name: Open Gitea PR on merge to main

# When main changes on GitHub (i.e. after a PR is merged here), push those
# commits to a branch on Gitea and open a pull request there, so the same
# change can be reviewed and landed on the Gitea side. One-way: GitHub -> Gitea.

on:
  push:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

jobs:
  open-gitea-pr:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
        with:
          fetch-depth: 0

      - name: Push main to Gitea and open a pull request
        env:
          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
          GITEA_HOST: git.zambazosmedia.group
          GITEA_USER: nomad
          GITEA_REPO: Commonwealth-Online/Commonwealth-Online-Server
          SYNC_BRANCH: sync/from-github
        run: |
          set -euo pipefail
          if [ -z "${GITEA_TOKEN:-}" ]; then
            echo "::error::Missing GITEA_TOKEN secret. Add a Gitea access token as a"
            echo "::error::repository secret named GITEA_TOKEN (Settings -> Secrets and"
            echo "::error::variables -> Actions -> New repository secret)."
            exit 1
          fi

          git config user.name  "github-sync"
          git config user.email "github-sync@users.noreply.github.com"

          # Mirror the current main onto a dedicated Gitea branch. Force is safe:
          # this branch is owned by the automation and only ever tracks GitHub main.
          git remote add gitea "https://${GITEA_USER}:${GITEA_TOKEN}@${GITEA_HOST}/${GITEA_REPO}.git"
          git push -f gitea "HEAD:refs/heads/${SYNC_BRANCH}"

          # Open a PR on Gitea: sync/from-github -> main. If one is already open,
          # the push above has already updated it, so a 409 is success too.
          http_code=$(curl -sS -o /tmp/gitea_pr.json -w "%{http_code}" -X POST \
            "https://${GITEA_HOST}/api/v1/repos/${GITEA_REPO}/pulls" \
            -H "Authorization: token ${GITEA_TOKEN}" \
            -H "Content-Type: application/json" \
            -d "{\"title\":\"Sync from GitHub main\",\"head\":\"${SYNC_BRANCH}\",\"base\":\"main\",\"body\":\"Automated: GitHub main was updated. Review and merge to land it on Gitea.\"}")

          echo "Gitea pulls API returned HTTP ${http_code}"
          cat /tmp/gitea_pr.json || true
          echo

          if [ "${http_code}" = "201" ]; then
            echo "Opened a new Gitea pull request."
          elif [ "${http_code}" = "409" ] || grep -qiE "already exist|issue_exist" /tmp/gitea_pr.json; then
            echo "A Gitea PR from ${SYNC_BRANCH} is already open; it now has the latest commits."
          else
            echo "::warning::Unexpected Gitea response (${http_code}). The branch was pushed;"
            echo "::warning::open the PR manually on Gitea if it did not appear."
          fi