#include "domain/hmi_model.h"
#include "domain/project_limits.h"
#include "domain/register_repository.h"
#include "domain/virtual_register_repository.h"
#include "services/hmi_runtime_service.h"
#include "services/offline_simulation_service.h"
#include "services/online_logic_monitor_service.h"
#include "services/software_logic_executor.h"
#include "support/test_support.h"

#include <QCoreApplication>

#include <array>
#include <iostream>
#include <stdexcept>
#include <string>
#include <vector>

namespace {

using TestSupport::require;

LogicNode contact(const std::string &id, int address,
                  ContactMode mode = ContactMode::NormallyOpen)
{
    return {id, ContactNodeConfig{RegisterAddress{RegisterArea::M, address}, mode}, true};
}

LogicNode edgeContact(const std::string &id, int address, EdgeMode mode)
{
    return {id,
            EdgeContactNodeConfig{
                RegisterAddress{RegisterArea::M, address}, mode},
            true};
}

WordOperand constantOperand(std::int16_t value)
{
    return {
        WordOperandKind::Constant,
        RegisterAddress{RegisterArea::D, 0},
        value};
}

WordOperand registerOperand(int address)
{
    return {
        WordOperandKind::Register,
        RegisterAddress{RegisterArea::D, address},
        0};
}

LogicNode move(
    const std::string &id,
    WordOperand source,
    int destination)
{
    return {
        id,
        MoveNodeConfig{
            source,
            RegisterAddress{RegisterArea::D, destination}},
        true};
}

LogicNode arithmetic(
    const std::string &id,
    ArithmeticOperation operation,
    WordOperand left,
    WordOperand right,
    int destination)
{
    return {
        id,
        ArithmeticNodeConfig{
            operation,
            left,
            right,
            RegisterAddress{RegisterArea::D, destination}},
        true};
}

LogicNode comparison(const std::string &id, int address,
                     ComparisonOperator operation, std::int16_t value)
{
    return {id,
            CompareNodeConfig{RegisterAddress{RegisterArea::D, address}, operation, value},
            true};
}

LogicNode coil(const std::string &id, int address,
               CoilMode mode = CoilMode::Normal)
{
    return {id, CoilNodeConfig{RegisterAddress{RegisterArea::M, address}, mode}, true};
}

LadderRung rung(const std::string &id,
                const std::vector<std::vector<LogicNode>> &stages,
                const LogicNode &output)
{
    LadderRung result;
    result.id = id;
    result.name = id;
    std::vector<ConditionExpression> series_children;
    for (std::size_t index = 0; index < stages.size(); ++index)
    {
        std::vector<ConditionExpression> parallel_children;
        for (const LogicNode &node : stages[index])
        {
            parallel_children.push_back(ConditionExpression::fromNode(node));
        }
        if (parallel_children.size() == 1U)
        {
            series_children.push_back(std::move(parallel_children.front()));
        }
        else
        {
            ConditionExpression parallel;
            parallel.id = id + "-parallel-" + std::to_string(index);
            parallel.kind = ConditionExpressionKind::Parallel;
            parallel.children = std::move(parallel_children);
            series_children.push_back(std::move(parallel));
        }
    }
    if (series_children.size() == 1U)
    {
        result.condition = std::move(series_children.front());
    }
    else
    {
        ConditionExpression series;
        series.id = id + "-series";
        series.kind = ConditionExpressionKind::Series;
        series.children = std::move(series_children);
        result.condition = std::move(series);
    }
    const int occupied_columns = static_cast<int>(stages.size());
    if (occupied_columns < ProjectLimits::kMaximumConditionColumns)
    {
        ConditionExpression wire = ConditionExpression::fromWire(
            id + "-output-wire",
            ProjectLimits::kMaximumConditionColumns - occupied_columns);
        if (result.condition->kind == ConditionExpressionKind::Series)
        {
            result.condition->children.push_back(std::move(wire));
        }
        else
        {
            ConditionExpression series;
            series.id = id + "-explicit-series";
            series.kind = ConditionExpressionKind::Series;
            series.children.push_back(std::move(*result.condition));
            series.children.push_back(std::move(wire));
            result.condition = std::move(series);
        }
    }
    result.output = output;
    return result;
}

