// SPDX-License-Identifier: MIT
#include "dbc_statement_handler.h"
#include "j1939.h"
#include "multiplex_graph.h"
#include "signal_layout.h"
#include "text_utils.h"
#include <charconv>
#include <cmath>
#include <limits>
#include <regex>
#include <sstream>
#include <stdexcept>

namespace {
    std::uint32_t ParseDecimal(const std::string &text,
                               std::uint32_t maximum,
                               const char *field) {
        std::uint32_t value = 0U;
        const std::from_chars_result parsed = std::from_chars(text.data(), text.data() + text.size(), value);
        if (text.empty() || parsed.ec != std::errc() ||
            parsed.ptr != text.data() + text.size() || value > maximum)
            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
        return value;
    }

    std::uint32_t ParseCanId(const std::string &text) {
        const std::uint32_t rawId = ParseDecimal(
                text, std::numeric_limits<std::uint32_t>::max(), "CAN ID");
        // Only bit 31 may accompany the actual 29-bit identifier.
        if ((rawId & 0x60000000U) != 0U)
            throw std::runtime_error("CAN ID exceeds the 29-bit identifier range.");
        return rawId;
    }

    double ParsePhysicalValue(const std::string &text, const char *field) {
        if (text.empty() || (text[0] == '+' &&
                             (text.size() == 1U || text[1] == '+' || text[1] == '-')))
            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
        // Floating-point from_chars is locale-independent and does not accept
        // a leading '+', which the DBC numeric grammar permits.
        const char *begin = text.data();
        const char *end = begin + text.size();
        if (*begin == '+')
            ++begin;
        double value = 0.0;
        const std::from_chars_result parsed =
                std::from_chars(begin, end, value, std::chars_format::general);
        // Keep the existing rejection of conversion underflow into subnormal values.
        if (parsed.ec != std::errc() || parsed.ptr != end || !std::isfinite(value) ||
            std::fpclassify(value) == FP_SUBNORMAL)
            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
        return value;
    }

    // Iterative scanning keeps stack use independent of the statement length.
    class SignalTokens {
    public:
        SignalTokens(const std::string &text, std::size_t position) : text(text), position(position) {}

        void SkipSpaces() {
            while (position < text.size() && (text[position] == ' ' || text[position] == '\t'))
                ++position;
        }

        char Character() {
            if (position == text.size())
                throw std::runtime_error("Incomplete SG_ signal definition.");
            return text[position++];
        }

        void Expect(char expected) {
            SkipSpaces();
            if (Character() != expected)
                throw std::runtime_error("Malformed SG_ signal definition.");
        }

        std::string Until(char delimiter) {
            const std::size_t end = text.find(delimiter, position);
            if (end == std::string::npos)
                throw std::runtime_error("Missing delimiter in SG_ signal definition.");
            const std::string value = text.substr(position, end - position);
            position = end + 1U;
            return value;
        }

        std::vector<std::string> Receivers() {
            if (position == text.size() || (text[position] != ' ' && text[position] != '\t'))
                throw std::runtime_error("Missing receiver separator in SG_ signal definition.");
            std::vector<std::string> receivers;
            for (;;) {
                const std::size_t end = text.find(',', position);
                const std::string receiver = dbc_detail::TrimText(text.substr(position, end - position));
                if (receiver.empty() || receiver.find_first_of(" \t\r\n") != std::string::npos)
                    throw std::runtime_error("Invalid SG_ receiver list.");
                receivers.push_back(receiver);
                if (end == std::string::npos)
                    return receivers;
                position = end + 1U;
            }
        }

    private:
        const std::string &text;
        std::size_t position = 0U;
    };

    Multiplexing ParseMultiplexingMarker(const std::string &marker) {
        Multiplexing result;
        if (marker == "M")
            result.role = MultiplexRole::Selector;
        else if (!marker.empty()) {
            if (marker[0] != 'm')
                throw std::runtime_error("Unsupported multiplexing marker.");
            const bool nested = marker.back() == 'M';
            const std::string value = marker.substr(1U, marker.size() - (nested ? 2U : 1U));
            const std::from_chars_result parsed =
                std::from_chars(value.data(), value.data() + value.size(), result.value);
            if (value.empty() || parsed.ec != std::errc() || parsed.ptr != value.data() + value.size())
                throw std::runtime_error("Invalid or unsupported multiplexing marker.");
            result.role = nested ? MultiplexRole::BranchSelector : MultiplexRole::Branch;
        }

