name: Performance Regression Detection

on:
  pull_request:
    branches: [main]
    paths:
      - 'ml/**'
      - 'common/**'
      - 'data/**'
      - 'trading_engine/**'
  workflow_dispatch:

env:
  RUST_BACKTRACE: 1
  CARGO_TERM_COLOR: always

jobs:
  performance-check:
    name: Check Performance Regression
    runs-on: ubuntu-latest
    timeout-minutes: 30

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0  # Full history for baseline comparison

      - name: Install Rust toolchain
        uses: dtolnay/rust-toolchain@stable
        with:
          components: rustfmt, clippy

      - name: Cache cargo registry
        uses: actions/cache@v3
        with:
          path: ~/.cargo/registry
          key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}

      - name: Cache cargo index
        uses: actions/cache@v3
        with:
          path: ~/.cargo/git
          key: ${{ runner.os }}-cargo-git-${{ hashFiles('**/Cargo.lock') }}

      - name: Cache target directory
        uses: actions/cache@v3
        with:
          path: target
          key: ${{ runner.os }}-target-${{ hashFiles('**/Cargo.lock') }}

      - name: Download baseline (if exists)
        id: download-baseline
        continue-on-error: true
        run: |
          # Download baseline from artifacts or S3 (configure as needed)
          # For now, use git to get baseline from main branch
          git fetch origin main
          git checkout origin/main -- ml/benchmark_results/performance_baseline.json || echo "No baseline found"

          if [ -f ml/benchmark_results/performance_baseline.json ]; then
            echo "baseline_exists=true" >> $GITHUB_OUTPUT
          else
            echo "baseline_exists=false" >> $GITHUB_OUTPUT
          fi

      - name: Build ML workspace
        run: cargo build --release -p ml

      - name: Run performance benchmark
        id: benchmark
        run: |
          # Run benchmark and capture metrics
          cargo run --release -p ml --example quick_performance_benchmark -- \
            --output ml/benchmark_results/current_performance.json \
            --git-commit ${{ github.event.pull_request.head.sha || github.sha }}

      - name: Check for regression
        id: regression-check
        if: steps.download-baseline.outputs.baseline_exists == 'true'
        run: |
          # Run regression detection
          cargo run --release -p ml --example check_performance_regression -- \
            --baseline ml/benchmark_results/performance_baseline.json \
            --current ml/benchmark_results/current_performance.json \
            --output ml/benchmark_results/regression_report.md

          # Capture exit code
          EXIT_CODE=$?
          echo "exit_code=$EXIT_CODE" >> $GITHUB_OUTPUT

          # Exit with regression status
          exit $EXIT_CODE

      - name: Upload regression report
        if: always() && steps.regression-check.outputs.exit_code != ''
        uses: actions/upload-artifact@v3
        with:
          name: regression-report
          path: ml/benchmark_results/regression_report.md
          retention-days: 30

      - name: Comment PR with results
        if: always() && github.event_name == 'pull_request' && steps.regression-check.outputs.exit_code != ''
        uses: actions/github-script@v6
        with:
          script: |
            const fs = require('fs');
            const reportPath = 'ml/benchmark_results/regression_report.md';

            if (fs.existsSync(reportPath)) {
              const report = fs.readFileSync(reportPath, 'utf8');
              const exitCode = '${{ steps.regression-check.outputs.exit_code }}';

              const header = exitCode === '0'
                ? '✅ **Performance Check Passed**'
                : '❌ **Performance Regression Detected**';

              await github.rest.issues.createComment({
                issue_number: context.issue.number,
                owner: context.repo.owner,
                repo: context.repo.repo,
                body: `${header}\n\n${report}`
              });
            }

      - name: Save baseline on main branch merge
        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
        run: |
          # Copy current metrics as new baseline
          mkdir -p ml/benchmark_results
          cp ml/benchmark_results/current_performance.json ml/benchmark_results/performance_baseline.json

          # Commit baseline (if configured)
          # git config user.name "GitHub Actions"
          # git config user.email "actions@github.com"
          # git add ml/benchmark_results/performance_baseline.json
          # git commit -m "Update performance baseline [skip ci]"
          # git push

      - name: Fail job on regression
        if: steps.regression-check.outputs.exit_code == '1'
        run: |
          echo "Performance regression detected. Please review the report."
          exit 1

      - name: First run - save initial baseline
        if: steps.download-baseline.outputs.baseline_exists == 'false'
        run: |
          echo "No baseline found. Saving current metrics as baseline."
          mkdir -p ml/benchmark_results
          cp ml/benchmark_results/current_performance.json ml/benchmark_results/performance_baseline.json
          echo "✅ Initial baseline saved. Future PRs will be compared against this."