ControlLogic logic(const std::vector<LadderRung> &rungs)
{
    return {"logic-1", "logic-1", rungs, true};
}

bool readBit(RegisterRepository &repository, int address)
{
    const BitReadResult result = repository.readBit(
        RegisterAddress{RegisterArea::M, address});
    require(result.succeeded, "test register read must succeed");
    return result.value;
}

void writeBit(RegisterRepository &repository, int address, bool value)
{
    require(repository.writeBit(RegisterAddress{RegisterArea::M, address}, value).succeeded,
            "test bit write must succeed");
}

void writeWord(RegisterRepository &repository, int address, std::int16_t value)
{
    require(repository.writeWord(RegisterAddress{RegisterArea::D, address}, value).succeeded,
            "test word write must succeed");
}

std::int16_t readWord(RegisterRepository &repository, int address)
{
    const WordReadResult result = repository.readWord(
        RegisterAddress{RegisterArea::D, address});
    require(result.succeeded, "test word read must succeed");
    return result.value;
}

void testNestedSeriesParallelExpression()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    ConditionExpression nested_series;
    nested_series.id = "nested-series";
    nested_series.kind = ConditionExpressionKind::Series;
    nested_series.children = {
        ConditionExpression::fromNode(contact("b", 1)),
        ConditionExpression::fromNode(contact("c", 2))};
    ConditionExpression padded_a;
    padded_a.id = "padded-a";
    padded_a.kind = ConditionExpressionKind::Series;
    padded_a.children = {
        ConditionExpression::fromNode(contact("a", 0)),
        ConditionExpression::fromWire("a-branch-wire", 1)};
    ConditionExpression parallel;
    parallel.id = "root-parallel";
    parallel.kind = ConditionExpressionKind::Parallel;
    parallel.children = {std::move(padded_a), nested_series};
    ConditionExpression root;
    root.id = "nested-output-series";
    root.kind = ConditionExpressionKind::Series;
    root.children = {
        std::move(parallel),
        ConditionExpression::fromWire("nested-output-wire", 8)};
    LadderRung nested_rung;
    nested_rung.id = "nested-rung";
    nested_rung.name = "nested-rung";
    nested_rung.condition = root;
    nested_rung.output = coil("nested-output", 10);
    const ControlLogic program = logic({nested_rung});

    writeBit(repository, 1, true);
    writeBit(repository, 2, true);
    LogicTraceSnapshot trace;
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "nested expression scan must succeed");
    require(readBit(repository, 10), "B AND C branch must energize A OR (B AND C)");
    require(trace.expressionValues.at("nested-series")
                && trace.expressionValues.at("root-parallel")
                && trace.rungValues.at("nested-rung"),
            "scan trace must expose active nested expression and rung values");

    writeBit(repository, 2, false);
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "nested false scan must succeed");
    require(!readBit(repository, 10), "incomplete B AND C branch must be false");
    writeBit(repository, 0, true);
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "alternate branch scan must succeed");
    require(readBit(repository, 10), "A branch must independently energize output");
}

void testUnconditionalCoil()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    LadderRung unconditional;
    unconditional.id = "unconditional-rung";
    unconditional.name = "unconditional-rung";
    unconditional.condition = ConditionExpression::fromWire(
        "unconditional-wire", ProjectLimits::kMaximumConditionColumns);
    unconditional.output = coil("unconditional-coil", 10);
    const ControlLogic program = logic({unconditional});

    LogicTraceSnapshot trace;
    require(executor.validate({program}).succeeded,
            "a full-width wire network must pass runtime validation");
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "a full-width wire network scan must succeed");
    require(readBit(repository, 10),
            "a full-width wire network must energize its coil as a constant-true rung");
    require(trace.rungValues.at("unconditional-rung")
                && trace.nodePowerValues.at("unconditional-coil"),
            "an unconditional rung must report energized power flow");
}

void testWirePassThroughAndPowerTrace()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    ConditionExpression root;
    root.id = "wire-series";
    root.kind = ConditionExpressionKind::Series;
    root.children = {
        ConditionExpression::fromNode(contact("wire-input", 0)),
        ConditionExpression::fromWire("wire-segment", 2),
        ConditionExpression::fromNode(contact("wire-output", 1)),
        ConditionExpression::fromWire("wire-output-padding", 6)};
    LadderRung wired_rung;
    wired_rung.id = "wired-rung";
    wired_rung.name = "wired-rung";
    wired_rung.condition = root;
    wired_rung.output = coil("wired-coil", 10);
    const ControlLogic program = logic({wired_rung});

