/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#include "common.h"
#include "utf-conv.h"
GIT_INLINE(DWORD) get_wc_flags(void)
{
        static char inited = 0;
        static DWORD flags;
        /* Invalid code point check supported on Vista+ only */
        if (!inited) {
                flags = git_has_win32_version(6, 0, 0) ? WC_ERR_INVALID_CHARS : 0;
                inited = 1;
        }
        return flags;
}
GIT_INLINE(void) git__set_errno(void)
{
        if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
                errno = ENAMETOOLONG;
        else
                errno = EINVAL;
}
/**
 * Converts a UTF-8 string to wide characters.
 *
 * @param dest The buffer to receive the wide string.
 * @param dest_size The size of the buffer, in characters.
 * @param src The UTF-8 string to convert.
 * @return The length of the wide string, in characters (not counting the NULL terminator), or < 0 for failure
 */
int git__utf8_to_16(wchar_t *dest, size_t dest_size, const char *src)
{
        int len;
        /* Length of -1 indicates NULL termination of the input string. Subtract 1 from the result to
        * turn 0 into -1 (an error code) and to not count the NULL terminator as part of the string's
        * length. MultiByteToWideChar never returns int's minvalue, so underflow is not possible */
        if ((len = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, dest, (int)dest_size) - 1) < 0)
                git__set_errno();
        return len;
}
/**
 * Converts a wide string to UTF-8.
 *
 * @param dest The buffer to receive the UTF-8 string.
 * @param dest_size The size of the buffer, in bytes.
 * @param src The wide string to convert.
 * @return The length of the UTF-8 string, in bytes (not counting the NULL terminator), or < 0 for failure
 */
int git__utf16_to_8(char *dest, size_t dest_size, const wchar_t *src)
{
        int len;
        /* Length of -1 indicates NULL termination of the input string. Subtract 1 from the result to
         * turn 0 into -1 (an error code) and to not count the NULL terminator as part of the string's
         * length. WideCharToMultiByte never returns int's minvalue, so underflow is not possible */
        if ((len = WideCharToMultiByte(CP_UTF8, get_wc_flags(), src, -1, dest, (int)dest_size, NULL, NULL) - 1) < 0)
                git__set_errno();
        return len;
}
/**
 * Converts a UTF-8 string to wide characters.
 * Memory is allocated to hold the converted string.
 * The caller is responsible for freeing the string with git__free.
 *
 * @param dest Receives a pointer to the wide string.
 * @param src The UTF-8 string to convert.
 * @return The length of the wide string, in characters (not counting the NULL terminator), or < 0 for failure
 */
int git__utf8_to_16_alloc(wchar_t **dest, const char *src)
{
        int utf16_size;
        *dest = NULL;
        /* Length of -1 indicates NULL termination of the input string */
        utf16_size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, NULL, 0);
        if (!utf16_size) {
                git__set_errno();
                return -1;
        }
        if (!(*dest = git__mallocarray(utf16_size, sizeof(wchar_t)))) {
                errno = ENOMEM;
                return -1;
        }
        utf16_size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, *dest, utf16_size);
        if (!utf16_size) {
                git__set_errno();
                git__free(*dest);
                *dest = NULL;
        }
        /* Subtract 1 from the result to turn 0 into -1 (an error code) and to not count the NULL
         * terminator as part of the string's length. MultiByteToWideChar never returns int's minvalue,
         * so underflow is not possible */
        return utf16_size - 1;
}
/**
 * Converts a wide string to UTF-8.
 * Memory is allocated to hold the converted string.
 * The caller is responsible for freeing the string with git__free.
 *
 * @param dest Receives a pointer to the UTF-8 string.
 * @param src The wide string to convert.
 * @return The length of the UTF-8 string, in bytes (not counting the NULL terminator), or < 0 for failure
 */
int git__utf16_to_8_alloc(char **dest, const wchar_t *src)
{
        int utf8_size;
        DWORD dwFlags = get_wc_flags();
        *dest = NULL;
        /* Length of -1 indicates NULL termination of the input string */
        utf8_size = WideCharToMultiByte(CP_UTF8, dwFlags, src, -1, NULL, 0, NULL, NULL);
        if (!utf8_size) {
                git__set_errno();
                return -1;
        }
        *dest = git__malloc(utf8_size);
        if (!*dest) {
                errno = ENOMEM;
                return -1;
        }
        utf8_size = WideCharToMultiByte(CP_UTF8, dwFlags, src, -1, *dest, utf8_size, NULL, NULL);
        if (!utf8_size) {
                git__set_errno();
                git__free(*dest);
                *dest = NULL;
        }
        /* Subtract 1 from the result to turn 0 into -1 (an error code) and to not count the NULL
         * terminator as part of the string's length. MultiByteToWideChar never returns int's minvalue,
         * so underflow is not possible */
        return utf8_size - 1;
}