/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
 * io_file.c
 *
 * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
 */
#define SQFS_BUILDING_DLL
#include "config.h"

#include "sqfs/io.h"
#include "sqfs/error.h"
#include "compat.h"

#include <stdlib.h>

#define WIN32_LEAN_AND_MEAN
#include <windows.h>


typedef struct {
	sqfs_file_t base;

	bool readonly;
	sqfs_u64 size;
	sqfs_file_handle_t fd;

	char name[];
} sqfs_file_stdio_t;


static void stdio_destroy(sqfs_object_t *base)
{
	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;

	CloseHandle(file->fd);
	free(file);
}

static sqfs_object_t *stdio_copy(const sqfs_object_t *base)
{
	const sqfs_file_stdio_t *file = (const sqfs_file_stdio_t *)base;
	sqfs_file_stdio_t *copy;
	size_t size;
	BOOL ret;

	if (!file->readonly) {
		SetLastError(ERROR_NOT_SUPPORTED);
		return NULL;
	}

	size = sizeof(*file) + strlen(file->name) + 1;
	copy = calloc(1, size);
	if (copy == NULL)
		return NULL;

	memcpy(copy, file, size);

	ret = DuplicateHandle(GetCurrentProcess(), file->fd,
			      GetCurrentProcess(), &copy->fd,
			      0, FALSE, DUPLICATE_SAME_ACCESS);

	if (!ret) {
		free(copy);
		return NULL;
	}

	return (sqfs_object_t *)copy;
}

static int stdio_read_at(sqfs_file_t *base, sqfs_u64 offset,
			 void *buffer, size_t size)
{
	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
	DWORD actually_read;
	LARGE_INTEGER pos;

	if (offset >= file->size)
		return SQFS_ERROR_OUT_OF_BOUNDS;

	if (size == 0)
		return 0;

	if ((offset + size - 1) >= file->size)
		return SQFS_ERROR_OUT_OF_BOUNDS;

	pos.QuadPart = offset;

	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
		return SQFS_ERROR_IO;

	while (size > 0) {
		if (!ReadFile(file->fd, buffer, size, &actually_read, NULL))
			return SQFS_ERROR_IO;

		size -= actually_read;
		buffer = (char *)buffer + actually_read;
	}

	return 0;
}

static int stdio_write_at(sqfs_file_t *base, sqfs_u64 offset,
			  const void *buffer, size_t size)
{
	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
	DWORD actually_read;
	LARGE_INTEGER pos;

	if (size == 0)
		return 0;

	pos.QuadPart = offset;

	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
		return SQFS_ERROR_IO;

	while (size > 0) {
		if (!WriteFile(file->fd, buffer, size, &actually_read, NULL))
			return SQFS_ERROR_IO;

		size -= actually_read;
		buffer = (char *)buffer + actually_read;
		offset += actually_read;

		if (offset > file->size)
			file->size = offset;
	}

	return 0;
}

static sqfs_u64 stdio_get_size(const sqfs_file_t *base)
{
	const sqfs_file_stdio_t *file = (const sqfs_file_stdio_t *)base;

	return file->size;
}

static int stdio_truncate(sqfs_file_t *base, sqfs_u64 size)
{
	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
	LARGE_INTEGER pos;

	pos.QuadPart = size;

	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
		return SQFS_ERROR_IO;

	if (!SetEndOfFile(file->fd))
		return SQFS_ERROR_IO;

	file->size = size;
	return 0;
}

static const char *stdio_get_filename(sqfs_file_t *file)
{
	return ((sqfs_file_stdio_t *)file)->name;
}

int sqfs_open_native_file(sqfs_file_handle_t *out, const char *filename,
			  sqfs_u32 flags)
{
	int access_flags, creation_mode, share_mode;
	WCHAR *wpath = NULL;
	DWORD length, err;

	*out = INVALID_HANDLE_VALUE;

	if (flags & ~SQFS_FILE_OPEN_ALL_FLAGS) {
		SetLastError(ERROR_INVALID_PARAMETER);
		return SQFS_ERROR_UNSUPPORTED;
	}

	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
		access_flags = GENERIC_READ;
		creation_mode = OPEN_EXISTING;
		share_mode = FILE_SHARE_READ;
	} else {
		access_flags = GENERIC_READ | GENERIC_WRITE;
		share_mode = 0;

		if (flags & SQFS_FILE_OPEN_OVERWRITE) {
			creation_mode = CREATE_ALWAYS;
		} else {
			creation_mode = CREATE_NEW;
		}
	}

	if (flags & SQFS_FILE_OPEN_NO_CHARSET_XFRM) {
		*out = CreateFileA(filename, access_flags, share_mode, NULL,
				   creation_mode, FILE_ATTRIBUTE_NORMAL, NULL);
	} else {
		length = MultiByteToWideChar(CP_UTF8, 0, filename, -1, NULL, 0);
		if (length <= 0)
			return SQFS_ERROR_INTERNAL;

		wpath = calloc(sizeof(wpath[0]), length + 1);
		if (wpath == NULL) {
			SetLastError(ERROR_NOT_ENOUGH_MEMORY);
			return SQFS_ERROR_ALLOC;
		}

		MultiByteToWideChar(CP_UTF8, 0, filename, -1,
				    wpath, length + 1);
		wpath[length] = '\0';

		*out = CreateFileW(wpath, access_flags, share_mode, NULL,
				   creation_mode, FILE_ATTRIBUTE_NORMAL,
				   NULL);

		err = GetLastError();
		free(wpath);
		SetLastError(err);
	}

	return (*out == INVALID_HANDLE_VALUE) ? SQFS_ERROR_IO : 0;
}

sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
{
	sqfs_file_stdio_t *file;
	size_t namelen, total;
	LARGE_INTEGER size;
	sqfs_file_t *base;
	DWORD err;

	namelen = strlen(filename);
	total = sizeof(*file) + 1;

	if (SZ_ADD_OV(total, namelen, &total)) {
		SetLastError(ERROR_NOT_ENOUGH_MEMORY);
		return NULL;
	}

	file = calloc(1, total);
	base = (sqfs_file_t *)file;
	if (file == NULL) {
		SetLastError(ERROR_NOT_ENOUGH_MEMORY);
		return NULL;
	}

	sqfs_object_init(file, stdio_destroy, stdio_copy);
	memcpy(file->name, filename, namelen);

	if (sqfs_open_native_file(&file->fd, filename, flags))
		goto fail;

	if (!GetFileSizeEx(file->fd, &size))
		goto fail;

	file->size = size.QuadPart;
	file->readonly = (flags & SQFS_FILE_OPEN_READ_ONLY) != 0;

	base->read_at = stdio_read_at;
	base->write_at = stdio_write_at;
	base->get_size = stdio_get_size;
	base->truncate = stdio_truncate;
	base->get_filename = stdio_get_filename;
	return base;
fail:
	err = GetLastError();
	if (file->fd != INVALID_HANDLE_VALUE)
		CloseHandle(file->fd);
	free(file);
	SetLastError(err);
	return NULL;
}