# Checks pkgs/by-name (see pkgs/by-name/README.md)
# using the nixpkgs-check-by-name tool (see pkgs/test/nixpkgs-check-by-name)
name: Check pkgs/by-name

# The pre-built tool is fetched from a channel,
# making it work predictable on all PRs.
on:
  # Using pull_request_target instead of pull_request avoids having to approve first time contributors
  pull_request_target

# The tool doesn't need any permissions, it only outputs success or not based on the checkout
permissions: {}

jobs:
  check:
    # This is x86_64-linux, for which the tool is always prebuilt on the nixos-* channels,
    # as specified in nixos/release-combined.nix
    runs-on: ubuntu-latest
    # This should take 1 minute at most, but let's be generous.
    # The default of 6 hours is definitely too long
    timeout-minutes: 10
    steps:
      # This step has to be in this file,
      # because it's needed to determine which revision of the repository to fetch,
      # and we can only use other files from the repository once it's fetched.
      - name: Resolving the merge commit
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          # This checks for mergeability of a pull request as recommended in
          # https://docs.github.com/en/rest/guides/using-the-rest-api-to-interact-with-your-git-database?apiVersion=2022-11-28#checking-mergeability-of-pull-requests

          # Retry the API query this many times
          retryCount=3
          # Start with 5 seconds, but double every retry
          retryInterval=5
          while true; do
            echo "Checking whether the pull request can be merged"
            prInfo=$(gh api \
              -H "Accept: application/vnd.github+json" \
              -H "X-GitHub-Api-Version: 2022-11-28" \
              /repos/"$GITHUB_REPOSITORY"/pulls/${{ github.event.pull_request.number }})
            mergeable=$(jq -r .mergeable <<< "$prInfo")
            mergedSha=$(jq -r .merge_commit_sha <<< "$prInfo")

            if [[ "$mergeable" == "null" ]]; then
              if (( retryCount == 0 )); then
                echo "Not retrying anymore, probably GitHub is having internal issues"
                exit 1
              else
                (( retryCount -= 1 )) || true

                # null indicates that GitHub is still computing whether it's mergeable
                # Wait a couple seconds before trying again
                echo "GitHub is still computing whether this PR can be merged, waiting $retryInterval seconds before trying again ($retryCount retries left)"
                sleep "$retryInterval"

                (( retryInterval *= 2 )) || true
              fi
            else
              break
            fi
          done

          if [[ "$mergeable" == "true" ]]; then
            echo "The PR can be merged, checking the merge commit $mergedSha"
          else
            echo "The PR cannot be merged, it has a merge conflict"
            exit 1
          fi
          echo "mergedSha=$mergedSha" >> "$GITHUB_ENV"
      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
        with:
          # pull_request_target checks out the base branch by default
          ref: ${{ env.mergedSha }}
          # Fetches the merge commit and its parents
          fetch-depth: 2
      - name: Determining PR git hashes
        run: |
          # For pull_request_target this is the same as $GITHUB_SHA
          echo "baseSha=$(git rev-parse HEAD^1)" >> "$GITHUB_ENV"

          echo "headSha=$(git rev-parse HEAD^2)" >> "$GITHUB_ENV"
      - uses: cachix/install-nix-action@7ac1ec25491415c381d9b62f0657c7a028df52a7 # v24
      - name: Fetching the tool
        run: pkgs/test/nixpkgs-check-by-name/scripts/fetch-tool.sh "$GITHUB_BASE_REF" result
      - name: Running nixpkgs-check-by-name
        run: |
          echo "Checking whether the check succeeds on the base branch $GITHUB_BASE_REF"
          git checkout -q "$baseSha"
          if baseOutput=$(result/bin/nixpkgs-check-by-name . 2>&1); then
            baseSuccess=1
          else
            baseSuccess=
          fi
          printf "%s\n" "$baseOutput"

          echo "Checking whether the check would succeed after merging this pull request"
          git checkout -q "$mergedSha"
          if mergedOutput=$(result/bin/nixpkgs-check-by-name . 2>&1); then
            mergedSuccess=1
            exitCode=0
          else
            mergedSuccess=
            exitCode=1
          fi
          printf "%s\n" "$mergedOutput"

          resultToEmoji() {
            if [[ -n "$1" ]]; then
              echo ":heavy_check_mark:"
            else
              echo ":x:"
            fi
          }

          # Print a markdown summary in GitHub actions
          {
            echo "| Nixpkgs version | Check result |"
            echo "| --- | --- |"
            echo "| Latest base commit | $(resultToEmoji "$baseSuccess") |"
            echo "| After merging this PR | $(resultToEmoji "$mergedSuccess") |"
            echo ""

            if [[ -n "$baseSuccess" ]]; then
              if [[ -n "$mergedSuccess" ]]; then
                echo "The check succeeds on both the base branch and after merging this PR"
              else
                echo "The check succeeds on the base branch, but would fail after merging this PR:"
                echo "\`\`\`"
                echo "$mergedOutput"
                echo "\`\`\`"
                echo ""
              fi
            else
              if [[ -n "$mergedSuccess" ]]; then
                echo "The check fails on the base branch, but this PR fixes it, nicely done!"
              else
                echo "The check fails on both the base branch and after merging this PR, unknown if only this PRs changes would satisfy the check, the base branch needs to be fixed first."
                echo ""
                echo "Failure on the base branch:"
                echo "\`\`\`"
                echo "$baseOutput"
                echo "\`\`\`"
                echo ""
                echo "Failure after merging this PR:"
                echo "\`\`\`"
                echo "$mergedOutput"
                echo "\`\`\`"
                echo ""
              fi
            fi

            echo "### Details"
            echo "- nixpkgs-check-by-name tool:"
            echo "  - Channel: $channel"
            echo "  - Nixpkgs commit: [$rev](https://github.com/${GITHUB_REPOSITORY}/commit/$rev)"
            echo "  - Store path: \`$(realpath result)\`"
            echo "- Tested Nixpkgs:"
            echo "  - Base branch: $GITHUB_BASE_REF"
            echo "  - Latest base branch commit: [$baseSha](https://github.com/${GITHUB_REPOSITORY}/commit/$baseSha)"
            echo "  - Latest PR commit: [$headSha](https://github.com/${GITHUB_REPOSITORY}/commit/$headSha)"
            echo "  - Merge commit: [$mergedSha](https://github.com/${GITHUB_REPOSITORY}/commit/$mergedSha)"
          } >> "$GITHUB_STEP_SUMMARY"

          exit "$exitCode"