#!/usr/bin/env bash
# =============================================================================
# run_benchmarks.sh — beckn-onix adapter benchmark runner
#
# Usage:
#   cd beckn-onix
#   bash benchmarks/run_benchmarks.sh
#
# Requirements:
#   - Go 1.24+ installed
#   - benchstat is declared as a tool in go.mod; invoked via "go tool benchstat"
#
# Output:
#   benchmarks/results/<YYYY-MM-DD_HH-MM-SS>/
#     run1.txt, run2.txt, run3.txt   — raw go test -bench output
#     parallel_cpu1.txt ... cpu16.txt — concurrency sweep
#     benchstat_summary.txt           — statistical aggregation
# =============================================================================
set -euo pipefail

SCRIPT_START=$(date +%s)
REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
BENCH_PKG="./benchmarks/e2e/..."
BENCH_TIMEOUT="10m"
BENCH_TIME_SERIAL="10s"
BENCH_TIME_PARALLEL="30s"
BENCH_COUNT=1             # benchstat uses the 3 serial files for stability

# Adapter version — reads from git tag, falls back to "dev"
ONIX_VERSION="$(git -C "$REPO_ROOT" describe --tags --abbrev=0 2>/dev/null || echo "dev")"
REPORT_TEMPLATE="$REPO_ROOT/benchmarks/reports/REPORT_TEMPLATE.md"

# ── -report-only <dir>: regenerate report from an existing results directory ──
if [[ "${1:-}" == "-report-only" ]]; then
  RESULTS_DIR="${2:-}"
  if [[ -z "$RESULTS_DIR" ]]; then
    echo "Usage: bash benchmarks/run_benchmarks.sh -report-only <results-dir>"
    echo "Example: bash benchmarks/run_benchmarks.sh -report-only benchmarks/results/2026-04-09_10-30-00"
    exit 1
  fi
  if [[ ! -d "$RESULTS_DIR" ]]; then
    echo "ERROR: results directory not found: $RESULTS_DIR"
    exit 1
  fi
  echo "=== Regenerating report from existing results ==="
  echo "Results dir : $RESULTS_DIR"
  echo ""
  cd "$REPO_ROOT"
  echo "Parsing results to CSV..."
  go run "$REPO_ROOT/benchmarks/tools/parse_results.go" \
    -dir="$RESULTS_DIR" -out="$RESULTS_DIR" 2>&1 || true
  echo ""
  echo "Generating benchmark report..."
  go run "$REPO_ROOT/benchmarks/tools/generate_report.go" \
    -dir="$RESULTS_DIR" \
    -template="$REPORT_TEMPLATE" \
    -version="$ONIX_VERSION"
  echo ""
  echo "Done. Report written to: $RESULTS_DIR/BENCHMARK_REPORT.md"
  exit 0
fi

RESULTS_DIR="$REPO_ROOT/benchmarks/results/$(date +%Y-%m-%d_%H-%M-%S)"

cd "$REPO_ROOT"

# ── benchstat is declared as a go tool in go.mod; no separate install needed ──
# Use: go tool benchstat  (works anywhere without PATH changes)

# bench_filter: tee full output to the .log file for debugging, and write a
# clean copy (only benchstat-parseable lines) to the .txt file.
# The adapter logger is silenced via zerolog.SetGlobalLevel(zerolog.Disabled)
# in TestMain, so stdout should already be clean; the grep is a safety net for
# any stray lines from go test itself (build output, redis warnings, etc.).
bench_filter() {
  local txt="$1" log="$2"
  tee "$log" | grep -E "^(Benchmark|goos:|goarch:|pkg:|cpu:|ok |PASS|FAIL|--- )" > "$txt" || true
}

# ── Create results directory ──────────────────────────────────────────────────
mkdir -p "$RESULTS_DIR"
echo "=== beckn-onix Benchmark Runner ==="
echo "Results dir : $RESULTS_DIR"
echo "Package     : $BENCH_PKG"
echo ""

# ── Serial runs (3x for benchstat stability) ──────────────────────────────────
echo "Running serial benchmarks (3 runs × ${BENCH_TIME_SERIAL})..."
for run in 1 2 3; do
  echo "  Run $run/3..."
  go test \
    -timeout="$BENCH_TIMEOUT" \
    -run=^$ \
    -bench="." \
    -benchtime="$BENCH_TIME_SERIAL" \
    -benchmem \
    -count="$BENCH_COUNT" \
    "$BENCH_PKG" 2>&1 | bench_filter "$RESULTS_DIR/run${run}.txt" "$RESULTS_DIR/run${run}.log"
  echo "    Saved → $RESULTS_DIR/run${run}.txt (full log → run${run}.log)"
done
echo ""

