#!/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'
export GIT_AUTHOR_EMAIL='author@example.invalid'
export GIT_COMMITTER_NAME='Example Author'
export GIT_COMMITTER_EMAIL='author@example.invalid'
export GIT_AUTHOR_DATE='2026-10-25T12:00:00+00:00'
export GIT_COMMITTER_DATE='2026-10-25T12:00:00+00:00'
test "$(git version)" = 'git version 2.56.0'

mkdir merge-example
cd merge-example
git init -q --template= --initial-branch=main --object-format=sha1
git config commit.gpgsign false
git config core.autocrlf false
printf 'base\n' > note.txt
printf 'original unrelated file\n' > later.txt
git add note.txt later.txt
git commit -qm 'Base note'
git switch -qc topic
printf 'topic version\n' > note.txt
git commit -qam 'Topic change'
git switch -q main
printf 'main version\n' > note.txt
git commit -qam 'Main change'
test -z "$(git status --porcelain=v1)"
head_before=$(git rev-parse HEAD)
file_before=$(git hash-object note.txt)

if git merge --no-edit topic; then
  printf 'Expected a conflict\n' >&2
  exit 1
fi
test -n "$(git ls-files --unmerged)"
printf 'Conflict: merge is paused with unresolved entries\n'
git status --short
git merge --abort
test "$(git rev-parse HEAD)" = "$head_before"
test "$(git hash-object note.txt)" = "$file_before"
test -z "$(git status --porcelain=v1)"
if git rev-parse --verify -q MERGE_HEAD; then
  printf 'Merge still in progress\n' >&2
  exit 1
fi
printf 'Abort: original commit and file restored; no merge in progress\n'
git log -1 --format='%h %s'

if git merge --no-edit topic; then
  exit 1
fi
printf 'chosen resolution\n' > note.txt
printf 'unrelated local work\n' > later.txt
git add --resolved -- note.txt later.txt
test -z "$(git ls-files --unmerged)"
test "$(git show :note.txt)" = 'chosen resolution'
test "$(git status --porcelain=v1 -- later.txt)" = ' M later.txt'
test -z "$(git diff --cached -- later.txt)"
git diff --cached -- note.txt
printf 'Resolved staging: resolution staged; unrelated tracked edit unstaged\n'
git merge --abort
test "$(git rev-parse HEAD)" = "$head_before"
test "$(git hash-object note.txt)" = "$file_before"
test "$(cat later.txt)" = 'unrelated local work'
printf 'Second abort: tracked file restored; unrelated tracked edit remains\n'