        return result;
    }

    RawSignalValue ParseValueKey(const std::string &number) {
        RawSignalValue key;
        if (!number.empty() && number[0] == '-') {
            std::int64_t value = 0;
            const std::from_chars_result parsed =
                std::from_chars(number.data(), number.data() + number.size(), value);
            if (parsed.ec != std::errc() || parsed.ptr != number.data() + number.size())
                throw std::runtime_error("Invalid VAL_ integer: " + number);
            key = NormalizeValueKey(RawSignalValue(value));
        } else {
            std::uint64_t value = 0;
            const std::from_chars_result parsed =
                std::from_chars(number.data(), number.data() + number.size(), value);
            if (number.empty() || parsed.ec != std::errc() || parsed.ptr != number.data() + number.size())
                throw std::runtime_error("Invalid VAL_ integer: " + number);
            key = value;
        }
        return key;
    }

    std::string UnescapeDescription(const std::string &quoted) {
        std::string description;
        for (std::size_t i = 0; i < quoted.size(); ++i) {
            if (quoted[i] == '\\')
                ++i;
            description += quoted[i];
        }
        return description;
    }

    FrameInfo *FindUniqueFrame(DbcDatabase &database, std::uint32_t canId, bool isExtended, const std::string &statement = "VAL_") {
        FrameInfo *frame = nullptr;
        for (FrameInfo &candidate : database.frames) {
            if (candidate.canId == canId && candidate.isExtended == isExtended) {
                if (frame)
                    throw std::runtime_error("Ambiguous " + statement + " frame reference.");
                frame = &candidate;
            }
        }
        if (!frame)
            throw std::runtime_error("Unresolved " + statement + " frame reference.");
        return frame;
    }

    SignalInfo *FindUniqueSignal(FrameInfo &frame, const std::string &signalName, const std::string &statement = "VAL_") {
        SignalInfo *signal = nullptr;
        for (SignalInfo &candidate : frame.signals) {
            if (candidate.name == signalName) {
                if (signal)
                    throw std::runtime_error("Ambiguous " + statement + " signal reference: " + signalName);
                signal = &candidate;
            }
        }
        if (!signal)
            throw std::runtime_error("Unresolved " + statement + " signal reference: " + signalName);
        return signal;
    }

    std::uint64_t NextSignalBit(std::uint64_t bit, bool isLittleEndian) {
        if (isLittleEndian)
            return bit + 1U;
        // From bit 0, Motorola continues at bit 7 of the next byte (0 -> 15).
        return bit % 8U == 0U ? bit + 15U : bit - 1U;
    }

    FrameInfo *FindFrameById(DbcDatabase &, std::uint32_t, bool);
    SignalInfo *FindSignalByName(FrameInfo &, const std::string &);
} // namespace

namespace {
    void NormalizeCanId(std::uint32_t rawCanId, std::uint32_t &normalizedCanId, bool &isExtended) {
        /*
         * DBC commonly stores extended identifiers with bit 31 set.
         * Example:
         * raw id = 0x80000000 | actual_29_bit_id
         */
        isExtended = (rawCanId & 0x80000000U) != 0U || rawCanId > 0x7FFU;
        normalizedCanId = rawCanId & 0x1FFFFFFFU;
    }
} // namespace

FrameInfo DbcFrameHandler::ParseFrameLine(const std::string &line) {
    /*
   * Example:
   * BO_ 256 EngineData: 8 EEC1
   */

    std::istringstream stream(line);
    std::string keyword;
    std::string idText;
    if (!(stream >> keyword >> idText) || keyword != "BO_")
        throw std::runtime_error("Missing CAN ID in frame definition.");

    const std::uint32_t rawCanId = ParseCanId(idText);

    std::string nameText;
    if (!std::getline(stream, nameText, ':') || stream.eof())
        throw std::runtime_error("Missing ':' in frame definition.");
    std::istringstream nameStream(nameText);
    FrameInfo frame;
    std::string extra;
    if (!(nameStream >> frame.name) || (nameStream >> extra))
        throw std::runtime_error("Missing or invalid frame name.");

    std::string lengthText;
    if (!(stream >> lengthText))
        throw std::runtime_error("Missing payload length in frame definition.");
    frame.dlc = static_cast<std::uint8_t>(ParseDecimal(
            lengthText, std::numeric_limits<std::uint8_t>::max(), "payload length"));
    if (!(stream >> frame.transmitter))
        throw std::runtime_error("Missing transmitter in frame definition.");
    if (stream >> extra)
        throw std::runtime_error("Unexpected trailing field in frame definition: " + extra);

