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# Source code for astropy.io.ascii.cds

    # Licensed under a 3-clause BSD style license - see LICENSE.rst
    """An extensible ASCII table reader and writer.

    cds.py:
      Classes to read CDS / Vizier table format

    :Copyright: Smithsonian Astrophysical Observatory (2011)
    :Author: Tom Aldcroft (aldcroft@head.cfa.harvard.edu)
    """

    from __future__ import absolute_import, division, print_function

    import fnmatch
    import itertools
    import re
    import os

    from . import core
    from . import fixedwidth

    from ...utils.compat import ignored

    __doctest_skip__ = ['*']

    class CdsHeader(core.BaseHeader):
        col_type_map = {'e': core.FloatType,
                        'f': core.FloatType,
                        'i': core.IntType,
                        'a': core.StrType}

        'The ReadMe file to construct header from.'
        readme = None

        def get_type_map_key(self, col):
            match = re.match(r'\d*(\S)', col.raw_type.lower())
            if not match:
                raise ValueError('Unrecognized CDS format "%s" for column "%s"' % (
                    col.raw_type, col.name))
            return match.group(1)

        def get_cols(self, lines):
            """
            Initialize the header Column objects from the table ``lines`` for a CDS
            header.

            Parameters
            ----------
            lines : list
                List of table lines

            """

            # Read header block for the table ``self.data.table_name`` from the read
            # me file ``self.readme``.
            if self.readme and self.data.table_name:
                in_header = False
                readme_inputter = core.BaseInputter()
                f = readme_inputter.get_lines(self.readme)
                # Header info is not in data lines but in a separate file.
                lines = []
                comment_lines = 0
                for line in f:
                    line = line.strip()
                    if in_header:
                        lines.append(line)
                        if line.startswith('------') or line.startswith('======='):
                            comment_lines += 1
                            if comment_lines == 3:
                                break
                    else:
                        match = re.match(r'Byte-by-byte Description of file: (?P<name>.+)$',
                                         line, re.IGNORECASE)
                        if match:
                            # Split 'name' in case in contains multiple files
                            names = [s for s in re.split('[, ]+', match.group('name'))
                                     if s]
                            # Iterate on names to find if one matches the tablename
                            # including wildcards.
                            for pattern in names:
                                if fnmatch.fnmatch(self.data.table_name, pattern):
                                    in_header = True
                                    lines.append(line)
                                    break

                else:
                    raise core.InconsistentTableError("Can't find table {0} in {1}".format(
                        self.data.table_name, self.readme))

            found_line = False

            for i_col_def, line in enumerate(lines):
                if re.match(r'Byte-by-byte Description', line, re.IGNORECASE):
                    found_line = True
                elif found_line: # First line after list of file descriptions
                    i_col_def -= 1 # Set i_col_def to last description line
                    break

            re_col_def = re.compile(r"""\s*
                                        (?P<start> \d+ \s* -)? \s*
                                        (?P<end>   \d+)        \s+
                                        (?P<format> [\w.]+)     \s+
                                        (?P<units> \S+)        \s+
                                        (?P<name>  \S+)        \s+
                                        (?P<descr> \S.+)""",
                                    re.VERBOSE)

            cols = []
            for line in itertools.islice(lines, i_col_def+4, None):
                if line.startswith('------') or line.startswith('======='):
                    break
                match = re_col_def.match(line)
                if match:
                    col = core.Column(name=match.group('name'))
                    col.start = int(re.sub(r'[-\s]', '',
                                           match.group('start') or match.group('end'))) - 1
                    col.end = int(match.group('end'))
                    col.unit = match.group('units')
                    if col.unit == '---':
                        col.unit = None  # "---" is the marker for no unit in CDS table
                    col.description = match.group('descr').strip()
                    col.raw_type = match.group('format')
                    col.type = self.get_col_type(col)

                    match = re.match(
                        r'\? (?P<equal> =)? (?P<nullval> \S*)', col.description, re.VERBOSE)
                    if match:
                        if issubclass(col.type, core.FloatType):
                            fillval = 'nan'
                        else:
                            fillval = '0'

                        if match.group('nullval') == '-':
                            col.null = '---'
                            # CDS tables can use -, --, ---, or ---- to mark missing values
                            # see https://github.com/astropy/astropy/issues/1335
                            for i in [1, 2, 3, 4]:
                                self.data.fill_values.append(('-'*i, fillval, col.name))
                        else:
                            col.null = match.group('nullval')
                            self.data.fill_values.append((col.null, fillval, col.name))

                    cols.append(col)
                else:  # could be a continuation of the previous col's description
                    if cols:
                        cols[-1].description += line.strip()
                    else:
                        raise ValueError('Line "%s" not parsable as CDS header' % line)

            self.names = [x.name for x in cols]

            self.cols = cols

    class CdsData(core.BaseData):
        """CDS table data reader
        """
        splitter_class = fixedwidth.FixedWidthSplitter

        def process_lines(self, lines):
            """Skip over CDS header by finding the last section delimiter"""
            # If the header has a ReadMe and data has a filename
            # then no need to skip, as the data lines do not have header
            # info. The ``read`` method adds the table_name to the ``data``
            # attribute.
            if self.header.readme and self.table_name:
                return lines
            i_sections = [i for (i, x) in enumerate(lines)
                          if x.startswith('------') or x.startswith('=======')]
            if not i_sections:
                raise core.InconsistentTableError('No CDS section delimiter found')
            return lines[i_sections[-1]+1:]

    class Cds(core.BaseReader):
        """Read a CDS format table.  See http://vizier.u-strasbg.fr/doc/catstd.htx.
        Example::

