/*
 * 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 "utf8.hpp"

#include "string.hpp"

#include <new> // IWYU pragma: keep - this is for placement new overloads.

namespace fud {

ExtUtf8 ExtUtf8::fromString(const String& fudString, size_t index) noexcept
{
    if (!fudString.valid()) {
        return invalidAscii();
    }


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

ExtUtf8 ExtUtf8::fromStringView(const StringView& view, size_t index) noexcept
{
    return fromStringView(StringView{view}, index);
}

ExtUtf8 ExtUtf8::fromStringView(StringView&& view, size_t index) noexcept
{
    auto len = view.length();
    const auto* data = view.data();
    if (data == nullptr) {
        return invalidAscii();
    }

    ExtUtf8 localChar{Ascii{data[index]}};
    if (localChar.valid()) {
        return localChar;
    }

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

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

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

    return invalidAscii();
}

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

FudStatus ext_lib_utf8_is_ascii(ExtUtf8* character, bool* isAscii)
{
    if (anyAreNull(character, isAscii)) {
        return FudStatus::NullPointer;
    }

    *isAscii = character->getType() == ExtUtf8Type::Ascii && character->valid();

    return FudStatus::Success;
}

namespace impl {

/* Assumes that predicate is not a null pointer! */
template <typename Predicate>
inline FudStatus isAsciiPredicate(ExtUtf8* character, bool* pred, Predicate&& predicate)
{
    if (anyAreNull(character, pred)) {
        return FudStatus::NullPointer;
    }

    auto maybeAscii = character->getAscii();
    if (!maybeAscii.has_value()) {
        return FudStatus::InvalidInput;
    }

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

    return FudStatus::Success;
}

} // namespace impl

bool ext_lib_char_is_alphanumeric(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

    return ext_lib_char_is_digit(character);
}

FudStatus ext_lib_utf8_is_alphanumeric(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_alphanumeric);
}

bool ext_lib_char_is_alpha(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

    return ext_lib_char_is_lowercase(character);
}

FudStatus ext_lib_utf8_is_alpha(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_alpha);
}

bool ext_lib_char_is_lowercase(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_lowercase(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_lowercase);
}

bool ext_lib_char_is_uppercase(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_uppercase(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_uppercase);
}

bool ext_lib_char_is_digit(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_digit(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_digit);
}

bool ext_lib_char_is_hex_digit(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_hex_digit(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_hex_digit);
}

bool ext_lib_char_is_control(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_control(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_control);
}

bool ext_lib_char_is_graphical(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

    return ext_lib_char_is_alphanumeric(character) || ext_lib_char_is_punctuation(character);
}

FudStatus ext_lib_utf8_is_graphical(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_graphical);
}

bool ext_lib_char_is_space(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_space(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_space);
}

bool ext_lib_char_is_blank(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_blank(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_blank);
}

bool ext_lib_char_is_printable(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_printable(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_printable);
}

bool ext_lib_char_is_punctuation(char character)
{
    if (!ext_lib_char_is_ascii(character)) {
        return false;
    }

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

FudStatus ext_lib_utf8_is_punctuation(ExtUtf8* character, bool* pred)
{
    return impl::isAsciiPredicate(character, pred, ext_lib_char_is_punctuation);
}

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

ExtUtf8* ext_lib_utf8_to_lower(ExtUtf8* character)
{
    if (character == nullptr) {
        return character;
    }

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

    return character;
}

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

ExtUtf8* ext_lib_utf8_to_upper(ExtUtf8* character)
{
    if (character == nullptr) {
        return character;
    }

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

    return character;
}

} // namespace ext_lib