#!/usr/bin/env bash
# Contract tests for paired CI benchmark collection and verdict quality.

set -euo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
WORK_DIR="$(mktemp -d)"
trap 'rm -rf "${WORK_DIR}"' EXIT

mkdir -p "${WORK_DIR}/bin" "${WORK_DIR}/candidate" "${WORK_DIR}/baseline"
cat > "${WORK_DIR}/bin/fixture.test" <<'EOF'
#!/usr/bin/env bash
[[ "$1" == '-test.bench=.' ]] || exit 91
[[ "${FAKE_BINARY_FAIL:-0}" == 0 ]] || exit 23
echo 'BenchmarkExample-4  1  100 ns/op  0 B/op  0 allocs/op'
EOF
chmod +x "${WORK_DIR}/bin/fixture.test"
export FAKE_BINARY="${WORK_DIR}/bin/fixture.test"
cat > "${WORK_DIR}/bin/go" <<'EOF'
#!/usr/bin/env bash
if [[ "$*" == version ]]; then
  echo 'go version go1.26.7 linux/amd64'
  exit 0
fi
printf '%s\t%s\n' "$PWD" "$*" >> "${FAKE_GO_LOG}"
args=("$@")
for ((i=0; i<${#args[@]}; i++)); do
  if [[ "${args[i]}" == -exec ]]; then
    exec "${args[i+1]}" "${FAKE_BINARY}" '-test.bench=.'
  fi
done
cat <<'RESULT'
goos: linux
goarch: amd64
pkg: example.test/bench
cpu: test
BenchmarkExample-4  1  100 ns/op  0 B/op  0 allocs/op
PASS
ok  example.test/bench  0.001s
RESULT
EOF
chmod +x "${WORK_DIR}/bin/go"

(
  cd "${WORK_DIR}/candidate"
  PATH="${WORK_DIR}/bin:${PATH}" \
    FAKE_GO_LOG="${WORK_DIR}/go.log" \
    PULSE_BENCH_CURRENT_DIR="${WORK_DIR}/candidate" \
    PULSE_BENCH_BASELINE_DIR="${WORK_DIR}/baseline" \
    PULSE_BENCH_SAMPLE_COUNT=2 \
    bash "${ROOT_DIR}/scripts/run-ci-benchmarks.sh" >/dev/null
)

[[ "$(grep -c '^BenchmarkExample' "${WORK_DIR}/candidate/bench-baseline.txt")" == 2 ]]
[[ "$(grep -c '^BenchmarkExample' "${WORK_DIR}/candidate/bench-results.txt")" == 2 ]]

# Warm-up is baseline then candidate. Measured rounds must alternate which tree
# goes first, avoiding a permanent order advantage.
mapfile -t calls < "${WORK_DIR}/go.log"
[[ "${#calls[@]}" == 6 ]]
[[ "${calls[2]}" == "${WORK_DIR}/baseline"$'\t'* ]]
[[ "${calls[3]}" == "${WORK_DIR}/candidate"$'\t'* ]]
[[ "${calls[4]}" == "${WORK_DIR}/candidate"$'\t'* ]]
[[ "${calls[5]}" == "${WORK_DIR}/baseline"$'\t'* ]]

metadata="${WORK_DIR}/candidate/bench-metadata.txt"
grep -qFx 'samples=2' "${metadata}"
grep -qFx 'benchtime=100ms' "${metadata}"
grep -qFx 'candidate.commit=unavailable' "${metadata}"
grep -qFx 'baseline.go=go version go1.26.7 linux/amd64' "${metadata}"
[[ "$(grep -c '^sample=' "${metadata}")" == 4 ]]
! grep -qF "${WORK_DIR}" "${metadata}"
digest="$(sha256sum "${FAKE_BINARY}")"
digest="${digest%% *}"
[[ "$(grep -c '^binary=' "${metadata}")" == 4 ]]
for tuple in baseline,1 candidate,1 candidate,2 baseline,2; do
  grep -qFx "binary=${tuple},fixture.test,${digest}" "${metadata}"
done

