#!/usr/bin/python

# See file COPYING distributed with ndar_unpack for copyright and license.

import sys
import os
import traceback
import errno
import argparse
import subprocess
import re
import tempfile
import shutil
import distutils.dir_util
import zipfile
import gzip
import struct
import json
import dicom
import boto.s3.connection

version = 'ndar_unpack 0.1.3'

# import nibabel if possible
# and since we're just using nibabel for MINC2, consider the import 
# unsuccessful if nibabel.Minc2Image doesn't exist
try:
    import nibabel
    nibabel.Minc2Image
except:
    nibabel = None

# SimpleITK for NRRD support
try:
    import SimpleITK
except:
    SimpleITK = None

description = """

ndar_unpack checks, describes, and unpacks imaging data from NDAR.

There are three main functions:

    Check: report whether the packaged data is sensible.  Is it just a header 
           without volume data?  Is it not volume data at all?  This is the 
           default action (if none others are given), but some describe and 
           unpack functions require a data check.

    Describe: derive as much of the image03 structure as possible from the 
              data itself.

    Unpack: create a volume of a given format or a thumbnail image from the 
            data, or download or unzip the data.

There are a number of outcomes from an ndar_unpack run.  Outcomes and their 
exit values are:

    Data is okay, and a successful ndar_unpack run.  Returns 0.

    Error in running ndar_unpack.  This is when ndar_unpack could not run 
    to completion for some reason, with the exception of the following 
    cases.  Returns 1.

    Command line error.  Mind your -ps and -qs.  Returns 2.

    Bad data.  The data is bad.  Maybe it's empty; maybe it's in an 
    unsupported format.  Returns 3.

AWS credentials can be specified in the environment as AWS_ACCESS_KEY_ID, 
AWS_SECRET_ACCESS_KEY, and (if using temporary tokens from NDAR) 
AWS_SECURITY_TOKEN.

Use ndar_unpack -S or ndar_unpack --self-check to check for programs used 
by ndar_unpack.  These flags override other functions, and ndar_unpack will 
exit immediately after running its checks, returning 0 if all programs are 
found and 1 otherwise.

Written by Christian Haselgrove, 2014.

"""

image03_fields = ('subjectkey', 'src_subject_id', 'interview_date', 
                  'interview_age', 'gender', 'comments_misc', 'image_file', 
                  'image_thumbnail_file', 'image_description', 
                  'image_file_format', 'image_modality', 
                  'scanner_manufacturer_pd', 'scanner_type_pd', 
                  'scanner_software_versions_pd', 'magnetic_field_strength', 
                  'mri_repetition_time_pd', 'mri_echo_time_pd', 'flip_angle', 
                  'acquisition_matrix', 'mri_field_of_view_pd', 
                  'patient_position', 'photomet_interpret', 'receive_coil', 
                  'transmit_coil', 'transformation_performed', 
                  'transformation_type', 'image_history', 
                  'image_num_dimensions', 'image_extent1', 'image_extent2', 
                  'image_extent3', 'image_extent4', 'extent4_type', 
                  'image_extent5', 'extent5_type', 'image_unit1', 
                  'image_unit2', 'image_unit3', 'image_unit4', 'image_unit5', 
                  'image_resolution1', 'image_resolution2', 
                  'image_resolution3', 'image_resolution4', 
                  'image_resolution5', 'image_slice_thickness', 
                  'image_orientation', 'qc_outcome', 'qc_description', 
                  'qc_fail_quest_reason', 'time_diff_units', 
                  'decay_correction', 'frame_end_times', 'frame_end_unit', 
                  'frame_start_times', 'frame_start_unit', 'pet_isotope', 
                  'pet_tracer', 'time_diff_inject_to_image', 'pulse_seq', 
                  'slice_acquisition', 'software_preproc', 'experiment_id', 
                  'scan_type', 'data_file2', 'data_file2_type')

# order matters; see NIfTI_1.__init__()
nifti_units_xyz = (('Meters', 1), 
                   ('Millimeters', 2), 
                   ('Micrometers', 3))

