// To make the binary (DOS_STUB_PROGRAM):
// $ cd tools/dos-stub
// $ nasm -f bin -o dos-stub.bin dos-stub.asm
// $ node -e "console.log([].map.call(fs.readFileSync('tools/dos-stub/dos-stub.bin'), (v)=>`0x${Buffer.from([v]).toString('hex')}`).join(','))"
//
// NOTE: the original dos-stub.asm program and the bit code in DOS_STUB_PROGRAM are under the 0-BSD license.

import ImageDataDirectoryArray from '../format/ImageDataDirectoryArray.js';
import ImageDosHeader from '../format/ImageDosHeader.js';
import ImageFileHeader from '../format/ImageFileHeader.js';
import ImageNtHeaders from '../format/ImageNtHeaders.js';
import ImageOptionalHeader from '../format/ImageOptionalHeader.js';
import ImageOptionalHeader64 from '../format/ImageOptionalHeader64.js';
import { copyBuffer, roundUp } from './functions.js';

// fill with '0x00' to make 8-bytes alignment
// prettier-ignore
const DOS_STUB_PROGRAM = new Uint8Array([
	0x0e,0x1f,0xba,0x0e,0x00,0xb4,0x09,0xcd,0x21,0xb8,0x01,0x4c,0xcd,0x21,0x44,0x4f,
	0x53,0x20,0x6d,0x6f,0x64,0x65,0x20,0x6e,0x6f,0x74,0x20,0x73,0x75,0x70,0x70,0x6f,
	0x72,0x74,0x65,0x64,0x2e,0x0d,0x0d,0x0a,0x24,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
]);

const DOS_STUB_SIZE = roundUp(
	ImageDosHeader.size + DOS_STUB_PROGRAM.length,
	0x80
);

const DEFAULT_FILE_ALIGNMENT = 512;

export function getDosStubDataSize(): number {
	return DOS_STUB_SIZE;
}

export function fillDosStubData(bin: ArrayBuffer | ArrayBufferView): void {
	const dos = ImageDosHeader.from(bin);
	dos.magic = ImageDosHeader.DEFAULT_MAGIC;
	// last page size
	dos.lastPageSize = DOS_STUB_SIZE % 512;
	// total page count
	dos.pages = Math.ceil(DOS_STUB_SIZE / 512);
	// no relocations
	dos.relocations = 0;
	// header size as paragraph count (1 paragraph = 16 bytes)
	dos.headerSizeInParagraph = Math.ceil(ImageDosHeader.size / 16);
	dos.minAllocParagraphs = 0;
	dos.maxAllocParagraphs = 0xffff;
	dos.initialSS = 0;
	dos.initialSP = 0x80;
	// (no relocations, but set offset after the header)
	dos.relocationTableAddress = ImageDosHeader.size;
	dos.newHeaderAddress = DOS_STUB_SIZE;

	copyBuffer(
		bin,
		ImageDosHeader.size,
		DOS_STUB_PROGRAM,
		0,
		DOS_STUB_PROGRAM.length
	);
}

export function estimateNewHeaderSize(is32Bit: boolean): number {
	return (
		// magic
		4 +
		ImageFileHeader.size +
		(is32Bit ? ImageOptionalHeader.size : ImageOptionalHeader64.size) +
		ImageDataDirectoryArray.size
	);
}

export function fillPeHeaderEmptyData(
	bin: ArrayBuffer | ArrayBufferView,
	offset: number,
	totalBinSize: number,
	is32Bit: boolean,
	isDLL: boolean
): void {
	let _bin: ArrayBuffer;
	let _offset: number;
	if ('buffer' in bin) {
		_bin = bin.buffer;
		_offset = bin.byteOffset + offset;
	} else {
		_bin = bin;
		_offset = offset;
	}

	new DataView(_bin, _offset).setUint32(
		0,
		ImageNtHeaders.DEFAULT_SIGNATURE,
		true
	);

	const fh = ImageFileHeader.from(_bin, _offset + 4);
	fh.machine = is32Bit ? 0x14c : 0x8664;
	fh.numberOfSections = 0; // no sections
	fh.timeDateStamp = 0;
	fh.pointerToSymbolTable = 0;
	fh.numberOfSymbols = 0;
	fh.sizeOfOptionalHeader =
		(is32Bit ? ImageOptionalHeader.size : ImageOptionalHeader64.size) +
		ImageDataDirectoryArray.size;
	fh.characteristics = isDLL ? 0x2102 : 0x102;

	const oh = (is32Bit ? ImageOptionalHeader : ImageOptionalHeader64).from(
		_bin,
		_offset + 4 + ImageFileHeader.size
	);
	oh.magic = is32Bit
		? ImageOptionalHeader.DEFAULT_MAGIC
		: ImageOptionalHeader64.DEFAULT_MAGIC;
	// oh.majorLinkerVersion = 0;
	// oh.minorLinkerVersion = 0;
	oh.sizeOfCode = 0;
	oh.sizeOfInitializedData = 0;
	oh.sizeOfUninitializedData = 0;
	oh.addressOfEntryPoint = 0;
	oh.baseOfCode = 0x1000;
	// oh.baseOfData = 0; // for 32bit only
	oh.imageBase = is32Bit ? 0x1000000 : 0x180000000;
	oh.sectionAlignment = 4096;
	oh.fileAlignment = DEFAULT_FILE_ALIGNMENT;
	oh.majorOperatingSystemVersion = 6;
	oh.minorOperatingSystemVersion = 0;
	// oh.majorImageVersion = 0;
	// oh.minorImageVersion = 0;
	oh.majorSubsystemVersion = 6;
	oh.minorSubsystemVersion = 0;
	// oh.win32VersionValue = 0;
	oh.sizeOfHeaders = roundUp(totalBinSize, oh.fileAlignment);
	// oh.checkSum = 0;
	oh.subsystem = 2; // IMAGE_SUBSYSTEM_WINDOWS_GUI
	oh.dllCharacteristics =
		(is32Bit ? 0 : 0x20) + // IMAGE_DLL_CHARACTERISTICS_HIGH_ENTROPY_VA
		0x40 + // IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE
		0x100; // IMAGE_DLLCHARACTERISTICS_NX_COMPAT
	oh.sizeOfStackReserve = 0x100000;
	oh.sizeOfStackCommit = 0x1000;
	oh.sizeOfHeapReserve = 0x100000;
	oh.sizeOfHeapCommit = 0x1000;
	// oh.loaderFlags = 0;
	oh.numberOfRvaAndSizes =
		ImageDataDirectoryArray.size / ImageDataDirectoryArray.itemSize;
}

export function makeEmptyNtExecutableBinary(
	is32Bit: boolean,
	isDLL: boolean
): ArrayBuffer {
	const bufferSize = roundUp(
		DOS_STUB_SIZE + estimateNewHeaderSize(is32Bit),
		DEFAULT_FILE_ALIGNMENT
	);
	const bin = new ArrayBuffer(bufferSize);

	fillDosStubData(bin);
	fillPeHeaderEmptyData(bin, DOS_STUB_SIZE, bufferSize, is32Bit, isDLL);

	return bin;
}