# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""Validate VO Services."""

# STDLIB
import multiprocessing
import os
import warnings
from collections import OrderedDict
from pathlib import Path

# ASTROPY
from astropy.io import votable
from astropy.io.votable.exceptions import E19
from astropy.io.votable.validator import html, result
from astroquery import log
from astropy.utils import data
from astropy.utils.exceptions import AstropyUserWarning
from astropy.utils.xml.unescaper import unescape_all

# LOCAL
from .tstquery import parse_cs
from .exceptions import (ValidationMultiprocessingError,
                         InvalidValidationAttribute)
from ..exceptions import VOSError
from ..vos_catalog import VOSDatabase, vo_tab_parse
from ...utils.timer import timefunc

# Import configurable items declared in __init__.py
from . import conf

__all__ = ['check_conesearch_sites']


@timefunc(num_tries=1)
def check_conesearch_sites(*, destdir=os.curdir, verbose=True, parallel=True,
                           url_list='default'):
    """
    Validate Cone Search Services.

    .. note::

        URLs are unescaped prior to validation.

        Only check queries with ``<testQuery>`` parameters.
        Does not perform meta-data and erroneous queries.

    Parameters
    ----------
    destdir : str, optional
        Directory to store output files. Will be created if does
        not exist. Existing files with these names will be deleted
        or replaced:

            * conesearch_good.json
            * conesearch_warn.json
            * conesearch_exception.json
            * conesearch_error.json

    verbose : bool, optional
        Print extra info to log.

    parallel : bool, optional
        Enable multiprocessing.

    url_list : list of string, optional
        Only check these access URLs against
        ``astroquery.vo_conesearch.validator.conf.conesearch_master_list``
        and ignore the others, which will not appear in output files.
        By default, check those in
        ``astroquery.vo_conesearch.validator.conf.conesearch_urls``.
        If `None`, check everything.

    Raises
    ------
    OSError
        Invalid destination directory.

    timeout
        URL request timed out.

    ValidationMultiprocessingError
        Multiprocessing failed.

    """
    if url_list == 'default':
        url_list = conf.conesearch_urls

    if (not isinstance(destdir, (str, Path))
            or os.path.exists(destdir) and not os.path.isdir(destdir)):
        raise OSError('Invalid destination directory')  # pragma: no cover

    if not os.path.exists(destdir):
        os.mkdir(destdir)

    # Output dir created by votable.validator
    out_dir = os.path.join(destdir, 'results')

    if not os.path.exists(out_dir):
        os.mkdir(out_dir)

    # Output files
    db_file = OrderedDict()
    db_file['good'] = os.path.join(destdir, 'conesearch_good.json')
    db_file['warn'] = os.path.join(destdir, 'conesearch_warn.json')
    db_file['excp'] = os.path.join(destdir, 'conesearch_exception.json')
    db_file['nerr'] = os.path.join(destdir, 'conesearch_error.json')

    # JSON dictionaries for output files
    js_tree = {}
    for key in db_file:
        js_tree[key] = VOSDatabase.create_empty()

        # Delete existing files, if any, to be on the safe side.
        # Else can cause confusion if program exited prior to
        # new files being written but old files are still there.
        if os.path.exists(db_file[key]):  # pragma: no cover
            os.remove(db_file[key])
            if verbose:
                log.info('Existing file {0} deleted'.format(db_file[key]))

    # Master VO database from registry. Silence all the warnings.
    with warnings.catch_warnings():
        warnings.simplefilter('ignore')
        js_mstr = VOSDatabase.from_registry(
            conf.conesearch_master_list, encoding='binary',
            show_progress=verbose)

    # Validate only a subset of the services.
    if url_list is not None:
        # Make sure URL is unique and fixed.
        url_list = set(map(
            unescape_all,
            [cur_url if isinstance(cur_url, str) else cur_url
             for cur_url in url_list]))
        uniq_rows = len(url_list)
        url_list_processed = []  # To track if given URL is valid in registry
        if verbose:
            log.info('Only {0}/{1} site(s) are validated'.format(uniq_rows,
                                                                 len(js_mstr)))
    # Validate all services.
    else:
        uniq_rows = len(js_mstr)

    key_lookup_by_url = {}

    # Process each catalog in the registry.
    for cur_key, cur_cat in js_mstr.get_catalogs():
        cur_url = cur_cat['url']

        # Skip if:
        #   a. not a Cone Search service
        #   b. not in given subset, if any
        if ((cur_cat['cap_type'] != 'conesearch')
                or (url_list is not None and cur_url not in url_list)):
            continue

        # Use testQuery to return non-empty VO table with max verbosity.
        testquery_pars = parse_cs(cur_cat['ivoid'], cap_index=cur_cat['cap_index'])
        cs_pars_arr = ['{}={}'.format(key, testquery_pars[key])
                       for key in testquery_pars]
        cs_pars_arr += ['VERB=3']

        # Track the service.
        key_lookup_by_url[cur_url + '&'.join(cs_pars_arr)] = cur_key
        if url_list is not None:
            url_list_processed.append(cur_url)

