name: Report backend memory

on:
  workflow_run:
    types: [completed]
    workflows:
      - Get backend memory usage # get-backend-memory.yml

jobs:
  compare-memory:
    runs-on: ubuntu-latest
    if: ${{ github.event.workflow_run.conclusion == 'success' }}
    permissions:
      pull-requests: write

    steps:
      - name: Download artifact
        uses: actions/github-script@v8.0.0
        with:
          script: |
            const fs = require('fs');
            let allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
              owner: context.repo.owner,
              repo: context.repo.repo,
              run_id: context.payload.workflow_run.id,
            });
            let matchArtifacts = allArtifacts.data.artifacts.filter((artifact) => {
              return artifact.name.startsWith("memory-artifact-") || artifact.name == "memory-artifact"
            });
            await Promise.all(matchArtifacts.map(async (artifact) => {
              let download = await github.rest.actions.downloadArtifact({
                owner: context.repo.owner,
                repo: context.repo.repo,
                artifact_id: artifact.id,
                archive_format: 'zip',
              });
              await fs.promises.writeFile(`${process.env.GITHUB_WORKSPACE}/${artifact.name}.zip`, Buffer.from(download.data));
            }));
      - name: Extract all artifacts
        run: |
          find . -mindepth 1 -maxdepth 1 -type f -name '*.zip' -exec unzip {} -d artifacts ';'
          ls -la artifacts/
      - name: Load PR Number
        id: load-pr-num
        run: echo "pr-number=$(cat artifacts/pr_number)" >> "$GITHUB_OUTPUT"

      - name: Output base
        run: cat ./artifacts/memory-base.json
      - name: Output head
        run: cat ./artifacts/memory-head.json
      - name: Compare memory usage
        id: compare
        run: |
          BASE_MEMORY=$(cat ./artifacts/memory-base.json)
          HEAD_MEMORY=$(cat ./artifacts/memory-head.json)

          variation() {
            calc() {
              BASE=$(echo "$BASE_MEMORY" | jq -r ".${1}.${2} // 0")
              HEAD=$(echo "$HEAD_MEMORY" | jq -r ".${1}.${2} // 0")

              DIFF=$((HEAD - BASE))
              if [ "$BASE" -gt 0 ]; then
                DIFF_PERCENT=$(echo "scale=2; ($DIFF * 100) / $BASE" | bc)
              else
                DIFF_PERCENT=0
              fi

              # Convert KB to MB for readability
              BASE_MB=$(echo "scale=2; $BASE / 1024" | bc)
              HEAD_MB=$(echo "scale=2; $HEAD / 1024" | bc)
              DIFF_MB=$(echo "scale=2; $DIFF / 1024" | bc)

              JSON=$(jq -c -n \
                --argjson base "$BASE_MB" \
                --argjson head "$HEAD_MB" \
                --argjson diff "$DIFF_MB" \
                --argjson diff_percent "$DIFF_PERCENT" \
                '{base: $base, head: $head, diff: $diff, diff_percent: $diff_percent}')

              echo "$JSON"
            }

            JSON=$(jq -c -n \
              --argjson VmRSS "$(calc $1 VmRSS)" \
              --argjson VmHWM "$(calc $1 VmHWM)" \
              --argjson VmSize "$(calc $1 VmSize)" \
              '{VmRSS: $VmRSS, VmHWM: $VmHWM, VmSize: $VmSize}')

            echo "$JSON"
          }

          JSON=$(jq -c -n \
            --argjson beforeGc "$(variation beforeGc)" \
            --argjson afterGc "$(variation afterGc)" \
            '{beforeGc: $beforeGc, afterGc: $afterGc}')

          echo "res=$JSON" >> "$GITHUB_OUTPUT"
      - id: build-comment
        name: Build memory comment
        run: |
          HEADER="## Backend memory usage comparison"
          FOOTER="[See workflow logs for details](https://github.com/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID})"

          echo "$HEADER" > ./output.md
          echo >> ./output.md

          table() {
            line() {
              BASE=$(echo "${{ steps.compare.outputs.res }}" | jq -r ".${1}.${2}.base")
              HEAD=$(echo "${{ steps.compare.outputs.res }}" | jq -r ".${1}.${2}.head")
              DIFF=$(echo "${{ steps.compare.outputs.res }}" | jq -r ".${1}.${2}.diff")
              DIFF_PERCENT=$(echo "${{ steps.compare.outputs.res }}" | jq -r ".${1}.${2}.diff_percent")

              echo "| ${2} | ${BASE} MB | ${HEAD} MB | ${DIFF} MB (${DIFF_PERCENT}%) |" >> ./output.md
            }

            echo "| Metric | base | head | Diff |" >> ./output.md
            echo "|--------|------|------|------|" >> ./output.md
            line $1 VmRSS
            line $1 VmHWM
            line $1 VmSize
          }

          echo "### Before GC" >> ./output.md
          table beforeGc
          echo >> ./output.md

          echo "### After GC" >> ./output.md
          table afterGc
          echo >> ./output.md

          # Determine if this is a significant change (more than 5% increase)
          if [ "$(echo "${{ steps.compare.outputs.res }}" | jq -r '.afterGc.VmRSS.diff_percent | tonumber > 5')" = "true" ]; then
            echo "⚠️ **Warning**: Memory usage has increased by more than 5%. Please verify this is not an unintended change." >> ./output.md
            echo >> ./output.md
          fi

          echo "$FOOTER" >> ./output.md
      - uses: thollander/actions-comment-pull-request@v3
        with:
          pr-number: ${{ steps.load-pr-num.outputs.pr-number }}
          comment-tag: show_memory_diff
          file-path: ./output.md
      - name: Tell error to PR
        uses: thollander/actions-comment-pull-request@v3
        if: failure() && steps.load-pr-num.outputs.pr-number
        with:
          pr-number: ${{ steps.load-pr-num.outputs.pr-number }}
          comment-tag: show_memory_diff_error
          message: |
            An error occurred while comparing backend memory usage. See [workflow logs](https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}) for details.