#!/usr/bin/env bash
#
# Write the updater manifest (`latest.json`) for one channel and attach it to that
# channel's release.
#
# WHY A SEPARATE STEP: the Linux and Windows bundles are built by two jobs in two
# workspaces, and neither can see the other's output — but ONE manifest has to
# describe both platforms. So this runs after both, reads what actually landed on
# the release, and writes the manifest from that. Building it inside either job
# would produce a manifest that silently omits the other platform, and a missing
# platform reads to a user as "no update available" rather than as a broken feed.
#
# WHAT IT READS: the release's own asset list. The signature for each bundle is a
# `.sig` asset published beside it (see publish-release.sh); its CONTENT is what
# goes in the manifest, which is why each one is downloaded rather than linked.
#
# Tauri's expected shape:
#   { "version": "0.1.0", "pub_date": "...", "notes": "...",
#     "platforms": { "<target>-<arch>": { "signature": "...", "url": "..." } } }
set -euo pipefail

: "${GITHUB_TOKEN:?GITHUB_TOKEN is required}"
: "${GITHUB_SERVER_URL:?GITHUB_SERVER_URL is required}"
: "${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required (owner/repo)}"
: "${RELEASE_TAG:?RELEASE_TAG is required (the release holding the bundles)}"
: "${APP_VERSION:?APP_VERSION is required (the version the bundles carry)}"

# Where the manifest is PUBLISHED, which need not be where the bundles live.
#
# That split is what makes the stable channel work at all. A versioned release
# (`v0.2.0`) holds the real assets, but the app can only read a URL that never
# changes — so the same manifest is also attached to a `stable` release whose tag is
# permanent and whose only content is this file. It points back at the versioned
# assets, so nothing is duplicated.
MANIFEST_TAG="${MANIFEST_TAG:-$RELEASE_TAG}"

API="$GITHUB_SERVER_URL/api/v1/repos/$GITHUB_REPOSITORY"
AUTH=(-H "Authorization: token $GITHUB_TOKEN")
NOTES="${RELEASE_NOTES:-}"

work="$(mktemp -d)"
trap 'rm -rf "$work"' EXIT INT TERM

echo "==> Reading assets on release $RELEASE_TAG"
release="$(curl -sS "${AUTH[@]}" "$API/releases/tags/$RELEASE_TAG")"
release_id="$(printf '%s' "$release" | grep -oE '"id"[[:space:]]*:[[:space:]]*[0-9]+' | head -1 | grep -oE '[0-9]+')"
[ -n "$release_id" ] || { echo "ERROR: no release tagged $RELEASE_TAG" >&2; exit 1; }
assets="$(curl -sS "${AUTH[@]}" "$API/releases/$release_id/assets")"

# Asset names, one per line. The API returns them in a single JSON blob; this is
# the only field needed, and grep beats adding a jq dependency to the CI image.
names="$(printf '%s' "$assets" | grep -oE '"name"[[:space:]]*:[[:space:]]*"[^"]+"' | sed -E 's/.*"([^"]+)"$/\1/')"

download_url() { printf '%s/%s/releases/download/%s/%s' "$GITHUB_SERVER_URL" "$GITHUB_REPOSITORY" "$RELEASE_TAG" "$1"; }

# One platform entry, or nothing if that platform's bundle or signature is absent.
# Emitting a partial entry would be worse than emitting none: the app would try to
# install something it can't verify.
platform_entry() {
  local target="$1" pattern="$2" bundle sig_name
  bundle="$(printf '%s\n' "$names" | grep -E "$pattern" | head -1 || true)"
  [ -n "$bundle" ] || { echo "    no bundle matching $pattern — skipping $target" >&2; return; }
  sig_name="$bundle.sig"
  if ! printf '%s\n' "$names" | grep -qxF "$sig_name"; then
    echo "    $bundle has no $sig_name — skipping $target (was the build signed?)" >&2
    return
  fi
  curl -fsSL "${AUTH[@]}" -o "$work/sig" "$(download_url "$sig_name")"
  # The signature is base64 on one line already; strip any stray newline so it
  # can't break the JSON string it's about to become.
  local signature
  signature="$(tr -d '\r\n' < "$work/sig")"
  printf '    "%s": { "signature": "%s", "url": "%s" }' "$target" "$signature" "$(download_url "$bundle")"
}