    writeBit(repository, 1, true);
    LogicTraceSnapshot trace;
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "wire expression scan must succeed");
    require(!readBit(repository, 10),
            "a horizontal wire must not bypass a false upstream series contact");
    require(trace.expressionValues.at("wire-segment")
                && !trace.expressionInputValues.at("wire-segment")
                && !trace.expressionPowerValues.at("wire-segment"),
            "a wire must remain logically true without showing false upstream power");

    writeBit(repository, 0, true);
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "powered wire expression scan must succeed");
    require(readBit(repository, 10)
                && trace.expressionInputValues.at("wire-segment")
                && trace.expressionPowerValues.at("wire-segment"),
            "a powered horizontal wire must pass current to the downstream contact");
}

void testSeriesParallelContactsAndSequentialVisibility()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    const ControlLogic program = logic({
        rung("rung-1",
             {{contact("start", 0), contact("alternate", 1)},
              {contact("stop", 2, ContactMode::NormallyClosed)}},
             coil("run", 3)),
        rung("rung-2", {{contact("run-feedback", 3)}}, coil("downstream", 4))});

    writeBit(repository, 1, true);
    require(executor.executeScan({program}, repository).succeeded,
            "parallel and series scan must succeed");
    require(readBit(repository, 3), "parallel OR and series AND must energize output");
    require(readBit(repository, 4),
            "a later rung must see an earlier rung write in the same scan");

    writeBit(repository, 2, true);
    require(executor.executeScan({program}, repository).succeeded,
            "normally closed scan must succeed");
    require(!readBit(repository, 3), "normally closed stop contact must open the rung");
    require(!readBit(repository, 4), "downstream normal coil must follow the new value");
}

void testAllComparisons()
{
    const std::array<ComparisonOperator, 6> operations{
        ComparisonOperator::Equal, ComparisonOperator::NotEqual,
        ComparisonOperator::LessThan, ComparisonOperator::LessThanOrEqual,
        ComparisonOperator::GreaterThan, ComparisonOperator::GreaterThanOrEqual};
    const std::array<std::int16_t, 6> actual_values{10, 9, 9, 10, 11, 10};

    for (std::size_t index = 0; index < operations.size(); ++index)
    {
        VirtualRegisterRepository repository;
        SoftwareLogicExecutor executor;
        writeWord(repository, 0, actual_values[index]);
        const ControlLogic program = logic({
            rung("compare-rung", {{comparison("compare", 0, operations[index], 10)},
                                   }, coil("result", 10))});
        require(executor.executeScan({program}, repository).succeeded,
                "comparison scan must succeed");
        require(readBit(repository, 10), "comparison operator must evaluate true");
    }
}

void testSetResetAndDisabledLogic()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    ControlLogic program = logic({
        rung("set-rung", {{contact("set-input", 0)}}, coil("set-output", 5, CoilMode::Set)),
        rung("reset-rung", {{contact("reset-input", 1)}},
             coil("reset-output", 6, CoilMode::Reset))});

    writeBit(repository, 0, true);
    require(executor.executeScan({program}, repository).succeeded, "set scan must succeed");
    require(readBit(repository, 5), "set coil must latch true");
    writeBit(repository, 0, false);
    require(executor.executeScan({program}, repository).succeeded,
            "inactive set scan must succeed");
    require(readBit(repository, 5), "inactive set coil must retain its value");
    writeBit(repository, 1, true);
    writeBit(repository, 6, true);
    require(executor.executeScan({program}, repository).succeeded,
            "reset scan must succeed");
    require(!readBit(repository, 6), "reset coil must write false");

    program.enabled = false;
    writeBit(repository, 5, true);
    require(executor.executeScan({program}, repository).succeeded,
            "disabled logic scan must be ignored successfully");
    require(readBit(repository, 5), "disabled logic must not change outputs");
}

void testMultipleLogicScanOrderAndTraceIsolation()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    ControlLogic first = logic({
        rung("rung-1", {{contact("input", 0)}}, coil("output", 1))});
    first.id = "logic-first";
    first.name = "First";
    ControlLogic second = logic({
        rung("rung-1", {{contact("input", 1)}}, coil("output", 2))});
    second.id = "logic-second";
    second.name = "Second";

    writeBit(repository, 0, true);
    LogicTraceSnapshot trace;
    require(executor.executeScan({first, second}, repository, &trace).succeeded,
            "all enabled logic modules must execute in project order");
    require(readBit(repository, 1) && readBit(repository, 2),
            "a later logic module must observe an earlier module write in one scan");
    require(trace.logicValues.size() == 2U
                && trace.forLogic(first.id).rungValues.at("rung-1")
                && trace.forLogic(second.id).rungValues.at("rung-1"),
            "runtime traces must be partitioned by logic id when node ids repeat");

