#!/bin/sh
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=$(git rev-parse --abbrev-ref @{upstream} &>/dev/null)
if [ -z "${upstream}" ]; then
    fixup_range="${GIT_DEFAULT_FIXUP_RANGE:-origin/master..HEAD}"
else
    fixup_range="${upstream}..HEAD"
fi

parent=$(git log --no-merges --oneline ${fixup_range} |
    fzf --height ${FZF_TMUX_HEIGHT:-40%} |
    cut -d' ' -f1)

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