#!/bin/sh

# Could generalise to a script that reads a git config value for the
# fingerprint to look for, updates branches specified by user and is
# able to handle updating by both merge and rebase

# Could do that propellor does in verifyOriginBranch instead of this
# -- it might be more robust

set -e

# To update a shallow clone we would do 'git fetch --depth 1' and then 'git
# reset --hard origin/master'.  But that would leave us vulnerable to an
# attacker causing us to check out an older signed commit than the one we have
# now.  So require an explicit 'git fetch --unshallow' from the user, or get
# Consfigurator to update repo from a snapshot from laptop, or something.
if [ "$(git rev-parse --is-shallow-repository)" = "true" ]; then
    echo >&2 "shallow dotfiles clone; refusing to reset to origin/master"
    exit 1
fi

git fetch origin
if git verify-commit-spw origin/master; then
    # we only fast-forward master, to avoid the possibility of an
    # attacker causing us to check out an older signed commit than the
    # one we have now
    if ! git merge-ff master origin/master; then
        echo >&2 "dotfiles remote head signed by Sean, but not fast-forward of master"
        echo >&2 "will not auto-rebase; manually rebase/reset master on/to origin/master"
        exit 1
    fi
else
    echo >&2 "uh oh, dotfiles remote head is not PGP-signed by Sean"
    exit 1
fi

# Migrate old normalise-mrconfig setup

perl -000 -i'' -wn \
     -e'/DO NOT EDIT THIS BLOCK; automatically updated/ or print' ~/.mrconfig

line="include = cat ~/src/dotfiles/lib-src/mr/config"
grep -Fxq "$line" ~/.mrconfig \
    || printf "%s\n\n" \
	      "# -*- mode: conf -*-" "$line" "$(sed -e1,2d ~/.mrconfig)" \
	      >~/.mrconfig