    NormalizeCanId(rawCanId, frame.canId, frame.isExtended);

    return frame;
}

SignalInfo DbcSignalHandler::ParseSignalLine(const std::string &line) {
    if (line.size() < 4U || line.compare(0U, 3U, "SG_") != 0 ||
        (line[3] != ' ' && line[3] != '\t'))
        throw std::runtime_error("Malformed SG_ signal definition.");
    SignalTokens tokens(line, 3U);
    SignalInfo signal;
    std::istringstream nameFields(tokens.Until(':'));
    std::string marker;
    std::string extra;
    nameFields >> signal.name >> marker;
    if (signal.name.empty() || (nameFields >> extra))
        throw std::runtime_error("Invalid signal name or multiplexing marker.");
    signal.multiplexing = ParseMultiplexingMarker(marker);

    signal.startBit = ParseDecimal(dbc_detail::TrimText(tokens.Until('|')),
                                   std::numeric_limits<std::uint32_t>::max(), "signal start bit");
    signal.length = ParseDecimal(dbc_detail::TrimText(tokens.Until('@')), 64U, "signal length");
    if (signal.length == 0U)
        throw std::runtime_error("Signal length must be within 1..64 bits.");
    tokens.SkipSpaces();
    const char byteOrder = tokens.Character();
    const char signedness = tokens.Character();
    if ((byteOrder != '0' && byteOrder != '1') || (signedness != '+' && signedness != '-'))
        throw std::runtime_error("Invalid SG_ byte order or signedness.");
    signal.isLittleEndian = byteOrder == '1';
    signal.isSigned = signedness == '-';

    tokens.Expect('(');
    signal.factor = ParsePhysicalValue(dbc_detail::TrimText(tokens.Until(',')), "signal factor");
    signal.offset = ParsePhysicalValue(dbc_detail::TrimText(tokens.Until(')')), "signal offset");
    tokens.Expect('[');
    signal.minimum = ParsePhysicalValue(dbc_detail::TrimText(tokens.Until('|')), "signal minimum");
    signal.maximum = ParsePhysicalValue(dbc_detail::TrimText(tokens.Until(']')), "signal maximum");
    if (signal.minimum > signal.maximum)
        throw std::runtime_error("Signal minimum exceeds maximum.");
    tokens.Expect('"');
    signal.unit = tokens.Until('"');
    if (signal.unit.find_first_of("\r\n") != std::string::npos)
        throw std::runtime_error("Invalid newline in SG_ unit.");
    signal.receivers = tokens.Receivers();
    return signal;
}


namespace {
    FrameInfo *FindFrameById(DbcDatabase &database,
                             std::uint32_t canId,
                             bool isExtended) {
        for (FrameInfo &frame : database.frames) {
            if (frame.canId == canId && frame.isExtended == isExtended)
                return &frame;
        }

        return nullptr;
    }

    SignalInfo *FindSignalByName(FrameInfo &frame, const std::string &signalName) {
        for (SignalInfo &signal : frame.signals) {
            if (signal.name == signalName)
                return &signal;
        }

        return nullptr;
    }
}// namespace

void DbcFrameHandler::Handle(const std::string &line, DbcParseContext &context) const {
    FrameInfo frame = ParseFrameLine(line);
    if (context.enableJ1939 && frame.isExtended) {
        frame.hasPgn = true;
        frame.pgn = ExtractJ1939Pgn(frame.canId);
    }
    if (FindFrameById(context.database, frame.canId, frame.isExtended) != nullptr)
        throw std::runtime_error("Duplicate " + std::string(frame.isExtended ? "extended" : "standard") +
                                 " frame CAN ID: " + std::to_string(frame.canId));
    context.database.frames.push_back(std::move(frame));
    context.currentFrame = &context.database.frames.back();
    context.signalLines.emplace_back();
}

void DbcSignalHandler::Handle(const std::string &line, DbcParseContext &context) const {
    if (context.currentFrame == nullptr)
        throw std::runtime_error("Signal found before any frame definition.");
    SignalInfo signal = ParseSignalLine(line);
    if (FindSignalByName(*context.currentFrame, signal.name) != nullptr)
        throw std::runtime_error("Duplicate signal name '" + signal.name +
                                 "' in frame '" + context.currentFrame->name + "'.");
    if (!IsValidSignalLayout(signal.startBit, signal.length, signal.isLittleEndian,
                            context.currentFrame->dlc))
        throw std::runtime_error("Signal exceeds the frame payload length.");
    context.currentFrame->signals.push_back(std::move(signal));
    context.signalLines.back().push_back(context.lineNumber);
}

