name: Deploy Backend (Azure Functions)

on:
  workflow_dispatch:

# Every job states its own permissions. This default is what the build job runs with: restore
# and build execute third-party code (NuGet MSBuild targets, the Functions worker SDK) and must
# never hold more than a read-only token.
permissions:
  contents: read

# Hosts (API, versions container) come from .github/scripts/Get-Endpoints.ps1.
env:
  FUNCTION_APP: autopilotmonitor-api-eu
  CSPROJ_PATH: src/Backend/AutopilotMonitor.Functions/AutopilotMonitor.Functions.csproj

jobs:
  # Runs only this repository's scripts. The deploy identity trusts the `production`
  # environment, which admits main only.
  reserve:
    name: Reserve build number
    runs-on: ubuntu-latest
    environment: production
    permissions:
      contents: read
      id-token: write   # OIDC federated login (secret-less)
    outputs:
      build_number: ${{ steps.version.outputs.build_number }}
      version: ${{ steps.version.outputs.version }}
      build_utc: ${{ steps.version.outputs.build_utc }}

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      - name: Load endpoints
        shell: pwsh
        run: ./.github/scripts/Get-Endpoints.ps1 -ExportToGitHubEnv

      - name: Login to Azure (OIDC)
        uses: azure/login@a641126d1b8aa4d1fa005f4f92df94a3a4c4c906 # v3.1.0
        with:
          client-id: ${{ secrets.AZURE_CLIENT_ID }}
          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}

      # Same counter mechanism as the agent line: reserve-before-build with ETag-CAS
      # against a per-component counter blob. BuildTimestampUtc is pinned here rather
      # than left to MSBuild's default so the published manifest and the value baked
      # into the assembly (reported by /api/health) are the same instant.
      - name: Reserve build number (counter blob CAS)
        id: version
        shell: pwsh
        run: |
          $buildNumber = & ./.github/scripts/Request-BuildNumber.ps1 -CounterUrl "$env:VERSIONS_CONTAINER_URL/backend.txt"

          $csproj = Get-Content ${{ env.CSPROJ_PATH }} -Raw
          if ($csproj -notmatch '<VersionPrefix>(\d+\.\d+)</VersionPrefix>') {
            throw "VersionPrefix not found in ${{ env.CSPROJ_PATH }}"
          }
          $version = "$($Matches[1]).$buildNumber"
          $buildUtc = [DateTime]::UtcNow.ToString('o')
          Write-Host "Backend version: $version (built $buildUtc)"

          "build_number=$buildNumber" >> $env:GITHUB_OUTPUT
          "version=$version" >> $env:GITHUB_OUTPUT
          "build_utc=$buildUtc" >> $env:GITHUB_OUTPUT

  # Build zone: no login, no secret, no id-token. Its only output is the artifact; the
  # deploy job treats that as data and never builds.
  build:
    name: Build
    needs: reserve
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      - name: Setup .NET 10
        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6.0.0
        with:
          dotnet-version: '10.0.x'

      - name: Restore dependencies
        run: dotnet restore ${{ env.CSPROJ_PATH }}

      - name: Build
        run: dotnet build ${{ env.CSPROJ_PATH }} --configuration Release --no-restore -p:SourceRevisionId=${{ github.sha }} -p:BuildNumber=${{ needs.reserve.outputs.build_number }} -p:BuildTimestampUtc=${{ needs.reserve.outputs.build_utc }}

      - name: Publish
        run: dotnet publish ${{ env.CSPROJ_PATH }} --configuration Release --output ./publish --no-build -p:SourceRevisionId=${{ github.sha }} -p:BuildNumber=${{ needs.reserve.outputs.build_number }} -p:BuildTimestampUtc=${{ needs.reserve.outputs.build_utc }}

      # One archive, not a folder upload: upload-artifact skips hidden files, and the
      # isolated worker cannot start without the publish output's .azurefunctions/ folder.
      - name: Package publish output
        run: tar -czf "$RUNNER_TEMP/backend-publish.tgz" -C publish .

