/*

 * Copyright (c) 2020-2021, the SerenityOS developers.

 * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#pragma once

#include <AK/Optional.h>

#include <AK/StringView.h>

#include <AK/Types.h>

#include <AK/Utf8View.h>

#include <LibWeb/CSS/Parser/Token.h>

#include <LibWeb/Forward.h>

namespace Web::CSS::Parser {

class U32Twin {

public:

    void set(size_t index, u32 value)

    {

        if (index == 0)

            first = value;

        if (index == 1)

            second = value;

    }

    u32 first {};

    u32 second {};

};

class U32Triplet {

public:

    void set(size_t index, u32 value)

    {

        if (index == 0)

            first = value;

        if (index == 1)

            second = value;

        if (index == 2)

            third = value;

    }

    U32Twin to_twin_12()

    {

        return { first, second };

    }

    U32Twin to_twin_23()

    {

        return { second, third };

    }

    u32 first {};

    u32 second {};

    u32 third {};

};

class Tokenizer {

public:

    static Vector<Token> tokenize(StringView input, StringView encoding);

    [[nodiscard]] static Token create_eof_token();

private:

    explicit Tokenizer(String decoded_input);

    [[nodiscard]] Vector<Token> tokenize();

    size_t current_byte_offset() const;

    String input_since(size_t offset) const;

    [[nodiscard]] u32 next_code_point();

    [[nodiscard]] u32 peek_code_point(size_t offset = 0) const;

    [[nodiscard]] U32Twin peek_twin() const;

    [[nodiscard]] U32Triplet peek_triplet() const;

    [[nodiscard]] U32Twin start_of_input_stream_twin();

    [[nodiscard]] U32Triplet start_of_input_stream_triplet();

    [[nodiscard]] static Token create_new_token(Token::Type);

    [[nodiscard]] static Token create_value_token(Token::Type, FlyString&& value, String&& representation);

    [[nodiscard]] static Token create_value_token(Token::Type, u32 value, String&& representation);

    [[nodiscard]] Token consume_a_token();

    [[nodiscard]] Token consume_string_token(u32 ending_code_point);

    [[nodiscard]] Token consume_a_numeric_token();

    [[nodiscard]] Token consume_an_ident_like_token();

    [[nodiscard]] Number consume_a_number();

    [[nodiscard]] double convert_a_string_to_a_number(StringView);

    [[nodiscard]] FlyString consume_an_ident_sequence();

    [[nodiscard]] u32 consume_escaped_code_point();

    [[nodiscard]] Token consume_a_url_token();

    void consume_the_remnants_of_a_bad_url();

    void consume_comments();

    void consume_as_much_whitespace_as_possible();

    void reconsume_current_input_code_point();

    [[nodiscard]] static bool is_valid_escape_sequence(U32Twin);

    [[nodiscard]] static bool would_start_an_ident_sequence(U32Triplet);

    [[nodiscard]] static bool would_start_a_number(U32Triplet);

    String m_decoded_input;

    Utf8View m_utf8_view;

    AK::Utf8CodePointIterator m_utf8_iterator;

    AK::Utf8CodePointIterator m_prev_utf8_iterator;

    Token::Position m_position;

    Token::Position m_prev_position;

};

}