    ControlLogic disabled_draft;
    disabled_draft.id = "logic-draft";
    disabled_draft.name = "Draft";
    disabled_draft.enabled = false;
    disabled_draft.rungs.push_back(
        {"rung-1", "Draft", {}, std::nullopt, std::nullopt});
    require(executor.validate({first, disabled_draft}).succeeded,
            "a disabled incomplete logic module must not block offline execution");
}

void testEdgeContactsAreOneScanPulsesAndAreLogicScoped()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    const ControlLogic program = logic({
        rung("rising-rung", {{edgeContact("rising", 0, EdgeMode::Rising)}},
             coil("rising-output", 10)),
        rung("falling-rung", {{edgeContact("falling", 1, EdgeMode::Falling)}},
             coil("falling-output", 11))});

    writeBit(repository, 0, true);
    require(executor.executeScan({program}, repository).succeeded,
            "the first high scan must evaluate rising edge input");
    require(readBit(repository, 10), "rising edge must pulse on OFF to ON");
    require(!readBit(repository, 11), "falling edge must stay off without ON to OFF");
    require(executor.executeScan({program}, repository).succeeded,
            "a repeated high scan must succeed");
    require(!readBit(repository, 10), "rising edge must clear after one scan");

    writeBit(repository, 1, true);
    require(executor.executeScan({program}, repository).succeeded,
            "the falling edge input must establish its previous high state");
    writeBit(repository, 1, false);
    require(executor.executeScan({program}, repository).succeeded,
            "the first low scan after high must succeed");
    require(readBit(repository, 11), "falling edge must pulse on ON to OFF");
    require(executor.executeScan({program}, repository).succeeded,
            "a repeated low scan must succeed");
    require(!readBit(repository, 11), "falling edge must clear after one scan");

    ControlLogic first = logic({
        rung("shared-rung-first", {{edgeContact("shared-edge", 2, EdgeMode::Rising)}},
             coil("shared-output-first", 20))});
    first.id = "logic-first";
    first.name = "First";
    ControlLogic second = logic({
        rung("shared-rung-second", {{edgeContact("shared-edge", 3, EdgeMode::Rising)}},
             coil("shared-output-second", 21))});
    second.id = "logic-second";
    second.name = "Second";
    writeBit(repository, 2, true);
    require(executor.executeScan({first, second}, repository).succeeded,
            "logic-scoped edge history must support duplicate node ids");
    writeBit(repository, 3, true);
    require(executor.executeScan({first, second}, repository).succeeded,
            "each duplicate edge node must update its own history");
    require(!readBit(repository, 20) && readBit(repository, 21),
            "duplicate node ids in different logic modules must not share edge history");

    executor.resetRuntime();
    require(executor.executeScan({first, second}, repository).succeeded,
            "resetting runtime must clear edge history");
    require(readBit(repository, 20) && readBit(repository, 21),
            "a restarted runtime must treat current ON inputs as fresh rising edges");
}

void testMoveAndSaturatingArithmetic()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    const ControlLogic program = logic({
        rung(
            "move-rung",
            {{contact("execute", 0)}},
            move("move", constantOperand(7), 10)),
        rung(
            "add-rung",
            {{contact("execute-add", 0)}},
            arithmetic(
                "add",
                ArithmeticOperation::Add,
                registerOperand(10),
                constantOperand(32767),
                11)),
        rung(
            "sub-rung",
            {{contact("execute-sub", 0)}},
            arithmetic(
                "sub",
                ArithmeticOperation::Subtract,
                constantOperand(-32768),
                constantOperand(1),
                12))});
    LogicTraceSnapshot trace;

