wasm-slim 0.1.1

# ABOUTME: Performance benchmarks with regression detection
# ABOUTME: Runs on PRs to detect regressions, updates baseline on main

name: Performance Benchmarks

on:
  push:
    branches: [main]
    paths-ignore:
      - '**.md'
      - 'LICENSE'
      - '.gitignore'
      - 'docs/**'
  pull_request:
    branches: [main]
    paths-ignore:
      - '**.md'
      - 'LICENSE'
      - '.gitignore'
      - 'docs/**'

# Cancel in-progress runs for the same PR
concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

env:
  CARGO_TERM_COLOR: always

permissions:
  contents: read
  pull-requests: write

jobs:
  benchmark:
    name: Run Benchmarks
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v6
        with:
          fetch-depth: 0  # Needed for git commit tracking

      - name: Install Rust toolchain
        uses: dtolnay/rust-toolchain@stable

      - name: Cache Rust dependencies
        uses: Swatinem/rust-cache@v2
        with:
          key: bench

      - name: Cache baseline (from main branch)
        uses: actions/cache@v5
        with:
          path: .wasm-slim/benchmarks
          key: benchmark-baseline-${{ github.ref }}
          restore-keys: |
            benchmark-baseline-refs/heads/main

      - name: Build bench-tracker
        run: cargo build --release --bin bench-tracker

      - name: Run benchmarks
        run: cargo bench --quiet

      - name: Check for regressions (PR only)
        if: github.event_name == 'pull_request'
        id: regression-check
        continue-on-error: true
        run: |
          cargo run --release --bin bench-tracker -- compare \
            --fail-on-regression \
            --max-regression 10.0

      - name: Compare with baseline (PR only)
        if: github.event_name == 'pull_request'
        id: compare
        run: |
          echo "## Benchmark Results" > benchmark-comment.md
          echo "" >> benchmark-comment.md

          if cargo run --release --bin bench-tracker -- compare > benchmark-output.txt 2>&1; then
            cat benchmark-output.txt >> benchmark-comment.md
            echo "" >> benchmark-comment.md
            echo "✓ No significant performance regressions detected" >> benchmark-comment.md
          else
            cat benchmark-output.txt >> benchmark-comment.md
            echo "" >> benchmark-comment.md
            echo "⚠️ Performance regressions detected!" >> benchmark-comment.md
          fi

      - name: Comment on PR with results
        if: github.event_name == 'pull_request'
        uses: actions/github-script@v8
        with:
          script: |
            const fs = require('fs');
            let body = '## Benchmark Results\n\n';

            try {
              const output = fs.readFileSync('benchmark-comment.md', 'utf8');
              body = output;
            } catch (err) {
              body += 'Benchmark comparison not available.\n';
            }

            // Add failure notice if regressions detected
            if ('${{ steps.regression-check.outcome }}' === 'failure') {
              body = '⚠️ **Performance Regression Detected**\n\n' + body;
            }

            // Find existing comment
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });

            const botComment = comments.find(comment =>
              comment.user.type === 'Bot' &&
              comment.body.includes('## Benchmark Results')
            );

            if (botComment) {
              // Update existing comment
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: botComment.id,
                body: body
              });
            } else {
              // Create new comment
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body: body
              });
            }

      - name: Update baseline (main branch only)
        if: github.ref == 'refs/heads/main' && github.event_name == 'push'
        run: |
          cargo run --release --bin bench-tracker -- baseline \
            --version "main-${{ github.sha }}"

      - name: Upload benchmark results
        uses: actions/upload-artifact@v6
        if: always()
        with:
          name: criterion-results
          path: target/criterion
          retention-days: 30

      - name: Upload baseline
        uses: actions/upload-artifact@v6
        if: github.ref == 'refs/heads/main'
        with:
          name: benchmark-baseline
          path: .wasm-slim/benchmarks/baseline.json
          retention-days: 90

      - name: Fail on regression
        if: steps.regression-check.outcome == 'failure'
        run: |
          echo "::error::Performance regression detected! Review the benchmark results above."
          exit 1