name: Update
on:
  # Runs everyday at noon
  schedule:
    - cron: "0 12 * * *"
  # Allow manual triggering
  workflow_dispatch:
    inputs:
      update_lock:
        type: boolean
        default: true
        description: Update flake.lock files
      generate:
        type: boolean
        default: true
        description: Update generated files
      re_apply:
        type: boolean
        default: true
        description: Re-apply additional commits from the PR

# Allow one concurrent update per branch
concurrency:
  group: "update-${{ github.ref_name }}"
  cancel-in-progress: true

# Allow pushing and creating PRs
permissions:
  contents: write
  pull-requests: write

jobs:
  update:
    name: Update the flake inputs and generate options
    runs-on: ubuntu-latest
    timeout-minutes: 40
    if: github.event_name != 'schedule' || github.repository == 'nix-community/nixvim'
    env:
      repo: ${{ github.repository }}
      base_branch: ${{ github.ref_name }}
      pr_branch: update/${{ github.ref_name }}
      workflow_run_id: ${{ github.run_id }}
      workflow_run_url: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}

    steps:
      - name: Create GitHub App token
        uses: actions/create-github-app-token@v2
        id: app-token
        with:
          app-id: ${{ vars.CI_APP_ID }}
          private-key: ${{ secrets.CI_APP_PRIVATE_KEY }}

      - name: Get GitHub App user info
        id: user-info
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
          slug: ${{ steps.app-token.outputs.app-slug }}
        run: |
          name="$slug[bot]"
          name_regex="$slug"'\[bot\]'
          id=$(gh api "/users/$name" --jq .id)
          {
            echo "id=$id"
            echo "name=$name"
            echo "email=$id+$name@users.noreply.github.com"
            echo 'author-regex=^'"$name_regex"' <'"$id+$name_regex"'@users\.noreply\.github\.com>$'
          } >> "$GITHUB_OUTPUT"

      - name: Configure git
        env:
          name: ${{ steps.user-info.outputs.name }}
          email: ${{ steps.user-info.outputs.email }}
        run: |
          git config --global user.name "$name"
          git config --global user.email "$email"

      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          token: ${{ steps.app-token.outputs.token }}

      - name: Install Nix
        uses: cachix/install-nix-action@v31
        with:
          nix_path: nixpkgs=channel:nixos-unstable
          github_access_token: ${{ steps.app-token.outputs.token }}

      - name: Create update branch
        run: |
          git branch -D "$pr_branch" || echo "Nothing to delete"
          git switch -c "$pr_branch"

      - name: Get info on the current PR
        id: open_pr_info
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
        run: |
          # Query for info about the already open update PR
          info=$(
            gh api graphql -F owner='{owner}' -F repo='{repo}' -F branch="$pr_branch" -f query='
              query($owner:String!, $repo:String!, $branch:String!) {
                repository(owner: $owner, name: $repo) {
                  pullRequests(first: 1, states: OPEN, headRefName: $branch) {
                    nodes {
                      number
                      url
                    }
                  }
                }
              }
            ' | jq --raw-output '
              .data.repository.pullRequests.nodes[]
              | to_entries[]
              | "\(.key)=\(.value)"
            '
          )
          if [[ -n "$info" ]]; then
            echo "PR info:"
            echo "$info"
            echo "$info" >> $GITHUB_OUTPUT
          else
            echo "No PR is currently open"
          fi

      - name: Fetch current PR's branch
        if: steps.open_pr_info.outputs.number
        run: |
          git fetch origin "$pr_branch"
          git branch --set-upstream-to "origin/$pr_branch"

      - name: Update flake.lock files
        id: update_flake_lock
        if: inputs.update_lock || github.event_name == 'schedule'
        run: |
          nix-build ./ci -A update
          ./result/bin/update --commit --github-output

      - name: Update generated files
        id: generate
        if: inputs.generate || github.event_name == 'schedule'
        run: |
          old=$(git show --no-patch --format=%h)
          nix-build ./ci -A generate
          ./result/bin/generate --commit
          new=$(git show --no-patch --format=%h)
          if [ "$old" != "$new" ]; then
            body=$(git show --no-patch --format=%b)
            echo "body<<EOF" >> "$GITHUB_OUTPUT"
            if [ -n "$body" ]; then
              # Multi-file changes are listed in the body
              echo "$body" >> "$GITHUB_OUTPUT"
            else
              # Single-file changes are only in the summary,
              # e.g. "generated: Updated none-ls.nix"
              git show --no-patch --format=%s | \
              sed -e 's/^generated:/-/' >> "$GITHUB_OUTPUT"
            fi
            echo "EOF" >> "$GITHUB_OUTPUT"
          fi

      - name: Apply commits from the open PR
        id: re_apply
        if: (inputs.re_apply || github.event_name == 'schedule') && steps.open_pr_info.outputs.number
        env:
          author_regex: ${{ steps.user-info.outputs.author-regex }}
        run: |
          # The base is the most recent commit on the remote branch authored by nixvim-ci
          # This should be a flake.lock bump or a generated-files update
          # We will cherry-pick all commits on the remote _after_ the $base commit
          remote="origin/$pr_branch"
          base=$(git rev-list --author="$author_regex" --max-count=1 "$remote")
          commits=( $(git rev-list --reverse "$base..$remote") )
          if [[ -n "$commits" ]]; then
            echo "Applying ${#commits[@]} commits..."
            echo "count=${#commits[@]}" >> $GITHUB_OUTPUT
            git cherry-pick \
              --strategy-option=theirs \
              --empty=drop \
              "${commits[@]}"
          else
            echo "Nothing to re-apply"
          fi

