#!/bin/bash

ME=$(basename $0)

###############################################################################
# BEGIN user-customizable section

# Buildah main repository; unlikely to change often
BUILDAH_REPO=github.com/containers/buildah

# Tag name used to identify the base checkout
BASE_TAG=buildah-bud-in-podman

# END   user-customizable section
###############################################################################

usage="Usage: $ME [--help] [--no-checkout] [--no-test] [--filter=TESTNAME]

Flags, useful for manual debugging:

  --no-checkout   Skip checkout step, go directly to running tests
  --no-test       Do checkout only, but do not run tests
  --filter=NAME   Passed on to bats; runs only tests that match NAME
"

# Parse command-line options (used in development only, not in CI)
do_checkout=y
do_test=y
declare -a bats_filter=()
for i; do
    value=$(expr "$i" : '[^=]*=\(.*\)')
    case "$i" in
        --no-checkout)  do_checkout= ; shift;;
        --no-test)      do_test=     ; shift;;
        --filter=*)     bats_filter=("--filter" "$value"); shift;;
        -h|--help)      echo "$usage"; exit 0;;
        *)              echo "$ME: Unrecognized option '$i'" >&2; exit 1;;
    esac
done

# Patches helpers.bash and potentially other files (bud.bats? Dockerfiles?)
#
# The patch file is horrible to generate:
#    1) cd to the checked-out buildah/tests directory
#    2) make your edits
#    3) git commit -asm 'blah blah blah'
#       3a) if checked-out directory already includes earlier patches,
#           you may need to 'git commit --amend' instead
#    4) git format-patch HEAD^
#    5) sed -e 's/ \+$//' 0001* >../PATCH-FILE-PATH
#    6) vim that file, remove trailing empty newlines
#    7) cd back out of buildah directory, and git-commit this new patch file
#
# FIXME: this makes me nervous. The diff will probably need tweaking
#        over time. I don't think we need to version it, because we
#        *have* to be in lockstep with a specific buildah version,
#        so problems should only arise when we re-vendor.
#        But I'm still nervous and can't put my finger on the reason.
#
# Complicated invocation needed because we 'cd' down below.
BUD_TEST_DIR=$(realpath $(dirname ${BASH_SOURCE[0]}))
PATCHES=${BUD_TEST_DIR}/buildah-tests.diff

# Friendlier relative path to our buildah-tests dir
BUD_TEST_DIR_REL=$(dirname $(git ls-files --full-name ${BASH_SOURCE[0]}))
# Path to podman binary; again, do it before we cd
PODMAN_BINARY=$(pwd)/bin/podman
REMOTE=
# If remote, start server & change path
if [[ "${PODBIN_NAME:-}" = "remote" ]]; then
    REMOTE=1
    PODMAN_BINARY+="-remote"
fi

function die() {
    failhint=
    echo "$ME: $*" >&2
    exit 1
}

# From here on out, any unexpected abort will try to offer helpful hints
failhint=
trap 'if [[ $? != 0 ]]; then if [[ -n $failhint ]]; then echo;echo "***************************************";echo "$failhint";echo;echo "Please see $BUD_TEST_DIR_REL/README.md for advice";fi;fi' 0

# Find the version of buildah we've vendored in, so we can run the right tests
buildah_version=$(awk "\$1 == \"$BUILDAH_REPO\" { print \$2 }" <go.mod)

if [[ -z "$buildah_version" ]]; then
    # This should not happen
    die "Did not find '$BUILDAH_REPO' in go.mod"
fi

# From here on out, any error is fatal
set -e

# Before pulling buildah (while still cd'ed to podman repo), try to determine
# if this is a PR, and if so if it's a revendoring of buildah. We use this to
# try to offer a helpful hint on failure.
is_revendor=
if [[ -n $CIRRUS_CHANGE_IN_REPO ]]; then
    if [[ -n $DEST_BRANCH ]]; then
        head=${CIRRUS_CHANGE_IN_REPO}
        # Base of this PR.
        base=$(set -x;git merge-base ${DEST_BRANCH} $head)
        changes=$(set -x;git diff --name-status $base $head)
        if [[ -n $changes ]]; then
            if [[ $changes =~ vendor/$BUILDAH_REPO ]]; then
                is_revendor=y
            fi
        fi
    fi
fi