# ── Concurrency sweep ─────────────────────────────────────────────────────────
echo "Running parallel concurrency sweep (cpu=1,2,4,8,16; ${BENCH_TIME_PARALLEL} each)..."
for cpu in 1 2 4 8 16; do
  echo "  GOMAXPROCS=$cpu..."
  go test \
    -timeout="$BENCH_TIMEOUT" \
    -run=^$ \
    -bench="BenchmarkBAPCaller_Discover_Parallel|BenchmarkBAPCaller_RPS" \
    -benchtime="$BENCH_TIME_PARALLEL" \
    -benchmem \
    -cpu="$cpu" \
    -count=1 \
    "$BENCH_PKG" 2>&1 | bench_filter "$RESULTS_DIR/parallel_cpu${cpu}.txt" "$RESULTS_DIR/parallel_cpu${cpu}.log"
  echo "    Saved → $RESULTS_DIR/parallel_cpu${cpu}.txt (full log → parallel_cpu${cpu}.log)"
done
echo ""

# ── Percentile benchmark ──────────────────────────────────────────────────────
echo "Running percentile benchmark (${BENCH_TIME_SERIAL})..."
go test \
  -timeout="$BENCH_TIMEOUT" \
  -run=^$ \
  -bench="BenchmarkBAPCaller_Discover_Percentiles" \
  -benchtime="$BENCH_TIME_SERIAL" \
  -benchmem \
  -count=1 \
  "$BENCH_PKG" 2>&1 | bench_filter "$RESULTS_DIR/percentiles.txt" "$RESULTS_DIR/percentiles.log"
echo "  Saved → $RESULTS_DIR/percentiles.txt (full log → percentiles.log)"
echo ""

# ── Cache comparison ──────────────────────────────────────────────────────────
echo "Running cache warm vs cold comparison..."
go test \
  -timeout="$BENCH_TIMEOUT" \
  -run=^$ \
  -bench="BenchmarkBAPCaller_Cache" \
  -benchtime="$BENCH_TIME_SERIAL" \
  -benchmem \
  -count=1 \
  "$BENCH_PKG" 2>&1 | bench_filter "$RESULTS_DIR/cache_comparison.txt" "$RESULTS_DIR/cache_comparison.log"
echo "  Saved → $RESULTS_DIR/cache_comparison.txt (full log → cache_comparison.log)"
echo ""

# ── benchstat statistical summary ─────────────────────────────────────────────
echo "Running benchstat statistical analysis..."
go tool benchstat \
  "$RESULTS_DIR/run1.txt" \
  "$RESULTS_DIR/run2.txt" \
  "$RESULTS_DIR/run3.txt" \
  > "$RESULTS_DIR/benchstat_summary.txt" 2>&1
echo "  Saved → $RESULTS_DIR/benchstat_summary.txt"
echo ""

# ── Parse results to CSV ──────────────────────────────────────────────────────
echo "Parsing results to CSV..."
go run "$REPO_ROOT/benchmarks/tools/parse_results.go" \
  -dir="$RESULTS_DIR" \
  -out="$RESULTS_DIR" 2>&1 || echo "  (parse_results.go: skipping on error)"
echo ""

# ── Generate human-readable report ───────────────────────────────────────────
echo "Generating benchmark report..."
if [[ -f "$REPORT_TEMPLATE" ]]; then
  go run "$REPO_ROOT/benchmarks/tools/generate_report.go" \
    -dir="$RESULTS_DIR" \
    -template="$REPORT_TEMPLATE" \
    -version="$ONIX_VERSION" 2>&1 || echo "  (generate_report.go: skipping on error)"
else
  echo "  WARNING: template not found at $REPORT_TEMPLATE — skipping report generation"
fi

# ── Summary ───────────────────────────────────────────────────────────────────
SCRIPT_END=$(date +%s)
ELAPSED_SECS=$(( SCRIPT_END - SCRIPT_START ))
ELAPSED_MIN=$(( ELAPSED_SECS / 60 ))
ELAPSED_SEC_REM=$(( ELAPSED_SECS % 60 ))

echo ""
echo "========================================"
echo "✅ Benchmark run complete!"
echo ""
echo "Total runtime : ${ELAPSED_MIN}m ${ELAPSED_SEC_REM}s"
echo ""
echo "Results written to:"
echo "  $RESULTS_DIR"
echo ""
echo "Key files:"
echo "  BENCHMARK_REPORT.md   — generated human-readable report"
echo "  benchstat_summary.txt — statistical analysis of 3 serial runs"
echo "  latency_report.csv    — per-benchmark latency and allocation data"
echo "  throughput_report.csv — RPS and latency by GOMAXPROCS level"
echo "  parallel_cpu*.txt     — concurrency sweep raw output"
echo "  percentiles.txt       — p50/p95/p99 latency data"
echo "  cache_comparison.txt  — warm vs cold Redis cache comparison"
echo ""
echo "To review the report:"
echo "  open $RESULTS_DIR/BENCHMARK_REPORT.md"
echo "========================================"