name: Benchmark ⏱️

env:
  NODE_OPTIONS: --max-old-space-size=6144

permissions:
  contents: read
  pull-requests: write

on:
  push:
    branches: [main]
    paths:
      - "packages/react-server/**"
      - "packages/rsc/**"
      - "examples/benchmark/**"
      - ".github/workflows/benchmark.yml"
  pull_request:
    paths:
      - "packages/react-server/**"
      - "packages/rsc/**"
      - "examples/benchmark/**"
      - ".github/workflows/benchmark.yml"

concurrency:
  group: benchmark-${{ github.event.number || github.sha }}
  cancel-in-progress: true

jobs:
  benchmark:
    name: Run benchmarks ⏱️
    runs-on: ubuntu-latest
    timeout-minutes: 30
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - uses: ./.github/workflows/actions/common-setup

      - name: Build benchmark example
        run: pnpm --filter @lazarv/react-server-example-benchmark build

      - name: Run benchmark
        working-directory: examples/benchmark
        run: node bench.mjs --save current

      - name: Upload benchmark results
        uses: actions/upload-artifact@v4
        with:
          name: benchmark-results-${{ github.sha }}
          path: examples/benchmark/results-current.json
          retention-days: 90

      # ── Main branch: save baseline to cache ──────────────────────────────
      - name: Copy results to baseline path
        if: github.ref == 'refs/heads/main'
        run: cp examples/benchmark/results-current.json examples/benchmark/benchmark-baseline.json

      - name: Save baseline to cache
        if: github.ref == 'refs/heads/main'
        uses: actions/cache/save@v4
        with:
          path: examples/benchmark/benchmark-baseline.json
          key: benchmark-baseline-${{ github.sha }}

      # ── Pull request: compare against main baseline ──────────────────────
      - name: Restore baseline from main
        if: github.event_name == 'pull_request'
        id: baseline
        uses: actions/cache/restore@v4
        with:
          path: examples/benchmark/benchmark-baseline.json
          key: benchmark-baseline-${{ github.event.pull_request.base.sha }}
          restore-keys: benchmark-baseline-

      - name: Generate comparison comment
        if: github.event_name == 'pull_request'
        working-directory: examples/benchmark
        env:
          HAS_BASELINE: ${{ steps.baseline.outputs.cache-matched-key != '' }}
          PR_SHA: ${{ github.event.pull_request.head.sha }}
          BASELINE_KEY: ${{ steps.baseline.outputs.cache-matched-key }}
        run: |
          node --input-type=module << 'SCRIPT'
          import { readFileSync, writeFileSync } from "node:fs";

          const prSha = process.env.PR_SHA?.slice(0, 7) || "unknown";
          const hasBaseline = process.env.HAS_BASELINE === "true";
          const baselineKey = process.env.BASELINE_KEY || "";
          const baselineSha = baselineKey.replace("benchmark-baseline-", "").slice(0, 7);

          const current = JSON.parse(readFileSync("results-current.json", "utf8"));

          let baseline = null;
          if (hasBaseline) {
            try {
              baseline = JSON.parse(readFileSync("benchmark-baseline.json", "utf8"));
            } catch {
              // baseline file not found or invalid
            }
          }

          const baselineMap = baseline
            ? new Map(baseline.results.map((r) => [r.name, r]))
            : null;

          function fmtDelta(current, base, lowerIsBetter = false) {
            if (base == null || base === 0) return "";
            const pct = ((current - base) / base) * 100;
            const sign = pct > 0 ? "+" : "";
            const good = lowerIsBetter ? pct < -1 : pct > 1;
            const bad = lowerIsBetter ? pct > 1 : pct < -1;
            const icon = good ? "\u{1f7e2}" : bad ? "\u{1f534}" : "\u{26aa}";
            return ` ${icon} ${sign}${pct.toFixed(1)}%`;
          }

          const lines = [];
          lines.push("<!-- benchmark-results -->");
          lines.push("## \u26a1 Benchmark Results");
          lines.push("");

          if (baselineMap) {
            lines.push(`| | **PR** \`${prSha}\` | **main** \`${baselineSha}\` |`);
            lines.push(`|---|---|---|`);
            lines.push(`| **Config** | ${current.config.connections} connections, ${current.config.duration}s/test | ${baseline.config.connections} connections, ${baseline.config.duration}s/test |`);
          } else {
            lines.push(`**Commit:** \`${prSha}\` | **No baseline available** (will be created when this PR's target is next pushed to main)`);
          }

          lines.push("");

          if (baselineMap) {
            lines.push("| Benchmark | Req/s | vs main | Avg Latency | vs main | P99 Latency | Throughput |");
            lines.push("|:----------|------:|--------:|------------:|--------:|------------:|-----------:|");