# order matters; see NIfTI_1.__init__()
nifti_units_t = (('Seconds', 8), 
                 ('Milliseconds', 16), 
                 ('Microseconds', 24))

def convert_dicom_time(val):
    return str(float(val)/1000.0)

def convert_dicom_date(val):
    mo = dicom_date_re.search(val)
    if mo is None:
        return None
    return '%s/%s/%s' % (mo.groupdict['month'], 
                         mo.groupdict['day'], 
                         mo.groupdict['year'])

def convert_dicom_float(val):
    if not isinstance(val, dicom.valuerep.DSfloat):
        return None
    return float(val)

dicom_date_re = re.compile('^(P<year>\d\d\d\d)(P<month>\d\d)(P<day>\d\d)$')

# image03 field => (DICOM tag, formatting/conversion function)
image03_dicom = {'gender': ('PatientSex', None), 
                 'image_modality': ('Modality', None), 
                 'scanner_manufacturer_pd': ('Manufacturer', None), 
                 'scanner_type_pd': ('ManufacturerModelName', None), 
                 'magnetic_field_strength': ('MagneticFieldStrength', 
                                             convert_dicom_float),  
                 'flip_angle': ('FlipAngle', convert_dicom_float), 
                 'acquisition_matrix': ('AcquisitionMatrix', None), 
                 'patient_position': ('PatientPosition', None), 
                 'photomet_interpret': ('PhotometricInterpretation', None), 
                 'receive_coil': ('ReceiveCoilName', None), 
                 'transmit_coil': ('TransmitCoilName', None), 
                 'interview_date': ('StudyDate', convert_dicom_date), 
                 'mri_repetition_time_pd': ('RepititionTime', 
                                            convert_dicom_time),
                 'mri_echo_time_pd': ('EchoTime', convert_dicom_time)}

def find_data_handler(tempdir):

    """attempt to find a class (BaseData subclass) that can handle the data"""

    # each class constructor will raise TypeError if it won't handle the data 
    # and DataError if it finds an error in the data, so hidden in this loop 
    # is also data checking

    message(NOTICE, 'inspecting data...')
    data = None
    for data_class in (NIfTIGzData, 
                       NIfTIData, 
                       AFNIData, 
                       MINCData, 
                       MINC2Data, 
                       NRRDData, 
                       DICOMData):
        try:
            message(DEBUG, 'trying %s' % str(data_class))
            data = data_class(tempdir)
        except TypeError, exc:
            message(DEBUG, 'class complains: %s' % str(exc))
            continue
    if not data:
        raise DataError('unrecognized data format')
    message(DEBUG, 'class %s accepted the data' % str(data.__class__))

    return data

SILENT = 0
ERROR = 1
NOTICE = 2
DEBUG = 3

#############################################################################
# exceptions
#

class BaseError(Exception):

    """base class for exceptions"""

    def __init__(self, error):
        self.error = error

    def __str__(self):
        return self.error

class DataError(BaseError):

    """error in the data"""

    def __str__(self):
        return 'bad data: %s' % self.error

class GeneralError(BaseError):

    """error running"""

#############################################################################
# classes
#

class NIfTI_1:

    """NIfTI-1 volume"""

    def __init__(self, fname):

        # read the header and check its length and the magic string
        if fname.endswith('.gz'):
            header_bytes = gzip.open(fname).read(348)
        else:
            header_bytes = open(fname).read(348)
        if len(header_bytes) < 348:
            raise ValueError('header too short in NIfTI-1 file')
        self.magic = header_bytes[344:]
        if self.magic != 'n+1\0':
            raise ValueError('bad magic string in NIfTI-1 file')

        # determine the byte ordering
        bo = '<'
        dim0 = struct.unpack('<h', header_bytes[40:42])[0]
        if dim0 < 1 or dim0 > 7:
            bo = '>'
            dim0 = struct.unpack('>h', header_bytes[40:42])[0]
            if dim0 < 1 or dim0 > 7:
                raise ValueError('couldn\'t determine byte ordering')
        self.sizeof_hdr = struct.unpack('%si' % bo, header_bytes[:4])[0]
        if self.sizeof_hdr != 348:
            raise ValueError('couldn\'t determine byte ordering')

        # unpack the header
        self.dim = struct.unpack('%s8h' % bo, header_bytes[40:56])
        self.datatype = struct.unpack('%sh' % bo, header_bytes[70:72])[0]
        self.bitpix = struct.unpack('%sh' % bo, header_bytes[72:74])[0]
        self.pixdim = struct.unpack('%s8f' % bo, header_bytes[76:108])
        self.vox_offset = struct.unpack('%sf' % bo, header_bytes[108:112])[0]
        self.xyzt_units = struct.unpack('%sB' % bo, header_bytes[123:124])[0]