          Table: Table name here
          = ==============================================================================
          Catalog reference paper
              Bibliography info here
          ================================================================================
          ADC_Keywords: Keyword ; Another keyword ; etc

          Description:
              Catalog description here.
          ================================================================================
          Byte-by-byte Description of file: datafile3.txt
          --------------------------------------------------------------------------------
             Bytes Format Units  Label  Explanations
          --------------------------------------------------------------------------------
             1-  3 I3     ---    Index  Running identification number
             5-  6 I2     h      RAh    Hour of Right Ascension (J2000)
             8-  9 I2     min    RAm    Minute of Right Ascension (J2000)
            11- 15 F5.2   s      RAs    Second of Right Ascension (J2000)
          --------------------------------------------------------------------------------
          Note (1): A CDS file can contain sections with various metadata.
                    Notes can be multiple lines.
          Note (2): Another note.
          --------------------------------------------------------------------------------
            1 03 28 39.09
            2 04 18 24.11

        **About parsing the CDS format**

        The CDS format consists of a table description and the table data.  These
        can be in separate files as a ``ReadMe`` file plus data file(s), or
        combined in a single file.  Different subsections within the description
        are separated by lines of dashes or equal signs ("------" or "======").
        The table which specifies the column information must be preceded by a line
        starting with "Byte-by-byte Description of file:".

        In the case where the table description is combined with the data values,
        the data must be in the last section and must be preceded by a section
        delimiter line (dashes or equal signs only).

        **Basic usage**

        Use the ``ascii.read()`` function as normal, with an optional ``readme``
        parameter indicating the CDS ReadMe file.  If not supplied it is assumed that
        the header information is at the top of the given table.  Examples::

          >>> from astropy.io import ascii
          >>> table = ascii.read("t/cds.dat")
          >>> table = ascii.read("t/vizier/table1.dat", readme="t/vizier/ReadMe")
          >>> table = ascii.read("t/cds/multi/lhs2065.dat", readme="t/cds/multi/ReadMe")
          >>> table = ascii.read("t/cds/glob/lmxbrefs.dat", readme="t/cds/glob/ReadMe")

        The table name and the CDS ReadMe file can be entered as URLs.  This can be used
        to directly load tables from the Internet.  For example, Vizier tables from the
        CDS::

          >>> table = ascii.read("ftp://cdsarc.u-strasbg.fr/pub/cats/VII/253/snrs.dat",
          ...             readme="ftp://cdsarc.u-strasbg.fr/pub/cats/VII/253/ReadMe")

        If the header (ReadMe) and data are stored in a single file and there
        is content between the header and the data (for instance Notes), then the
        parsing process may fail.  In this case you can instruct the reader to
        guess the actual start of the data by supplying ``data_start='guess'`` in the
        call to the ``ascii.read()`` function.  You should verify that the output
        data table matches expectation based on the input CDS file.

        **Using a reader object**

        When ``Cds`` reader object is created with a ``readme`` parameter
        passed to it at initialization, then when the ``read`` method is
        executed with a table filename, the header information for the
        specified table is taken from the ``readme`` file.  An
        ``InconsistentTableError`` is raised if the ``readme`` file does not
        have header information for the given table.

          >>> readme = "t/vizier/ReadMe"
          >>> r = ascii.get_reader(ascii.Cds, readme=readme)
          >>> table = r.read("t/vizier/table1.dat")
          >>> # table5.dat has the same ReadMe file
          >>> table = r.read("t/vizier/table5.dat")

        If no ``readme`` parameter is specified, then the header
        information is assumed to be at the top of the given table.

          >>> r = ascii.get_reader(ascii.Cds)
          >>> table = r.read("t/cds.dat")
          >>> #The following gives InconsistentTableError, since no
          >>> #readme file was given and table1.dat does not have a header.
          >>> table = r.read("t/vizier/table1.dat")
          Traceback (most recent call last):
            ...
          InconsistentTableError: No CDS section delimiter found

        Caveats:

        * The Units and Explanations are available in the column ``unit`` and
          ``description`` attributes, respectively.
        * The other metadata defined by this format is not available in the output table.
        """
        _format_name = 'cds'
        _io_registry_format_aliases = ['cds']
        _io_registry_can_write = False
        _description = 'CDS format table'

        data_class = CdsData
        header_class = CdsHeader

        def __init__(self, readme=None):
            super(Cds, self).__init__()
            self.header.readme = readme

        def write(self, table=None):
            """Not available for the Cds class (raises NotImplementedError)"""
            raise NotImplementedError

        def read(self, table):
            # If the read kwarg `data_start` is 'guess' then the table may have extraneous
            # lines between the end of the header and the beginning of data.
            if self.data.start_line == 'guess':
                # Replicate the first part of BaseReader.read up to the point where
                # the table lines are initially read in.
                with ignored(TypeError):
                    # For strings only
                    if os.linesep not in table + '':
                        self.data.table_name = os.path.basename(table)

                self.data.header = self.header
                self.header.data = self.data

                # Get a list of the lines (rows) in the table
                lines = self.inputter.get_lines(table)

                # Now try increasing data.start_line by one until the table reads successfully.
                # For efficiency use the in-memory list of lines instead of `table`, which
                # could be a file.
                for data_start in range(len(lines)):
                    self.data.start_line = data_start
                    with ignored(Exception):
                        table = super(Cds, self).read(lines)
                        return table
            else:
                return super(Cds, self).read(table)