            for (const r of current.results) {
              const b = baselineMap.get(r.name);
              const reqDelta = fmtDelta(r.reqSec, b?.reqSec);
              const latDelta = fmtDelta(r.latencyAvg, b?.latencyAvg, true);
              lines.push(
                `| **${r.name}** | ${r.reqSec.toFixed(0)} | ${reqDelta} | ${r.latencyAvg} ms | ${latDelta} | ${r.latencyP99} ms | ${r.throughputMB} MB/s |`
              );
            }
          } else {
            lines.push("| Benchmark | Req/s | Avg Latency | P50 | P99 | Throughput |");
            lines.push("|:----------|------:|------------:|----:|----:|-----------:|");

            for (const r of current.results) {
              lines.push(
                `| **${r.name}** | ${r.reqSec.toFixed(0)} | ${r.latencyAvg} ms | ${r.latencyP50} ms | ${r.latencyP99} ms | ${r.throughputMB} MB/s |`
              );
            }
          }

          lines.push("");
          lines.push("<details><summary>Legend</summary>");
          lines.push("");
          lines.push("\u{1f7e2} > 1% improvement | \u{1f534} > 1% regression | \u{26aa} within noise margin");
          lines.push("");
          lines.push("Benchmarks run on GitHub Actions runners (shared infrastructure) — expect ~5% variance between runs. Consistent directional changes across multiple routes are more meaningful than any single number.");
          lines.push("");
          lines.push("</details>");

          writeFileSync("comment.md", lines.join("\n") + "\n");
          console.log("Generated comment.md");
          SCRIPT

      - name: Post or update PR comment
        if: github.event_name == 'pull_request'
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          PR_NUMBER=${{ github.event.pull_request.number }}
          REPO=${{ github.repository }}

          # Find existing benchmark comment by HTML marker
          COMMENT_ID=$(gh api "repos/${REPO}/issues/${PR_NUMBER}/comments" \
            --paginate --jq '.[] | select(.body | contains("<!-- benchmark-results -->")) | .id' \
            | head -1)

          if [ -n "$COMMENT_ID" ]; then
            echo "Updating existing comment ${COMMENT_ID}"
            gh api "repos/${REPO}/issues/comments/${COMMENT_ID}" \
              -X PATCH \
              -F "body=@examples/benchmark/comment.md"
          else
            echo "Creating new comment"
            gh pr comment "$PR_NUMBER" --body-file examples/benchmark/comment.md
          fi

  flight-benchmark:
    name: Flight protocol benchmark
    runs-on: ubuntu-latest
    timeout-minutes: 15
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - uses: ./.github/workflows/actions/common-setup

      - name: Run flight benchmarks
        working-directory: packages/rsc
        run: pnpm bench:json
        env:
          NODE_OPTIONS: --max-old-space-size=6144

      - name: Process results & generate report
        working-directory: packages/rsc
        run: node __bench__/report.mjs --current bench-raw.json --output bench-results.json --markdown comment.md --commit ${{ github.sha }}

      - name: Upload benchmark results
        uses: actions/upload-artifact@v4
        with:
          name: flight-bench-${{ github.sha }}
          path: packages/rsc/bench-results.json
          retention-days: 90

      # ── Main branch: save baseline to cache ──────────────────────────────
      - name: Save baseline to cache
        if: github.ref == 'refs/heads/main'
        uses: actions/cache/save@v4
        with:
          path: packages/rsc/bench-results.json
          key: flight-bench-baseline-${{ github.sha }}

      # ── Pull request: compare against main baseline ──────────────────────
      - name: Restore baseline from main
        if: github.event_name == 'pull_request'
        id: flight-baseline
        uses: actions/cache/restore@v4
        with:
          path: packages/rsc/flight-baseline.json
          key: flight-bench-baseline-${{ github.event.pull_request.base.sha }}
          restore-keys: flight-bench-baseline-

      - name: Generate comparison report
        if: github.event_name == 'pull_request' && steps.flight-baseline.outputs.cache-matched-key != ''
        working-directory: packages/rsc
        run: node __bench__/report.mjs --current bench-results.json --baseline flight-baseline.json --markdown comment.md --commit ${{ github.sha }}

      - name: Post or update PR comment
        if: github.event_name == 'pull_request'
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          PR_NUMBER=${{ github.event.pull_request.number }}
          REPO=${{ github.repository }}

          # Find existing flight benchmark comment by HTML marker
          COMMENT_ID=$(gh api "repos/${REPO}/issues/${PR_NUMBER}/comments" \
            --paginate --jq '.[] | select(.body | contains("<!-- flight-bench-results -->")) | .id' \
            | head -1)

          if [ -n "$COMMENT_ID" ]; then
            echo "Updating existing comment ${COMMENT_ID}"
            gh api "repos/${REPO}/issues/comments/${COMMENT_ID}" \
              -X PATCH \
              -F "body=@packages/rsc/comment.md"
          else
            echo "Creating new comment"
            gh pr comment "$PR_NUMBER" --body-file packages/rsc/comment.md
          fi