#!/usr/bin/env python
"""Generate the errors module from PostgreSQL source code.

The script can be run at a new PostgreSQL release to refresh the module.
"""

# Copyright (C) 2018 Daniele Varrazzo  <daniele.varrazzo@gmail.com>
#
# psycopg2 is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
# License for more details.
from __future__ import print_function

import os
import re
import sys
import urllib2
from collections import defaultdict


def main():
    filename = os.path.join(
        os.path.dirname(__file__), "../psycopg/sqlstate_errors.h")

    # If you add a version to the list fix the docs (in errors.rst)
    classes, errors = fetch_errors(
        ['9.1', '9.2', '9.3', '9.4', '9.5', '9.6', '10', '11'])

    f = open(filename, "w")
    print("/*\n * Autogenerated by 'scripts/make_errors.py'.\n */\n", file=f)
    for line in generate_module_data(classes, errors):
        print(line, file=f)


def parse_errors_txt(url):
    classes = {}
    errors = defaultdict(dict)

    page = urllib2.urlopen(url)
    for line in page:
        # Strip comments and skip blanks
        line = line.split('#')[0].strip()
        if not line:
            continue

        # Parse a section
        m = re.match(r"Section: (Class (..) - .+)", line)
        if m:
            label, class_ = m.groups()
            classes[class_] = label
            continue

        # Parse an error
        m = re.match(r"(.....)\s+(?:E|W|S)\s+ERRCODE_(\S+)(?:\s+(\S+))?$", line)
        if m:
            errcode, macro, spec = m.groups()
            # skip errcodes without specs as they are not publically visible
            if not spec:
                continue
            errlabel = spec.upper()
            errors[class_][errcode] = errlabel
            continue

        # We don't expect anything else
        raise ValueError("unexpected line:\n%s" % line)

    return classes, errors


errors_txt_url = \
    "http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob_plain;" \
    "f=src/backend/utils/errcodes.txt;hb=%s"


def fetch_errors(versions):
    classes = {}
    errors = defaultdict(dict)

    for version in versions:
        print(version, file=sys.stderr)
        tver = tuple(map(int, version.split()[0].split('.')))
        tag = '%s%s_STABLE' % (
            (tver[0] >= 10 and 'REL_' or 'REL'),
            version.replace('.', '_'))
        c1, e1 = parse_errors_txt(errors_txt_url % tag)
        classes.update(c1)

        for c, cerrs in e1.items():
            errors[c].update(cerrs)

    return classes, errors


def generate_module_data(classes, errors):
    tmpl = '{"%(errcode)s", "%(cls)s"},'
    specific = {
        '38002': 'ModifyingSqlDataNotPermittedExt',
        '38003': 'ProhibitedSqlStatementAttemptedExt',
        '38004': 'ReadingSqlDataNotPermittedExt',
        '39004': 'NullValueNotAllowedExt',
        'XX000': 'InternalError_',
    }

    seen = set("""
        Error Warning InterfaceError DataError DatabaseError ProgrammingError
        IntegrityError InternalError NotSupportedError OperationalError
        QueryCanceledError TransactionRollbackError
        """.split())

    for clscode, clslabel in sorted(classes.items()):
        if clscode in ('00', '01'):
            # success and warning - never raised
            continue

        yield "\n/* %s */" % clslabel

        for errcode, errlabel in sorted(errors[clscode].items()):
            if errcode in specific:
                clsname = specific[errcode]
            else:
                clsname = errlabel.title().replace('_', '')
            if clsname in seen:
                raise Exception("class already existing: %s" % clsname)
            seen.add(clsname)

            yield tmpl % {
                'cls': clsname,
                'errcode': errcode
            }


if __name__ == '__main__':
    sys.exit(main())