#!/usr/bin/env python3
#
# Tests the toplevel crate with *every* combination of cargo features.
# (But, not any sets that don't include any `minimal-*` feature.)
#
# This script, obviously, runs cargo a number of times which is
# *exponential* in the number of cargo features.
#
# But, most of those builds don't do very much, because cargo caches
# builds of a particular crate with particular features separately,
# and can retain multiple versions.
#
# And the set of combinations that cargo needs to build for is also
# reduced a bit because it's the *effective* feature set that counts.
#
# In practice a from scratch run of this script currently takes 65s
# on my laptop.  That seems fine.  But this is why we're just running
# `cargo check` and not actually running any of the tests.

import argparse
import subprocess
import toml.decoder
from typing import Iterable, Tuple, TypeVar
from itertools import chain, combinations

T = TypeVar('T')

# Copied from https://docs.python.org/3/library/itertools.html
# retrieved 2024-06-21.  Licence there is as follows:
#  This page is licensed under
#    the Python Software Foundation License Version 2.
#   Examples, recipes, and other code in the documentation are
#    additionally licensed under the Zero Clause BSD License. 
def powerset(iterable: Iterable[T]) -> Iterable[Iterable[T]]:
    "powerset([1,2,3]) → () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

def main() -> None:
    parser = argparse.ArgumentParser()
    args = parser.parse_args()

    t = toml.decoder.load('Cargo.toml')
    features = list(t['features'])
    print(repr(features))
    for f in features:
        print('found feature %s' % f)
    combs = []

    for feats in powerset(features):
        print("considering: %s" % ' '.join(feats))
        if not(any([s.startswith('minimal-') for s in feats])):
            print('no minimal-* feature enabled')
            continue
        combs.append(feats)

    for i, feats in enumerate(combs):
        print('==================== %d/%d ===================='
              % (i, len(combs)),
              flush=True)

        scriptlet = '''
${CARGO-cargo} check --no-default-features $1
'''
        cmd = ['sh','-xec', scriptlet, 'x', '--features=' + ','.join(feats)]
        subprocess.run(cmd, check=True)

    print('==================== %d complete, ok ====================' %
          len(combs))

main()