(self, obj: LTComponentT) -> None:
        """place an object."""
        for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
            if k not in self._grid:
                r: List[LTComponentT] = []
                self._grid[k] = r
            else:
                r = self._grid[k]
            r.append(obj)
        self._seq.append(obj)
        self._objs.add(obj)

    def remove(self, obj: LTComponentT) -> None:
        """displace an object."""
        for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
            try:
                self._grid[k].remove(obj)
            except (KeyError, ValueError):
                pass
        self._objs.remove(obj)

    def find(self, bbox: Rect) -> Iterator[LTComponentT]:
        """finds objects that are in a certain area."""
        (x0, y0, x1, y1) = bbox
        done = set()
        for k in self._getrange(bbox):
            if k not in self._grid:
                continue
            for obj in self._grid[k]:
                if obj in done:
                    continue
                done.add(obj)
                if obj.x1 <= x0 or x1 <= obj.x0 or obj.y1 <= y0 \
                        or y1 <= obj.y0:
                    continue
                yield obj