#!/bin/bash

# This script checks gnome.org policy about how people are supposed to
# use git; the intent of the policy is to keep people from shooting
# themselve in the foot.
#
# Eventually, we'd like to have an ability to override policy; one way
# it could work is that if you did 'git push --exec=force' and you
# were a member of the right group, then run-git-or-special-cmd
# would set an environment variable that this script would interpret.

# Used in some of the messages
server=git.labs.libre-entreprise.org

GIT_DIR=$(git rev-parse --git-dir 2>/dev/null)

in_import() {
    test -e "$GIT_DIR/pending"
}

forced() {
    test -n "$GNOME_GIT_FORCE"
}

check_commit() {
    commit=$1

    email="$(git log $commit -1 --pretty=format:%ae)"
    case "$email" in
	*localhost.localdomain|*\(none\))
	    if ! in_import && ! forced ; then
		cat <<EOF >&2
---
The commits you are trying to push contain the author email
address '$email'. Please configure your
username and email address. See:

  http://live.gnome.org/Git/Help/AuthorEmail

For instructions about how to do this and how to fix your
existing commits.
---
EOF
		exit 1
	    fi
	    ;;
    esac

    subject="$(git log $commit -1 --pretty=format:%s)"
    if expr "$subject" : ".*Merge branch.*of.*\(git\|ssh\):" > /dev/null 2>&1; then
	if ! in_import && ! forced ; then
	    cat <<EOF >&2
---
The commit:

EOF
	    git log $commit -1 >&2
	    cat <<EOF >&2

Looks like it was produced by typing 'git pull' without the --rebase
option when you had local changes. Running 'git  pull --rebase' now
will fix the problem. Then please try, 'git push' again. Please see:

  http://live.gnome.org/Git/Help/ExtraMergeCommits
---
EOF
	    exit 1
	fi
    fi
}

check_ref_update() {
    oldrev=$1
    newrev=$2
    refname=$3

    change_type=update
    if expr $oldrev : "^0\+$" > /dev/null 2>&1; then
	change_type=create
    fi

    if expr $newrev : "^0\+$" > /dev/null 2>&1; then
	if [ x$change_type = xcreate ] ; then
	    # Deleting an invalid ref, allow
	    return 0
	fi
	change_type=delete
    fi

    case $refname in
	refs/heads/*)
	    # Branch update
	    branchname=${refname#refs/heads/}

	    range=
	    case $change_type in
		create)
		    range="$newrev"
		    ;;
		delete)
		    # We really don't like to allow deleting any branch, but
		    # people need to do it to clean up accidentally pushed
		    # branches. Deleting master, however, has no purpose other
		    # than getting around the no-fast-forward restrictions
		    if [ "x$branchname" = xmaster ] ; then
			cat <<EOF >&2
---
You are trying to delete the branch 'master'.
---
EOF
			exit 1
		    fi
		    ;;
		update)
		    range="$oldrev..$newrev"
		    if [ `git merge-base $oldrev $newrev` != $oldrev ] && ! forced ; then
		        # Non-fast-forward update. Right now we have
		        # receive.denyNonFastforwards in the git configs for
		        # our repositories anyways, but catching it here would
		        # allow overriding without having to change the config
			# temporarily.
			cat <<EOF >&2
---
You are trying to update the branch '$branchname' in a way that is not
a fast-forward update. Please see:

  http://live.gnome.org/Git/Help/NonFastForward
---
EOF
			exit 1
		    fi
		    ;;
	    esac

	    # For new commits introduced with this branch update, we want to run some
	    # checks to catch common mistakes.
	    #
	    # Expression here is same as in post-receive-notify-cia; we take 
	    # all the branches in the repo, as "^/ref/heads/branchname", other than the
            # branch we are actualy committing to, and exclude commits already on those
            # branches from the list of commits between $oldrev and $newrev.

	    if [ -n "$range" ] ; then
		for merged in $(git rev-parse --symbolic-full-name --not --branches | \
                    egrep -v "^\^$refname$" | \
		    git rev-list --reverse --stdin "$range"); do
		    check_commit $merged
		done
	    fi
	    ;;
	refs/tags/*)
	    # Tag update
	    tagname=${refname#refs/tags/}

	    case $change_type in
		create)
		    object_type=`git cat-file -t $newrev`
		    case $object_type in
			commit)
			    # Lightweight tag; we allow an import containing these
			    # tags, but forbid them in general
			    if ! in_import && ! forced ; then
				cat <<EOF >&2
---
You are trying to push the lightweight tag '$tagname'. You should use
a signed tag instead. See:

  http://live.gnome.org/Git/Help/LightweightTags
---
EOF
				exit 1
			    fi
			    ;;
			tag)
			    # Annotated tag
			    ;;
			*)
			    # git is happy to allow tagging random objects, we aren't
			    cat <<EOF >&2
---
You are trying to push the tag '$tagname', which points to an object
of type $object_type. (It should point to a commit or tag object.)
---
EOF
			    exit 1
			    ;;
		    esac
		    ;;
		delete)
		    # Deleting a tag is probably someone trying to work-around
		    # not being able to update a tag. Disallowing lightweight
		    # tags will cut down on accidentally pushing tags called 'list'
		    # or whatever. During import we allow the user to clean up
		    # accidentally pushed tags.
		    if ! in_import && ! forced ; then
			cat <<EOF >&2
---
You are trying to delete the tag '$tagname'.

  http://live.gnome.org/Git/Help/TagUpdates
---
EOF
			exit 1
		    fi
		    ;;
		update)
		    if  ! forced ; then
			cat <<EOF >&2
---
You are trying to replace the tag '$tagname' with a new tag. Please see:

  http://live.gnome.org/Git/Help/TagUpdates
---
EOF
			exit 1
		    fi
		    ;;
	    esac
	    ;;
	refs/remotes/*)
	    # Remote tracking branch
	    cat <<EOF >&2
---
You are trying to push the remote tracking branch:

  $refname

to $server.
---
EOF
	    exit 1
	    ;;
	*)
	    # Something else
	    cat <<EOF >&2
---
You are trying to push the ref:

  $refname

to $server. This isn't a branch or tag.
---
EOF
	    exit 1
	    ;;
    esac

    return 0
}

if [ $# = 3 ] ; then
    check_ref_update $@
else
    while read oldrev newrev refname; do
	check_ref_update $oldrev $newrev $refname
    done
fi

exit 0