#!/usr/bin/env bash
set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
CORE_IDE_DIR="${ROOT}/core_ide"
PATCH_DIR="${ROOT}/patches/lapce"
SERIES_FILE="${PATCH_DIR}/series"

BASE_REF=""

usage() {
  cat <<'EOF'
Usage:
  ./scripts/core-ide-export-patches.sh [--base <git-ref>]

Exports the commits in core_ide (BASE..HEAD) as patch files into:
  patches/lapce/*.patch
and rewrites:
  patches/lapce/series

If --base is not provided, the script tries (first match):
  upstream/master, upstream/main, origin/master, origin/main
EOF
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    -h|--help)
      usage
      exit 0
      ;;
    --base)
      BASE_REF="${2:-}"
      shift 2
      ;;
    *)
      echo "Unknown argument: $1" >&2
      usage >&2
      exit 2
      ;;
  esac
done

if [[ ! -d "${CORE_IDE_DIR}/.git" ]]; then
  echo "Missing core_ide git checkout: ${CORE_IDE_DIR}" >&2
  exit 1
fi

mkdir -p "${PATCH_DIR}"

if [[ ! -f "${SERIES_FILE}" ]]; then
  echo "Missing series file: ${SERIES_FILE}" >&2
  exit 1
fi

if [[ -n "$(git -C "${CORE_IDE_DIR}" status --porcelain)" ]]; then
  echo "core_ide working tree is not clean. Commit changes before exporting patches." >&2
  exit 1
fi

ref_exists() {
  git -C "${CORE_IDE_DIR}" show-ref --verify --quiet "refs/remotes/$1" \
    || git -C "${CORE_IDE_DIR}" show-ref --verify --quiet "refs/heads/$1" \
    || git -C "${CORE_IDE_DIR}" rev-parse --verify --quiet "$1" >/dev/null 2>&1
}

if [[ -z "${BASE_REF}" ]]; then
  for candidate in "upstream/master" "upstream/main" "origin/master" "origin/main"; do
    if ref_exists "${candidate}"; then
      BASE_REF="${candidate}"
      break
    fi
  done
fi

if [[ -z "${BASE_REF}" ]]; then
  echo "Could not auto-detect a base ref. Provide --base <ref>." >&2
  exit 1
fi

HEAD_SHA="$(git -C "${CORE_IDE_DIR}" rev-parse HEAD)"
BASE_SHA="$(git -C "${CORE_IDE_DIR}" rev-parse "${BASE_REF}")"

if [[ "${HEAD_SHA}" == "${BASE_SHA}" ]]; then
  echo "No commits to export (HEAD equals base ${BASE_REF})."
  rm -f "${PATCH_DIR}"/*.patch
  printf "%s\n" \
    "# List Lapce patch files (one per line)." \
    "# This file is consumed by: ./scripts/core-ide-apply-patches.sh" \
    "" \
    >"${SERIES_FILE}"
  exit 0
fi

rm -f "${PATCH_DIR}"/*.patch

git -C "${CORE_IDE_DIR}" format-patch \
  --output-directory "${PATCH_DIR}" \
  --no-stat \
  --no-signature \
  "${BASE_REF}..HEAD"

(
  cd "${PATCH_DIR}"
  {
    echo "# List Lapce patch files (one per line)."
    echo "# This file is consumed by: ./scripts/core-ide-apply-patches.sh"
    echo
    ls -1 *.patch 2>/dev/null | sort
  } >"${SERIES_FILE}"
)

echo "OK: exported patches to ${PATCH_DIR} (base=${BASE_REF})."