wchar_t ToLowerCase(wchar_t a) {
    if (a >= 'A' && a <= 'Z') a += 32;
    return a;
}

wchar_t ToUpperCase(wchar_t a) {
    if (a >= 'a' && a <= 'z') a -= 32;
    return a;
}

bool IsWhitespace(wchar_t w) {
    bool result = w == '\n' || w == ' ' || w == '\t' || w == '\v' || w == '\r';
    return result;
}

bool IsSymbol(wchar_t w) {
    bool result = (w >= '!' && w <= '/') || (w >= ':' && w <= '@') || (w >= '[' && w <= '`') || (w >= '{' && w <= '~');
    return result;
}

bool IsAlphabetic(wchar_t a) {
    bool result = (a >= 'a' && a <= 'z') || (a >= 'A' && a <= 'Z');
    return result;
}

bool IsIdent(wchar_t a) {
    bool result = (a >= 'a' && a <= 'z') || (a >= 'A' && a <= 'Z') || a == '_';
    return result;
}

bool IsDigit(wchar_t a) {
    bool result = a >= '0' && a <= '9';
    return result;
}

bool IsAlphanumeric(wchar_t a) {
    bool result = IsDigit(a) || IsAlphabetic(a);
    return result;
}

bool AreEqual(String16 a, String16 b, unsigned ignore_case = false) {
    if (a.len != b.len) return false;
    for (int64_t i = 0; i < a.len; i++) {
        wchar_t A = a.data[i];
        wchar_t B = b.data[i];
        if (ignore_case) {
            A = ToLowerCase(A);
            B = ToLowerCase(B);
        }
        if (A != B)
            return false;
    }
    return true;
}
inline bool operator==(String16 a, String16 b) { return AreEqual(a, b); }
inline bool operator!=(String16 a, String16 b) { return !AreEqual(a, b); }

String16 Merge(Allocator allocator, Array<String16> list, String16 separator = " ") {
    int64_t char_count = 0;
    For(list) char_count += it.len;
    if (char_count == 0) return {};
    int64_t node_count = list.len;

    int64_t  base_size = (char_count + 1);
    int64_t  sep_size  = (node_count - 1) * separator.len;
    int64_t  size      = base_size + sep_size;
    wchar_t *buff      = (wchar_t *)AllocSize(allocator, sizeof(wchar_t) * (size + 1));
    String16 string    = {buff, 0};
    For(list) {
        Assert(string.len + it.len <= size);
        memcpy(string.data + string.len, it.data, it.len * sizeof(wchar_t));
        string.len += it.len;
        if (!IsLast(list, it)) {
            memcpy(string.data + string.len, separator.data, separator.len * sizeof(wchar_t));
            string.len += separator.len;
        }
    }
    Assert(string.len == size - 1);
    string.data[size] = 0;
    return string;
}

bool Seek(String16 string, String16 find, int64_t *index_out = NULL, SeekFlag flags = SeekFlag_None) {
    bool ignore_case = flags & SeekFlag_IgnoreCase ? true : false;
    bool result      = false;
    if (flags & SeekFlag_MatchFindLast) {
        for (int64_t i = string.len; i != 0; i--) {
            int64_t  index     = i - 1;
            String16 substring = GetSlice(string, index, index + find.len);
            if (AreEqual(substring, find, ignore_case)) {
                if (index_out)
                    *index_out = index;
                result = true;
                break;
            }
        }
    } else {
        for (int64_t i = 0; i < string.len; i++) {
            String16 substring = GetSlice(string, i, i + find.len);
            if (AreEqual(substring, find, ignore_case)) {
                if (index_out)
                    *index_out = i;
                result = true;
                break;
            }
        }
    }

    return result;
}

String16 ChopLastSlash(String16 s) {
    String16 result = s;
    Seek(s, L"/", &result.len, SeekFlag_MatchFindLast);
    return result;
}

String16 ChopLastPeriod(String16 s) {
    String16 result = s;
    Seek(s, L".", &result.len, SeekFlag_MatchFindLast);
    return result;
}

String16 SkipToLastSlash(String16 s) {
    int64_t  pos;
    String16 result = s;
    if (Seek(s, L"/", &pos, SeekFlag_MatchFindLast)) {
        result = Skip(result, pos + 1);
    }
    return result;
}

String16 SkipToLastPeriod(String16 s) {
    int64_t  pos;
    String16 result = s;
    if (Seek(s, L".", &pos, SeekFlag_MatchFindLast)) {
        result = Skip(result, pos + 1);
    }
    return result;
}

String16 CutPrefix(String16 *string, int64_t len) {
    String16 result = GetPrefix(*string, len);
    *string         = Skip(*string, len);
    return result;
}

String16 CutPostfix(String16 *string, int64_t len) {
    String16 result = GetPostfix(*string, len);
    *string         = Chop(*string, len);
    return result;
}