#!/usr/bin/env python3

'''

    Tiny dumb script that generates virtual bundled `Provides` from a repo that

    uses go modules and vendoring.

'''

import sys

import re

def main():

    repos = get_repos_from_go_mod()

    print_provides_from_modules_txt(repos)

def get_repos_from_go_mod():

    repos = {}

    in_reqs = False

    for line in open('go.mod'):

        line = line.strip()

        if in_reqs and line.startswith(')'):

            break

        if not in_reqs:

            if line.startswith('require ('):

                in_reqs = True

            continue

        req = line.split()

        repo = req[0]

        tag = req[1]

        repos[repo] = go_mod_tag_to_rpm_provides_version(tag)

    return repos

def go_mod_tag_to_rpm_provides_version(tag):

    # go.mod tags are either exact git tags, or may be "pseudo-versions". We

    # want to convert these tags to something resembling a version string that

    # RPM won't fail on. For more information, see

    # https://golang.org/cmd/go/#hdr-Pseudo_versions and following sections.

    # trim off any +incompatible

    if tag.endswith('+incompatible'):

        tag = tag[:-len('+incompatible')]

    # git tags are normally of the form v$VERSION

    if tag.startswith('v'):

        tag = tag[1:]

    # is this a pseudo-version? e.g. v0.0.0-20181031085051-9002847aa142

    m = re.match("(.*)-([0-9]{14})-([a-f0-9]{12})", tag)

    if m:

        # rpm doesn't like multiple dashes in the version, so just merge the

        # timestamp and the commit checksum into the "release" field

        tag = f"{m.group(1)}-{m.group(2)}.git{m.group(3)}"

    return tag

def print_provides_from_modules_txt(repos):

    for line in open('vendor/modules.txt'):

        if line.startswith('#'):

            continue

        gopkg = line.strip()

        repo = lookup_repo_for_pkg(repos, gopkg)

        if not repo:

            # must be a pkg for tests only; ignore

            continue

        tag = repos[repo]

        print(f"Provides: bundled(golang({gopkg})) = {tag}")

def lookup_repo_for_pkg(repos, gopkg):

    for repo in repos:

        if gopkg.startswith(repo):

            return repo

if __name__ == '__main__':

    sys.exit(main())