    require(executor.executeScan({program}, repository, &trace).succeeded,
            "inactive data instructions must scan successfully");
    require(readWord(repository, 10) == 0,
            "MOVE must not write while its rung is false");

    writeBit(repository, 0, true);
    require(executor.executeScan({program}, repository, &trace).succeeded,
            "active data instructions must scan successfully");
    require(readWord(repository, 10) == 7,
            "MOVE must copy a constant into the destination D register");
    require(readWord(repository, 11) == 32767
                && trace.wordValues.at("add").overflow,
            "ADD must saturate positive overflow and expose the overflow trace");
    require(readWord(repository, 12) == -32768
                && trace.wordValues.at("sub").overflow,
            "SUB must saturate negative overflow and expose the overflow trace");

    const ControlLogic repeated_add = logic({
        rung(
            "repeated-add-rung",
            {{contact("repeated-add-input", 1)}},
            arithmetic(
                "repeated-add",
                ArithmeticOperation::Add,
                registerOperand(20),
                constantOperand(1),
                20))});
    writeBit(repository, 1, true);
    require(executor.executeScan({repeated_add}, repository).succeeded
                && executor.executeScan({repeated_add}, repository).succeeded,
            "ADD must execute on every scan while its rung remains true");
    require(readWord(repository, 20) == 2,
            "ADD with the same source and destination must accumulate by scan");
}

void testSetResetPairOnSameAddress()
{
    VirtualRegisterRepository repository;
    SoftwareLogicExecutor executor;
    const ControlLogic program = logic({
        rung("low-level-rung",
             {{comparison("low-level", 0,
                          ComparisonOperator::LessThanOrEqual, 30)}},
             coil("pump-set", 20, CoilMode::Set)),
        rung("high-level-rung",
             {{comparison("high-level", 0,
                          ComparisonOperator::GreaterThanOrEqual, 80)}},
             coil("pump-reset", 20, CoilMode::Reset))});

    writeWord(repository, 0, 20);
    require(executor.executeScan({program}, repository).succeeded,
            "set/reset pair scan must succeed at the low limit");
    require(readBit(repository, 20), "low level must latch the pump on");

    writeWord(repository, 0, 50);
    require(executor.executeScan({program}, repository).succeeded,
            "set/reset pair scan must succeed inside the deadband");
    require(readBit(repository, 20), "deadband must retain the latched on state");

    writeWord(repository, 0, 90);
    require(executor.executeScan({program}, repository).succeeded,
            "set/reset pair scan must succeed at the high limit");
    require(!readBit(repository, 20), "high level must reset the pump");

    writeWord(repository, 0, 50);
    require(executor.executeScan({program}, repository).succeeded,
            "set/reset pair rescan must succeed inside the deadband");
    require(!readBit(repository, 20), "deadband must retain the reset state");
}

void testConflictingCoilsAreRejected()
{
    SoftwareLogicExecutor executor;
    const ControlLogic normal_and_set = logic({
        rung("normal-rung", {{contact("normal-input", 0)}}, coil("normal", 8)),
        rung("set-rung", {{contact("set-input", 1)}}, coil("set", 8, CoilMode::Set))});
    const LogicScanResult set_result = executor.validate({normal_and_set});
    require(!set_result.succeeded
                && set_result.error == LogicScanError::ConflictingOutput,
            "normal and set coils for one address must be rejected");
    require(set_result.rungId == "set-rung" && set_result.nodeId == "set",
            "conflict error must identify the offending rung and node");

    const ControlLogic reset_and_normal = logic({
        rung("reset-rung", {{contact("reset-input", 0)}},
             coil("reset", 9, CoilMode::Reset)),
        rung("normal-rung", {{contact("normal-input", 1)}}, coil("normal", 9))});
    const LogicScanResult reset_result = executor.validate({reset_and_normal});
    require(!reset_result.succeeded
                && reset_result.error == LogicScanError::ConflictingOutput,
            "reset and normal coils for one address must be rejected");
}

