#!/usr/bin/env bash
# Fetches the exact Ekklesia source revision Signage's external-package integration runs against.
# The ref is fetched only to make the pinned object reachable; the checkout is always by full SHA.
set -Eeuo pipefail

root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
out="$root/build/platform"

fail() {
  echo "fetch-platform: $*" >&2
  exit 1
}

(($# == 0)) || fail "this command takes no arguments."

pin() {
  local value
  value="$(sed -n "s/^$1=//p" "$root/ci/platform.env")"
  [[ -n "$value" ]] || fail "ci/platform.env has no $1."
  printf '%s' "$value"
}

repository="$(pin EKKLESIA_PLATFORM_REPOSITORY)"
ref="$(pin EKKLESIA_PLATFORM_REF)"
commit="$(pin EKKLESIA_PLATFORM_COMMIT)"
[[ "$commit" =~ ^[0-9a-f]{40}$ ]] || fail "EKKLESIA_PLATFORM_COMMIT must be a full commit SHA."
[[ "$ref" == refs/* ]] || fail "EKKLESIA_PLATFORM_REF must be a full Git ref."

rm -rf "$out"
mkdir -p "$out"
git -C "$out" init --quiet
git -C "$out" remote add origin "$repository"
git -C "$out" fetch --quiet --no-tags --depth=1 origin "+${ref}:refs/remotes/pinned" ||
  fail "cannot fetch the pinned platform ref."
[[ "$(git -C "$out" rev-parse refs/remotes/pinned)" == "$commit" ]] ||
  fail "the pinned ref does not resolve to EKKLESIA_PLATFORM_COMMIT."
git -C "$out" -c advice.detachedHead=false checkout --quiet --detach "$commit"
rm -rf "$out/.git"
echo "fetch-platform: Ekklesia ${commit}"