# Create a documentation preview in the pull request
# --------------------------------------------------
# This GitHub Actions workflow triggers by commenting '/docs-preview' on a PR.
# It creates a new Read the Docs version for the PR branch and triggers a build.
#
# Key Steps:
# 1. Use the script (.github/scripts/pr_detect_changed_subtrees.py) to detect changed project
# 2. Get the PR branch name and derive the RTD version slug
# 3. Activate the branch as a new version on Read the Docs (key difference from update-docs.yml)
# 4. Trigger a build for that version
# 5. Comment the preview URL back on the PR
#
# Note: if multiple projects are changed in one PR, only the first detected project is previewed.

name: Docs Preview

on:
  issue_comment:
    types: [created, edited]

permissions:
  contents: read
  pull-requests: write

jobs:
  build:
    runs-on: ubuntu-latest
    # Only run when '/docs-preview' is commented on a PR by a member or owner
    if: >-
      github.event.issue.pull_request != null &&
      contains(github.event.comment.body, '/docs-preview') &&
      (github.event.comment.author_association == 'MEMBER' ||
      github.event.comment.author_association == 'OWNER')
    steps:
      - name: Generate a token
        id: generate-token
        uses: actions/create-github-app-token@a8d616148505b5069dccd32f177bb87d7f39123b # v2.1.1
        with:
          app-id: ${{ secrets.APP_ID }}
          private-key: ${{ secrets.APP_PRIVATE_KEY }}
          owner: ${{ github.repository_owner }}

      - name: Checkout config files only
        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
        with:
          sparse-checkout: .github
          sparse-checkout-cone-mode: true
          token: ${{ steps.generate-token.outputs.token }}

      - name: Set up Python
        uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0
        with:
          python-version: '3.10'

      - name: Install python dependencies
        run: |
          python -m pip install --upgrade pip
          pip install pydantic requests

      - name: Set up Git user
        run: |
          git config user.name "assistant-librarian[bot]"
          git config user.email "assistant-librarian[bot]@users.noreply.github.com"

      - name: Detect changed subtrees from PR
        id: detect
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
        run: |
          python .github/scripts/pr_detect_changed_subtrees.py \
            --repo "${{ github.repository }}" \
            --pr "${{ github.event.issue.number }}" \
            --config ".github/repos-config.json" \

      - name: Extract first project
        id: extract
        run: |
          # pr_detect_changed_subtrees.py returns a string of project names
          # separated by "\n", i.e. "projects/rocprim\nprojects/hipblaslt\nshared/tensile"
          # head -n1: extracts the first project, i.e. "projects/rocprim"
          # cut -d'/' -f2:  cuts the "projects/" prefix, leaving "rocprim" for project_name
          project=$(echo "${{ steps.detect.outputs.subtrees }}" | head -n1)
          echo "project=$project" >> $GITHUB_OUTPUT
          echo "project_name=$(echo "$project" | cut -d'/' -f2)" >> $GITHUB_OUTPUT

      - name: Get PR branch
        if: steps.extract.outputs.project
        id: pr
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
        run: |
          PR_DATA=$(gh api repos/${{ github.repository }}/pulls/${{ github.event.issue.number }})
          echo "branch=$(echo $PR_DATA | jq -r .head.ref)" >> $GITHUB_OUTPUT

      - name: Derive RTD slugs and verify project exists
        if: steps.extract.outputs.project
        id: rtd
        env:
          RTD_TOKEN: ${{ secrets.RTD_TOKEN }}
        run: |
          branch_name="${{ steps.pr.outputs.branch }}"
          # Generate slug like 'user-me-my_test_branch' from 'user/me/my_test_branch'
          version_slug="${branch_name//\//-}"
          project_slug="advanced-micro-devices-${{ steps.extract.outputs.project_name }}"

          echo "version_slug=$version_slug" >> $GITHUB_OUTPUT
          echo "project_slug=$project_slug" >> $GITHUB_OUTPUT

          # The API call returns upto 300 projects information from RTD
          # jq extracts the project slug from the list
          project_list=$(curl \
            --connect-timeout 180 \
            --header "Authorization: Token $RTD_TOKEN" \
            "https://app.readthedocs.com/api/v3/projects/?expand=advanced-micro-devices&limit=300" \
            | jq -r '.results[].slug')

          if echo "$project_list" | grep -Fxq "$project_slug"; then
            echo "exists=true" >> $GITHUB_OUTPUT

