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# \file git.subr
# Utilities to invoke git, similar to shtk_cvs(3).
#
# This is an shtk module and, given its generic functionality and its
# similiarity to shtk_cvs(3), it should live in the shtk distribution.
# TODO(jmmv): Move this module to shtk once stabilized.

shtk_import cli
shtk_import process


git_fetch() {
    local url="${1}"; shift
    local branch="${1}"; shift
    local directory="${1}"; shift

    if [ -d "${directory}" ]; then
        git_update "${url}" "${branch}" "${directory}"
    else
        git_clone "${url}" "${branch}" "${directory}"
    fi
}


git_clone() {
    local url="${1}"; shift
    local branch="${1}"; shift
    local directory="${1}"; shift

    local rflag=
    [ -z "${tag}" ] || rflag="-r${tag}"

    [ ! -d "${directory}" ] || shtk_cli_error "Cannot clone into" \
        "${directory}; directory already exists"
    if ! shtk_process_run git clone -b "${branch}" "${url}" "${directory}"
    then
        rm -rf "${directory}"
        shtk_cli_error "Git clone failed"
    fi
}


git_update() {
    local url="${1}"; shift
    local branch="${1}"; shift
    local directory="${1}"; shift

    [ -d "${directory}" ] || shtk_cli_error "Cannot update ${directory};" \
        "directory does not exist"

    (
        cd "${directory}"

        shtk_process_run git fetch "${url}" "${branch}" \
            || shtk_cli_error "Git fetch failed"

        local modified=no
        [ -z "$(git status --porcelain 2>&1 | grep -vE '^(\?\?|!!)')" ] \
            || modified=yes

        # It is tempting to use "git stash save --all"... but depending on how
        # pkg_comp has been configured, the distfiles and the packages may be
        # located within the pkgsrc tree and these are not recorded in
        # .gitignore (because git is not authoritative).  Stashing these large
        # binary files would cause a lot of churn for little benefit.
        [ "${modified}" = no ] || \
            shtk_process_run git stash save \
                || shtk_cli_error "Local changes detected but could not save" \
                "them"

        # The pkgsrc repository's history often gets rewritten because the
        # commit messages are amended in the master CVS repository.  This causes
        # a simple pull to fail, so be more aggressive.
        shtk_process_run git checkout "${branch}" \
            || shtk_cli_error "Failed to switch to desired branch"
        shtk_process_run git reset --hard FETCH_HEAD \
            || shtk_cli_error "Failed to update branch to fetched head"

        [ "${modified}" = no ] || \
            shtk_process_run git stash apply \
                || shtk_cli_error "Failed to restore local changes after" \
                                  "branch update"
    ) || exit  # Error messages reported by subshell so just propagate code.
}
