#!/usr/bin/env bash

set -euo pipefail

SCRIPT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
ROOT_DIR=$(cd -- "${SCRIPT_DIR}/.." && pwd)
CONFIG_FILE="${ROOT_DIR}/config/mesa-opt.conf"

if [[ ! -f "${CONFIG_FILE}" ]]; then
  echo "missing config: ${CONFIG_FILE}" >&2
  exit 1
fi

# shellcheck disable=SC1090
source "${CONFIG_FILE}"

require_cmd() {
  local cmd
  for cmd in "$@"; do
    command -v "${cmd}" >/dev/null 2>&1 || {
      echo "missing command: ${cmd}" >&2
      exit 1
    }
  done
}

require_cmd dpkg-deb git meson ninja python3

WORK_DIR="${ROOT_DIR}/work"
LIBDRM_SRC_DIR="${WORK_DIR}/libdrm"
LIBDRM_BUILD_DIR="${WORK_DIR}/build-libdrm"
SRC_DIR="${WORK_DIR}/mesa"
BUILD_DIR="${WORK_DIR}/build"
PKG_DIR="${WORK_DIR}/pkg"
PREREQ_DIR="${WORK_DIR}/prereq"
DIST_DIR="${ROOT_DIR}/dist"

mkdir -p "${WORK_DIR}" "${DIST_DIR}"
rm -rf "${LIBDRM_SRC_DIR}" "${LIBDRM_BUILD_DIR}" "${SRC_DIR}" "${BUILD_DIR}" "${PKG_DIR}" "${PREREQ_DIR}"
mkdir -p "${PKG_DIR}"

UPSTREAM_REF="${MESA_UPSTREAM_REF:-${UPSTREAM_GIT_REF}}"
LIBDRM_REF="${LIBDRM_UPSTREAM_REF:-${LIBDRM_GIT_REF}}"

git clone --depth 1 --branch "${LIBDRM_REF}" "${LIBDRM_GIT_URL}" "${LIBDRM_SRC_DIR}"

meson setup "${LIBDRM_BUILD_DIR}" "${LIBDRM_SRC_DIR}" \
  --buildtype="${BUILD_TYPE}" \
  --prefix="${INSTALL_PREFIX}"

ninja -C "${LIBDRM_BUILD_DIR}"
DESTDIR="${PREREQ_DIR}" ninja -C "${LIBDRM_BUILD_DIR}" install

# Debian's xf86drm.h includes <drm.h>, while newer libdrm installs it below
# include/libdrm/. Mirror the headers into the prefix root so Mesa finds them.
if [[ -d "${PREREQ_DIR}${INSTALL_PREFIX}/include/libdrm" ]]; then
  ln -sf libdrm/drm.h "${PREREQ_DIR}${INSTALL_PREFIX}/include/drm.h"
  ln -sf libdrm/drm_mode.h "${PREREQ_DIR}${INSTALL_PREFIX}/include/drm_mode.h"
  ln -sf libdrm/libsync.h "${PREREQ_DIR}${INSTALL_PREFIX}/include/libsync.h"
fi

# libdrm's pkg-config metadata points to the real prefix path. Mirror the staged
# files there during the Mesa build so compiler and linker can resolve them.
mkdir -p "${INSTALL_PREFIX}"
cp -a "${PREREQ_DIR}${INSTALL_PREFIX}/." "${INSTALL_PREFIX}/"

export PKG_CONFIG_PATH="${PREREQ_DIR}${INSTALL_PREFIX}/lib/x86_64-linux-gnu/pkgconfig:${PREREQ_DIR}${INSTALL_PREFIX}/lib/pkgconfig:${PKG_CONFIG_PATH:-}"
export LD_LIBRARY_PATH="${PREREQ_DIR}${INSTALL_PREFIX}/lib/x86_64-linux-gnu:${PREREQ_DIR}${INSTALL_PREFIX}/lib:${LD_LIBRARY_PATH:-}"

git clone --depth 1 --branch "${UPSTREAM_REF}" "${UPSTREAM_GIT_URL}" "${SRC_DIR}"

detect_upstream_version() {
  local source_dir="${1}"

  if [[ -f "${source_dir}/VERSION" ]]; then
    sed -n '1p' "${source_dir}/VERSION"
    return
  fi

  awk -F"'" '/project\(/ { for (i = 1; i <= NF; ++i) if ($i ~ /^[0-9][0-9A-Za-z.+~:-]*$/) { print $i; exit } }' \
    "${source_dir}/meson.build"
}