        # order matters here; xyzt_units = 3 will match both Meters (1) and 
        # Micrometers (3), so we go from less to more specific
        self.xyz_units = None
        for (name, value) in nifti_units_xyz:
            if self.xyzt_units & value == value:
                self.xyz_units = name

        # again, order matters and we go from less to more specific
        self.t_units = None
        for (name, value) in nifti_units_t:
            if self.xyzt_units & value == value:
                self.t_units = name

        return

class BaseData:

    """base class for data handling classes

    Subclasses should define:

        @property image03(), which returns a dictionary containing the 
        image03 structure

        nii_gz(), which creates a .nii.gz.  If a file name is specified, 
        the NIfTI volume should be written to that file; otherwise a 
        temporary file should be created.  Returns the file name.

        header(), which returns a string containing the header information (in 
        an arbitrary format).

    Each subclass should define __init__() such that it returns only if 
    it is prepared to handle the data in the passed temporary directory.  
    If the class rejects the data (e.g. a DICOM handler recieves a NIfTI 
    file), __init__() should raise TypeError; if the class accepts the 
    data but finds an error (e.g. a DICOM handler finds more than one 
    series), __init__() should raise DataError.
    """

    def __init__(self, tempdir):
        self.tempdir = tempdir
        self.contents = []
        self.unpacked_dir = os.path.join(self.tempdir, 'unpacked')
        for (dir, dirs, files) in os.walk(self.unpacked_dir):
            for f in files:
                self.contents.append(os.path.join(dir, f))
        # a serial number for process output
        self.process_index = 0
        self._image03 = None
        return

    def _image03_from_nifti(self):
        """fill as much of the image03 structure as possible from the NIfTI 
        volume

        this also initializes _image03 with the known fields
        """

        self._image03 = {}
        for field in image03_fields:
            self._image03[field] = None

        vol = NIfTI_1(self.nii_gz())

        self._image03['image_num_dimensions'] = vol.dim[0]

        for i in xrange(1, vol.dim[0]+1):
            self._image03['image_extent%d' % i] = vol.dim[i]
            self._image03['image_resolution%d' % i] = vol.pixdim[i]
            if i < 4 and vol.xyz_units:
                self._image03['image_unit%d' % i] = vol.xyz_units
            if i == 4 and vol.t_units:
                self._image03['image_unit4'] = vol.t_units

        return self._image03

    def stdout_fname(self):
        return os.path.join(os.path.join(self.tempdir, 'output'), 
                            '%d.out' % self.process_index)

    def stderr_fname(self):
        return os.path.join(os.path.join(self.tempdir, 'output'), 
                            '%d.err' % self.process_index)

    def call(self, args):
        message(DEBUG, 'running (%d) %s' % (self.process_index, ' '.join(args)))
        stdout_f = None
        stderr_f = None
        self.process_index += 1
        stdout_fname = self.stdout_fname()
        stderr_fname = self.stderr_fname()
        try:
            stdout_f = open(stdout_fname, 'w')
            stderr_f = open(stderr_fname, 'w')
            rv = subprocess.call(args, stdout=stdout_f, stderr=stderr_f)
        except OSError, exc:
            # ENOENT if the program couldn't be found
            if exc.errno == errno.ENOENT:
                msg = 'couldn\'t find %s' % args[0]
            else:
                msg = str(exc)
            raise GeneralError(msg)
        finally:
            if stdout_f:
                stdout_f.close()
            if stderr_f:
                stderr_f.close()
        if rv < 0:
            raise GeneralError('%s killed by signal %d' % (args[0], -rv))
        if args[0] == 'mri_convert':
            stderr = open(stderr_fname).read()
            if 'ERROR: FreeSurfer license file' in stderr:
                raise GeneralError('FreeSurfer license not found')
        return rv

    def check_call(self, args):
        rv = self.call(args)
        if rv:
            raise GeneralError('error running %s' % args[0])
        return

class NIfTIGzData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) != 1:
            raise TypeError('too many files')
        if not self.contents[0].endswith('.nii.gz'):
            raise TypeError('bad extension')
        rv = self.call(['mri_convert', '-ro', self.contents[0]])
        if rv:
            raise DataError('could not read .nii.gz')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'NIfTI'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            return self.contents[0]
        shutil.copy(self.contents[0], path)
        return path