void DbcCommentHandler::Handle(const std::string &line, DbcParseContext &context) const {
    std::istringstream stream(line);
    std::string keyword;
    std::string target;
    stream >> keyword >> target;
    if (keyword != "CM_" || (target != "BO_" && target != "SG_"))
        return;

    PendingComment pending;
    pending.isSignal = target == "SG_";
    pending.lineNumber = context.lineNumber;
    std::string idText;
    if (!(stream >> idText))
        throw std::runtime_error("Missing CAN ID in CM_ statement.");
    NormalizeCanId(ParseCanId(idText), pending.canId, pending.isExtended);
    if (pending.isSignal && (!(stream >> pending.signalName) ||
                             pending.signalName.find_first_of("\";") != std::string::npos))
        throw std::runtime_error("Missing or invalid signal name in CM_ statement.");

    stream >> std::ws;
    if (stream.get() != '"')
        throw std::runtime_error("Missing opening quote in CM_ statement.");
    bool closed = false;
    char character;
    while (stream.get(character)) {
        if (character == '"') {
            closed = true;
            break;
        }
        if (character == '\\') {
            if (!stream.get(character) || (character != '"' && character != '\\'))
                throw std::runtime_error("Invalid escape in CM_ statement.");
        }
        pending.comment += character;
    }
    if (!closed)
        throw std::runtime_error("Unterminated CM_ comment.");
    stream >> std::ws;
    if (stream.get() != ';')
        throw std::runtime_error("Missing semicolon in CM_ statement.");
    stream >> std::ws;
    if (!stream.eof())
        throw std::runtime_error("Unexpected trailing text in CM_ statement.");
    context.pendingComments.push_back(std::move(pending));
}

void DbcParseContext::ResolveComments(const std::string &filePath) {
    for (const PendingComment &pending: pendingComments) {
        FrameInfo *frame = FindFrameById(database, pending.canId, pending.isExtended);
        if (!frame)
            throw DbcDiagnosticError(DbcDiagnosticCode::InvalidStatement, filePath,
                                     pending.lineNumber, "Unresolved CM_ frame reference.");
        if (pending.isSignal) {
            SignalInfo *signal = FindSignalByName(*frame, pending.signalName);
            if (!signal)
                throw DbcDiagnosticError(DbcDiagnosticCode::InvalidStatement, filePath,
                                         pending.lineNumber, "Unresolved CM_ signal reference: " + pending.signalName);
            signal->comment = pending.comment;
        } else {
            frame->comment = pending.comment;
        }
    }
}

DbcStatementDispatcher::DbcStatementDispatcher() {
    RegisterType<DbcHeaderHandler>("VERSION");
    RegisterType<DbcHeaderHandler>("NS_");
    RegisterType<DbcHeaderHandler>("NS_:");
    RegisterType<DbcHeaderHandler>("BS_");
    RegisterType<DbcHeaderHandler>("BS_:");
    RegisterType<DbcHeaderHandler>("BU_");
    RegisterType<DbcHeaderHandler>("BU_:");
    RegisterType<DbcMultiplexingHandler>("SG_MUL_VAL_");
    RegisterType<DbcFrameHandler>("BO_");
    RegisterType<DbcSignalHandler>("SG_");
    RegisterType<DbcUnsupportedSignalTypeHandler>("SIG_VALTYPE_");
    RegisterType<DbcCommentHandler>("CM_");
    RegisterType<DbcValueDescriptionHandler>("VAL_");
    RegisterType<DbcAttributeHandler>("BA_DEF_");
    RegisterType<DbcAttributeHandler>("BA_DEF_DEF_");
    RegisterType<DbcAttributeHandler>("BA_");
}

void DbcUnsupportedSignalTypeHandler::Handle(const std::string &, DbcParseContext &) const {
    throw std::runtime_error("SIG_VALTYPE_ declarations are unsupported; refusing potentially incorrect integer decoding.");
}

