// Copyright 2015 The Chromium Authors. All rights reserved.
// Copyright (C) 2016-2021 Apple Inc. All rights reserved.
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#include "config.h"
#include "CSSVariableParser.h"

#include "CSSCustomPropertyValue.h"
#include "CSSParserContext.h"
#include "CSSParserIdioms.h"
#include "CSSParserTokenRange.h"
#include "CSSPropertyParserHelpers.h"

namespace WebCore {

bool CSSVariableParser::isValidVariableName(const CSSParserToken& token)
{
    if (token.type() != IdentToken)
        return false;

    StringView value = token.value();
    return value.length() >= 2 && value[0] == '-' && value[1] == '-';
}

bool CSSVariableParser::isValidVariableName(const String& string)
{
    return string.length() >= 2 && string[0] == '-' && string[1] == '-';
}

static bool isValidConstantName(const CSSParserToken& token)
{
    return token.type() == IdentToken;
}

static bool isValidVariableReference(CSSParserTokenRange, bool& hasAtApplyRule, const CSSParserContext&);
static bool isValidConstantReference(CSSParserTokenRange, bool& hasAtApplyRule, const CSSParserContext&);

static bool classifyBlock(CSSParserTokenRange range, bool& hasReferences, bool& hasAtApplyRule, const CSSParserContext& parserContext, bool isTopLevelBlock = true)
{
    while (!range.atEnd()) {
        if (range.peek().getBlockType() == CSSParserToken::BlockStart) {
            const CSSParserToken& token = range.peek();
            CSSParserTokenRange block = range.consumeBlock();
            if (token.functionId() == CSSValueVar) {
                if (!isValidVariableReference(block, hasAtApplyRule, parserContext))
                    return false; // Bail if any references are invalid
                hasReferences = true;
                continue;
            }
            if (token.functionId() == CSSValueEnv && parserContext.constantPropertiesEnabled) {
                if (!isValidConstantReference(block, hasAtApplyRule, parserContext))
                    return false; // Bail if any references are invalid
                hasReferences = true;
                continue;
            }
            if (!classifyBlock(block, hasReferences, hasAtApplyRule, parserContext, false))
                return false;
            continue;
        }

        ASSERT(range.peek().getBlockType() != CSSParserToken::BlockEnd);

        const CSSParserToken& token = range.consume();
        switch (token.type()) {
        case AtKeywordToken: {
            if (equalIgnoringASCIICase(token.value(), "apply")) {
                range.consumeWhitespace();
                const CSSParserToken& variableName = range.consumeIncludingWhitespace();
                if (!CSSVariableParser::isValidVariableName(variableName)
                    || !(range.atEnd() || range.peek().type() == SemicolonToken || range.peek().type() == RightBraceToken))
                    return false;
                hasAtApplyRule = true;
            }
            break;
        }
        case DelimiterToken: {
            if (token.delimiter() == '!' && isTopLevelBlock)
                return false;
            break;
        }
        case RightParenthesisToken:
        case RightBraceToken:
        case RightBracketToken:
        case BadStringToken:
        case BadUrlToken:
            return false;
        case SemicolonToken:
            if (isTopLevelBlock)
                return false;
            break;
        default:
            break;
        }
    }
    return true;
}

bool isValidVariableReference(CSSParserTokenRange range, bool& hasAtApplyRule, const CSSParserContext& parserContext)
{
    range.consumeWhitespace();
    if (!CSSVariableParser::isValidVariableName(range.consumeIncludingWhitespace()))
        return false;
    if (range.atEnd())
        return true;

    if (!CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(range))
        return false;
    if (range.atEnd())
        return true;

    bool hasReferences = false;
    return classifyBlock(range, hasReferences, hasAtApplyRule, parserContext);
}

bool isValidConstantReference(CSSParserTokenRange range, bool& hasAtApplyRule, const CSSParserContext& parserContext)
{
    range.consumeWhitespace();
    if (!isValidConstantName(range.consumeIncludingWhitespace()))
        return false;
    if (range.atEnd())
        return true;

    if (!CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(range))
        return false;
    if (range.atEnd())
        return true;

    bool hasReferences = false;
    return classifyBlock(range, hasReferences, hasAtApplyRule, parserContext);
}

static CSSValueID classifyVariableRange(CSSParserTokenRange range, bool& hasReferences, bool& hasAtApplyRule, const CSSParserContext& parserContext)
{
    hasReferences = false;
    hasAtApplyRule = false;

    range.consumeWhitespace();
    if (range.peek().type() == IdentToken) {
        CSSValueID id = range.consumeIncludingWhitespace().id();
        if (range.atEnd() && isCSSWideKeyword(id))
            return id;
    }

    if (classifyBlock(range, hasReferences, hasAtApplyRule, parserContext))
        return CSSValueInternalVariableValue;
    return CSSValueInvalid;
}

bool CSSVariableParser::containsValidVariableReferences(CSSParserTokenRange range, const CSSParserContext& parserContext)
{
    bool hasReferences;
    bool hasAtApplyRule;
    CSSValueID type = classifyVariableRange(range, hasReferences, hasAtApplyRule, parserContext);
    return type == CSSValueInternalVariableValue && hasReferences && !hasAtApplyRule;
}

RefPtr<CSSCustomPropertyValue> CSSVariableParser::parseDeclarationValue(const AtomString& variableName, CSSParserTokenRange range, const CSSParserContext& parserContext)
{
    if (range.atEnd())
        return nullptr;

    bool hasReferences;
    bool hasAtApplyRule;
    CSSValueID type = classifyVariableRange(range, hasReferences, hasAtApplyRule, parserContext);

    if (type == CSSValueInvalid)
        return nullptr;
    if (type == CSSValueInternalVariableValue)
        return CSSCustomPropertyValue::createUnresolved(variableName, CSSVariableReferenceValue::create(range, parserContext));
    return CSSCustomPropertyValue::createUnresolved(variableName, type);
}

} // namespace WebCore