/*
 * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "CSSKeywordValue.h"
#include <AK/StringBuilder.h>
#include <LibWeb/Bindings/CSSKeywordValue.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/Keyword.h>
#include <LibWeb/CSS/PropertyNameAndID.h>
#include <LibWeb/CSS/Serialize.h>
#include <LibWeb/CSS/StyleValues/CustomIdentStyleValue.h>
#include <LibWeb/CSS/StyleValues/DisplayStyleValue.h>
#include <LibWeb/CSS/StyleValues/KeywordStyleValue.h>
#include <LibWeb/WebIDL/ExceptionOr.h>

namespace Web::CSS {

GC_DEFINE_ALLOCATOR(CSSKeywordValue);

GC::Ref<CSSKeywordValue> CSSKeywordValue::create(JS::Realm& realm, FlyString value)
{
    return realm.create<CSSKeywordValue>(realm, move(value));
}

// https://drafts.css-houdini.org/css-typed-om-1/#dom-csskeywordvalue-csskeywordvalue
WebIDL::ExceptionOr<GC::Ref<CSSKeywordValue>> CSSKeywordValue::construct_impl(JS::Realm& realm, FlyString value)
{
    // 1. If value is an empty string, throw a TypeError.
    if (value.is_empty())
        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "Cannot create a CSSKeywordValue with an empty string as the value"sv };

    // 2. Otherwise, return a new CSSKeywordValue with its value internal slot set to value.
    return CSSKeywordValue::create(realm, move(value));
}

CSSKeywordValue::CSSKeywordValue(JS::Realm& realm, FlyString value)
    : CSSStyleValue(realm)
    , m_value(move(value))
{
}

void CSSKeywordValue::initialize(JS::Realm& realm)
{
    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSKeywordValue);
    Base::initialize(realm);
}

// https://drafts.css-houdini.org/css-typed-om-1/#dom-csskeywordvalue-value
WebIDL::ExceptionOr<void> CSSKeywordValue::set_value(FlyString value)
{
    // 1. If value is an empty string, throw a TypeError.
    if (value.is_empty())
        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "Cannot set CSSKeywordValue.value to an empty string"sv };

    // 2. Otherwise, set this’s value internal slot, to value.
    m_value = move(value);
    return {};
}

// https://drafts.css-houdini.org/css-typed-om-1/#keywordvalue-serialization
void CSSKeywordValue::serialize(StringBuilder& builder) const
{
    // To serialize a CSSKeywordValue this:
    // 1. Return this’s value internal slot.
    // AD-HOC: Serialize it as an identifier. Spec issue: https://github.com/w3c/csswg-drafts/issues/12545
    serialize_an_identifier(builder, m_value);
}

WebIDL::ExceptionOr<String> CSSKeywordValue::to_string() const
{
    StringBuilder builder;
    serialize(builder);
    return builder.to_string_without_validation();
}

// https://drafts.css-houdini.org/css-typed-om-1/#create-an-internal-representation
WebIDL::ExceptionOr<NonnullRefPtr<StyleValue const>> CSSKeywordValue::create_an_internal_representation(PropertyNameAndID const& property, PerformTypeCheck perform_type_check) const
{
    // If value is a CSSStyleValue subclass,
    //     If value does not match the grammar of a list-valued property iteration of property, throw a TypeError.
    bool const matches_grammar = [&] {
        // https://drafts.css-houdini.org/css-typed-om-1/#cssstylevalue-match-a-grammar
        // A CSSKeywordValue matches an <ident> specified in a grammar if its value internal slot matches the
        // identifier.
        // If case-folding rules are in effect normally for that <ident> (such as Auto matching the keyword auto
        // specified in the grammar for width), they apply to this comparison as well.
        if (is_css_wide_keyword(m_value))
            return true;
        if (property.is_custom_property()) {
            // FIXME: If this is a registered custom property, check if that allows the keyword.
            return true;
        }
        auto keyword = keyword_from_string(m_value);
        return keyword.has_value() && property_accepts_keyword(property.id(), keyword.value());
    }();
    if (perform_type_check == PerformTypeCheck::Yes && !matches_grammar) {
        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("Property '{}' does not accept the keyword '{}'", property.name(), m_value)) };
    }

    //     If any component of property’s CSS grammar has a limited numeric range, and the corresponding part of value
    //     is a CSSUnitValue that is outside of that range, replace that value with the result of wrapping it in a
    //     fresh CSSMathSum whose values internal slot contains only that part of value.
    // NB: Non-applicable.

    //     Return the value.
    if (auto keyword = keyword_from_string(m_value); keyword.has_value()) {
        if (!is_css_wide_keyword(m_value)) {
            // NB: Non-css-wide keyword `display` values are represented internally by DisplayStyleValue, not KeywordStyleValue.
            if (property.id() == PropertyID::Display)
                return DisplayStyleValue::create(Display::from_keyword(keyword.release_value()));
        }

        return KeywordStyleValue::create(*keyword);
    }
    return CustomIdentStyleValue::create(m_value);
}

// https://drafts.css-houdini.org/css-typed-om-1/#rectify-a-keywordish-value
GC::Ref<CSSKeywordValue> rectify_a_keywordish_value(JS::Realm& realm, CSSKeywordish const& keywordish)
{
    // To rectify a keywordish value val, perform the following steps:
    return keywordish.visit(
        // 1. If val is a CSSKeywordValue, return val.
        [](GC::Ref<CSSKeywordValue> const& value) -> GC::Ref<CSSKeywordValue> {
            return value;
        },

        // 2. If val is a DOMString, return a new CSSKeywordValue with its value internal slot set to val.
        [&realm](FlyString const& value) -> GC::Ref<CSSKeywordValue> {
            return CSSKeywordValue::create(realm, value);
        });
}

}
