#!/bin/bash

# Testing this script locally requires you to set the following environment
# variables:
# CIRCLE_BRANCH, GIT_USERNAME and GIT_TOKEN

# fail if trying to reference a variable that is not set.
set -u
# exit immediately if a command fails
set -e
# Fail on pipe failures
set -o pipefail

PR_BRANCH="${CIRCLE_BRANCH}"
ENTERPRISE_REMOTE="https://${GIT_USERNAME}:${GIT_TOKEN}@github.com/citusdata/citus-enterprise"

# shellcheck disable=SC1091
source ci/ci_helpers.sh

# List executed commands. This is done so debugging this script is easier when
# it fails. It's explicitly done after git remote add so username and password
# are not shown in CI output (even though it's also filtered out by CircleCI)
set -x

check_compile () {
    echo "INFO: checking if merged code can be compiled"
    ./configure --without-libcurl
    make -j10
}

# Clone current git repo (which should be community) to a temporary working
# directory and go there
GIT_DIR_ROOT="$(git rev-parse --show-toplevel)"
TMP_GIT_DIR="$(mktemp --directory -t citus-merge-check.XXXXXXXXX)"
git clone "$GIT_DIR_ROOT" "$TMP_GIT_DIR"
cd "$TMP_GIT_DIR"

# Fails in CI without this
git config user.email "citus-bot@microsoft.com"
git config user.name "citus bot"

# Disable "set -x" temporarily, because $ENTERPRISE_REMOTE contains passwords
{ set +x ; } 2> /dev/null
git remote add enterprise "$ENTERPRISE_REMOTE"
set -x

git remote set-url --push enterprise no-pushing

# Fetch enterprise-master
git fetch enterprise enterprise-master


git checkout "enterprise/enterprise-master"

if git merge --no-commit "origin/$PR_BRANCH"; then
    echo "INFO: community PR branch could be merged into enterprise-master"
    # check that we can compile after the merge
    if check_compile; then
        exit 0
    fi

    echo "WARN: Failed to compile after community PR branch was merged into enterprise"
fi

# undo partial merge
git merge --abort

# If we have a conflict on enterprise merge on the master branch, we have a problem.
# Provide an error message to indicate that enterprise merge is needed to fix this check.
if [[ $PR_BRANCH = master ]]; then
    echo "ERROR: Master branch has merge conflicts with enterprise-master."
    echo "Try re-running this CI job after merging your changes into enterprise-master."
    exit 1
fi

if ! git fetch enterprise "$PR_BRANCH" ; then
    echo "ERROR: enterprise/$PR_BRANCH was not found and community PR branch could not be merged into enterprise-master"
    exit 1
fi

# Show the top commit of the enterprise PR branch to make debugging easier
git log -n 1 "enterprise/$PR_BRANCH"

# Check that this branch contains the top commit of the current community PR
# branch. If it does not it means it's not up to date with the current PR, so
# the enterprise branch should be updated.
if ! git merge-base --is-ancestor "origin/$PR_BRANCH" "enterprise/$PR_BRANCH" ; then
    echo "ERROR: enterprise/$PR_BRANCH is not up to date with community PR branch"
    exit 1
fi

# Now check if we can merge the enterprise PR into enterprise-master without
# issues.
git merge --no-commit "enterprise/$PR_BRANCH"
# check that we can compile after the merge
check_compile