#include "software_logic_executor.h"

#include <algorithm>
#include <limits>
#include <map>
#include <type_traits>

namespace {

LogicScanResult success()
{
    return {true, LogicScanError::None, {}, {}, {}, {}};
}

LogicScanResult failure(
    LogicScanError error,
    const std::string &message,
    const std::string &logic_id = {},
    const std::string &rung_id = {},
    const std::string &node_id = {})
{
    return {false, error, message, logic_id, rung_id, node_id};
}

bool compareWord(
    std::int16_t actual,
    ComparisonOperator comparison,
    std::int16_t expected)
{
    switch (comparison)
    {
    case ComparisonOperator::Equal:
    {
        return actual == expected;
    }
    case ComparisonOperator::NotEqual:
    {
        return actual != expected;
    }
    case ComparisonOperator::LessThan:
    {
        return actual < expected;
    }
    case ComparisonOperator::LessThanOrEqual:
    {
        return actual <= expected;
    }
    case ComparisonOperator::GreaterThan:
    {
        return actual > expected;
    }
    case ComparisonOperator::GreaterThanOrEqual:
    {
        return actual >= expected;
    }
    default:
    {
        return false;
    }
    }
}

bool coilModesAreCompatible(CoilMode existing, CoilMode current)
{
    if (existing == current)
    {
        return true;
    }
    return existing != CoilMode::Normal && current != CoilMode::Normal;
}

} // namespace

void LogicTraceValues::clear()
{
    nodeValues.clear();
    expressionValues.clear();
    rungValues.clear();
    tonValues.clear();
    counterValues.clear();
    wordValues.clear();
}

void LogicTraceSnapshot::clear()
{
    LogicTraceValues::clear();
    logicValues.clear();
}

LogicTraceSnapshot LogicTraceSnapshot::forLogic(
    const std::string &logic_id) const
{
    LogicTraceSnapshot projection;
    const auto values = logicValues.find(logic_id);
    if (values != logicValues.cend())
    {
        projection.nodeValues = values->second.nodeValues;
        projection.expressionValues = values->second.expressionValues;
        projection.rungValues = values->second.rungValues;
        projection.tonValues = values->second.tonValues;
        projection.counterValues = values->second.counterValues;
        projection.wordValues = values->second.wordValues;
    }
    return projection;
}

LogicScanResult SoftwareLogicExecutor::validate(
    const std::vector<ControlLogic> &logics) const
{
    std::map<int, CoilMode> output_modes;
    for (const ControlLogic &logic : logics)
    {
        std::string validation_error;
        if (!logic.validateStructure(&validation_error))
        {
            return failure(
                LogicScanError::InvalidLogic,
                validation_error,
                logic.id);
        }
        if (!logic.enabled)
        {
            continue;
        }
        if (!logic.validateForRunning(&validation_error))
        {
            return failure(
                LogicScanError::InvalidLogic,
                validation_error,
                logic.id);
        }
        for (const LadderRung &rung : logic.rungs)
        {
            if (!rung.output.has_value())
            {
                continue;
            }
            const auto *output = std::get_if<CoilNodeConfig>(&rung.output->config);
            if (output == nullptr)
            {
                if (std::holds_alternative<TonNodeConfig>(rung.output->config)
                    || std::holds_alternative<CounterNodeConfig>(rung.output->config)
                    || std::holds_alternative<MoveNodeConfig>(rung.output->config)
                    || std::holds_alternative<ArithmeticNodeConfig>(
                        rung.output->config))
                {
                    continue;
                }
                return failure(
                    LogicScanError::InvalidLogic,
                    "梯形图输出不是有效的输出指令",
                    logic.id,
                    rung.id,
                    rung.output->id);
            }
            const auto existing = output_modes.find(output->address.index());
            if (existing != output_modes.end()
                && !coilModesAreCompatible(existing->second, output->mode))
            {
                return failure(
                    LogicScanError::ConflictingOutput,
                    "同一地址使用了不同线圈模式：" + output->address.toString(),
                    logic.id,
                    rung.id,
                    rung.output->id);
            }
            output_modes[output->address.index()] = output->mode;
        }
    }
    std::string resource_error;
    if (!validateLogicResourceReferencesForRunning(logics, &resource_error))
    {
        return failure(LogicScanError::InvalidLogic, resource_error);
    }
    return success();
}

void SoftwareLogicExecutor::resetRuntime()
{
    previous_edge_inputs_.clear();
    previous_counter_inputs_.clear();
    ton_states_.clear();
    counter_states_.clear();
}

