#!/bin/sh
# SPDX-License-Identifier: MIT
set -eu
export TZ=UTC LC_ALL=C
export GIT_CONFIG_NOSYSTEM=1 GIT_CONFIG_GLOBAL=/dev/null
export GIT_AUTHOR_NAME='Example Author' GIT_AUTHOR_EMAIL='author@example.invalid'
export GIT_COMMITTER_NAME='Example Author' GIT_COMMITTER_EMAIL='author@example.invalid'
export GIT_AUTHOR_DATE='2026-10-27T12:00:00+00:00'
export GIT_COMMITTER_DATE='2026-10-27T12:00:00+00:00'
test "$(git version)" = 'git version 2.56.0'

mkdir fetch-example
cd fetch-example
git init --template= --bare -q --initial-branch=main origin.git
git init --template= -q --initial-branch=main publisher
cd publisher
printf 'base\n' > note.txt
git add note.txt
git commit -qm 'Base'
git remote add origin ../origin.git
git push -q -u origin main >/dev/null
cd ..
git clone --template= -q origin.git reader
cd publisher
printf 'upstream\n' >> note.txt
git commit -qam 'Upstream change'
git push -q origin main
cd ../reader
before=$(git rev-parse HEAD)
git fetch -q origin
test "$(git rev-parse HEAD)" = "$before"
test "$(git rev-list --count HEAD..origin/main)" = 1
printf 'Fetch kept HEAD; incoming commits: '
git rev-list --count HEAD..origin/main
git pull --ff-only -q origin main >/dev/null
test "$(git rev-parse HEAD)" = "$(git rev-parse origin/main)"
printf 'Fast-forward pull integrated the fetched commit\n'
cd ..
git clone --template= -q origin.git merge-client
git clone --template= -q origin.git rebase-client
for client in merge-client rebase-client; do
  (cd "$client" && printf 'local\n' > local.txt && git add local.txt && git commit -qm 'Local change')
done
cd publisher
printf 'remote\n' > remote.txt
git add remote.txt
git commit -qm 'Another upstream change'
git push -q origin main
cd ../merge-client
git pull -q --no-rebase --no-edit origin main >/dev/null
test "$(git rev-list --parents -n 1 HEAD | wc -w | tr -d ' ')" = 3
printf 'Merge pull created a commit with two parents\n'
cd ../rebase-client
git pull -q --rebase origin main >/dev/null 2>&1
test "$(git log -1 --format=%s)" = 'Local change'
test "$(git log -2 --format=%s | tail -1)" = 'Another upstream change'
printf 'Rebase pull replayed the local commit after upstream\n'