      - name: Upload publish output
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        with:
          name: backend-publish
          path: ${{ runner.temp }}/backend-publish.tgz
          if-no-files-found: error
          retention-days: 1

  # Trust zone: only this repository's scripts and pinned actions run here, never a restore
  # or build. The package is unpacked outside the checkout, so nothing in it can replace the
  # scripts this job runs.
  deploy:
    name: Deploy and verify
    needs: [reserve, build]
    runs-on: ubuntu-latest
    environment: production
    permissions:
      contents: read
      id-token: write   # OIDC federated login (secret-less)

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      - name: Load endpoints
        shell: pwsh
        run: ./.github/scripts/Get-Endpoints.ps1 -ExportToGitHubEnv

      - name: Download publish output
        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
        with:
          name: backend-publish
          path: ${{ runner.temp }}/backend-artifact

      # GNU tar refuses members with '..' and strips leading '/'.
      - name: Unpack publish output
        run: |
          mkdir "$RUNNER_TEMP/publish"
          tar -xzf "$RUNNER_TEMP/backend-artifact/backend-publish.tgz" -C "$RUNNER_TEMP/publish"

      - name: Login to Azure (OIDC)
        uses: azure/login@a641126d1b8aa4d1fa005f4f92df94a3a4c4c906 # v3.1.0
        with:
          client-id: ${{ secrets.AZURE_CLIENT_ID }}
          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}

      - name: Deploy to Azure Functions
        uses: Azure/functions-action@c5060b3b8bb1ebbcb531abd00c822ecbaa8ea656 # v1.5.7
        with:
          app-name: ${{ env.FUNCTION_APP }}
          package: ${{ runner.temp }}/publish

      # A green deploy step only means the package was accepted. This gate makes the
      # workflow assert what is actually being served, so the manifest published below
      # can be trusted as "this is live" rather than "this was uploaded".
      # /api/health is IP rate-limited at 30/min; one poll per 10s stays well under.
      - name: Verify deployed build is live
        shell: pwsh
        env:
          EXPECTED_VERSION: ${{ needs.reserve.outputs.version }}
        run: |
          $expectedCommit = '${{ github.sha }}'.Substring(0, 7)
          $expectedVersion = $env:EXPECTED_VERSION
          $deadline = [DateTime]::UtcNow.AddMinutes(3)
          $attempt = 0

          while ([DateTime]::UtcNow -lt $deadline) {
            $attempt++
            try {
              $health = Invoke-RestMethod -Uri "$env:API_BASE_URL/api/health" -Method Get -TimeoutSec 30
              if ($health.commitHash -eq $expectedCommit -and $health.version -eq $expectedVersion) {
                Write-Host "Live after $attempt attempt(s): $($health.version) @ $($health.commitHash), built $($health.buildUtc)"
                exit 0
              }
              Write-Host "Attempt ${attempt}: serving $($health.version) @ $($health.commitHash) -- waiting for $expectedVersion @ $expectedCommit"
            } catch {
              Write-Host "Attempt ${attempt}: /api/health not answering yet -- $($_.Exception.Message)"
            }
            Start-Sleep -Seconds 10
          }

          throw "Backend did not report $expectedVersion @ $expectedCommit within 3 minutes -- deployment not verified, version manifest NOT published"

      # The manifest is the cross-component record of what is deployed where. It is
      # written last and only on a verified deploy, so a difference between the
      # manifest and /api/health means the running app drifted after the fact
      # (rollback, stale instance) rather than a half-finished pipeline.
      - name: Publish version manifest
        shell: pwsh
        env:
          BACKEND_VERSION: ${{ needs.reserve.outputs.version }}
          BACKEND_BUILD_UTC: ${{ needs.reserve.outputs.build_utc }}
        run: |
          $manifest = [ordered]@{
            component   = 'backend'
            version     = $env:BACKEND_VERSION
            commit      = '${{ github.sha }}'.Substring(0, 7)
            buildUtc    = $env:BACKEND_BUILD_UTC
            deployedUtc = [DateTime]::UtcNow.ToString('o')
            runId       = '${{ github.run_id }}'
          } | ConvertTo-Json

          $authHeaders = & ./.github/scripts/Get-StorageAuthHeaders.ps1
          $url = "$env:VERSIONS_CONTAINER_URL/backend.json"
          # no-cache: rotating pointer, must never be served stale by any fronting cache.
          Invoke-RestMethod -Uri $url -Method Put -Headers ($authHeaders + @{ 'x-ms-blob-type' = 'BlockBlob'; 'x-ms-blob-cache-control' = 'no-cache' }) -Body $manifest -ContentType 'application/json' | Out-Null
          Write-Host "Published versions/backend.json"
          Write-Host $manifest