LogicScanResult SoftwareLogicExecutor::executeScan(
    const std::vector<ControlLogic> &logics,
    RegisterRepository &repository,
    LogicTraceSnapshot *trace)
{
    return executeScanAt(logics, repository, Clock::now(), trace);
}

LogicScanResult SoftwareLogicExecutor::executeScanAt(
    const std::vector<ControlLogic> &logics,
    RegisterRepository &repository,
    TimePoint now,
    LogicTraceSnapshot *trace)
{
    const LogicScanResult validation = validate(logics);
    if (!validation.succeeded)
    {
        return validation;
    }

    if (trace != nullptr)
    {
        trace->clear();
    }
    for (const ControlLogic &logic : logics)
    {
        if (!logic.enabled)
        {
            continue;
        }
        LogicTraceValues *logic_trace = trace == nullptr
            ? nullptr : &trace->logicValues[logic.id];
        for (const LadderRung &rung : logic.rungs)
        {
            if (!rung.condition.has_value() && !rung.output.has_value())
            {
                continue;
            }

            bool rung_value = false;
            LogicScanResult result = evaluateExpression(
                logic.id, *rung.condition, repository, logic_trace, &rung_value);
            if (!result.succeeded)
            {
                result.logicId = logic.id;
                result.rungId = rung.id;
                return result;
            }
            if (logic_trace != nullptr)
            {
                logic_trace->rungValues[rung.id] = rung_value;
                logic_trace->nodeValues[rung.output->id] = rung_value;
            }
            bool output_value = false;
            result = executeOutput(
                logic.id,
                *rung.output,
                rung_value,
                repository,
                now,
                logic_trace,
                &output_value);
            if (!result.succeeded)
            {
                result.logicId = logic.id;
                result.rungId = rung.id;
                return result;
            }
            if (logic_trace != nullptr)
            {
                logic_trace->nodeValues[rung.output->id] = output_value;
            }
        }
    }
    if (trace != nullptr)
    {
        const auto first_enabled = std::find_if(
            logics.cbegin(), logics.cend(),
            [](const ControlLogic &logic) { return logic.enabled; });
        if (first_enabled != logics.cend())
        {
            const auto values = trace->logicValues.find(first_enabled->id);
            if (values != trace->logicValues.cend())
            {
                trace->nodeValues = values->second.nodeValues;
                trace->expressionValues = values->second.expressionValues;
                trace->rungValues = values->second.rungValues;
                trace->tonValues = values->second.tonValues;
                trace->counterValues = values->second.counterValues;
                trace->wordValues = values->second.wordValues;
            }
        }
    }
    return success();
}

LogicScanResult SoftwareLogicExecutor::evaluateExpression(
    const std::string &logic_id,
    const ConditionExpression &expression,
    RegisterRepository &repository,
    LogicTraceValues *trace,
    bool *value)
{
    if (value == nullptr)
    {
        return failure(LogicScanError::InvalidLogic, "缺少表达式结果接收对象");
    }
    if (expression.kind == ConditionExpressionKind::Node)
    {
        LogicScanResult result = evaluateCondition(
            logic_id, *expression.node, repository, value);
        if (result.succeeded && trace != nullptr)
        {
            trace->nodeValues[expression.node->id] = *value;
            trace->expressionValues[expression.id] = *value;
        }
        return result;
    }

    bool accumulated = expression.kind == ConditionExpressionKind::Series;
    for (const ConditionExpression &child : expression.children)
    {
        bool child_value = false;
        LogicScanResult result = evaluateExpression(
            logic_id, child, repository, trace, &child_value);
        if (!result.succeeded)
        {
            return result;
        }
        accumulated = expression.kind == ConditionExpressionKind::Series
            ? accumulated && child_value : accumulated || child_value;
    }
    *value = accumulated;
    if (trace != nullptr)
    {
        trace->expressionValues[expression.id] = accumulated;
    }
    return success();
}

