# CI: every push runs the checks of the pre-push hook (tool/check.sh); a push to main is
# then deployed to learn.halkyon.eu (deploy/redeploy.sh). Both jobs run on the runner on
# sahaquiel, directly on the host as an unprivileged user (deploy/runner/).
#
# Pushes only, no pull requests: a pull request from a fork would run its own code on
# the production server's runner.
name: CI

on:
  push:
  # Runs the workflow again from the web UI, e.g. to retry a failed deploy.
  workflow_dispatch:

jobs:
  check:
    runs-on: sahaquiel
    timeout-minutes: 45
    env:
      # The Flutter the app is developed with; move it together with the local one.
      FLUTTER_VERSION: 3.47.5
    steps:
      # Before anything else runs, the job proves it can neither see nor reach production
      # (the runner's sandbox, deploy/runner/). If it can, nothing else should run.
      - name: Sandbox
        run: |
          fail() { echo "The runner's sandbox leaks: $*" >&2; exit 1; }
          # Only the runner's own processes are visible. A container's process shows up
          # (in a process namespace of its own) if it runs under the runner's user ID,
          # and then its environment and files are readable too.
          [ "$(ps -e -o uid= | sort -u | wc -l)" -eq 1 ] || fail "other users' processes are visible"
          namespaces=$(for p in /proc/[0-9]*; do readlink "$p/ns/pid"; done 2>/dev/null | sort -u | wc -l)
          [ "$namespaces" -le 1 ] || fail "processes of $namespaces process namespaces are visible"
          # deploy's home (.env, the checkout, the dumps) and the Docker socket are out of
          # reach.
          [ ! -e /home/deploy ] || fail "/home/deploy is visible"
          { [ ! -r /run/docker.sock ] && [ ! -w /run/docker.sock ]; } || fail "the Docker socket is usable"
          # Docker's networks, where the database listens, are unreachable. Caddy listens on
          # every address of the host, the Docker bridge's included.
          if timeout 5 bash -c 'exec 3<>/dev/tcp/172.17.0.1/443' 2>/dev/null; then
            fail "Docker's network is reachable"
          fi
          echo "This job can neither see nor reach production."

      - name: Check out
        env:
          TOKEN: ${{ github.token }}
        run: |
          git init -q .
          # The job's token as a header from the environment, so it never shows in a
          # command line; plain git, so the host needs no Node.js for actions/checkout.
          export GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=http.extraHeader \
            GIT_CONFIG_VALUE_0="Authorization: Basic $(printf 'ci:%s' "$TOKEN" | base64 -w0)"
          git fetch -q --depth 1 "${{ github.server_url }}/${{ github.repository }}.git" "${{ github.sha }}"
          git checkout -q -f FETCH_HEAD
          git clean -q -ffdx

      - name: Flutter
        run: |
          sdk="$HOME/sdk/flutter-$FLUTTER_VERSION"
          if [ ! -x "$sdk/bin/flutter" ]; then
            rm -rf "$sdk"
            git clone -q --depth 1 --branch "$FLUTTER_VERSION" https://github.com/flutter/flutter.git "$sdk"
            "$sdk/bin/flutter" config --no-analytics >/dev/null
            "$sdk/bin/dart" --disable-analytics >/dev/null
          fi
          echo "$sdk/bin" >> "$FORGEJO_PATH"
          "$sdk/bin/flutter" --version

      - name: Dependencies
        run: flutter pub get

      - name: Checks
        run: tool/check.sh

  deploy:
    needs: check
    if: github.ref == 'refs/heads/main'
    runs-on: sahaquiel
    timeout-minutes: 30
    steps:
      # The key can run nothing but deploy/redeploy.sh, and only from sahaquiel itself.
      - name: Deploy to learn.halkyon.eu
        run: >-
          ssh -i "$HOME/.ssh/deploy_trigger" -o IdentitiesOnly=yes -o BatchMode=yes
          -o StrictHostKeyChecking=yes -o UserKnownHostsFile="$HOME/.ssh/known_hosts"
          deploy@127.0.0.1 "${{ github.sha }}"