    # Give warning if any of the user given subset is not in the registry.
    if url_list is not None:
        url_list_skipped = url_list - set(url_list_processed)
        n_skipped = len(url_list_skipped)
        if n_skipped > 0:
            warn_str = '{0} not found in registry! Skipped:\n'.format(
                n_skipped)
            for cur_url in url_list_skipped:
                warn_str += '\t{0}\n'.format(cur_url)
            warnings.warn(warn_str, AstropyUserWarning)

    all_urls = list(key_lookup_by_url)
    timeout = data.conf.remote_timeout

    map_args = [(out_dir, url.encode('utf-8'), timeout) for url in all_urls]

    # Validate URLs
    if parallel:
        pool = multiprocessing.Pool()
        try:
            mp_list = pool.map(_do_validation, map_args)
        except Exception as exc:  # pragma: no cover
            raise ValidationMultiprocessingError(
                'An exception occurred during parallel processing '
                'of validation results: {0}'.format(exc))
    else:
        mp_list = map(_do_validation, map_args)

    # Categorize validation results
    for r in mp_list:
        db_key = r['out_db_name']
        cat_key = key_lookup_by_url[r.url.decode('utf-8')]
        cur_cat = js_mstr.get_catalog(cat_key)
        _copy_r_to_cat(r, cur_cat)
        js_tree[db_key].add_catalog(cat_key, cur_cat)

    # Write to HTML
    html_subsets = result.get_result_subsets(mp_list, out_dir)
    html.write_index(html_subsets, all_urls, out_dir)
    if parallel:
        html_subindex_args = [(out_dir, html_subset, uniq_rows)
                              for html_subset in html_subsets]
        pool.map(_html_subindex, html_subindex_args)
    else:
        for html_subset in html_subsets:
            _html_subindex((out_dir, html_subset, uniq_rows))

    # Write to JSON
    n = {}
    n_tot = 0
    for key in db_file:
        n[key] = len(js_tree[key])
        n_tot += n[key]
        js_tree[key].to_json(db_file[key], overwrite=True)
        if verbose:
            log.info('{0}: {1} catalog(s)'.format(key, n[key]))

    # Checksum
    if verbose:
        log.info('total: {0} out of {1} catalog(s)'.format(n_tot, uniq_rows))

    if n['good'] == 0:  # pragma: no cover
        warnings.warn(
            'No good sites available for Cone Search.', AstropyUserWarning)


def _do_validation(args):
    """Validation for multiprocessing support."""

    root, url, timeout = args

    votable.table.reset_vo_warnings()

    r = result.Result(url, root=root, timeout=timeout)
    r.validate_vo()

    _categorize_result(r)

    # This was already checked above.
    # Calling this again to get VOTableFile object to catch
    # well-formed error responses in downloaded XML.
    #
    # 'incorrect' is also added in case user wants to use
    # 'conesearch_warn.json' anyway.
    #
    # If using cached data, it will not detect network error
    # like the first run, but will raise exception.
    #
    # When SR is not 0, VOSError is raised for empty table.
    #
    if r['expected'] in ('good', 'incorrect') and r['nexceptions'] == 0:
        nexceptions = 0
        nwarnings = 0
        lines = []

        with warnings.catch_warnings(record=True) as warning_lines:
            try:
                vo_tab_parse(votable.table.parse(
                    r.get_vo_xml_path(), verify='warn'), r.url, {})
            except (E19, IndexError, VOSError) as e:  # pragma: no cover
                lines.append(str(e))
                nexceptions += 1
        lines = [str(x.message) for x in warning_lines] + lines

        warning_types = set()
        for line in lines:  # pragma: no cover
            w = votable.exceptions.parse_vowarning(line)
            if w['is_warning']:
                nwarnings += 1
            if w['is_exception']:
                nexceptions += 1
            warning_types.add(w['warning'])

        r['nwarnings'] += nwarnings
        r['nexceptions'] += nexceptions
        r['warnings'] += lines
        r['warning_types'] = r['warning_types'].union(warning_types)

        _categorize_result(r)

    html.write_result(r)
    return r


def _categorize_result(r):
    """
    Set success codes.

    Parameters
    ----------
    r : `astropy.io.votable.validator.result.Result`

    Raises
    ------
    InvalidValidationAttribute
        Unhandled validation result attributes.

    """
    from . import conf

    if ('network_error' in r
            and r['network_error'] is not None):  # pragma: no cover
        r['out_db_name'] = 'nerr'
        r['expected'] = 'broken'
    elif ((r['nexceptions'] == 0 and r['nwarnings'] == 0)
            or r['warning_types'].issubset(conf.noncritical_warnings)):
        r['out_db_name'] = 'good'
        r['expected'] = 'good'
    elif r['nexceptions'] > 0:  # pragma: no cover
        r['out_db_name'] = 'excp'
        r['expected'] = 'incorrect'
    elif r['nwarnings'] > 0:  # pragma: no cover
        r['out_db_name'] = 'warn'
        r['expected'] = 'incorrect'
    else:  # pragma: no cover
        raise InvalidValidationAttribute('Unhandled validation result attrib'
                                         'utes: {0}'.format(r._attributes))


def _html_subindex(args):
    """HTML writer for multiprocessing support."""
    out_dir, subset, total = args
    html.write_index_table(out_dir, *subset, total=total)


def _copy_r_to_cat(r, cat):
    """
    Copy validation result attributes to given VO catalog.

    Parameters
    ----------
    r : `astropy.io.votable.validate.result.Result`

    cat : `astroquery.vo_conesearch.vos_catalog.VOSCatalog`

    """
    for key in r._attributes:
        new_key = 'validate_' + key
        cat[new_key] = r._attributes[key]
