/* SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2020 WireGuard LLC. All Rights Reserved.
 */

package resource

import (
	"errors"
	"fmt"
	"unsafe"

	"golang.org/x/sys/windows"
)

func MAKEINTRESOURCE(i uint16) *uint16 {
	return (*uint16)(unsafe.Pointer(uintptr(i)))
}

// Predefined Resource Types
var (
	VS_VERSION_INFO uint16 = 1

	RT_CURSOR                                          = MAKEINTRESOURCE(1)
	RT_BITMAP                                          = MAKEINTRESOURCE(2)
	RT_ICON                                            = MAKEINTRESOURCE(3)
	RT_MENU                                            = MAKEINTRESOURCE(4)
	RT_DIALOG                                          = MAKEINTRESOURCE(5)
	RT_STRING                                          = MAKEINTRESOURCE(6)
	RT_FONTDIR                                         = MAKEINTRESOURCE(7)
	RT_FONT                                            = MAKEINTRESOURCE(8)
	RT_ACCELERATOR                                     = MAKEINTRESOURCE(9)
	RT_RCDATA                                          = MAKEINTRESOURCE(10)
	RT_MESSAGETABLE                                    = MAKEINTRESOURCE(11)
	RT_GROUP_CURSOR                                    = MAKEINTRESOURCE(12)
	RT_GROUP_ICON                                      = MAKEINTRESOURCE(14)
	RT_VERSION                                         = MAKEINTRESOURCE(16)
	RT_DLGINCLUDE                                      = MAKEINTRESOURCE(17)
	RT_PLUGPLAY                                        = MAKEINTRESOURCE(19)
	RT_VXD                                             = MAKEINTRESOURCE(20)
	RT_ANICURSOR                                       = MAKEINTRESOURCE(21)
	RT_ANIICON                                         = MAKEINTRESOURCE(22)
	RT_HTML                                            = MAKEINTRESOURCE(23)
	RT_MANIFEST                                        = MAKEINTRESOURCE(24)
	CREATEPROCESS_MANIFEST_RESOURCE_ID                 = MAKEINTRESOURCE(1)
	ISOLATIONAWARE_MANIFEST_RESOURCE_ID                = MAKEINTRESOURCE(2)
	ISOLATIONAWARE_NOSTATICIMPORT_MANIFEST_RESOURCE_ID = MAKEINTRESOURCE(3)
	ISOLATIONPOLICY_MANIFEST_RESOURCE_ID               = MAKEINTRESOURCE(4)
	ISOLATIONPOLICY_BROWSER_MANIFEST_RESOURCE_ID       = MAKEINTRESOURCE(5)
	MINIMUM_RESERVED_MANIFEST_RESOURCE_ID              = MAKEINTRESOURCE(1 /*inclusive*/)
	MAXIMUM_RESERVED_MANIFEST_RESOURCE_ID              = MAKEINTRESOURCE(16 /*inclusive*/)
)

//sys	findResource(module windows.Handle, name *uint16, resType *uint16) (resInfo windows.Handle, err error) = kernel32.FindResourceW

func FindByID(module windows.Handle, id uint16, resType *uint16) (resInfo windows.Handle, err error) {
	return findResource(module, MAKEINTRESOURCE(id), resType)
}

func FindByName(module windows.Handle, name string, resType *uint16) (resInfo windows.Handle, err error) {
	var name16 *uint16
	name16, err = windows.UTF16PtrFromString(name)
	if err != nil {
		return
	}
	resInfo, err = findResource(module, name16, resType)
	return
}

//sys	sizeofResource(module windows.Handle, resInfo windows.Handle) (size uint32, err error) = kernel32.SizeofResource
//sys	loadResource(module windows.Handle, resInfo windows.Handle) (resData windows.Handle, err error) = kernel32.LoadResource
//sys	lockResource(resData windows.Handle) (addr uintptr, err error) = kernel32.LockResource

func Load(module, resInfo windows.Handle) (data []byte, err error) {
	size, err := sizeofResource(module, resInfo)
	if err != nil {
		err = fmt.Errorf("Unable to size resource: %w", err)
		return
	}
	resData, err := loadResource(module, resInfo)
	if err != nil {
		err = fmt.Errorf("Unable to load resource: %w", err)
		return
	}
	ptr, err := lockResource(resData)
	if err != nil {
		err = fmt.Errorf("Unable to lock resource: %w", err)
		return
	}
	unsafeSlice(unsafe.Pointer(&data), unsafe.Pointer(ptr), int(size))
	return
}

type VS_FIXEDFILEINFO struct {
	Signature        uint32
	StrucVersion     uint32
	FileVersionMS    uint32
	FileVersionLS    uint32
	ProductVersionMS uint32
	ProductVersionLS uint32
	FileFlagsMask    uint32
	FileFlags        uint32
	FileOS           uint32
	FileType         uint32
	FileSubtype      uint32
	FileDateMS       uint32
	FileDateLS       uint32
}

//sys	verQueryValue(block *byte, section *uint16, value **byte, size *uint32) (err error) = version.VerQueryValueW

func VerQueryRootValue(block []byte) (ffi *VS_FIXEDFILEINFO, err error) {
	var data *byte
	var size uint32
	err = verQueryValue(&block[0], windows.StringToUTF16Ptr("\\"), &data, &size)
	if err != nil {
		return
	}
	if uintptr(size) < unsafe.Sizeof(VS_FIXEDFILEINFO{}) {
		err = errors.New("Incomplete VS_FIXEDFILEINFO")
		return
	}
	ffi = (*VS_FIXEDFILEINFO)(unsafe.Pointer(data))
	return
}

// unsafeSlice updates the slice slicePtr to be a slice
// referencing the provided data with its length & capacity set to
// lenCap.
//
// TODO: when Go 1.16 or Go 1.17 is the minimum supported version,
// update callers to use unsafe.Slice instead of this.
func unsafeSlice(slicePtr, data unsafe.Pointer, lenCap int) {
	type sliceHeader struct {
		Data unsafe.Pointer
		Len  int
		Cap  int
	}
	h := (*sliceHeader)(slicePtr)
	h.Data = data
	h.Len = lenCap
	h.Cap = lenCap
}