#!/bin/bash

set -ef -o pipefail

scripts=$(dirname $0)
. $scripts/jenkins-helpers.sh

artifacts=$(pwd)/artifacts

fresh_dir $artifacts "$artifacts/manifests/*" "$artifacts/jenkins/*"

# Process bisect-only args
convert_args_to_variables "$@"
shift "$SHIFT_CONVERTED_ARGS"

bad_rev="${bad_rev:-default}"
baseline_rev="${baseline_rev:-baseline}"
BUILD_URL="${BUILD_URL:-$(pwd)}"
reproduce_bisect="${reproduce_bisect:-false}"

# Process build args and record them in build-parameters.sh
convert_args_to_variables ^^ $reproduce_bisect %% $artifacts/manifests/build-parameters.sh "$@"
$reproduce_bisect || manifest_pop

obligatory_variables current_project toolchain

linux_config="${linux_config:-defconfig}"
target="${target:-native}"
verbose="${verbose:-true}"

set -u

if $verbose; then set -x; fi

trap "eval \"echo ERROR at \${FUNCNAME[0]}:\${BASH_LINENO[0]}\" > $artifacts/failures" EXIT

if [ x"$bad_rev" = x"default" ]; then
    echo "ERROR: Need explicit --bad_rev"
    exit 1
else
    bad_rev=$(git -C $current_project rev-parse "$bad_rev")
fi

# Build baseline that we are going to re-use to speed-up bisection.
# (This also confirms that infrastructure is OK.)
echo "Testing baseline_rev $baseline_rev (should be success)"
$scripts/tcwg_kernel-build.sh \
    ^^ $reproduce_bisect \
    %% $artifacts/manifests/build-baseline.sh \
    @@ $artifacts/manifests/build-parameters.sh \
    --mode "baseline" \
    --current_rev "$baseline_rev" \
    --reset_baseline true \
    --top_artifacts "$artifacts/build-baseline" \
    --verbose "$verbose"

assert ! [ -f $artifacts/failures ]

cd $current_project

# Remember $good_rev from the baseline build above.
good_rev=$(git rev-parse HEAD)
baseline_rev="$good_rev"
ln -f -s "build-baseline" "$artifacts/build-$baseline_rev"
ln -f -s "build-baseline.sh" "$artifacts/manifests/build-$baseline_rev.sh"
echo "$baseline_rev" >> $artifacts/good_revs

cat <<EOF | manifest_out
declare -g reproduce_bisect=true
declare -g bad_rev=$bad_rev
declare -g baseline_rev=$baseline_rev
EOF

# Bisect script.
#
# With this script we find the first commit that has regressed compared
# to baseline, but not, necessarily, the commit that caused regression in
# $bad_rev.  Consider the scenario:
# - rev_10 produced good result "2000" -- this is current baseline
# - rev_20 completely broke the build (say, result "10")
# - rev_22 fixed the build
# - rev_30 regressed the build to result "1000" -- this is the regression we
#   detected vs "2000" baseline.
#
# The script will identify rev_20 as the first failing commit, which will
# cause the baseline to be reset to rev_20 with metric "10".  When we then
# rebuild master (at rev_30) we will see a /progression/ from "10" to "1000",
# thus missing the regression of "2000" to "1000".
#
# To catch the "2000" to "1000" regression someone would need to manually
# trigger bisect between rev_22 and rev_30.
#
# TODO: We could skip revisions (exit 125) that are worse than metric
# for $bad_rev (result metric <1000 in the above scenario), so we would
# skip revisions between rev_20 and rev_22.  This might cause other edge
# cases to be handled sub-optimally, though.
cat > $artifacts/test.sh <<EOF
#!/bin/sh
rev=\$(git rev-parse HEAD)
cd ..
$scripts/tcwg_kernel-build.sh \
  ^^ $reproduce_bisect \
  %% $artifacts/manifests/build-\$rev.sh \
  @@ $artifacts/manifests/build-parameters.sh \
  --mode bisect \
  --top_artifacts $artifacts/build-\$rev \
  --verbose "$verbose" &
res=0 && wait \$! || res=\$?
if [ -f $artifacts/build-\$rev/failures ]; then
  echo "\$rev" >> $artifacts/bad_revs
  exit 1
elif [ x"\$res" != x"0" ]; then
  echo "\$rev" >> $artifacts/skipped_revs
  exit 125
else
  echo "\$rev" >> $artifacts/good_revs
  exit 0
fi
EOF
chmod +x $artifacts/test.sh

