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# Source code for fabio.mrcimage

    """
    MRC image for FabIO

    Authors: Jerome Kieffer
    email:  Jerome.Kieffer@terre-adelie.org

    Specifications from:
    http://ami.scripps.edu/software/mrctools/mrc_specification.php
    """
    # Get ready for python3:
    from __future__ import with_statement, print_function

    __authors__ = ["Jérôme Kieffer"]
    __contact__ = "Jerome.Kieffer@terre-adelie.org"
    __license__ = "GPLv3+"
    __copyright__ = "Jérôme Kieffer"
    __version__ = "29 Oct 2013"

    import numpy, logging, sys
    from .fabioimage import fabioimage
    logger = logging.getLogger("mrcimage")
    if sys.version_info < (3.0):
        bytes = str

    class mrcimage(fabioimage):
        """
        FabIO image class for Images from a mrc image stack
        """
        KEYS = ("NX", "NY", "NZ", "MODE", "NXSTART", "NYSTART", "NZSTART",
                "MX", "MY", "MZ", "CELL_A", "CELL_B", "CELL_C",
                "CELL_ALPHA", "CELL_BETA", "CELL_GAMMA",
                "MAPC", "MAPR", "MAPS", "DMIN", "DMAX", "DMEAN", "ISPG", "NSYMBT",
                "EXTRA", "ORIGIN", "MAP", "MACHST", "RMS", "NLABL")
        def __init__(self, *arg, **kwargs):
            """
            Generic constructor
            """
            fabioimage.__init__(self, *arg, **kwargs)
            self.data = None
            self.header = {}
            self.dim1 = self.dim2 = 0
            self.m = self.maxval = self.stddev = self.minval = None
            self.header_keys = self.header.keys()
            self.bytecode = None

        def _readheader(self, infile):
            """
            Read and decode the header of an image:

            @param infile: Opened python file (can be stringIO or bipped file)
            """
            # list of header key to keep the order (when writing)
            self.header = {}
            self.header_keys = []
            # header is composed of 56-int32 plus 10x80char lines
            int_block = numpy.fromstring(infile.read(56 * 4), dtype=numpy.int32)
            for key, value in zip(self.KEYS, int_block):
                self.header_keys.append(key)
                self.header[key] = value
            assert self.header["MAP"] == 542130509  # "MAP " in int32 !

            for i in range(10):
                label = "LABEL_%02i" % i
                self.header_keys.append(label)
                self.header[label] = infile.read(80).strip()
            self.dim1 = self.header["NX"]
            self.dim2 = self.header["NY"]
            self.nframes = self.header["NZ"]
            mode = self.header["MODE"]
            if mode == 0:
                self.bytecode = numpy.int8
            elif mode == 1:
                self.bytecode = numpy.int16
            elif mode == 2:
                self.bytecode = numpy.float32
            elif mode == 3:
                self.bytecode = numpy.complex64
            elif mode == 4:
                self.bytecode = numpy.complex64
            elif mode == 6:
                self.bytecode = numpy.uint16
            self.imagesize = self.dim1 * self.dim2 * numpy.dtype(self.bytecode).itemsize

        def read(self, fname, frame=None):
            """
            try to read image
            @param fname: name of the file
            @param frame:
            """

            self.resetvals()
            self.sequencefilename = fname
            self.currentframe = frame or 0

            with self._open(fname) as infile:
                self._readheader(infile)
                self._readframe(infile, self.currentframe)
            return self

        def _calc_offset(self, frame):
            """
            Calculate the frame position in the file

            @param frame: frame number
            """
            assert frame < self.nframes
            return 1024 + frame * self.imagesize

        def _makeframename(self):
            self.filename = "%s$%04d" % (self.sequencefilename,
                                         self.currentframe)

        def _readframe(self, infile, img_num):
            """
            Read a frame an populate data
            @param infile: opened file
            @param img_num: frame number (int)
            """
            if (img_num > self.nframes or img_num < 0):
                raise RuntimeError("Requested frame number is out of range")
            imgstart = self.header['offset'] + img_num * (512 * 476 * 2 + 24)
            infile.seek(self.calc_offset(img_num), 0)
            self.data = numpy.fromstring(infile.read(self.imagesize),
                                          self.bytecode)
            self.data.shape = self.dim2, self.dim1
            self.currentframe = int(img_num)
            self._makeframename()

        def write(self, fname, force_type=numpy.uint16):
            raise NotImplementedError("Write is not implemented")

        def getframe(self, num):
            """
            Returns a frame as a new fabioimage object
            @param num: frame number
            """
            if num < 0 or num > self.nframes:
                raise RuntimeError("Requested frame number is out of range")
            # Do a deep copy of the header to make a new one
            frame = mrcimage(header=self.header.copy())
            frame.header_keys = self.header_keys[:]
            for key in ("dim1", "dim2", "nframes", "bytecode", "imagesize", "sequencefilename"):
                frame.__setattr__(key, self.__getattribute__(key))
            with frame._open(self.sequencefilename, "rb") as infile:
                frame._readframe(infile, num)
            return frame

        def next(self):
            """
            Get the next image in a series as a fabio image
            """
            if self.currentframe < (self.nframes - 1) and self.nframes > 1:
                return self.getframe(self.currentframe + 1)
            else:
                newobj = mrcimage()
                newobj.read(next_filename(
                    self.sequencefilename))
                return newobj

        def previous(self):
            """
            Get the previous image in a series as a fabio image
            """
            if self.currentframe > 0:
                return self.getframe(self.currentframe - 1)
            else:
                newobj = mrcimage()
                newobj.read(previous_filename(
                    self.sequencefilename))
                return newobj

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