#
# The Python Imaging Library.
# $Id$
#
# base class for image file handlers
#
# history:
# 1995-09-09 fl   Created
# 1996-03-11 fl   Fixed load mechanism.
# 1996-04-15 fl   Added pcx/xbm decoders.
# 1996-04-30 fl   Added encoders.
# 1996-12-14 fl   Added load helpers
# 1997-01-11 fl   Use encode_to_file where possible
# 1997-08-27 fl   Flush output in _save
# 1998-03-05 fl   Use memory mapping for some modes
# 1999-02-04 fl   Use memory mapping also for "I;16" and "I;16B"
# 1999-05-31 fl   Added image parser
# 2000-10-12 fl   Set readonly flag on memory-mapped images
# 2002-03-20 fl   Use better messages for common decoder errors
# 2003-04-21 fl   Fall back on mmap/map_buffer if map is not available
# 2003-10-30 fl   Added StubImageFile class
# 2004-02-25 fl   Made incremental parser more robust
#
# Copyright (c) 1997-2004 by Secret Labs AB
# Copyright (c) 1995-2004 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#

from . import Image
from ._util import isPath
import io
import sys
import struct

MAXBLOCK = 65536

SAFEBLOCK = 1024 * 1024

LOAD_TRUNCATED_IMAGES = False

ERRORS = {
    -1: "image buffer overrun error",
    -2: "decoding error",
    -3: "unknown error",
    -8: "bad configuration",
    -9: "out of memory error",
}


def raise_ioerror(error):
    try:
        message = Image.core.getcodecstatus(error)
    except AttributeError:
        message = ERRORS.get(error)
    if not message:
        message = "decoder error %d" % error
    raise IOError(message + " when reading image file")


#
# --------------------------------------------------------------------
# Helpers


def _tilesort(t):
    # sort on offset
    return t[2]


#
# --------------------------------------------------------------------
# ImageFile base class


class ImageFile(Image.Image):
    "Base class for image file format handlers."

    def __init__(self, fp=None, filename=None):
        Image.Image.__init__(self)

        self._min_frame = 0

        self.custom_mimetype = None

        self.tile = None
        self.readonly = 1  # until we know better

        self.decoderconfig = ()
        self.decodermaxblock = MAXBLOCK

        if isPath(fp):
            # filename
            self.fp = open(fp, "rb")
            self.filename = fp
            self._exclusive_fp = True
        else:
            # stream
            self.fp = fp
            self.filename = filename
            # can be overridden
            self._exclusive_fp = None

        try:
            self._open()
        except (
            IndexError,  # end of data
            TypeError,  # end of data (ord)
            KeyError,  # unsupported mode
            EOFError,  # got header but not the first frame
            struct.error,
        ) as v:
            # close the file only if we have opened it this constructor
            if self._exclusive_fp:
                self.fp.close()
            raise SyntaxError(v)

        if not self.mode or self.size[0] <= 0:
            raise SyntaxError("not identified by this driver")

    def draft(self, mode, size):
        """Set draft mode"""

        pass

    def get_format_mimetype(self):
        if self.custom_mimetype:
            return self.custom_mimetype
        if self.format is not None:
            return Image.MIME.get(self.format.upper())

    def verify(self):
        """Check file integrity"""

        # raise exception if something's wrong.  must be called
        # directly after open, and closes file when finished.
        if self._exclusive_fp:
            self.fp.close()
        self.fp = None

    def load(self):
        """Load image data based on tile list"""

        pixel = Image.Image.load(self)

        if self.tile is None:
            raise IOError("cannot load this image")
        if not self.tile:
            return pixel

        self.map = None
        use_mmap = self.filename and len(self.tile) == 1
        # As of pypy 2.1.0, memory mapping was failing here.
        use_mmap = use_mmap and not hasattr(sys, "pypy_version_info")

        readonly = 0

        # look for read/seek overrides
        try:
            read = self.load_read
            # don't use mmap if there are custom read/seek functions
            use_mmap = False
        except AttributeError:
            read = self.fp.read

        try:
            seek = self.load_seek
            use_mmap = False
        except AttributeError:
            seek = self.fp.seek

        if use_mmap:
            # try memory mapping
            decoder_name, extents, offset, args = self.tile[0]
            if (
                decoder_name == "raw"
                and len(args) >= 3
                and args[0] == self.mode
                and args[0] in Image._MAPMODES
            ):
                try:
                    if hasattr(Image.core, "map"):
                        # use built-in mapper  WIN32 only
                        self.map = Image.core.map(self.filename)
                        self.map.seek(offset)
                        self.im = self.map.readimage(
                            self.mode, self.size, args[1], args[2]
                        )
                    else:
                        # use mmap, if possible
                        import mmap