echo "==> Building the manifest"
entries=()
# `.AppImage` only on Linux: the updater replaces the running bundle in place, which
# a package-manager install (deb/pacman) must never have done to it.
if entry="$(platform_entry "linux-x86_64" '\.AppImage$')" && [ -n "$entry" ]; then entries+=("$entry"); fi
if entry="$(platform_entry "windows-x86_64" '\.exe$')" && [ -n "$entry" ]; then entries+=("$entry"); fi

if [ ${#entries[@]} -eq 0 ]; then
  echo "ERROR: no signed bundle on $RELEASE_TAG — refusing to publish an empty manifest." >&2
  echo "       (An empty manifest would tell every client it is up to date.)" >&2
  exit 1
fi

# No `date -u -Is` — busybox date in the CI image doesn't take it.
pub_date="$(date -u '+%Y-%m-%dT%H:%M:%SZ')"
{
  printf '{\n'
  printf '  "version": "%s",\n' "$APP_VERSION"
  printf '  "pub_date": "%s",\n' "$pub_date"
  printf '  "notes": "%s",\n' "$NOTES"
  printf '  "platforms": {\n'
  for i in "${!entries[@]}"; do
    [ "$i" -eq 0 ] || printf ',\n'
    printf '%s' "${entries[$i]}"
  done
  printf '\n  }\n'
  printf '}\n'
} > "$work/latest.json"

echo "==> Manifest:"
cat "$work/latest.json"

# --- resolve the release the manifest is published TO ------------------------
if [ "$MANIFEST_TAG" = "$RELEASE_TAG" ]; then
  target_id="$release_id"
  target_assets="$assets"
else
  echo "==> Resolving the $MANIFEST_TAG channel release"
  target="$(curl -sS "${AUTH[@]}" "$API/releases/tags/$MANIFEST_TAG")"
  target_id="$(printf '%s' "$target" | grep -oE '"id"[[:space:]]*:[[:space:]]*[0-9]+' | head -1 | grep -oE '[0-9]+' || true)"
  if [ -z "${target_id:-}" ]; then
    # First publish to this channel. A pointer release: no bundles of its own, just
    # a permanent tag for the manifest to live under.
    echo "    creating it (pointer release, manifest only)"
    body="{\"tag_name\":\"$MANIFEST_TAG\",\"name\":\"ThoughtSync ($MANIFEST_TAG channel)\",\"draft\":false,\"prerelease\":false,\"body\":\"Update channel pointer. The installable builds live on the versioned releases; this holds only the updater manifest.\"}"
    target="$(curl -sS -X POST "${AUTH[@]}" -H "Content-Type: application/json" -d "$body" "$API/releases")"
    target_id="$(printf '%s' "$target" | grep -oE '"id"[[:space:]]*:[[:space:]]*[0-9]+' | head -1 | grep -oE '[0-9]+')"
  fi
  [ -n "${target_id:-}" ] || { echo "ERROR: could not resolve the $MANIFEST_TAG release" >&2; exit 1; }
  target_assets="$(curl -sS "${AUTH[@]}" "$API/releases/$target_id/assets")"
fi

# Replace rather than duplicate: Forgejo rejects a second asset with the same name,
# and this file is rewritten on every publish by design.
old_id="$(printf '%s' "$target_assets" \
  | grep -oE "\"id\"[[:space:]]*:[[:space:]]*[0-9]+[^}]*\"name\"[[:space:]]*:[[:space:]]*\"latest\.json\"" \
  | head -1 | grep -oE '[0-9]+' | head -1 || true)"
if [ -n "${old_id:-}" ]; then
  echo "==> Removing the previous latest.json (id $old_id)"
  curl -fsS -X DELETE "${AUTH[@]}" "$API/releases/$target_id/assets/$old_id" >/dev/null
fi

echo "==> Uploading latest.json to $MANIFEST_TAG"
curl -fsS -X POST "${AUTH[@]}" "$API/releases/$target_id/assets?name=latest.json" \
  -F "attachment=@$work/latest.json" >/dev/null

echo "==> Done. $MANIFEST_TAG now advertises $APP_VERSION for ${#entries[@]} platform(s)."