/*
 * libfud
 * Copyright 2024 Dominick Allen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "fud_utf8.hpp"

#include "fud_string.hpp"

namespace fud {

FudUtf8 FudUtf8::from(const String& fudString, size_t index) noexcept
{
    if (!fudString.valid()) {
        return invalidAscii();
    }


    return from(StringView{fudString}, index);
}

FudUtf8 FudUtf8::from(StringView view, size_t index) noexcept
{
    auto viewLocal{view};
    auto len = viewLocal.length();
    const auto* vData = viewLocal.data();
    if (vData == nullptr) {
        return invalidAscii();
    }

    FudUtf8 localChar{Ascii{vData[index]}};
    if (localChar.valid()) {
        return localChar;
    }

    if (index + 1 < len) {
        localChar.m_variant = Utf82Byte{vData[index], vData[index + 1]};
    }
    if (localChar.valid()) {
        return localChar;
    }

    if (index + 2 < len) {
        localChar.m_variant = Utf83Byte{vData[index], vData[index + 1], vData[index + 2]};
    }
    if (localChar.valid()) {
        return localChar;
    }

    if (index + 3 < len) {
        localChar.m_variant = Utf84Byte{vData[index], vData[index + 1], vData[index + 2], vData[index + 3]};
    }
    if (localChar.valid()) {
        return localChar;
    }

    return invalidAscii();
}

bool charIsAscii(char character)
{
    return static_cast<uint8_t>(character & ~ASCII_MASK) == 0;
}

bool utf8IsAscii(FudUtf8 character)
{
    return character.getType() == Utf8Type::Ascii && character.valid();
}

namespace impl {

template <typename Predicate>
bool isAsciiPredicate(FudUtf8 character, Predicate&& predicate)
{
    auto maybeAscii = character.getAscii();
    if (!maybeAscii.has_value()) {
        return false;
    }

    auto asciiChar = *maybeAscii;
    return std::forward<Predicate>(predicate)(asciiChar.asChar());
}

} // namespace impl

bool charIsAlphanumeric(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    if (charIsAlpha(character)) {
        return true;
    }

    return charIsDigit(character);
}

bool utf8IsAlphanumeric(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsAlphanumeric);
}

bool charIsAlpha(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    if (charIsUppercase(character)) {
        return true;
    }

    return charIsLowercase(character);
}

bool utf8IsAlpha(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsAlpha);
}

bool charIsLowercase(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return 'a' <= character && character <= 'z';
}

bool utf8IsLowercase(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsLowercase);
}

bool charIsUppercase(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return 'A' <= character && character <= 'Z';
}

bool utf8IsUppercase(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsUppercase);
}

bool charIsDigit(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return '0' <= character && character <= '9';
}

bool utf8IsDigit(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsDigit);
}

bool charIsHexDigit(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return ('0' <= character && character <= '9') || ('a' <= character && character <= 'f') ||
        ('A' <= character && character <= 'F');
}

bool utf8IsHexDigit(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsHexDigit);
}

bool charIsControl(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    constexpr char maxControlChar = 0x1F;
    constexpr const char deleteChar = 0x7F;
    return ((static_cast<uint8_t>(character) <= maxControlChar)) || character == deleteChar;
}

bool utf8IsControl(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsControl);
}

bool charIsGraphical(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return charIsAlphanumeric(character) || charIsPunctuation(character);
}

bool utf8IsGraphical(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsGraphical);
}

bool charIsSpace(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return character == ' ' || character == '\t' || character == '\n' || character == '\r' || character == '\v';
}

bool utf8IsSpace(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsSpace);
}

bool charIsBlank(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return character == ' ' || character == '\t';
}

bool utf8IsBlank(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsBlank);
}

bool charIsPrintable(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return (character >= ' ' && character <= '~');
}

bool utf8IsPrintable(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsPrintable);
}

bool charIsPunctuation(char character)
{
    if (!charIsAscii(character)) {
        return false;
    }

    return (character >= '!' && character <= '/') || (character >= ':' && character <= '@') ||
        (character >= '[' && character <= '`') || (character >= '{' && character <= '~');
}

bool utf8IsPunctuation(FudUtf8 character)
{
    return impl::isAsciiPredicate(character, charIsPunctuation);
}

uint8_t charToLower(uint8_t character)
{
    if (charIsUppercase(static_cast<char>(character))) {
        constexpr uint8_t lowerA = 'a';
        constexpr uint8_t upperA = 'A';
        return static_cast<uint8_t>(character - upperA) + lowerA;
    }
    return character;
}

FudUtf8 utf8ToLower(FudUtf8 character)
{
    static_cast<void>(character.transformAscii([](Ascii& ascii) {
        ascii = Ascii{charToLower(static_cast<uint8_t>(ascii.asChar()))};
    }));

    return character;
}

uint8_t charToUpper(uint8_t character)
{
    if (charIsLowercase(static_cast<char>(character))) {
        constexpr uint8_t lowerA = 'a';
        constexpr uint8_t upperA = 'A';
        return static_cast<uint8_t>(character - lowerA) + upperA;
    }
    return character;
}

FudUtf8 utf8ToUpper(FudUtf8 character)
{
    static_cast<void>(character.transformAscii([](Ascii& ascii) {
        ascii = Ascii{charToUpper(static_cast<uint8_t>(ascii.asChar()))};
    }));

    return character;
}

} // namespace fud