    def header(self):
        args = ['nifti_tool', '-disp_hdr', '-infiles', self.contents[0]]
        self.check_call(args)
        return open(self.stdout_fname()).read()

class NIfTIData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) != 1:
            raise TypeError('too many files')
        if not self.contents[0].endswith('.nii'):
            raise TypeError('bad extension')
        rv = self.call(['mri_convert', '-ro', self.contents[0]])
        if rv:
            raise DataError('could not read .nii')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'NIfTI'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        self.check_call(['mri_convert', self.contents[0], path])
        return path

    def header(self):
        args = ['nifti_tool', '-disp_hdr', '-infiles', self.contents[0]]
        self.check_call(args)
        return open(self.stdout_fname()).read()

class AFNIData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) != 2:
            raise TypeError('wrong number of files')
        base = os.path.commonprefix(self.contents)
        if not base:
            raise TypeError('no common prefix')
        if not base.endswith('.'):
            raise TypeError('common prefix does not end with "."')
        self.head = '%sHEAD' % base
        self.brik = '%sBRIK' % base
        if self.head not in self.contents or self.brik not in self.contents:
            raise TypeError('not a HEAD/BRIK pair')
        rv = self.call(['mri_convert', '-ro', self.brik])
        if rv:
            raise DataError('could not read .BRIK')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'AFNI'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        self.check_call(['mri_convert', self.brik, path])
        return path

    def header(self):
        return open(self.head).read()

class MINCData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) > 1:
            raise TypeError('too many files')
        if not self.contents[0].endswith('.mnc'):
            raise TypeError('bad extension')
        # since both MINC and MINC2 use .mnc, we also check the NetCDF magic 
        # number here
        if open(self.contents[0]).read(3) != 'CDF':
            raise TypeError('bad magic number')
        rv = self.call(['mri_convert', '-ro', self.contents[0]])
        if rv:
            raise DataError('could not read .mnc')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'MINC'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        self.check_call(['mri_convert', self.contents[0], path])
        return path

    def header(self):
        self.check_call(['mincheader', self.contents[0]])
        return open(self.stdout_fname()).read()

class MINC2Data(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not nibabel:
            raise TypeError('MINC2 unsupported')
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) > 1:
            raise TypeError('too many files')
        if not self.contents[0].endswith('.mnc'):
            raise TypeError('bad extension')
        try:
            self.im = nibabel.load(self.contents[0])
        except:
            raise TypeError('could not read .mnc')
        if not isinstance(self.im, nibabel.Minc2Image):
            raise TypeError('not MINC2')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'MINC'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        nibabel.save(self.im, path)
        return path

    def header(self):
        data = 'data_layout: %s\n' % self.im.header.data_layout
        data += 'default_x_flip: %s\n' % self.im.header.default_x_flip
        data += 'dtype: %s\n' % str(self.im.header.get_data_dtype())
        data += 'shape: %s\n' % str(self.im.header.get_data_shape())
        data += 'zooms: %s\n' % str(self.im.header.get_zooms())
        data += 'base affine:\n'
        data += str(self.im.header.get_base_affine())
        data += '\n'
        data += 'best affine:\n'
        data += str(self.im.header.get_best_affine())
        data += '\n'
        return data

class NRRDData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not SimpleITK:
            raise TypeError('NRRD unsupported')
        if not self.contents:
            raise TypeError('no files')
        if len(self.contents) > 1:
            raise TypeError('too many files')
        if not self.contents[0].endswith('.nrrd'):
            raise TypeError('bad extension')
        try:
            self.im = SimpleITK.ReadImage(self.contents[0])
        except:
            raise TypeError('could not read .nrrd')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        self._image03['image_file_format'] = 'MINC'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        SimpleITK.WriteImage(self.im, path)
        return path

    def header(self):
        data = 'dimension: %s\n' % str(self.im.GetDimension())
        data += 'size: %s\n' % str(self.im.GetSize())
        data += 'spacing: %s\n' % str(self.im.GetSpacing())
        data += 'origin: %s\n' % str(self.im.GetOrigin())
        data += 'direction: %s\n' % str(self.im.GetDirection())
        cpp = str(self.im.GetNumberOfComponentsPerPixel())
        data += 'components per pixel: %s\n' % cpp
        data += 'metadata:\n'
        for key in self.im.GetMetaDataKeys():
            data += '    %s = %s\n' % (key, str(self.im.GetMetaData(key)))
        return data

