Select a fixup commit using fzf

git-fixup

#!/usr/bin/env bash
# SPDX-FileCopyrightText: 2019 Martin Wallgren
#
# SPDX-License-Identifier: MIT
#
# SPDX-FileContributor: Anthony Accioly <[email protected]>
#
# Changelog:
# - 2025-06-16: Anthony Accioly - Added fzf preview, pbcopy support and default branch detection
#
# Original at: https://gist.github.com/MartinWallgren/5c00716d176350a842f46037a79f9230
function usage() {
    echo "Git command to help you select which commit to create a fixup commit for."
    echo ""
    echo "The command will let you select a commit from a range and commit the current"
    echo "staging area using the selected commit as argument to the --fixup= option. Any"
    echo "extra options passed to this command will be forwarded to the git commit"
    echo "command."
    echo ""
    echo "The range will be the current upstream to HEAD. If no upstream is set for the"
    echo "current branch, the default range will be used. You can set the default range"
    echo "with GIT_DEFAULT_FIXUP_RANGE, if not set, origin/master..HEAD will be used as"
    echo "default range."
    echo "Example: GIT_DEFAULT_FIXUP_RANGE=origin/develop..HEAD git-fixup."
    echo "Note that a configured upstream branch will take precedence over the default range."
    echo ""
    echo "This command depends on fzf (https://github.com/junegunn/fzf)"
    echo ""
    echo "git-fixup"
    echo -e "\t-h --help"
    echo ""
}

while [ ! $# -eq 0 ]; do
    case "$1" in
    --help | -h)
        usage
        exit
        ;;
    esac
    shift
done

upstream=$(git rev-parse --abbrev-ref "@{upstream}" &>/dev/null)
# Determine the current branch and the default branch name dynamically.
current_branch=$(git rev-parse --abbrev-ref HEAD)
default_branch=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
if [ -z "$default_branch" ]; then
    default_branch="main"
fi

if [[ "${current_branch}" == "${default_branch}" ]]; then
    # If on the default branch, use all commits since root.
    fixup_range="$(git rev-list --max-parents=0 HEAD)..HEAD"
elif [ -z "${upstream}" ]; then
    fixup_range="${GIT_DEFAULT_FIXUP_RANGE:-origin/${default_branch}..HEAD}"
else
    fixup_range="${upstream}..HEAD"
fi

parent=$(git log --no-merges --oneline "${fixup_range}" |
    fzf --height "${FZF_TMUX_HEIGHT:-40%}" \
        --preview "git show {1} --color=always" \
        --bind "ctrl-y:execute-silent(echo {1} | cut -d' ' -f1 | pbcopy)+abort" |
    cut -d' ' -f1)

if [ -z "${parent}" ]; then
    echo "No commit found to fix."
else
    git commit --fixup="${parent}" "$@"
fi