name: Sync Torch Version

on:
  workflow_dispatch:
  schedule:
    - cron: "0 2 * * 1"

permissions:
  contents: write
  pull-requests: write

concurrency:
  group: sync-torch-version
  cancel-in-progress: false

jobs:
  sync:
    name: Sync torch pin with vLLM
    runs-on: ubuntu-latest
    timeout-minutes: 10

    steps:
      - name: Check out dev branch
        uses: actions/checkout@v4
        with:
          ref: dev
          token: ${{ github.token }}
          fetch-depth: 0

      - name: Sync torch version with vLLM
        id: sync
        shell: bash
        run: |
          set -Eeuo pipefail

          readonly UPSTREAM_URL="https://raw.githubusercontent.com/vllm-project/vllm/main/pyproject.toml"
          readonly TARGET_FILE="pyproject.toml"

          tmp_upstream="$(mktemp)"
          tmp_output="$(mktemp)"

          cleanup() {
            rm -f "$tmp_upstream" "$tmp_output"
          }
          trap cleanup EXIT

          echo "Fetching upstream pyproject.toml from vLLM..."
          curl \
            --fail \
            --show-error \
            --silent \
            --location \
            --retry 3 \
            --retry-delay 2 \
            --connect-timeout 10 \
            "$UPSTREAM_URL" \
            -o "$tmp_upstream"

          extract_torch_version() {
            local file="$1"
            sed -nE 's/.*torch[[:space:]]*==[[:space:]]*([0-9]+(\.[0-9]+){1,2}).*/\1/p' "$file"
          }

          mapfile -t upstream_matches < <(extract_torch_version "$tmp_upstream")
          mapfile -t current_matches < <(extract_torch_version "$TARGET_FILE")

          if [[ "${#upstream_matches[@]}" -ne 1 ]]; then
            echo "Expected exactly one torch pin in upstream file, found ${#upstream_matches[@]}"
            printf 'Matches: %s\n' "${upstream_matches[@]:-<none>}"
            exit 1
          fi

          if [[ "${#current_matches[@]}" -ne 1 ]]; then
            echo "Expected exactly one torch pin in ${TARGET_FILE}, found ${#current_matches[@]}"
            printf 'Matches: %s\n' "${current_matches[@]:-<none>}"
            exit 1
          fi

          upstream="${upstream_matches[0]}"
          current="${current_matches[0]}"

          echo "Current torch version : $current"
          echo "Upstream torch version: $upstream"

          {
            echo "current=$current"
            echo "upstream=$upstream"
          } >> "$GITHUB_OUTPUT"

          if [[ "$upstream" == "$current" ]]; then
            echo "Torch version already up to date."
            echo "changed=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          awk -v new_ver="$upstream" '
            BEGIN { updated = 0 }
            {
              if ($0 ~ /torch[[:space:]]*==[[:space:]]*[0-9]+(\.[0-9]+){1,2}/) {
                sub(/torch[[:space:]]*==[[:space:]]*[0-9]+(\.[0-9]+){1,2}/, "torch==" new_ver)
                updated++
              }
              print
            }
            END {
              if (updated != 1) {
                printf("Expected to update exactly one torch pin, updated %d\n", updated) > "/dev/stderr"
                exit 1
              }
            }
          ' "$TARGET_FILE" > "$tmp_output"

          mv "$tmp_output" "$TARGET_FILE"

          if git diff --quiet -- "$TARGET_FILE"; then
            echo "No file change detected after update."
            echo "changed=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          echo "changed=true" >> "$GITHUB_OUTPUT"

      - name: Create pull request
        if: steps.sync.outputs.changed == 'true'
        uses: peter-evans/create-pull-request@v8
        with:
          token: ${{ github.token }}
          branch: automation/sync-torch-version
          base: dev
          delete-branch: true
          signoff: true
          add-paths: |
            pyproject.toml
          commit-message: "[Build] sync torch version with vLLM (${{
            steps.sync.outputs.upstream }})"
          title: "[Build] sync torch version with vLLM (${{
            steps.sync.outputs.upstream }})"
          body: |
            Auto-sync the pinned torch version in `pyproject.toml` with vLLM.

            - Current: `${{ steps.sync.outputs.current }}`
            - Upstream: `${{ steps.sync.outputs.upstream }}`

            This PR was generated automatically by GitHub Actions.
          labels: |
            dependencies
            automation