#!/usr/bin/env bash
#
# One monotonic versionCode rule, shared by CI and manual builds
# (fdroid-repo-ci#6). Two implementations of "the next version code" is the
# whole failure mode this avoids, so both paths call this one script rather
# than each computing their own.
#
#     next-version-code.sh <index-v2.json URL or local path> <application-id> \
#         <committer-timestamp>
#
# <committer-timestamp> is the COMMITTER date (not author date -- a rebase
# leaves author date unchanged, which would defeat the backwards clamp) of
# the commit being built, as Unix seconds: `git log -1 --format=%ct`. This
# script takes it as an argument rather than reading git itself, on purpose
# -- the caller already knows its own commit, and it keeps the underlying
# Python pure and testable without a git checkout.
#
# Prints the integer to stdout and nothing else:
#
#     versionCode=$(bash next-version-code.sh "$INDEX_URL" "$APPLICATION_ID" \
#         "$(git log -1 --format=%ct)")
#
# The index source may be an http(s) URL -- what both CI and a manual build
# use in practice, and needs no credentials, since this repo and the F-Droid
# repo it reads are both public (weblib-viewer#16: buildable when CI is
# down) -- or a local file path, which is mainly what the offline test suite
# uses but is equally valid for a build that already has the index checked
# out.
#
# Fails loudly (non-zero exit, message on stderr, nothing on stdout) if the
# index cannot be fetched or parsed -- see next_version_code.py for why that
# is never allowed to fall back to a guess. An index with no entry at all for
# this application id is NOT an error: that is a normal first-ever publish
# for a channel, and yields the bare (clamped) candidate. A commit dated
# implausibly far in the future is also NOT a hard failure -- it is clamped
# to roughly now and a warning is printed on stderr; see next_version_code.py
# for why rejecting it outright would be worse.
#
# The rule itself, and why each part of it is shaped this way, lives in
# next_version_code.py's own docstring -- read that, not this file, for the
# reasoning. This script only resolves the pinned interpreter and forwards
# arguments; everything that can be unit-tested without nix lives in the
# stdlib-only Python module next to it.
#
# Pins python3 (stdlib json/urllib/datetime/argparse does the rest -- no
# other package) via with-nixpkgs.sh/nixpkgs-pin, next to this script.
set -euo pipefail

here=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)

if [ "$#" -ne 3 ]; then
  cat >&2 <<'USAGE'
usage: next-version-code.sh <index-v2.json URL or local path> <application-id> <committer-timestamp>
USAGE
  exit 2
fi

exec bash "$here/with-nixpkgs.sh" python3 python3 "$here/next_version_code.py" "$@"