name: Validate Terraform

on:
  pull_request:
    paths:
      - "terraform/**"
      - ".github/workflows/validate-terraform.yml"

permissions:
  contents: read
  pull-requests: write

# Requires these repository secrets:
#   AGE_SECRET_KEY     — age private key for SOPS decryption
#
# Dependabot PRs run with no access to these secrets and a read-only token,
# so they take a lightweight, secret-free path (init + validate, no plan/
# comment). Provider-version bumps are still resolved and validated.

jobs:
  plan:
    name: tofu plan
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6

      - name: Install OpenTofu
        uses: opentofu/setup-opentofu@v2
        with:
          tofu_version: 1.9.0

      # --- Dependabot: secret-free validation -------------------------------
      - name: Validate (no secrets)
        if: github.actor == 'dependabot[bot]'
        working-directory: terraform/
        run: |
          # secrets.yaml is decrypted from SOPS at plan time and can't be
          # produced here, so stub the keys the config reads (kept in sync by
          # deriving them from the actual secrets["..."] references).
          grep -rhoE 'secrets\["[^"]+"\]' . \
            | sed -E 's/.*secrets\["([^"]+)"\].*/\1: "stub"/' \
            | sort -u > secrets.yaml
          tofu init -backend=false
          tofu validate

      # --- Human PRs: full plan against real backend ------------------------
      - name: Install SOPS
        if: github.actor != 'dependabot[bot]'
        run: |
          wget -qO /tmp/sops.deb https://github.com/getsops/sops/releases/download/v3.9.4/sops_3.9.4_amd64.deb
          sudo dpkg -i /tmp/sops.deb

      - name: Decrypt secrets
        if: github.actor != 'dependabot[bot]'
        env:
          SOPS_AGE_KEY: ${{ secrets.AGE_SECRET_KEY }}
        run: |
          find . -name '*.enc.yml' -o -name '*.enc.yaml' | while read f; do
            out="${f/.enc/}"
            sops -d "$f" > "$out"
            echo "Decrypted: $f -> $out"
          done

      - name: Set backend credentials
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        run: |
          echo "AWS_ACCESS_KEY_ID=$(yq '.backblaze_keyID' secrets.yaml)" >> "$GITHUB_ENV"
          echo "AWS_SECRET_ACCESS_KEY=$(yq '.backblaze_applicationKey' secrets.yaml)" >> "$GITHUB_ENV"

      - name: tofu init
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        run: tofu init

      - name: tofu validate
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        run: tofu validate

      - name: tofu plan
        id: plan
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        continue-on-error: true
        run: |
          set -o pipefail
          tofu plan -no-color 2>&1 | tee plan_output.txt

      - name: Post plan as PR comment
        if: github.actor != 'dependabot[bot]'
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const raw = fs.readFileSync('terraform/plan_output.txt', 'utf8');
            const filtered = raw.split('\n').filter(l => !l.includes(': Refreshing state...')).join('\n');
            const truncated = filtered.length > 65000
              ? filtered.slice(0, 65000) + '\n\n...(output truncated)'
              : filtered;
            const outcome = '${{ steps.plan.outcome }}';
            const header = outcome === 'failure' ? '## Terraform Plan — FAILED' : '## Terraform Plan';
            const body = `${header}\n\`\`\`\n${truncated}\n\`\`\``;

            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            const existing = comments.find(c => c.body.startsWith('## Terraform Plan'));
            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }

      - name: Fail if plan failed
        if: github.actor != 'dependabot[bot]' && steps.plan.outcome == 'failure'
        run: exit 1