class DICOMData(BaseData):

    def __init__(self, tempdir):
        BaseData.__init__(self, tempdir)
        if not self.contents:
            raise TypeError('no files')
        series_uids = []
        for f in self.contents:
            try:
                do = dicom.read_file(f)
            except:
                raise TypeError('non-DICOM found')
            try:
                uid = str(do.SeriesInstanceUID)
            except AttributeError:
                raise DataError('DICOM file without Series Instance UID')
            if not uid:
                raise DataError('DICOM file with empty Series Instance UID')
            if uid not in series_uids:
                series_uids.append(uid)
        if len(series_uids) > 1:
            raise DataError('multiple series found')
        return

    @property
    def image03(self):
        if self._image03:
            return self._image03
        self._image03_from_nifti()
        do = dicom.read_file(self.contents[0])
        for (field, (tag, converter)) in image03_dicom.iteritems():
            try:
                value = getattr(do, tag)
                if not value:
                    value = None
                elif converter is not None:
                    value = converter(value)
                self._image03[field] = value
            except AttributeError:
                pass
        self._image03['image_file_format'] = 'DICOM'
        return self._image03

    def nii_gz(self, path=None):
        if not path:
            path = os.path.join(self.tempdir, 'volume.nii.gz')
        self.check_call(['mri_convert', self.contents[0], path])
        return path

    def header(self):
        do = dicom.read_file(self.contents[0])
        return '%s\n' % str(do)

#############################################################################
# functions
#

def message(level, msg):
    fo = sys.stdout
    if level > output_level:
        return
    if level == DEBUG:
        prefix = 'DEBUG: '
    elif level == ERROR:
        fo = sys.stderr
        prefix = '%s: ' % progname
    else:
        prefix = ''
    for line in msg.split('\n'):
        fo.write('%s%s\n' % (prefix, line))
    return

#############################################################################
# command line parsing
#

progname = os.path.basename(sys.argv[0])

parser = argparse.ArgumentParser(description=description, 
                                 formatter_class=argparse.RawTextHelpFormatter)

parser.add_argument('--self-check', '-S', 
                    default=False, 
                    dest='self_check_flag', 
                    action='store_true', 
                    help='run self check')
parser.add_argument('--version', 
                    default=False, 
                    dest='version_flag', 
                    action='store_true', 
                    help='print version and exit')
parser.add_argument('--download', '-d', 
                    dest='download_dir', 
                    metavar='<directory>', 
                    help='copy the source file')
parser.add_argument('--unpack', '-u', 
                    dest='unpack_dir', 
                    metavar='<directory>', 
                    help='unpack the source file')
parser.add_argument('--header', '-H')
parser.add_argument('--volume', '-v', 
                    metavar='<output volume>', 
                    action='append')
parser.add_argument('--thumbnail', '-t')
parser.add_argument('--image03', '-i')
parser.add_argument('--format', '-f', 
                    default='text', 
                    help='image03 output format', 
                    choices=('text', 'json'))
parser.add_argument('--contents', '-c')
parser.add_argument('--aws-access-key-id', 
                    default=os.environ.get('AWS_ACCESS_KEY_ID'))
parser.add_argument('--aws-secret-access-key', 
                    default=os.environ.get('AWS_SECRET_ACCESS_KEY'))
parser.add_argument('--aws-security-token', 
                    default=os.environ.get('AWS_SECURITY_TOKEN'))
parser.add_argument('--debug', '-D', 
                    default=False, 
                    dest='debug_flag', 
                    action='store_true', 
                    help='debug flag; overrides -q')
parser.add_argument('--dont-clean', 
                    default=True, 
                    dest='clean_flag', 
                    action='store_false', 
                    help='don\'t remove the temporary directory on exit')
parser.add_argument('--quiet', '-q', 
                    default=0, 
                    action='count', 
                    help='quiet flag; set twice for no output')
parser.add_argument('input', 
                    nargs='?', 
                    help='the input file or S3 URL')

args = parser.parse_args()