                        with open(self.filename, "r") as fp:
                            self.map = mmap.mmap(
                                fp.fileno(), 0, access=mmap.ACCESS_READ
                            )
                        self.im = Image.core.map_buffer(
                            self.map, self.size, decoder_name, extents, offset, args
                        )
                    readonly = 1
                    # After trashing self.im,
                    # we might need to reload the palette data.
                    if self.palette:
                        self.palette.dirty = 1
                except (AttributeError, EnvironmentError, ImportError):
                    self.map = None

        self.load_prepare()
        err_code = -3  # initialize to unknown error
        if not self.map:
            # sort tiles in file order
            self.tile.sort(key=_tilesort)

            try:
                # FIXME: This is a hack to handle TIFF's JpegTables tag.
                prefix = self.tile_prefix
            except AttributeError:
                prefix = b""

            for decoder_name, extents, offset, args in self.tile:
                decoder = Image._getdecoder(
                    self.mode, decoder_name, args, self.decoderconfig
                )
                try:
                    seek(offset)
                    decoder.setimage(self.im, extents)
                    if decoder.pulls_fd:
                        decoder.setfd(self.fp)
                        status, err_code = decoder.decode(b"")
                    else:
                        b = prefix
                        while True:
                            try:
                                s = read(self.decodermaxblock)
                            except (IndexError, struct.error):
                                # truncated png/gif
                                if LOAD_TRUNCATED_IMAGES:
                                    break
                                else:
                                    raise IOError("image file is truncated")

                            if not s:  # truncated jpeg
                                if LOAD_TRUNCATED_IMAGES:
                                    break
                                else:
                                    self.tile = []
                                    raise IOError(
                                        "image file is truncated "
                                        "(%d bytes not processed)" % len(b)
                                    )

                            b = b + s
                            n, err_code = decoder.decode(b)
                            if n < 0:
                                break
                            b = b[n:]
                finally:
                    # Need to cleanup here to prevent leaks
                    decoder.cleanup()

        self.tile = []
        self.readonly = readonly

        self.load_end()

        if self._exclusive_fp and self._close_exclusive_fp_after_loading:
            self.fp.close()
        self.fp = None

        if not self.map and not LOAD_TRUNCATED_IMAGES and err_code < 0:
            # still raised if decoder fails to return anything
            raise_ioerror(err_code)

        return Image.Image.load(self)

    def load_prepare(self):
        # create image memory if necessary
        if not self.im or self.im.mode != self.mode or self.im.size != self.size:
            self.im = Image.core.new(self.mode, self.size)
        # create palette (optional)
        if self.mode == "P":
            Image.Image.load(self)

    def load_end(self):
        # may be overridden
        pass

    # may be defined for contained formats
    # def load_seek(self, pos):
    #     pass

    # may be defined for blocked formats (e.g. PNG)
    # def load_read(self, bytes):
    #     pass

    def _seek_check(self, frame):
        if (
            frame < self._min_frame
            # Only check upper limit on frames if additional seek operations
            # are not required to do so
            or (
                not (hasattr(self, "_n_frames") and self._n_frames is None)
                and frame >= self.n_frames + self._min_frame
            )
        ):
            raise EOFError("attempt to seek outside sequence")

        return self.tell() != frame


class StubImageFile(ImageFile):
    """
    Base class for stub image loaders.

    A stub loader is an image loader that can identify files of a
    certain format, but relies on external code to load the file.
    """

    def _open(self):
        raise NotImplementedError("StubImageFile subclass must implement _open")

    def load(self):
        loader = self._load()
        if loader is None:
            raise IOError("cannot find loader for this %s file" % self.format)
        image = loader.load(self)
        assert image is not None
        # become the other object (!)
        self.__class__ = image.__class__
        self.__dict__ = image.__dict__

    def _load(self):
        """(Hook) Find actual image loader."""
        raise NotImplementedError("StubImageFile subclass must implement _load")


class Parser(object):
    """
    Incremental image parser.  This class implements the standard
    feed/close consumer interface.
    """

    incremental = None
    image = None
    data = None