            # Fetch documentation URL
            doc_url=$(curl \
              --connect-timeout 180 \
              --silent \
              --header "Authorization: Token $RTD_TOKEN" \
              "https://app.readthedocs.com/api/v3/projects/$project_slug/" \
              | jq --raw-output '.urls.documentation')

            # Strip trailing version segment (e.g. "latest/") to get the base url
            doc_base=$(echo "$doc_url" | sed 's|/[^/]\+/\?$||')
            echo "doc_base=$doc_base" >> $GITHUB_OUTPUT
          else
            echo "${{ steps.extract.outputs.project_name }} does not exist on Read the Docs, skipping."
            echo "exists=false" >> $GITHUB_OUTPUT
          fi

      - name: Sync RTD versions to discover PR branch
        # Without a GitHub webhook configured on the repo, RTD is unaware of new branches.
        # Triggering a sync forces RTD to re-scan the repository and register the PR branch
        # as a version before we attempt to activate it in the next step.
        if: steps.rtd.outputs.exists == 'true'
        env:
          RTD_TOKEN: ${{ secrets.RTD_TOKEN }}
        run: |
          curl \
            --connect-timeout 180 \
            --fail \
            --request POST \
            --header "Authorization: Token $RTD_TOKEN" \
            "https://app.readthedocs.com/api/v3/projects/${{ steps.rtd.outputs.project_slug }}/sync-versions/"

      - name: Wait for RTD to register PR branch version
        if: steps.rtd.outputs.exists == 'true'
        env:
          RTD_TOKEN: ${{ secrets.RTD_TOKEN }}
        run: |
          declare version_url="https://app.readthedocs.com/api/v3/projects/${{ steps.rtd.outputs.project_slug }}/versions/${{ steps.rtd.outputs.version_slug }}/"

          declare -i MAXIMUM_NUMBER_OF_POLLS=20
          declare -i SLEEP_BETWEEN_POLLS_SECONDS=15

          echo "Polling for version to appear: $version_url"
          for i in $(seq 1 ${MAXIMUM_NUMBER_OF_POLLS}); do
            status=$(curl --silent --output /dev/null --write-out "%{http_code}" \
              --header "Authorization: Token $RTD_TOKEN" \
              "$version_url")
            if [ "$status" = "200" ]; then
              echo "Version found after $i attempt(s)."
              exit 0
            fi
            echo "Attempt $i: version not yet registered (HTTP $status), waiting 15s..."
            sleep ${SLEEP_BETWEEN_POLLS_SECONDS}
          done
          echo "Timed out waiting for RTD to register version."
          exit 1

      - name: Activate PR branch as a new RTD version
        if: steps.rtd.outputs.exists == 'true'
        env:
          RTD_TOKEN: ${{ secrets.RTD_TOKEN }}
        run: |
          curl \
            --connect-timeout 180 \
            --fail \
            --request PATCH \
            --header "Authorization: Token $RTD_TOKEN" \
            --header "Content-Type: application/json" \
            --data '{"active": true, "hidden": true, "privacy_level": "private"}' \
            "https://app.readthedocs.com/api/v3/projects/${{ steps.rtd.outputs.project_slug }}/versions/${{ steps.rtd.outputs.version_slug }}/"

      - name: Trigger RTD build for PR branch
        if: steps.rtd.outputs.exists == 'true'
        env:
          RTD_TOKEN: ${{ secrets.RTD_TOKEN }}
        run: |
          curl \
            --fail \
            --silent \
            --request POST \
            --header "Authorization: Token $RTD_TOKEN" \
            "https://app.readthedocs.com/api/v3/projects/${{ steps.rtd.outputs.project_slug }}/versions/${{ steps.rtd.outputs.version_slug }}/builds/"

      - name: Comment RTD preview URL on PR
        if: steps.rtd.outputs.exists == 'true'
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
        run: |
          preview_url="${{ steps.rtd.outputs.doc_base }}/${{ steps.rtd.outputs.version_slug }}/"
          gh pr comment ${{ github.event.issue.number }} \
            --repo ${{ github.repository }} \
            --body "Docs preview for **${{ steps.extract.outputs.project_name }}** is building on Read the Docs: $preview_url \
            (Note: If a pull request includes multiple projects, only the preview for the first project will be built.)"