void DbcHeaderHandler::Handle(const std::string &, DbcParseContext &) const {}

bool DbcStatementDispatcher::Dispatch(const std::string &line,
                                      DbcParseContext &context) const {
    std::istringstream stream(line);
    std::string keyword;
    stream >> keyword;
    const HandlerMap::const_iterator handler = m_handlers.find(keyword);
    if (handler == m_handlers.end())
        return false;
    handler->second->Handle(line, context);
    return true;
}

void DbcValueDescriptionHandler::Handle(const std::string &line, DbcParseContext &context) const {
    static const std::regex header(R"(^VAL_[ \t]+([^ \t]+)[ \t]+([^ \t;]+)[ \t]+(.*)$)");
    static const std::regex pair(R"dbc(^([^ \t]+)[ \t]+"((?:[^"\\]|\\["\\])*)")dbc");
    std::smatch fields;
    if (!std::regex_match(line, fields, header))
        throw std::runtime_error("Malformed or unsupported VAL_ statement.");
    const std::uint32_t rawId = ParseDecimal(fields[1].str(), std::numeric_limits<std::uint32_t>::max(), "VAL_ CAN ID");
    if ((rawId & 0x60000000U) != 0U)
        throw std::runtime_error("VAL_ CAN ID exceeds the 29-bit identifier range.");
    PendingValueDescriptions pending;
    NormalizeCanId(rawId, pending.canId, pending.isExtended);
    pending.signalName = fields[2].str();
    pending.lineNumber = context.lineNumber;
    std::string rest = fields[3].str();
    while (rest != ";") {
        if (!std::regex_search(rest, fields, pair))
            throw std::runtime_error("Malformed VAL_ value/description pair or missing semicolon.");
        const std::string number = fields[1].str();
        const RawSignalValue key = ParseValueKey(number);
        const std::string description = UnescapeDescription(fields[2].str());
        if (!pending.descriptions.emplace(key, description).second)
            throw std::runtime_error("Duplicate VAL_ value key: " + number);
        const std::size_t consumed = static_cast<std::size_t>(fields.length());
        rest.erase(0, consumed);
        if (!rest.empty() && rest[0] != ';' && rest[0] != ' ' && rest[0] != '\t')
            throw std::runtime_error("Missing whitespace between VAL_ pairs.");
        rest = dbc_detail::TrimText(rest);
    }
    if (pending.descriptions.empty())
        throw std::runtime_error("VAL_ requires at least one value/description pair.");
    context.pendingValues.push_back(std::move(pending));
}

void DbcParseContext::ResolveValueDescriptions(const std::string &filePath) {
    for (const PendingValueDescriptions &pending: pendingValues) {
        try {
            FrameInfo *frame = FindUniqueFrame(database, pending.canId, pending.isExtended);
            SignalInfo *signal = FindUniqueSignal(*frame, pending.signalName);
            for (const ValueDescriptions::value_type &entry: pending.descriptions) {
                if (!signal->valueDescriptions.insert(entry).second)
                    throw std::runtime_error("Duplicate VAL_ value key for signal: " + pending.signalName);
            }
        } catch (const std::exception &error) {
            throw DbcDiagnosticError(DbcDiagnosticCode::InvalidValueDescription,
                                     filePath, pending.lineNumber, error.what());
        }
    }
}

void DbcMultiplexingHandler::Handle(const std::string &line, DbcParseContext &context) const {
    static const std::regex syntax(R"(^SG_MUL_VAL_[ \t]+([0-9]+)[ \t]+([^ \t;]+)[ \t]+([^ \t;]+)[ \t]+(.+);[ \t]*$)");
    static const std::regex rangeSyntax(R"(^[ \t]*([0-9]+)[ \t]*-[ \t]*([0-9]+)[ \t]*$)");
    std::smatch fields;
    if (!std::regex_match(line, fields, syntax))
        throw std::runtime_error("Malformed SG_MUL_VAL_ statement.");
    PendingMultiplexing pending;
    NormalizeCanId(ParseCanId(fields[1].str()), pending.canId, pending.isExtended);
    pending.signalName = fields[2].str();
    pending.selectorName = fields[3].str();
    pending.lineNumber = context.lineNumber;
    const std::string list = fields[4].str();
    std::size_t begin = 0U;
    for (;;) {
        const std::size_t comma = list.find(',', begin);
        const std::string item = list.substr(begin, comma == std::string::npos ? comma : comma - begin);
        if (!std::regex_match(item, fields, rangeSyntax))
            throw std::runtime_error("Malformed multiplex range.");
        MultiplexRange range;
        const std::string lower = fields[1].str();
        const std::string upper = fields[2].str();
        const std::from_chars_result low = std::from_chars(lower.data(), lower.data() + lower.size(), range.minimum);
        const std::from_chars_result high = std::from_chars(upper.data(), upper.data() + upper.size(), range.maximum);
        if (low.ec != std::errc() || high.ec != std::errc() || range.minimum > range.maximum)
            throw std::runtime_error("Invalid multiplex range.");
        pending.ranges.push_back(range);
        if (comma == std::string::npos)
            break;
        begin = comma + 1U;
    }
    context.pendingMultiplexing.push_back(std::move(pending));
}

