name: Deploy

on:
  workflow_dispatch:
    inputs:
      run_id:
        description: "CI run ID to deploy (defaults to the last successful CI run on main)"
        required: false
        type: string

concurrency:
  group: pages
  cancel-in-progress: false

jobs:
  pages:
    name: Upload to Github Pages
    runs-on: ubuntu-latest
    permissions:
      actions: read
      pages: write
      id-token: write

    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}

    steps:
      - name: Find run to deploy
        id: find
        env:
          GH_TOKEN: ${{ github.token }}
          GH_REPO: ${{ github.repository }}
          INPUT_RUN_ID: ${{ inputs.run_id }}
        run: |
          set -euo pipefail

          if [ -n "$INPUT_RUN_ID" ]; then
            echo "run_id=$INPUT_RUN_ID" >> "$GITHUB_OUTPUT"
            echo "Using explicitly requested run $INPUT_RUN_ID"
            exit 0
          fi

          # walk back through recent successful CI runs on main until we find one
          # whose frontend artifact hasn't expired yet
          runs=$(gh run list --workflow=main.yml --branch=main --status=success \
            --limit 20 --json databaseId --jq '.[].databaseId')

          for run in $runs; do
            if gh api "repos/$GH_REPO/actions/runs/$run/artifacts" \
              --jq '.artifacts[] | select(.name == "frontend" and .expired == false) | .name' \
              | grep -q frontend; then
              echo "run_id=$run" >> "$GITHUB_OUTPUT"
              echo "Deploying artifact from run $run"
              exit 0
            fi
            echo "Run $run has no usable frontend artifact, trying older run"
          done

          echo "::error::No successful CI run on main has an unexpired frontend artifact"
          exit 1

      - name: Get artifacts
        uses: actions/download-artifact@v4
        with:
          name: frontend
          path: .
          run-id: ${{ steps.find.outputs.run_id }}
          github-token: ${{ github.token }}

      - name: Upload pages artifact
        uses: actions/upload-pages-artifact@v3
        with:
          path: .

      - name: Deploy to github
        id: deployment
        uses: actions/deploy-pages@v4