#!/usr/bin/env bash

# git pre-push hook script to:
# 0) Call the pre-commit hook, if it is available
# 1) prevent "fixup!" and "squash!" commit from ending up in master, release-*
#    or maint-*
# 2) Disallow pushing branches other than master, release-*
#    and maint-* to origin (e.g. gitweb.torproject.org)
#
# To install this script, copy it into .git/hooks/pre-push path in your
# local copy of git repository. Make sure it has permission to execute.
# Furthermore, make sure that TOR_UPSTREAM_REMOTE_NAME environment
# variable is set to local name of git remote that corresponds to upstream
# repository on e.g. git.torproject.org.
#
# The following sample script was used as starting point:
# https://github.com/git/git/blob/master/templates/hooks--pre-push.sample

# Are you adding a new check to the git hooks?
#  - Common checks belong in the pre-commit hook
#  - Push-only checks belong in the pre-push hook

echo "Running pre-push hook"

z40=0000000000000000000000000000000000000000

upstream_name=${TOR_UPSTREAM_REMOTE_NAME:-"upstream"}

workdir=$(git rev-parse --show-toplevel)

remote="$1"
remote_name=$(git remote --verbose | grep "$2" | awk '{print $1}' | head -n 1)


ref_is_upstream_branch() {
    if [ "$1" == "refs/heads/master" ] ||
        [[ "$1" == refs/heads/release-* ]] ||
        [[ "$1" == refs/heads/maint-* ]]; then
        return 1
    fi
}

# shellcheck disable=SC2034
while read -r local_ref local_sha remote_ref remote_sha
do
    if [ "$local_sha" = $z40 ]; then
        # Handle delete
        :
    else
        if [ "$remote_sha" = $z40 ]; then
            # New branch, examine commits not in master
            range="master...$local_sha"
        else
            # Update to existing branch, examine new commits
            range="$remote_sha..$local_sha"
        fi

        # Call the pre-commit hook for the common checks, if it is executable
        # Only check the files newly modified in this branch
        CHECK_FILTER="git diff --name-only --diff-filter=ACMR $range"
        # Use the appropriate owned tor source list to filter the changed files
        if [ -d src/lib ]; then
            # This is the layout in 0.3.5
            CHECK_FILES="$($CHECK_FILTER \
                               src/lib/*/*.[ch] \
                               src/core/*/*.[ch] \
                               src/feature/*/*.[ch] \
                               src/app/*/*.[ch] \
                               src/test/*.[ch] \
                               src/test/*/*.[ch] \
                               src/tools/*.[ch] \
                          )"
        elif [ -d src/common ]; then
            # This was the layout before 0.3.5
            CHECK_FILES="$($CHECK_FILTER \
                               src/common/*/*.[ch] \
                               src/or/*/*.[ch] \
                               src/test/*.[ch] \
                               src/test/*/*.[ch] \
                               src/tools/*.[ch]
                          )"
        fi

        # We want word splitting here, because file names are space separated
        # shellcheck disable=SC2086
        if ! "$workdir/"scripts/git/pre-commit.git-hook $CHECK_FILES; then
            exit 1
        fi

        if [[ "$remote_name" != "$upstream_name" ]]; then
            echo "Not pushing to upstream - refraining from further checks"
            continue
        fi

        if (ref_is_upstream_branch "$local_ref" == 0 ||
                ref_is_upstream_branch "$remote_ref"  == 0) &&
            [ "$local_ref" != "$remote_ref" ]; then
            if [ "$remote" == "origin" ]; then
                echo >&2 "Not pushing: $local_ref to $remote_ref"
                echo >&2 "If you really want to push this, use --no-verify."
                exit 1
            else
                continue
            fi
        fi

        # Check for fixup! commit
        commit=$(git rev-list -n 1 --grep '^fixup!' "$range")
        if [ -n "$commit" ]; then
            echo >&2 "Found fixup! commit in $local_ref, not pushing"
            echo >&2 "If you really want to push this, use --no-verify."
            exit 1
        fi

        # Check for squash! commit
        commit=$(git rev-list -n 1 --grep '^squash!' "$range")
        if [ -n "$commit" ]; then
            echo >&2 "Found squash! commit in $local_ref, not pushing"
            echo >&2 "If you really want to push this, use --no-verify."
            exit 1
        fi
    fi
done

exit 0