#############################################################################
# command line/input checks
#

output_level = NOTICE
if args.debug_flag:
    output_level = DEBUG
elif args.quiet:
    if args.quiet == 1:
        output_level = ERROR
    else:
        output_level = SILENT

if args.version_flag:
    print version
    sys.exit(0)

if args.self_check_flag:
    dev_null = open('/dev/null', 'w')
    ev = 0
    # (program name, ndar_unpack functionality)
    programs = (('mri_convert', 'most functions'), 
                ('fslreorient2std', 'thumbnail generation'), 
                ('slicer', 'thumbnail generation'), 
                ('nifti_tool', 'NIfTI header dumping'), 
                ('mincheader', 'MINC header dumping'))
    for (pn, fct) in programs:
        try:
            subprocess.call([pn], stdout=dev_null, stderr=subprocess.STDOUT)
        except:
            message(NOTICE, '%s not found: %s will fail' % (pn, fct))
            ev = 1
        else:
            message(NOTICE, '%s okay' % pn)
    if not nibabel:
        message(NOTICE, 'nibabel.Minc2Image not found: MINC2 reading will fail')
        ev = 1
    else:
        message(NOTICE, 'nibabel.Minc2Image okay')
    if not SimpleITK:
        message(NOTICE, 'SimpleITK not found: NRRD reading will fail')
        ev = 1
    else:
        message(NOTICE, 'SimpleITK okay')
    sys.exit(ev)

# we allow --self-check and --version to override the need for a positional 
# argument; since we can't have argparse require the argument, we have to 
# check for that explicitly here
if args.input is None:
    parser.print_usage(sys.stderr)
    msg = '%s: error: too few arguments\n' % os.path.basename(sys.argv[0])
    sys.stderr.write(msg)
    sys.exit(2)

errors = []

if args.volume:
    for fname in args.volume:
        if os.path.exists(fname):
            errors.append('%s exists' % fname)
        else:
            if not fname.endswith('.nii.gz'):
                errors.append('unknown extension for volume %s' % fname)

if args.thumbnail and os.path.exists(args.thumbnail):
    errors.append('%s exists' % args.thumbnail)

if args.image03 and args.image03 != '-' and os.path.exists(args.image03):
    errors.append('%s exists' % args.image03)

if args.contents and args.contents != '-' and os.path.exists(args.contents):
    errors.append('%s exists' % args.contents)

if args.header and args.header != '-' and os.path.exists(args.header):
    errors.append('%s exists' % args.header)

if args.input.startswith('s3://'):
    if not args.aws_access_key_id:
        errors.append('input is from S3 but no AWS access key ID given')
    if not args.aws_secret_access_key:
        errors.append('input is from S3 but no AWS secret access key given')

if args.download_dir and not os.path.isdir(args.download_dir):
    errors.append('%s: not a directory' % args.download_dir)

if args.unpack_dir and not os.path.isdir(args.unpack_dir):
    errors.append('%s: not a directory' % args.unpack_dir)

if errors:
    for e in errors:
        message(ERROR, e)
    sys.exit(1)

#############################################################################
# begin execution
#

try:

    tempdir = tempfile.mkdtemp()
    source_dir = os.path.join(tempdir, 'source')
    unpacked_dir = os.path.join(tempdir, 'unpacked')
    output_dir = os.path.join(tempdir, 'output')
    os.mkdir(source_dir)
    os.mkdir(unpacked_dir)
    os.mkdir(output_dir)

    source_basename = os.path.basename(args.input)
    temp_source = os.path.join(source_dir, source_basename)

    if args.input.startswith('s3://'):
        try:
            message(NOTICE, 'downloading data...')
            parts = args.input[5:].split('/', 1)
            # s3://bucket or s3://bucket/
            if len(parts) == 1 or not parts[1]:
                raise GeneralError('incomplete S3 URL')
            (bucket, path) = parts
            cf = boto.s3.connection.OrdinaryCallingFormat()
            conn = boto.connect_s3(args.aws_access_key_id, 
                                   args.aws_secret_access_key,
                                   security_token=args.aws_security_token,
                                   calling_format=cf)
            message(DEBUG, 'getting S3 bucket %s' % bucket)
            b = conn.get_bucket(bucket)
            message(DEBUG, 'looking for S3 object %s' % path)
            k = b.get_key(path)
            if not k:
                raise GeneralError('%s not found' % args.input)
            message(DEBUG, 'downloading S3 object to %s' % temp_source)
            k.get_contents_to_filename(temp_source)
            k.close()
            conn.close()
        except boto.exception.S3ResponseError, exc:
            raise GeneralError('S3 error: %s' % str(exc).strip('\n'))
    else:
        message(DEBUG, 'linking source to %s' % temp_source)
        os.symlink(os.path.abspath(args.input), temp_source)