void DbcParseContext::ResolveMultiplexing(const std::string &filePath) {
    for (const PendingMultiplexing &pending: pendingMultiplexing) {
        try {
            FrameInfo *frame = FindUniqueFrame(database, pending.canId, pending.isExtended, "SG_MUL_VAL_");
            SignalInfo *signal = FindUniqueSignal(*frame, pending.signalName, "SG_MUL_VAL_");
            SignalInfo *selector = FindUniqueSignal(*frame, pending.selectorName, "SG_MUL_VAL_");
            if (!IsMultiplexSelector(selector->multiplexing.role) || selector->isSigned)
                throw std::runtime_error("Referenced signal must be an unsigned multiplex selector.");
            if (!signal->multiplexing.selector.empty() && signal->multiplexing.selector != pending.selectorName)
                throw std::runtime_error("Multiple parent selectors for one signal are unsupported.");
            for (const MultiplexRange &range: pending.ranges) {
                if (selector->length < 64U && range.maximum >= (std::uint64_t(1U) << selector->length))
                    throw std::runtime_error("Branch value exceeds selector raw range.");
            }
            signal->multiplexing.selector = pending.selectorName;
            signal->multiplexing.ranges.insert(signal->multiplexing.ranges.end(), pending.ranges.begin(), pending.ranges.end());
            if (!IsMultiplexSelector(signal->multiplexing.role))
                signal->multiplexing.role = MultiplexRole::Branch;
            else
                signal->multiplexing.role = MultiplexRole::BranchSelector;
        } catch (const std::exception &error) {
            throw DbcDiagnosticError(DbcDiagnosticCode::InvalidMultiplexing, filePath, pending.lineNumber, error.what());
        }
    }
}

namespace {
    std::vector<std::uint64_t> SignalBits(const SignalInfo &signal) {
        std::vector<std::uint64_t> bits;
        std::uint64_t bit = signal.startBit;
        for (std::uint32_t index = 0U; index < signal.length; ++index) {
            bits.push_back(bit);
            bit = NextSignalBit(bit, signal.isLittleEndian);
        }
        return bits;
    }

    bool SignalsOverlap(const SignalInfo &first, const SignalInfo &second) {
        const std::vector<std::uint64_t> firstBits = SignalBits(first);
        const std::vector<std::uint64_t> secondBits = SignalBits(second);
        for (const std::uint64_t firstBit : firstBits) {
            for (const std::uint64_t secondBit : secondBits) {
                if (firstBit == secondBit)
                    return true;
            }
        }
        return false;
    }
}

void DbcParseContext::ValidateMultiplexing(const std::string &filePath) const {
    for (std::size_t frameIndex = 0U; frameIndex < database.frames.size(); ++frameIndex) {
        const FrameInfo &frame = database.frames[frameIndex];
        try {
            const dbc_detail::MultiplexGraph graph(frame.signals);
            for (std::size_t index = 0U; index < frame.signals.size(); ++index) {
                const SignalInfo &signal = frame.signals[index];
                if (IsMultiplexSelector(signal.multiplexing.role) && signal.isSigned)
                    throw dbc_detail::MultiplexError(index, "Multiplex selectors must be unsigned.");
                for (std::size_t previous = 0U; previous < index; ++previous) {
                    if (!graph.AreMutuallyExclusive(index, previous) && SignalsOverlap(signal, frame.signals[previous]))
                        throw dbc_detail::MultiplexError(index, "Signals overlap without mutually exclusive multiplexing conditions.");
                }
            }
        } catch (const dbc_detail::MultiplexError &error) {
            throw DbcDiagnosticError(DbcDiagnosticCode::InvalidMultiplexing, filePath,
                                     signalLines[frameIndex][error.index], error.what());
        }
    }
}