void testHmiSimulationClosedLoop()
{
    VirtualRegisterRepository repository;
    HmiRuntimeService hmi(repository);
    SoftwareLogicExecutor executor;
    HmiControl start;
    start.id = "start-button";
    start.type = HmiControlType::Button;
    start.bounds = {0, 0, 80, 30};
    start.text = "start";
    start.binding = RegisterAddress{RegisterArea::M, 0};
    start.buttonOperation = HmiButtonOperation::MomentaryOn;
    HmiControl indicator;
    indicator.id = "run-indicator";
    indicator.type = HmiControlType::Indicator;
    indicator.bounds = {0, 40, 80, 30};
    indicator.text = "run";
    indicator.binding = RegisterAddress{RegisterArea::M, 2};
    const ControlLogic program = logic({
        rung("hold-rung",
             {{contact("stop", 1, ContactMode::NormallyClosed)},
              {contact("start", 0), contact("feedback", 2)}},
             coil("run", 2))});

    require(hmi.operateButton(start, HmiButtonEvent::Pressed).succeeded,
            "HMI start button press must write virtual M");
    require(executor.executeScan({program}, repository).succeeded,
            "closed-loop scan must succeed");
    require(hmi.readControl(indicator).bit_value,
            "HMI indicator must observe the logic output");
    require(hmi.operateButton(start, HmiButtonEvent::Released).succeeded,
            "HMI start button release must write virtual M");
    require(executor.executeScan({program}, repository).succeeded, "holding scan must succeed");
    require(hmi.readControl(indicator).bit_value,
            "feedback contact must hold the output after start turns off");
    writeBit(repository, 1, true);
    require(executor.executeScan({program}, repository).succeeded, "stop scan must succeed");
    require(!hmi.readControl(indicator).bit_value,
            "stop contact must clear the HMI run indication");
}

void testSimulationLifecycleSnapshotAndFault()
{
    VirtualRegisterRepository repository;
    OfflineSimulationService simulation(repository);
    ControlLogic program = logic({
        rung("snapshot-rung", {{contact("input", 0)}}, coil("output", 1))});
    writeBit(repository, 0, true);
    require(simulation.start({program}).succeeded, "simulation must start");
    require(simulation.state() == SimulationState::Running, "simulation must report running");
    require(!readBit(repository, 0), "starting a session must clear virtual registers");
    require(simulation.scanIntervalMs() == 50, "default scan interval must be 50 ms");
    writeBit(repository, 0, true);
    program.rungs.front().output = coil("changed-output", 9);
    require(simulation.executeOnce().succeeded, "manual lifecycle scan must succeed");
    require(readBit(repository, 1), "simulation must use its start-time snapshot");
    require(simulation.successfulScanCount() == 1, "successful scans must be counted");
    simulation.stop();
    require(simulation.state() == SimulationState::Stopped, "simulation must stop");
    require(simulation.start({program}).succeeded, "stopped simulation must support restart");
    require(!readBit(repository, 1), "new session must clear prior output values");
    simulation.stop();
}

void testSimulationUsesInitialValuesAndDiscardsRuntimeOutputs()
{
    VirtualRegisterRepository repository;
    VirtualRegisterRepository initial_repository;
    OfflineSimulationService simulation(repository, &initial_repository);
    const ControlLogic program = logic({
        rung("initial-rung", {{contact("initial-input", 0)}}, coil("runtime-output", 1))});

    writeBit(initial_repository, 0, true);
    writeWord(initial_repository, 10, 321);
    require(simulation.start({program}).succeeded,
            "simulation must start from the explicit initial repository");
    require(readBit(repository, 0)
                && readWord(repository, 10) == 321,
            "simulation startup must copy initial M/D values into its runtime repository");
    require(simulation.executeOnce().succeeded && readBit(repository, 1),
            "simulation must execute against the copied initial values");
    simulation.stop();
    require(!readBit(repository, 1)
                && readBit(repository, 0)
                && readWord(repository, 10) == 321,
            "stopping simulation must restore initial values instead of runtime outputs");

    writeBit(initial_repository, 0, false);
    require(simulation.start({program}).succeeded,
            "simulation must support restart with changed initial values");
    require(!readBit(repository, 0) && !readBit(repository, 1),
            "restart must use the latest initial values and discard the previous output");
    simulation.stop();
}

class FailingVirtualRegisterRepository final : public VirtualRegisterRepository
{
public:
    BitReadResult readBit(const RegisterAddress &) const override
    {
        return {false, false, RegisterError::Unavailable};
    }
};

void testRepositoryFailureEntersFaultState()
{
    FailingVirtualRegisterRepository repository;
    OfflineSimulationService simulation(repository);
    const ControlLogic program = logic({
        rung("fault-rung", {{contact("fault-input", 0)}}, coil("fault-output", 1))});

