#!/usr/bin/env sh
# hooks/pre-commit -- regenerate README.md from README.org on commit.
#
# When README.org (or build.el) is part of the commit, re-run the batch
# Org -> Markdown export and stage the refreshed README.md so it travels
# in the same commit.  GitHub and MELPA render Markdown better than Org.
#
# Lightweight by design: no sentinel file, no post-commit --amend.  If
# nothing relevant changed, the hook exits immediately.
#
# Install:  make hooks   (or: ln -s ../../hooks/pre-commit .git/hooks/pre-commit)
#
# Set EMACS in the environment if the Emacs binary is not named "emacs"
# on the PATH git sees (common on Windows/MSYS2).

set -e

REPO_ROOT="$(git rev-parse --show-toplevel)"
cd "$REPO_ROOT"

# Only act when README.org or the exporter itself is staged.
if ! git diff --cached --name-only | grep -Eq '^(README\.org|build\.el)$'; then
    exit 0
fi

EMACS_BIN="${EMACS:-emacs}"
if ! command -v "$EMACS_BIN" >/dev/null 2>&1; then
    echo "pre-commit: WARNING: '$EMACS_BIN' not found; README.md not regenerated." >&2
    echo "pre-commit:   set EMACS to your Emacs binary, or run 'make readme'." >&2
    exit 0
fi

echo "pre-commit: regenerating README.md from README.org"
"$EMACS_BIN" -Q --batch -l build.el

git add README.md
exit 0