#!/bin/sh
# Make the wiki repository of this repo hold exactly the converter output.
#
#   wiki-push.sh <output-dir> <version>
#
# Environment:
#   WIKI_TOKEN          token with write access to the wiki (required)
#   GITHUB_SERVER_URL   set by the runner; GITHUB_REPOSITORY likewise
#   WIKI_REMOTE         overrides the wiki clone URL (the tests point it at a local repository)
#
# The wiki is a mirror, never a source: every file in it is replaced by the converter output, so
# a page the converter no longer produces disappears. Afterwards the working tree minus .git/ and
# the output directory are compared, and any difference fails the script before anything is
# pushed. An unchanged result ends with exit 0 and no commit.
set -eu

out="${1:?usage: wiki-push.sh <output-dir> <version>}"
version="${2:?usage: wiki-push.sh <output-dir> <version>}"

if [ -z "${WIKI_TOKEN:-}" ]; then
  echo "ERROR WIKI_TOKEN is empty: the wiki mirror needs a token that may push to the wiki repository." >&2
  echo "      The job token (gitea.token) is used with 'permissions: wiki: write'; if Gitea still refuses it," >&2
  echo "      the repository's Actions settings cap the token, or the operator adds a secret with write access." >&2
  exit 1
fi
[ -f "$out/Home.md" ] || { echo "ERROR $out/Home.md is missing - not a converter output" >&2; exit 1; }

server="${GITHUB_SERVER_URL:-}"
repo="${GITHUB_REPOSITORY:-}"
remote="${WIKI_REMOTE:-${server}/${repo}.wiki.git}"
api="${server}/api/v1/repos/${repo}"

# The token travels in a header, not in the URL, so it appears in no git message or process list.
auth="Authorization: Basic $(printf 'wiki-mirror:%s' "$WIKI_TOKEN" | base64 | tr -d '\n')"
git_remote() { git -c "http.extraheader=${auth}" "$@"; }

work="$(mktemp -d)"
trap 'rm -rf "$work"' EXIT
wiki="$work/wiki"

if ! git_remote clone -q "$remote" "$wiki" 2>"$work/clone.err"; then
  echo "Cloning ${remote} failed:"
  cat "$work/clone.err"
  # A wiki that has never had a page has no repository yet; the first page created through
  # the API brings it into existence.
  echo "Creating the first page through the API to bring the wiki repository into existence."
  content="$(base64 < "$out/Home.md" | tr -d '\n')"
  jq -n --arg title Home --arg content "$content" --arg message "Mirror docs at v${version}" \
    '{title: $title, content_base64: $content, message: $message}' > "$work/first-page.json"
  status="$(curl -sS -o "$work/first-page.out" -w '%{http_code}' -X POST "${api}/wiki/new" \
    -H "Authorization: token ${WIKI_TOKEN}" -H 'Content-Type: application/json' \
    --data-binary @"$work/first-page.json")"
  case "$status" in
    2??) ;;
    *)
      echo "ERROR the API refused the first page (HTTP ${status}):" >&2
      cat "$work/first-page.out" >&2
      exit 1
      ;;
  esac
  git_remote clone -q "$remote" "$wiki"
fi

find "$wiki" -mindepth 1 -maxdepth 1 ! -name .git -exec rm -rf {} +
cp -R "$out"/. "$wiki"/
git -C "$wiki" add -A

if ! diff -r -x .git "$out" "$wiki" > "$work/diff.txt"; then
  echo "ERROR the wiki working tree differs from the converter output after copying:" >&2
  cat "$work/diff.txt" >&2
  exit 1
fi

if git -C "$wiki" diff --cached --quiet; then
  echo "Wiki already matches v${version}"
  exit 0
fi

git -C "$wiki" -c user.name='Wiki Mirror' -c user.email='wiki-mirror@noreply.invalid' \
  commit -q -m "Mirror docs at v${version}"
git_remote -C "$wiki" push -q origin HEAD
echo "Wiki now mirrors v${version}"