/*

 * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>

 *

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

 */

#include <AK/GenericLexer.h>

#include <AK/String.h>

#include <AK/StringBuilder.h>

#include <LibWeb/Fetch/Infrastructure/HTTP.h>

namespace Web::Fetch::Infrastructure {

// https://fetch.spec.whatwg.org/#collect-an-http-quoted-string

String collect_an_http_quoted_string(GenericLexer& lexer, HttpQuotedStringExtractValue extract_value)

{

    // To collect an HTTP quoted string from a string input, given a position variable position and optionally an extract-value flag, run these steps:

    // 1. Let positionStart be position.

    auto position_start = lexer.tell();

    // 2. Let value be the empty string.

    StringBuilder value;

    // 3. Assert: the code point at position within input is U+0022 (").

    VERIFY(lexer.peek() == '"');

    // 4. Advance position by 1.

    lexer.ignore(1);

    // 5. While true:

    while (true) {

        // 1. Append the result of collecting a sequence of code points that are not U+0022 (") or U+005C (\) from input, given position, to value.

        auto value_part = lexer.consume_until([](char ch) {

            return ch == '"' || ch == '\\';

        });

        value.append(value_part);

        // 2. If position is past the end of input, then break.

        if (lexer.is_eof())

            break;

        // 3. Let quoteOrBackslash be the code point at position within input.

        // 4. Advance position by 1.

        char quote_or_backslash = lexer.consume();

        // 5. If quoteOrBackslash is U+005C (\), then:

        if (quote_or_backslash == '\\') {

            // 1. If position is past the end of input, then append U+005C (\) to value and break.

            if (lexer.is_eof()) {

                value.append('\\');

                break;

            }

            // 2. Append the code point at position within input to value.

            // 3. Advance position by 1.

            value.append(lexer.consume());

        }

        // 6. Otherwise:

        else {

            // 1. Assert: quoteOrBackslash is U+0022 (").

            VERIFY(quote_or_backslash == '"');

            // 2. Break.

            break;

        }

    }

    // 6. If the extract-value flag is set, then return value.

    if (extract_value == HttpQuotedStringExtractValue::Yes)

        return MUST(value.to_string());

    // 7. Return the code points from positionStart to position, inclusive, within input.

    return MUST(String::from_utf8(lexer.input().substring_view(position_start, lexer.tell() - position_start)));

}

}