GIT_SHA=$(git -C "${SRC_DIR}" rev-parse --short=12 HEAD)
GIT_SHA_FULL=$(git -C "${SRC_DIR}" rev-parse HEAD)
UPSTREAM_VERSION="${PACKAGE_VERSION_PREFIX:-$(detect_upstream_version "${SRC_DIR}")}"
UPSTREAM_SERIES="$(printf '%s' "${UPSTREAM_VERSION}" | sed -E 's/^([0-9]+\.[0-9]+).*/\1/')"
PACKAGE_VERSION="${UPSTREAM_SERIES}+git${GIT_SHA}-${PACKAGE_RELEASE}"
OUTPUT_DEB="${DIST_DIR}/${PACKAGE_NAME}_${PACKAGE_VERSION}_${PACKAGE_ARCH}.deb"

meson setup "${BUILD_DIR}" "${SRC_DIR}" \
  --buildtype="${BUILD_TYPE}" \
  --prefix="${INSTALL_PREFIX}" \
  -Dplatforms="${PLATFORMS}" \
  -Dgallium-drivers="${GALLIUM_DRIVERS}" \
  -Dvulkan-drivers="${VULKAN_DRIVERS}" \
  -Dvulkan-layers="${VULKAN_LAYERS}" \
  -Dglx=dri \
  -Dllvm=enabled \
  -Dshared-glapi=enabled

ninja -C "${BUILD_DIR}"
cp -a "${PREREQ_DIR}/." "${PKG_DIR}/"
DESTDIR="${PKG_DIR}" ninja -C "${BUILD_DIR}" install

mkdir -p \
  "${PKG_DIR}/DEBIAN" \
  "${PKG_DIR}/usr/share/doc/${PACKAGE_NAME}" \
  "${PKG_DIR}/usr/bin"

cat > "${PKG_DIR}/DEBIAN/control" <<EOF
Package: ${PACKAGE_NAME}
Version: ${PACKAGE_VERSION}
Section: libs
Priority: optional
Architecture: ${PACKAGE_ARCH}
Maintainer: magges <magges@local>
Depends: libc6, libexpat1, libgcc-s1, libgl1, libllvm${LLVM_RUNTIME_VERSION:-19}, libstdc++6, libvulkan1, libwayland-client0, libx11-6, zlib1g
Description: Mesa snapshot build installed below ${INSTALL_PREFIX}
 Built from ${UPSTREAM_GIT_URL} (${UPSTREAM_REF}) with bundled libdrm from
 ${LIBDRM_GIT_URL} (${LIBDRM_REF}) and installed into ${INSTALL_PREFIX}.
EOF

cat > "${PKG_DIR}/usr/share/doc/${PACKAGE_NAME}/README.Debian" <<EOF
This package installs a standalone Mesa snapshot in ${INSTALL_PREFIX}.

Use it with:
  export LD_LIBRARY_PATH=${INSTALL_PREFIX}/lib/x86_64-linux-gnu:${INSTALL_PREFIX}/lib:\$LD_LIBRARY_PATH
  export LIBGL_DRIVERS_PATH=${INSTALL_PREFIX}/lib/x86_64-linux-gnu/dri
  export VK_LAYER_PATH=${INSTALL_PREFIX}/share/vulkan/explicit_layer.d
  export VK_ICD_FILENAMES=\$(printf '%s:' ${INSTALL_PREFIX}/share/vulkan/icd.d/*.json | sed 's/:$//')
EOF

cat > "${PKG_DIR}/usr/bin/${PACKAGE_NAME}-env" <<EOF
#!/usr/bin/env bash
set -euo pipefail
export LD_LIBRARY_PATH="${INSTALL_PREFIX}/lib/x86_64-linux-gnu:${INSTALL_PREFIX}/lib:\${LD_LIBRARY_PATH:-}"
export LIBGL_DRIVERS_PATH="${INSTALL_PREFIX}/lib/x86_64-linux-gnu/dri"
export VK_LAYER_PATH="${INSTALL_PREFIX}/share/vulkan/explicit_layer.d"
if compgen -G "${INSTALL_PREFIX}/share/vulkan/icd.d/*.json" >/dev/null; then
  icd_files=(${INSTALL_PREFIX}/share/vulkan/icd.d/*.json)
  icd_joined=\$(printf '%s:' "\${icd_files[@]}")
  export VK_ICD_FILENAMES="\${icd_joined%:}"
  export VK_DRIVER_FILES="\${VK_ICD_FILENAMES}"
fi
exec "\$@"
EOF
chmod 0755 "${PKG_DIR}/usr/bin/${PACKAGE_NAME}-env"

find "${PKG_DIR}" -type d -exec chmod 0755 {} +
find "${PKG_DIR}" -path "${PKG_DIR}/DEBIAN" -prune -o -type f -exec chmod 0644 {} +
chmod 0755 "${PKG_DIR}/usr/bin/${PACKAGE_NAME}-env"

dpkg-deb --build "${PKG_DIR}" "${OUTPUT_DEB}"
cat > "${DIST_DIR}/package-info.env" <<EOF
PACKAGE_NAME=${PACKAGE_NAME}
PACKAGE_VERSION=${PACKAGE_VERSION}
PACKAGE_FILE=$(basename "${OUTPUT_DEB}")
PACKAGE_ARCH=${PACKAGE_ARCH}
APT_SUITE=${APT_SUITE:-stable}
APT_COMPONENT=${APT_COMPONENT:-main}
APT_PUBLIC_BASE_URL=${APT_PUBLIC_BASE_URL:-}
UPSTREAM_GIT_URL=${UPSTREAM_GIT_URL}
UPSTREAM_GIT_REF=${UPSTREAM_REF}
UPSTREAM_GIT_SHA=${GIT_SHA_FULL}
UPSTREAM_GIT_SHA_SHORT=${GIT_SHA}
EOF
echo "built ${OUTPUT_DEB}"