# Pull buildah, including tests
buildah_dir=test-buildah-$buildah_version
if [[ -n $do_checkout ]]; then
    if [[ -d $buildah_dir ]]; then
        die "Directory already exists: $buildah_dir"
    fi

    # buildah_version should usually be vX.Y, but sometimes a PR under test
    # will need a special unreleased version (go calls then "pseudoversions").
    # In the usual case, we can do a shallow git clone:
    shallow_checkout="--branch $buildah_version"
    if [[ $buildah_version =~ .*-.*\.[0-9]{14}-.* ]]; then
        # ...but with a pseudoversion, we must git-clone the entire repo,
        # then do a git checkout within it
        shallow_checkout=
    fi

    failhint="'git clone' failed - this should never happen!"
    (set -x;git clone -q $shallow_checkout https://$BUILDAH_REPO $buildah_dir)

    cd $buildah_dir
    if [[ -z $shallow_checkout ]]; then
        # extract the SHA (rightmost field) from, e.g., v1.2-YYYMMDD-<sha>
        sha=${buildah_version##*-}

        failhint="'git checkout $sha' failed - this should never happen!"
        (set -x;git checkout -q $sha)
    fi

    # Give it a recognizable tag; this will be useful if we need to update
    # the set of patches
    (set -x;git tag $BASE_TAG)

    # Build buildah and the copy helper
    failhint="error building buildah. This should never happen."
    (set -x;make bin/buildah)
    failhint="error building buildah's copy helper. This should never happen."
    (set -x;make bin/copy)

    # The upcoming patch may fail. Before we try it, create a helper script
    # for a developer to push a new set of diffs to podman-land.
    failhint=
    sed -e "s,\[BASETAG\],${BASE_TAG},g" \
        -e "s,\[BUILDAHREPO\],${BUILDAH_REPO},g" \
        < ${BUD_TEST_DIR}/make-new-buildah-diffs \
        > make-new-buildah-diffs
    chmod 755 make-new-buildah-diffs

    # Apply custom patches. We do this _after_ building, although it shouldn't
    # matter because these patches should only apply to test scripts and not
    # to any buildah sources.
    failhint="
Error applying patch file. This can happen when you vendor in a new buildah.
You will want to:

  - look for 'test/*.rej'
  - resolve conflicts manually
  - git add test/helpers.bash
  - git am --continue
  - ./make-new-buildah-diffs
"
    (set -x;git am --reject <$PATCHES)

    # Now apply our custom skips and error-message changes. This is maintained
    # in a custom script, not a .diff file, because diffs are WAY too hard for
    # humans to read and update.
    APPLY=apply-podman-deltas
    failhint="
Error applying podman-specific deltas. This sometimes happens when you
vendor in a new buildah. You will want to:

  - inspect the errors shown above
  - find the corresponding lines in $BUD_TEST_DIR_REL/$APPLY
  - edit/delete them as necessary
"
    (set -x;$BUD_TEST_DIR/$APPLY)
else
    # Called with --no-checkout
    test -d $buildah_dir || die "Called with --no-checkout, but $buildah_dir does not exist"

    cd $buildah_dir
fi

if [[ -n $do_test ]]; then
    failhint="Error running buildah bud tests under podman."
    if [[ -n $is_revendor ]]; then
        failhint+="

It looks like you're vendoring in a new buildah. The likely failure
here is that there's a new test in bud.bats that uses functionality
not (yet) in podman build. You will likely need to 'skip' that test.
"
    else
        failhint+="

Is it possible that your PR breaks podman build in some way? Please
review the test failure and double-check your changes.
"
    fi

    (set -x;sudo env TMPDIR=/var/tmp \
                 PODMAN_BINARY=$PODMAN_BINARY \
                 REMOTE=$REMOTE \
                 BUILDAH_BINARY=$(pwd)/bin/buildah \
                 COPY_BINARY=$(pwd)/bin/copy \
                 bats "${bats_filter[@]}" tests/bud.bats)
fi