name: Sign Android Release

on:
  workflow_call:
    inputs:
      version:
        description: "Android artifact version, for example v1.6.0-20261002."
        required: true
        type: string
    secrets:
      ANDROID_KEYSTORE_BASE64:
        required: true
      ANDROID_KEYSTORE_PASSWORD:
        required: true
      ANDROID_KEY_ALIAS:
        required: true
      ANDROID_KEY_PASSWORD:
        required: true
  workflow_dispatch:
    inputs:
      source_tag:
        description: "Existing Android release to sign without rebuilding, for example android-v1.6.0-20261002."
        required: true
        type: string

permissions:
  contents: read

jobs:
  sign:
    name: Sign and verify Android APK
    runs-on: ubuntu-24.04
    timeout-minutes: 15
    env:
      VERSION: ${{ inputs.version }}
      SOURCE_TAG: ${{ inputs.source_tag }}
    steps:
      - name: Validate signing configuration
        shell: python
        env:
          ANDROID_KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
          ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
          ANDROID_KEY_ALIAS: ${{ secrets.ANDROID_KEY_ALIAS }}
          ANDROID_KEY_PASSWORD: ${{ secrets.ANDROID_KEY_PASSWORD }}
        run: |
          import os
          names = ("ANDROID_KEYSTORE_BASE64", "ANDROID_KEYSTORE_PASSWORD",
                   "ANDROID_KEY_ALIAS", "ANDROID_KEY_PASSWORD")
          missing = [name for name in names if not os.environ.get(name)]
          if missing:
              raise ValueError("Missing repository signing secrets: " + ", ".join(missing))

      - name: Resolve artifact version
        id: version
        shell: python
        run: |
          import datetime
          import os
          import re
          version = os.environ["VERSION"]
          if os.environ["GITHUB_EVENT_NAME"] == "workflow_dispatch" and not version:
              tag = os.environ["SOURCE_TAG"]
              if not tag.startswith("android-v"):
                  raise ValueError("Use an existing android-v<app-version>-YYYYMMDD release")
              version = tag.removeprefix("android-")
          match = re.fullmatch(r"v[0-9]+\.[0-9]+\.[0-9]+-([0-9]{8})", version)
          if not match:
              raise ValueError("Invalid Android artifact version")
          datetime.datetime.strptime(match[1], "%Y%m%d")
          with open(os.environ["GITHUB_OUTPUT"], "a") as stream:
              stream.write(f"version={version}\n")

      - name: Download unsigned build artifact
        if: github.event_name != 'workflow_dispatch' || inputs.version != ''
        uses: actions/download-artifact@v8
        with:
          name: crossdesk-android-arm64-unsigned-${{ steps.version.outputs.version }}
          path: unsigned

      - name: Download unsigned APK from existing release
        if: github.event_name == 'workflow_dispatch' && inputs.version == ''
        env:
          GH_TOKEN: ${{ github.token }}
          APK_VERSION: ${{ steps.version.outputs.version }}
        run: |
          gh release view "${SOURCE_TAG}" --repo "${GITHUB_REPOSITORY}" \
            --json isDraft,isPrerelease > release.json
          python3 - <<'PY'
          import json
          from pathlib import Path
          release = json.loads(Path('release.json').read_text())
          if release['isDraft'] or release['isPrerelease']:
              raise ValueError('Use a published stable Android release')
          PY
          gh release download "${SOURCE_TAG}" --repo "${GITHUB_REPOSITORY}" \
            --pattern "crossdesk-android-arm64-unsigned-${APK_VERSION}.apk" --dir unsigned

      - name: Set up Java
        uses: actions/setup-java@v5
        with:
          distribution: temurin
          java-version: "17"

      - name: Set up Android signing tools
        uses: android-actions/setup-android@v3
        with:
          packages: "build-tools;36.0.0"

      # This job never checks out or executes application source with the key present.
      - name: Align, sign and verify Release APK
        env:
          APK_VERSION: ${{ steps.version.outputs.version }}
          ANDROID_KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
          ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
          ANDROID_KEY_ALIAS: ${{ secrets.ANDROID_KEY_ALIAS }}
          ANDROID_KEY_PASSWORD: ${{ secrets.ANDROID_KEY_PASSWORD }}
        run: |
          umask 077
          crossdesk_signing_dir="$(mktemp -d "${RUNNER_TEMP}/crossdesk-signing.XXXXXX")"
          trap 'rm -rf -- "${crossdesk_signing_dir}"' EXIT
          printf '%s' "${ANDROID_KEYSTORE_BASE64}" | base64 --decode > "${crossdesk_signing_dir}/release.keystore"
          crossdesk_tools="${ANDROID_HOME}/build-tools/36.0.0"
          crossdesk_output="${RUNNER_TEMP}/crossdesk-android-signed"
          mkdir -p "${crossdesk_output}"
          "${crossdesk_tools}/zipalign" -P 16 -f -v 4 \
            "unsigned/crossdesk-android-arm64-unsigned-${APK_VERSION}.apk" \
            "${crossdesk_signing_dir}/aligned.apk"
          "${crossdesk_tools}/apksigner" sign \
            --ks "${crossdesk_signing_dir}/release.keystore" \
            --ks-key-alias "${ANDROID_KEY_ALIAS}" \
            --ks-pass env:ANDROID_KEYSTORE_PASSWORD --key-pass env:ANDROID_KEY_PASSWORD \
            --out "${crossdesk_output}/crossdesk-android-arm64-${APK_VERSION}.apk" \
            "${crossdesk_signing_dir}/aligned.apk"
          "${crossdesk_tools}/apksigner" verify --verbose --print-certs \
            "${crossdesk_output}/crossdesk-android-arm64-${APK_VERSION}.apk"
          "${crossdesk_tools}/zipalign" -c -P 16 -v 4 \
            "${crossdesk_output}/crossdesk-android-arm64-${APK_VERSION}.apk"

      - name: Upload signed Release APK
        uses: actions/upload-artifact@v6
        with:
          name: crossdesk-android-arm64-${{ steps.version.outputs.version }}
          path: ${{ runner.temp }}/crossdesk-android-signed/*.apk
          if-no-files-found: error

      - name: Summarize signing
        env:
          APK_VERSION: ${{ steps.version.outputs.version }}
        run: |
          echo "Android ${APK_VERSION}: Release APK signed with the fixed publishing key; APK signature and 16 KB ZIP alignment verified." >> "${GITHUB_STEP_SUMMARY}"
          if [[ "${GITHUB_EVENT_NAME}" == "workflow_dispatch" && -z "${VERSION}" ]]; then
            echo "Signed an existing release without rebuilding. Download the signed Actions artifact to publish it." >> "${GITHUB_STEP_SUMMARY}"
          fi