#!/bin/sh

# Helper function to set local config option if it is not set locally already.
# In newer Git versions `git config --local <option>` can be used to determine
# if an option is set locally, but in Git 1.7.1 this does not work. Hence we
# specify the local Git config file explictly.
set_local_option() {
    local_git_config="$(git rev-parse --git-dir)/config"
    if [ -z "$(git config --file "$local_git_config" "$1")" ]; then
        git config --file "$local_git_config" "$1" "$2"
    fi
}

# Avoid merge commits by rebasing (supported since 1.7.9)
set_local_option pull.rebase true
# Automatically stash local changes (supported since 1.8.4)
set_local_option rebase.autostash true

# Handy alias that emulates "git pull --rebase --autostash" for Git versions
# older than 2.9. I have tested this in particular with Git 1.7.1 (RHEL 6's
# version). The code is copied more or less verbatim from
#  https://github.com/git/git/blob/master/git-rebase.sh
# Right now the only difference is that this does not do garbage collection in
# the form of "git gc --auto" in the end.
git config alias.pc-update '!f() {
    if ! stash_sha1=$(git stash create "autostash"); then
        echo Cannot autostash
        exit 1
    fi
    if [ -n "$stash_sha1" ]; then
        echo Created autostash: $(git rev-parse --short $stash_sha1)
        git reset --hard
    fi
    git pull --rebase
    if [ -n "$stash_sha1" ]; then
        if git stash apply $stash_sha1 2>&1 >/dev/null; then
            echo Applied autostash.
        else
            if ! git stash store -m "autostash" -q $stash_sha1; then
                echo Cannot store \$stash_sha1
                exit 1
            fi
            echo Applying autostash resulted in conflicts.
            echo Your changes are safe in the stash.
            echo You can run "git stash pop" or "git stash drop" at any time.
        fi
    fi
}; f'

# Shorten "pc-update" to "up" if the latter is not defined already
set_local_option alias.up '!git pc-update'