# Real Git roots retain exact identities; a repeated run replaces old metadata.
for tree in candidate baseline; do
  git -C "${WORK_DIR}/${tree}" init -q
  git -C "${WORK_DIR}/${tree}" -c user.name=Test -c user.email=test@example.invalid \
    commit -qm fixture --allow-empty
done
PATH="${WORK_DIR}/bin:${PATH}" FAKE_GO_LOG="${WORK_DIR}/go.log" \
  PULSE_BENCH_CURRENT_DIR="${WORK_DIR}/candidate" \
  PULSE_BENCH_BASELINE_DIR="${WORK_DIR}/baseline" PULSE_BENCH_SAMPLE_COUNT=1 \
  bash "${ROOT_DIR}/scripts/run-ci-benchmarks.sh" >/dev/null
grep -qFx "candidate.commit=$(git -C "${WORK_DIR}/candidate" rev-parse HEAD)" "${metadata}"
grep -qFx "baseline.tree=$(git -C "${WORK_DIR}/baseline" rev-parse 'HEAD^{tree}')" "${metadata}"
[[ "$(grep -c '^sample=' "${metadata}")" == 2 ]]

# A nested archive has no identity of its own; never attribute its parent's SHA.
mkdir -p "${WORK_DIR}/candidate/archive"
PATH="${WORK_DIR}/bin:${PATH}" FAKE_GO_LOG="${WORK_DIR}/go.log" \
  PULSE_BENCH_CURRENT_DIR="${WORK_DIR}/candidate/archive" \
  PULSE_BENCH_BASELINE_DIR='' PULSE_BENCH_SAMPLE_COUNT=1 \
  bash "${ROOT_DIR}/scripts/run-ci-benchmarks.sh" >/dev/null
grep -qFx 'candidate.commit=unavailable' "${WORK_DIR}/candidate/archive/bench-metadata.txt"
! grep -q '^baseline\.' "${WORK_DIR}/candidate/archive/bench-metadata.txt"

grep -qFx "binary=candidate,unpaired,fixture.test,${digest}" \
  "${WORK_DIR}/candidate/archive/bench-metadata.txt"

# The wrapper must not turn a failed executable into successful evidence.
set +e
PATH="${WORK_DIR}/bin:${PATH}" FAKE_GO_LOG="${WORK_DIR}/go.log" \
  FAKE_BINARY_FAIL=1 PULSE_BENCH_CURRENT_DIR="${WORK_DIR}/candidate" \
  PULSE_BENCH_BASELINE_DIR='' PULSE_BENCH_SAMPLE_COUNT=1 \
  bash "${ROOT_DIR}/scripts/run-ci-benchmarks.sh" >/dev/null
status=$?
set -e
[[ "${status}" == 23 ]]
grep -qFx "binary=candidate,unpaired,fixture.test,${digest}" "${metadata}"

cat > "${WORK_DIR}/adequate.txt" <<'EOF'
Example-4  100.0n ± 1%  111.0n ± 1%  +11.00% (p=0.001 n=10)
EOF
set +e
output="$(bash "${ROOT_DIR}/scripts/check-bench-regression.sh" "${WORK_DIR}/adequate.txt" 2>&1)"
status=$?
set -e
if [[ "${status}" == 0 ]]; then
  echo "adequately sampled regression was not rejected" >&2
  exit 1
fi
grep -qF "BENCHMARK REGRESSION DETECTED" <<<"${output}"

cat > "${WORK_DIR}/undersampled.txt" <<'EOF'
Example-4  100.0n ± ∞ ¹  111.0n ± ∞ ¹  +11.00% (p=0.008 n=5)
EOF
set +e
output="$(bash "${ROOT_DIR}/scripts/check-bench-regression.sh" "${WORK_DIR}/undersampled.txt" 2>&1)"
status=$?
set -e
[[ "${status}" != 0 ]]
grep -qF "BENCHMARK EVIDENCE INSUFFICIENT" <<<"${output}"

cat > "${WORK_DIR}/clean.txt" <<'EOF'
Example-4  100.0n ± 1%  105.0n ± 1%  +5.00% (p=0.001 n=10)
EOF
bash "${ROOT_DIR}/scripts/check-bench-regression.sh" "${WORK_DIR}/clean.txt" >/dev/null

echo "all CI benchmark tests passed"