    if args.input.endswith('.zip'):
        message(NOTICE, 'unpacking ZIP file...')
        try:
            zf = zipfile.ZipFile(temp_source)
            zf.extractall(unpacked_dir)
            zf.close()
        except zipfile.BadZipfile:
            raise DataError('error in zip file')
    else:
        message(DEBUG, 'linking source to unpacked/')
        os.symlink(temp_source, os.path.join(unpacked_dir, source_basename))

    if args.download_dir:
        message(NOTICE, 'copying source to %s...' % args.download_dir)
        shutil.copy(temp_source, args.download_dir)

    if args.unpack_dir:
        message(NOTICE, 'copying unpacked data to %s...' % args.unpack_dir)
        distutils.dir_util.copy_tree(unpacked_dir, args.unpack_dir, verbose=0)

    if args.contents:
        if args.contents == '-':
            fo = sys.stdout
        else:
            message(NOTICE, 'writing contents to %s...' % args.contents)
            fo = open(args.contents, 'w')
        try:
            # traverse the directory tree under the unpacked directory
            # relpath is the path relative to this directory (so relative 
            # to the root of the zip file)
            # normpath will remove the leading './' that will appear in 
            # top-level entries
            for (dirpath, dirnames, filenames) in os.walk(unpacked_dir):
                relpath = os.path.relpath(unpacked_dir, dirpath)
                for dname in dirnames:
                    path = os.path.normpath(os.path.join(relpath, dname))
                    fo.write('%s/\n' % path)
                for fname in filenames:
                    path = os.path.normpath(os.path.join(relpath, fname))
                    fo.write('%s\n' % path)
        finally:
            if fo is not sys.stdout:
                fo.close()

    data = None

    if args.header:
        if not data:
            data = find_data_handler(tempdir)
        if args.header == '-':
            fo = sys.stdout
        else:
            message(NOTICE, 'writing header to %s...' % args.header)
            fo = open(args.header, 'w')
        try:
            fo.write(data.header())
        finally:
            if fo is not sys.stdout:
                fo.close()

    if args.volume:
        if not data:
            data = find_data_handler(tempdir)
        for fname in args.volume:
            message(NOTICE, 'creating %s...' % fname)
            if fname.endswith('.nii.gz'):
                data.nii_gz(fname)

    if args.thumbnail:
        if not data:
            data = find_data_handler(tempdir)
        message(NOTICE, 'creating %s...' % args.thumbnail)
        vol_r = os.path.join(tempdir, 'vol_r.nii.gz')
        data.check_call(['fslreorient2std', data.nii_gz(), vol_r])
        data.check_call(['slicer', vol_r, '-a', args.thumbnail])

    if args.image03:
        if not data:
            data = find_data_handler(tempdir)
        if args.image03 == '-':
            fo = sys.stdout
        else:
            message(NOTICE, 'writing image03 to %s...' % args.image03)
            fo = open(args.image03, 'w')
        try:
            if args.format == 'text':
                max_width = max([ len(f) for f in image03_fields ])
                for field in image03_fields:
                    val = data.image03[field]
                    if val is None:
                        str_val = ''
                    else:
                        str_val = str(val)
                    fo.write('%s = %s\n' % (field.ljust(max_width), str_val))
            else:
                json.dump(data.image03, fo)
                fo.write('\n')
        finally:
            if fo is not sys.stdout:
                fo.close()

    # print a message if no other actions were taken
    if not args.volume \
       and not args.thumbnail \
       and not args.image03 \
       and not args.header \
       and not args.download_dir \
       and not args.unpack_dir \
       and not args.contents:
        if not data:
            data = find_data_handler(tempdir)
        message(NOTICE, 'data okay')

    if not data:
        message(NOTICE, 'data was not checked')

except Exception, exc:

    if isinstance(exc, DataError):
        ev = 3
    else:
        ev = 1

    if args.debug_flag:
        message(DEBUG, traceback.format_exc(exc))
    else:
        message(ERROR, str(exc))

    sys.exit(ev)

except KeyboardInterrupt:

    message(ERROR, 'caught keyboard interrupt, exiting')
    sys.exit(1)

finally:

    if args.clean_flag:
        message(DEBUG, 'removing temporary directory %s' % tempdir)
        shutil.rmtree(tempdir)
    else:
        message(NOTICE, 'leaving temporary directory %s' % tempdir)

sys.exit(0)

# eof