# Workaround linux-next/master rebasing on top of linux-next/stable.
# Try to find $good_rev that is "good" compared to baseline
# and that is an ancesstor of both $baseline_rev and $bad_rev.
merge_base=$(git merge-base $bad_rev HEAD)
origin=$(git remote get-url origin)
origin=$(basename "$origin")
if [ x"$merge_base" != x"$good_rev" -a x"$origin" = x"linux-next.git" ]; then
    echo "Testing merge_base $merge_base (hoping for success)"
    git checkout --detach "$merge_base"
    $artifacts/test.sh &
    res=0 && wait $! || res=$?
    if [ x"$res" != x"0" ]; then
	# Check if we can use linux-next/stable as our pre-last resort.
	linux_next_stable="${linux_next_stable-$(git rev-parse refs/remotes/origin/stable)}"
	cat <<EOF | manifest_out
declare -g linux_next_stable=$linux_next_stable
EOF
	echo "Testing linux_next:stable $linux_next_stable (hoping for success)"
	git checkout --detach $linux_next_stable
	$artifacts/test.sh &
	res=0 && wait $! || res=$?
	if [ x"$res" = x"0" ]; then
	    good_rev=$linux_next_stable
	else
	    # Check if we can use linux-mainline/master as our last resort.
	    url=git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
	    git remote add mainline "$url" > /dev/null 2>&1 || true
	    git remote set-url mainline "$url"
	    clone_or_update_repo . refs/remotes/mainline/master "$url"

	    merge_base=$(git merge-base $bad_rev HEAD)
	    mainline_master="${mainline_master-$merge_base}"
	    cat <<EOF | manifest_out
declare -g mainline_master=$mainline_master
EOF
	    echo "Testing mainline_master $mainline_master (hoping for success)"
	    git checkout --detach $mainline_master
	    $artifacts/test.sh &
	    res=0 && wait $! || res=$?
	    if [ x"$res" = x"0" ]; then
		good_rev=$mainline_master
	    else
		:
		# Below bisect will fail :-(
	    fi
	fi
    else
	:
	# With good merge-base below bisect should succeed.
    fi
fi

ln -f -s "build-$good_rev" "$artifacts/build-good"
ln -f -s "build-$good_rev.sh" "$artifacts/manifests/build-good.sh"

git checkout --detach $bad_rev
$artifacts/test.sh &
res=0 && wait $! || res=$?

if [ x"$res" = x"0" ]; then
    echo "WARNING: build for bad_rev $bad_rev succeeded"
    # Build job had a spurious failure.  Re-try.
    cat > $artifacts/trigger-2-build-master <<EOF
current_project=$current_project
current_rev=$bad_rev
EOF
    rm -f $artifacts/jenkins/mail-recipients.txt
    trap "" EXIT
    exit 0
fi

ln -f -s "build-$bad_rev" "$artifacts/build-bad"
ln -f -s "build-$bad_rev.sh" "$artifacts/manifests/build-bad.sh"

git bisect start $bad_rev $good_rev 2>&1 | tee $artifacts/bisect.log

# "git bisect run" can fail (exit with non-zero) in a number of cases:
# - on trivial bisects (e.g., between HEAD^ and HEAD),
# - when merge-base between baseline and bad is worse than baseline,
# - something else?
# In all these cases we want to reset baseline to HEAD, so that we catch
# most of the commits that introduced change in the result metric.
git bisect run $artifacts/test.sh 2>&1 | tee -a $artifacts/bisect.log &
res=0 && wait $! || res=$?

if [ x"$res" = x"0" ]; then
    first_bad=$(cat .git/BISECT_RUN | head -n 1 | grep "is the first bad commit" | cut -d" " -f 1)
    assert [ x"$first_bad" != x"" ]
    echo $first_bad > $artifacts/first-bad
else
    first_bad=$(git rev-parse HEAD)
    if ! [ -f .git/BISECT_LOG ]; then
	# It seems this was a trivial bisect with $bad_rev^ == $good_rev.
	first_bad=$bad_rev
	echo $first_bad > $artifacts/first-bad
    fi
fi
cd ..

# Save BISECT_* logs
mkdir $artifacts/git-logs
find "$current_project" -path "$current_project/.git/BISECT_*" -print0 | xargs -0 -I@ mv @ $artifacts/git-logs/

# Reset baseline to the regressed commit so that we will catch subsequent
# regressions (worse than $bad_rev).
cat > $artifacts/trigger-1-reset-baseline <<EOF
current_project=$current_project
current_rev=$first_bad
reset_baseline=true
EOF

# Trigger master build now instead of waiting for next timed SCM trigger.
cat > $artifacts/trigger-2-build-master <<EOF
current_project=$current_project
EOF

if [ -f $artifacts/first-bad ]; then
    mkdir -p $artifacts/jenkins
    touch $artifacts/jenkins/build-name
    sed -i -e "s/\$/-$first_bad/" $artifacts/jenkins/build-name

    ln -f -s "build-$first_bad" "$artifacts/build-first_bad"
    ln -f -s "build-$first_bad.sh" "$artifacts/manifests/build-first_bad.sh"

    last_good=$(git -C $current_project rev-parse $first_bad^)

    good_name="last_good"
    good_sha1="$last_good"
    bad_name="first_bad"
    bad_sha1="$first_bad"

