#!/bin/sh -e

# Apply a pull request

# Copyright (C) 2014 Linaro Limited
# Author: Peter Maydell <peter.maydell@linaro.org>
# This work is licensed under the terms of the GNU GPL version 2 or later.

# Usage: apply-pullreq [options] remote-url remote-branch-or-tagname
#
# Valid options:
#  --no-verify-sig : disable the gpg signature verification
#  --submodule-ok : allow merges which change submodules
#                   (disabled by default to prevent accidental downgrades)
# --apply-only : do the merge, but don't push to gitlab or kick off local builds
# --on-top : relax the "is staging up to date" check, so that one pullreq
#            can be applied on top of another
#
# The intent of --apply-only and --on-top is to allow multiple pullreqs
# to be tested in one CI run, for example:
#   apply-pullreq --apply-only url1 tag1
#   apply-pullreq --apply-only --on-top url2 tag2
#   apply-pullreq --on-top url3 tag3

# This makes a bunch of assumptions about repo setup and
# preferred build-and-test commands.

VRFY=yes
SUBMODULE=no
APPLY_ONLY=no
ON_TOP=no

while [ $# -ge 1 ]; do
    case "$1" in
        --no-verify-sig)
            shift
            VRFY=no
            ;;
        --submodule-ok)
            shift
            SUBMODULE=yes
            ;;
        --apply-only)
            shift
            APPLY_ONLY=yes
            ;;
        --on-top)
            shift
            ON_TOP=yes
            ;;
        *)
            break
            ;;
    esac
done

if [ $# != 2 ]; then
    echo "Usage: apply-pullreq [options] remote-url branch-or-tagname"
    exit 1
fi

REMOTEURL="$1"
REMOTETAG="$2"

# hard newline
NL='
'

BRANCH="$(git symbolic-ref -q HEAD || true)"
# NB that in the "detached head" case BRANCH will be the empty string

if [ "$BRANCH" != "refs/heads/staging" ]; then
    echo "Must be on staging branch"
    exit 1
fi

git checkout master
git pull
git checkout staging

if [ "$ON_TOP" = "yes" ]; then
    # Applying this pullreq on top of another: loosen the check
    # on whether staging is up to date
    if ! git merge-base --is-ancestor master staging; then
        echo "staging not up to date : suggest 'git reset --hard master'"
        exit 1
    fi
elif [ "$(git rev-parse master)" != "$(git rev-parse staging)" ]; then
    # This is our first pullreq to be applied, so staging and master
    # must be identical
    echo "staging not up to date : suggest 'git reset --hard master'"
    exit 1
fi

# Check we're not accidentally trying to merge after the
# final release was tagged and before we reopened the devtree.
VER="$(cat VERSION)"
VERMIN="${VER##*.}"

if [ "$VERMIN" = "0" ]; then
    echo "VERSION says this a release version: forgot to reopen devtree?"
    exit 1
fi

echo "fetching from remote $REMOTEURL $REMOTETAG"
git fetch "$REMOTEURL" "$REMOTETAG"

if [ "$VRFY" = "yes" ]; then
    if ! git verify-tag FETCH_HEAD; then
        echo "Does not appear to be a signed tag"
        echo "(use --no-verify-sig to override)"
        exit 1
    fi
fi

echo "merging..."
git merge --no-edit --no-ff --log FETCH_HEAD
# Edit the merge commit to add our signoff line
git commit --amend --signoff --no-edit

# Check whether there seems to be a submodule update here. NB that this
# can have false positives..
if git diff master..staging | grep -q 'Subproject commit'; then
    if [ "$SUBMODULE" = "no" ]; then
        echo "ERROR: pull request includes submodule update"
        echo "(use --submodule-ok to override)"
        exit 1
    fi
    echo "WARNING: pull appears to include submodule update, please check it!"
fi

# Check whether any authors needs to be corrected after SPF rewrites
if git shortlog --author='qemu-.*@nongnu\.org' master..staging | grep .; then
    echo "ERROR: pull request includes commits attributed to list"
    exit 1
fi


# Check for incorrect UTF-8 copy/pasting
# This is a very dubious heuristic that is essentially just looking
# for mangled é or for =nn hex escapes. Still, it's better than nothing.
if git log master..staging \
    | grep -E "^ +[[:alpha:]-]+-by: .*(=[0-9A-F]{2}|é).*@"; then
    echo "ERROR: pull request includes tag with UTF-8 error in person name"
    exit 1
fi

if [ "$APPLY_ONLY" = "yes" ]; then
    echo "--apply-only specified: not running tests"
    exit 0
fi

# This should exit with an error status if any of the sub-builds fails.
parallel-buildtest

echo "WARNING: please check these results files!"

echo "Looks good; trying a dry-run publish:"
git push --dry-run publish-gitlab staging:master

# For obvious reasons we don't let the script automatically
# do the publish to upstream master...

echo "OK; to publish for real run:"
echo "git push publish-gitlab staging:master"