##
# systr_record_commit_mesg <commit> <branch> [<mesg>]
#
# Setup and present user with an editor to enter a commit message for
# the given commit ID.  If <mesg> is given, that content will be the
# default in the opened file.  If <branch> does not match TRAC, an
# additional message will be given to the user, letting them know they
# are committing to another branch.  Once user is finished, the file
# is moved into the repository root, awaiting a call to systr_repo_finish_commit.
##
function systr_record_commit_mesg
{
    if [ $# -lt 2 ]; then
        echo "Fatal: too few args to record_commit_mesg" >&2
        exit 1
    fi

    commit="$1"
    branch="$2"

    if [ $# -gt 2 ]; then
        mesg="$3"
    else
        mesg=""
    fi

    echo "$mesg" >.systr/commit-edit-mesg.txt
    echo "# --" >>.systr/commit-edit-mesg.txt

    if [[ "$branch" != "$TRAC" ]]; then
        echo "# Committing to $branch" >>.systr/commit-edit-mesg.txt
        echo "#" >>.systr/commit-edit-mesg.txt
    fi

    systrunk status | sed 's/^/# /' >>.systr/commit-edit-mesg.txt
    vi .systr/commit-edit-mesg.txt
    sed '/^#/ d' <.systr/commit-edit-mesg.txt >"$path/revs/$commit.mesg"
}

##
# systrunk commit [<branch>=TRAC]
#
# Create a snapshot of the current state of the worktree and record
# it in the repository.  Your worktree must be up-to-date with <branch>
# before you can commit.  The branch committed to is updated to
# reference the new commit.  If <branch> does not exist in the
# repository, it is created.  If <branch> is a commit ID instead of
# a symbolic reference, the new commit will not exist on any branch,
# but an anonymous one referenced by TRAC.
##
function systr_commit
{
    if [ $# -gt 0 ]; then
        branch="$1"
    else
        branch="$TRAC"
    fi

    if [[ "$branch" == "BASE" ]]; then
        echo "Fatal: bad branch name BASE" >&2
        exit 1
    elif [[ "$branch" == "TRAC" ]]; then
        echo "Fatal: bad branch name TRAC" >&2
        exit 1
    elif [[ "$branch" == "NULL" ]]; then
        echo "Fatal: bad branch name NULL" >&2
        exit 1
    elif [[ "$branch" == "MERG" ]]; then
        echo "Fatal: bad branch name MERG" >&2
        exit 1
    fi

    branchcommit=$(systr_repo_resolve_reference "$branch" 2>/dev/null) || branchcommit="$BASE"
    systr_repo_resolve_reference "$branch" >/dev/null 2>&1 || echo "Creating new branch $branch"

    if [[ "$BASE" != "$branchcommit" ]]; then
        echo "Worktree is out-of-date, won't commit" >&2
        exit 1
    fi

    commit=$(systr_repo_create_commit)

    if [[ "$MERG" == "NULL" ]]; then
        systr_record_commit_mesg "$commit" "$branch"
    else
        systr_record_commit_mesg "$commit" "$branch" "Merge $MERG into $TRAC"
    fi

    echo "Sending files..."

    if [[ "$branchcommit" != "NULL" ]]; then
        systr_rsync_normal . "$path/revs/$commit/" "../$branchcommit/"
    else
        systr_rsync_normal . "$path/revs/$commit/"
    fi

    if [[ "$MERG" == "NULL" ]]; then
        systr_repo_finish_commit "$commit" "$branchcommit"
    else
        mergecommit=$(systr_repo_resolve_reference "$MERG")
        systr_repo_finish_commit "$commit" "$branchcommit" "$mergecommit"
    fi

    echo "$commit" >.systr/BASE
    echo "NULL" >.systr/MERG
    date >.systr/updated

    if [[ "$branch" != "$branchcommit" ]]; then
        systr_repo_set_reference "$branch" "$commit"
    fi

    if [[ "$TRAC" == "$BASE" ]]; then
        echo "$commit" >.systr/TRAC
    else
        echo "$branch" >.systr/TRAC
    fi
}

##
# systrunk reset <branch>
#
# Similar to systrunk commit, but doesn't require the worktree to
# be up-to-date with <branch>.  This command can be used to rollback
# a branch to a previous state by running systrunk checkout followed
# by this command.  If <branch> does not exist, this command will
# fail.  If <branch> is a commit ID instead of a symbolic reference,
# no action is taken.
##
function systr_reset
{
    if [ $# -lt 1 ]; then
        echo "Fatal: too few args to reset" >&2
        exit 1
    fi

    branch="$1"

    if [[ "$branch" == "BASE" ]]; then
        echo "Fatal: bad branch name BASE" >&2
        exit 1
    elif [[ "$branch" == "TRAC" ]]; then
        echo "Fatal: bad branch name TRAC" >&2
        exit 1
    elif [[ "$branch" == "NULL" ]]; then
        echo "Fatal: bad branch name NULL" >&2
        exit 1
    elif [[ "$branch" == "MERG" ]]; then
        echo "Fatal: bad branch name MERG" >&2
        exit 1
    fi

    if [[ "$MERG" != "NULL" ]]; then
        echo "Fatal: merge in progress, won't reset" >&2
        exit 1
    fi

    branchcommit=$(systr_repo_resolve_reference "$branch")

    if [[ "$branchcommit" == "$branch" ]]; then
        echo "Fatal: $branch is a commit ID, not a symbolic reference" >&2
        exit 1
    fi

    commit=$(systr_repo_create_commit)
    systr_record_commit_mesg "$commit" "$branch" "Reset $branch to state at $BASE"
    echo "Performing RESET"
    echo "Sending files..."

    if [[ "$BASE" != "NULL" ]]; then
        systr_rsync_normal . "$path/revs/$commit/" "../$BASE/"
    else
        systr_rsync_normal . "$path/revs/$commit/"
    fi

    systr_repo_finish_commit "$commit" "$branchcommit"
    echo "$commit" >.systr/BASE
    echo "NULL" >.systr/MERG
    date >.systr/updated
    systr_repo_set_reference "$branch" "$commit"
    echo "$branch" >.systr/TRAC
}