    if ! grep -q $last_good "$artifacts/good_revs"; then
	# It seems that git-bisect assumes parent commit as "good" on
	# the basis of one of its children being "good".  Therefore we
	# can have a situation when we have parent P with children C1 and C2,
	# and child C1 has a child of its own CB.  Git-bisect tests C2 as
	# "good", and CB as "bad".  From C2 being good it assumes P as "good",
	# and it knows CB is "bad", so git-bisect returns C1 as the first bad
	# commit.
	# To simplify investigations we explicitly test parent of $first_bad.
	cd $current_project
	echo "Testing last_good $last_good (hoping for success)"
	git checkout --detach "$last_good"
	$artifacts/test.sh &
	res=0 && wait $! || res=$?
	if [ x"$res" != x"0" ]; then
	    # It seems $last_good was on a path that tested good, even though
	    # it itself is bad.  Not much we can do here -- fallback to $good_rev.
	    echo "WARNING: build for last_good $last_good failed"
	    last_good="$good_rev"
	    good_name="good_rev"
	    good_sha1="$good_rev"
	fi
	cd ..
    fi

    ln -f -s "build-$last_good" "$artifacts/build-last_good"
    ln -f -s "build-$last_good.sh" "$artifacts/manifests/build-last_good.sh"

    cat >> $artifacts/jenkins/mail-body.txt <<EOF
Successfully identified regression in $current_project on $target @ $toolchain-${rr[${toolchain}_version]} @ linux-${rr[linux_version]}-$linux_config between bad $bad_rev and baseline $baseline_rev .

Culprit:
<cut>
$(git -C $current_project log -n 1 $first_bad)
</cut>

EOF
else
    good_name="good_rev"
    good_sha1="$good_rev"
    bad_name="bad"
    bad_sha1="$bad_rev"
    cat >> $artifacts/jenkins/mail-body.txt <<EOF
Could not identify regression in $current_project on $target @ $toolchain-${rr[${toolchain}_version]} @ linux-${rr[linux_version]}-$linux_config between bad $bad_rev and baseline $baseline_rev down to a single commit.  See 'Bisect log' in the links below for bisection details.

EOF
fi

cat >> $artifacts/jenkins/mail-body.txt <<EOF
Results regressed from (for $good_name == $good_sha1)

<cut>
$(cat $artifacts/build-$good_sha1/results)
</cut>

to (for $bad_name == $bad_sha1)

<cut>
$(cat $artifacts/build-$bad_sha1/results)
</cut>

Artifacts of $good_name build: ${BUILD_URL}artifact/artifacts/build-$good_sha1/
Artifacts of $bad_name build: ${BUILD_URL}artifact/artifacts/build-$bad_sha1/

Reproduce builds:
<cut>
mkdir investigate-$current_project-$bad_sha1
cd investigate-$current_project-$bad_sha1
git clone https://git.linaro.org/toolchain/jenkins-scripts
mkdir reproduce-$good_name
cd reproduce-$good_name
wget ${BUILD_URL}artifact/artifacts/manifests/build-$good_sha1.sh
../jenkins-scripts/tcwg_kernel-build.sh @@ build-$good_sha1.sh
cd ..
mkdir reproduce-$bad_name
cd reproduce-$bad_name
wget ${BUILD_URL}artifact/artifacts/manifests/build-$bad_sha1.sh
../jenkins-scripts/tcwg_kernel-build.sh @@ build-$bad_sha1.sh
cd ..
</cut>

History of pending regressions and results: https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/ci/tcwg_kernel/$toolchain-${rr[${toolchain}_version]}-$target-${rr[linux_version]}-$linux_config

Bisect log: ${BUILD_URL}artifact/artifacts/bisect.log/*view*/
Artifacts: ${BUILD_URL}artifact/artifacts/
Build URL: $BUILD_URL
Build log: ${BUILD_URL}consoleText
EOF

if [ -f $artifacts/first-bad ]; then
    cat >> $artifacts/jenkins/mail-body.txt <<EOF

Full commit:
<cut>
$(git -C $current_project show $first_bad)
</cut>
EOF
fi

# Set mail recipients last to preserve catch-error value from tcwg_kernel.yaml.
# Email developers.
CI_MAIL_RECIPIENTS="tcwg-validation@linaro.org"
case "$toolchain:$current_project" in
    gnu:*) CI_MAIL_RECIPIENTS="$CI_MAIL_RECIPIENTS, christophe.lyon@linaro.org, maxim.kuvyrkov@linaro.org" ;;
    llvm:linux) CI_MAIL_RECIPIENTS="$CI_MAIL_RECIPIENTS, arnd@linaro.org, mark.brown@linaro.org, ndesaulniers@google.com, trong@google.com" ;;
    llvm:llvm) CI_MAIL_RECIPIENTS="$CI_MAIL_RECIPIENTS, adhemerval.zanella@linaro.org, maxim.kuvyrkov@linaro.org, ndesaulniers@google.com, trong@google.com, yvan.roux@linaro.org" ;;
esac
cat > $artifacts/jenkins/mail-recipients.txt <<EOF
$CI_MAIL_RECIPIENTS
EOF

trap "" EXIT