      - name: Check if there are differences to push
        id: diff
        env:
          pr_num: ${{ steps.open_pr_info.outputs.number }}
        run: |
          if [[ -n "$pr_num" ]]; then
            remote="origin/$pr_branch"
          else
            remote="origin/$base_branch"
          fi
          diff=( $(git diff --cached --name-only "$remote") )
          if [[ -n "$diff" ]]; then
            echo "${#diff[@]} files different to $remote"
            for file in "${diff[@]}"; do
              echo "- $file"
            done
            echo "count=${#diff[@]}" >> $GITHUB_OUTPUT
          else
            echo "No files are different to $remote"
          fi

      - name: Create or Update Pull Request
        id: updated_pr
        if: steps.diff.outputs.count
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
          pr_num: ${{ steps.open_pr_info.outputs.number }}
          title: |
            [${{ github.ref_name }}] Update flake.lock & generated files
          root_lock: ${{ steps.update_flake_lock.outputs.root_lock_body }}
          dev_lock: ${{ steps.update_flake_lock.outputs.dev_lock_body }}
          generated: ${{ steps.generate.outputs.body }}
        run: |
          echo "Pushing to remote branch $pr_branch"
          git push --force --set-upstream origin "$pr_branch"

          echo "Writing PR body file"
          (
            if [[ -z "$root_lock$dev_lock$generated" ]]; then
              echo '## No changes'
              echo
            fi
            if [[ -n "$root_lock" ]]; then
              echo '## Root lockfile'
              echo '```'
              echo "$root_lock"
              echo '```'
              echo
            fi
            if [[ -n "$dev_lock" ]]; then
              echo '## Dev lockfile'
              echo '```'
              echo "$dev_lock"
              echo '```'
              echo
            fi
            if [[ -n "$generated" ]]; then
              echo '## Generated files'
              echo "$generated"
              echo
            fi
            run_cmd='gh workflow run update.yml'
            if [[ "$base_branch" != "main" ]]; then
              run_cmd+=" --ref $base_branch"
            fi
            echo '---'
            echo
            echo -n 'This PR was most recently updated by workflow run '
            echo "[$workflow_run_id]($workflow_run_url)."
            echo
            echo -n 'You can re-run the update by going to the '
            echo -n '[workflow'"'"'s page](https://github.com/nix-community/nixvim/actions/workflows/update.yml) '
            echo 'or by using the `gh` command:'
            echo '```sh'
            echo "$run_cmd"
            echo '```'
            echo
            echo -n 'If needed, you can also specify workflow inputs on the command line, '
            echo 'using the `-F --field`, `-f --raw-field`, or `--json` flags.'
            echo 'See `gh workflow run --help`.'
            echo
          ) > body.md

          if [[ -n "$pr_num" ]]; then
            echo "Editing existing PR #$pr_num"
            operation=updated
            gh pr edit "$pr_num" --body-file body.md
          else
            echo "Creating new PR"
            operation=created
            gh pr create \
              --base "$base_branch" \
              --title "$title" \
              --body-file body.md
          fi

          pr_info=$(
            # Get info from `gh pr view`
            gh pr view --json 'headRefName,number,url' --jq '
              to_entries[]
              | .key |=
                  # Rename headRefName -> branch
                  if . == "headRefName" then "branch"
                  else . end
              | "\(.key)=\(.value)"
            '
            # Get additional info locally
            echo "head=$(git rev-parse HEAD)"
            echo "operation=$operation"
          )
          echo "PR Info:"
          echo "$pr_info"
          echo "$pr_info" >> $GITHUB_OUTPUT

      - name: Print summary
        if: steps.updated_pr.outputs.number
        env:
          pr_num: ${{ steps.updated_pr.outputs.number }}
          pr_url: ${{ steps.updated_pr.outputs.url }}
          pr_branch: ${{ steps.updated_pr.outputs.branch }}
          head: ${{ steps.updated_pr.outputs.head }}
          operation: ${{ steps.updated_pr.outputs.operation }}
          re_apply_count: ${{ steps.re_apply.outputs.count }}
        run: |
          short=${head:0:6}
          # stdout
          echo "${short} pushed to ${pr_branch}"
          echo "#${pr_num} was ${operation}: ${pr_url}"
          ( # markdown summary
            echo "## ${{ github.ref_name }}"
            echo
            echo "\`${short}\` pushed to \`${pr_branch}\`"
            echo
            echo "[#${pr_num}](${pr_url}) was ${operation}."
            echo
            if [[ -n "$re_apply_count" ]]; then
              echo "Re-applied $re_apply_count commits from the existing PR."
            fi
            echo
          ) >> $GITHUB_STEP_SUMMARY

      - name: Print cancellation summary
        if: (!steps.updated_pr.outputs.number)
        env:
          pr_num: ${{ steps.open_pr_info.outputs.number }}
          pr_url: ${{ steps.open_pr_info.outputs.url }}
          changes: ${{ steps.diff.outputs.count || '0' }}
          re_apply_count: ${{ steps.re_apply.outputs.count }}
        run: |
          (
            echo "## Not updated"
            echo
            echo -n "$changes files with differences compared to "
            if [[ -n "$pr_num" ]]; then
              echo "[#$pr_num]($pr_url)."
            else
              echo "\`$base_branch\`"
            fi
            echo
            if [[ -n "$re_apply_count" ]]; then
              echo "Re-applied $re_apply_count commits from the existing PR."
            fi
            echo
          ) >> $GITHUB_STEP_SUMMARY