#!/bin/sh
# version -- print slosh's version string, derived from git tags with ./VERSION
# as the floor (and the answer when there is no git at all).
#
# One script, so a build, the artifact it is packaged into, and the string the
# binary prints for `--version` can never disagree: the main Makefile bakes it
# in, Makefile.macos names the signed zip with it, and the release target names
# the linux tarballs with it. The ladder:
#
#   on a tag        v0.2.0            -> 0.2.0
#   past a tag      v0.2.0-5-gabc123  -> 0.2.0-5-gabc123     (sorts after 0.2.0)
#   before any tag  <VERSION>-<count>-g<short>               (+ -dirty if dirty)
#   no .git at all  <VERSION>                                (verbatim)
#
# ./VERSION is the committed floor and the only value a source tarball without
# git can show -- a cgit snapshot, which is how Homebrew builds from source. The
# commit count is in the tag-less form so `brew upgrade` sees a later build as
# later: without it 0.1.0-gabc123 vs 0.1.0-gdef456 would sort alphabetically,
# which has nothing to do with which came first.
set -eu

root="$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)"
base="$(cat "$root/VERSION" 2>/dev/null || echo 0.0.0)"

if git -C "$root" rev-parse --git-dir >/dev/null 2>&1; then
    d="$(git -C "$root" describe --tags --match 'v[0-9]*' --dirty 2>/dev/null || true)"
    if [ -n "$d" ]; then
        printf '%s\n' "${d#v}"
    else
        count="$(git -C "$root" rev-list --count HEAD 2>/dev/null || echo 0)"
        short="$(git -C "$root" rev-parse --short=8 HEAD 2>/dev/null || echo unknown)"
        dirty=""; git -C "$root" diff --quiet 2>/dev/null || dirty="-dirty"
        printf '%s-%s-g%s%s\n' "$base" "$count" "$short" "$dirty"
    fi
else
    printf '%s\n' "$base"
fi