    require(simulation.start({program}).succeeded,
            "valid logic must pass simulation startup");
    const LogicScanResult result = simulation.executeOnce();
    require(!result.succeeded && result.error == LogicScanError::RegisterReadFailed,
            "repository read failure must fail the scan");
    require(simulation.state() == SimulationState::Faulted,
            "repository failure must enter the fault state");
    require(simulation.lastError().logicId == "logic-1"
                && simulation.lastError().rungId == "fault-rung"
                && simulation.lastError().nodeId == "fault-input",
            "fault feedback must retain logic, rung and node context");
}

void testOnlineMonitorUsesTemporaryRegistersWithoutWritingPlcSource()
{
    VirtualRegisterRepository plc_source;
    OnlineLogicMonitorService monitor(plc_source);
    const ControlLogic program = logic({
        rung("online-rung-1", {{contact("online-input", 0)}},
             coil("online-output-1", 1)),
        rung("online-rung-2", {{contact("online-feedback", 1)}},
             coil("online-output-2", 2))});

    writeBit(plc_source, 0, true);
    require(monitor.start({program}).succeeded,
            "online monitor must start from the PLC source snapshot");
    const LogicTraceSnapshot &first_trace = monitor.traceSnapshot();
    require(first_trace.rungValues.at("online-rung-1")
                && first_trace.rungValues.at("online-rung-2"),
            "a local output must be visible to later rungs in the same temporary scan");
    require(!readBit(plc_source, 1) && !readBit(plc_source, 2),
            "local trace outputs must never change the PLC source repository");

    writeBit(plc_source, 0, false);
    require(monitor.executeOnce().succeeded,
            "a new PLC snapshot must support another local trace scan");
    const LogicTraceSnapshot &second_trace = monitor.traceSnapshot();
    require(!second_trace.rungValues.at("online-rung-1")
                && !second_trace.rungValues.at("online-rung-2"),
            "each local scan must restart from the latest PLC source values");
    require(!readBit(plc_source, 1) && !readBit(plc_source, 2),
            "repeated local scans must remain read-only toward the PLC source");
}

void testOnlineMonitorPreservesFaultAfterStopping()
{
    FailingVirtualRegisterRepository plc_source;
    OnlineLogicMonitorService monitor(plc_source);
    const ControlLogic program = logic({
        rung("online-fault-rung", {{contact("online-fault-input", 0)}},
             coil("online-fault-output", 1))});

    const OnlineLogicMonitorStartResult start = monitor.start({program});
    require(!start.succeeded
                && start.detail.error == LogicScanError::RegisterReadFailed,
            "an online snapshot failure must be reported at startup");
    monitor.stop();
    require(monitor.state() == OnlineLogicMonitorState::Stopped,
            "stopping a failed online monitor must leave it stopped");
    require(!monitor.lastError().succeeded
                && monitor.lastError().error == LogicScanError::RegisterReadFailed,
            "stopping after a local trace fault must preserve its diagnostic");
}

} // namespace

int main(int argc, char *argv[])
{
    QCoreApplication application(argc, argv);
    try
    {
        testSeriesParallelContactsAndSequentialVisibility();
        testNestedSeriesParallelExpression();
        testUnconditionalCoil();
        testWirePassThroughAndPowerTrace();
        testAllComparisons();
        testSetResetAndDisabledLogic();
        testMultipleLogicScanOrderAndTraceIsolation();
        testEdgeContactsAreOneScanPulsesAndAreLogicScoped();
        testMoveAndSaturatingArithmetic();
        testSetResetPairOnSameAddress();
        testConflictingCoilsAreRejected();
        testHmiSimulationClosedLoop();
        testSimulationLifecycleSnapshotAndFault();
        testSimulationUsesInitialValuesAndDiscardsRuntimeOutputs();
        testRepositoryFailureEntersFaultState();
        testOnlineMonitorUsesTemporaryRegistersWithoutWritingPlcSource();
        testOnlineMonitorPreservesFaultAfterStopping();
    }
    catch (const std::exception &error)
    {
        std::cerr << "offline simulation service tests failed: " << error.what() << '\n';
        return 1;
    }
    std::cout << "offline simulation service tests passed\n";
    return 0;
}