LogicScanResult SoftwareLogicExecutor::evaluateCondition(
    const std::string &logic_id,
    const LogicNode &node,
    RegisterRepository &repository,
    bool *value)
{
    if (value == nullptr)
    {
        return failure(
            LogicScanError::InvalidLogic,
            "缺少条件结果接收对象",
            {},
            {},
            node.id);
    }

    return std::visit(
        [this, &logic_id, &repository, value, &node](
            const auto &config) -> LogicScanResult
        {
            using Config = std::decay_t<decltype(config)>;
            if constexpr (std::is_same_v<Config, ContactNodeConfig>)
            {
                const BitReadResult read = repository.readBit(config.address);
                if (!read.succeeded)
                {
                    return failure(
                        LogicScanError::RegisterReadFailed,
                        "读取寄存器失败：" + config.address.toString(),
                        {},
                        {},
                        node.id);
                }
                *value = config.mode == ContactMode::NormallyOpen
                    ? read.value : !read.value;
                return success();
            }
            else if constexpr (std::is_same_v<Config, EdgeContactNodeConfig>)
            {
                const BitReadResult read = repository.readBit(config.address);
                if (!read.succeeded)
                {
                    return failure(
                        LogicScanError::RegisterReadFailed,
                        "读取寄存器失败：" + config.address.toString(),
                        {},
                        {},
                        node.id);
                }
                const auto runtime_key = std::make_pair(logic_id, node.id);
                const bool previous = previous_edge_inputs_[runtime_key];
                *value = config.mode == EdgeMode::Rising
                    ? read.value && !previous : !read.value && previous;
                previous_edge_inputs_[runtime_key] = read.value;
                return success();
            }
            else if constexpr (std::is_same_v<Config, TimerContactNodeConfig>)
            {
                const bool done = ton_states_[config.address.index()].done;
                *value = config.mode == ContactMode::NormallyOpen ? done : !done;
                return success();
            }
            else if constexpr (std::is_same_v<Config, CounterContactNodeConfig>)
            {
                const bool done = counter_states_[config.address.index()].done;
                *value = config.mode == ContactMode::NormallyOpen ? done : !done;
                return success();
            }
            else if constexpr (std::is_same_v<Config, CompareNodeConfig>)
            {
                const WordReadResult read = repository.readWord(config.address);
                if (!read.succeeded)
                {
                    return failure(
                        LogicScanError::RegisterReadFailed,
                        "读取寄存器失败：" + config.address.toString(),
                        {},
                        {},
                        node.id);
                }
                *value = compareWord(read.value, config.comparison, config.value);
                return success();
            }
            else
            {
                return failure(
                    LogicScanError::InvalidLogic,
                    "条件节点不能包含输出节点",
                    {},
                    {},
                    node.id);
            }
        },
        node.config);
}

LogicScanResult SoftwareLogicExecutor::readWordOperand(
    const WordOperand &operand,
    RegisterRepository &repository,
    std::int16_t *value,
    const std::string &node_id) const
{
    if (value == nullptr)
    {
        return failure(
            LogicScanError::InvalidLogic,
            "缺少字操作数结果接收对象",
            {},
            {},
            node_id);
    }
    if (operand.kind == WordOperandKind::Constant)
    {
        *value = operand.constant;
        return success();
    }
    if (operand.kind != WordOperandKind::Register)
    {
        return failure(
            LogicScanError::InvalidLogic,
            "字操作数类型无效",
            {},
            {},
            node_id);
    }
    const WordReadResult read = repository.readWord(operand.address);
    if (!read.succeeded)
    {
        return failure(
            LogicScanError::RegisterReadFailed,
            "读取寄存器失败：" + operand.address.toString(),
            {},
            {},
            node_id);
    }
    *value = read.value;
    return success();
}

LogicScanResult SoftwareLogicExecutor::executeOutput(
    const std::string &logic_id,
    const LogicNode &node,
    bool rung_value,
    RegisterRepository &repository,
    TimePoint now,
    LogicTraceValues *trace,
    bool *output_value)
{
    if (output_value == nullptr)
    {
        return failure(
            LogicScanError::InvalidLogic,
            "缺少输出指令结果接收对象",
            {},
            {},
            node.id);
    }
    if (const auto *ton = std::get_if<TonNodeConfig>(&node.config))
    {
        TonRuntimeState &state = ton_states_[ton->address.index()];
        if (!rung_value)
        {
            state = TonRuntimeState{};
        }
        else if (!state.timing)
        {
            state.timing = true;
            state.startedAt = now;
            state.elapsed = std::chrono::milliseconds{0};
            state.done = false;
        }
        else
        {
            state.elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
                now >= state.startedAt ? now - state.startedAt : TimePoint::duration::zero());
            state.done = state.elapsed.count() >= ton->presetMs;
        }
        *output_value = state.done;
        if (trace != nullptr)
        {
            trace->tonValues[node.id] = {
                rung_value,
                state.done,
                state.elapsed.count(),
                ton->presetMs};
        }
        return success();
    }

    if (const auto *counter = std::get_if<CounterNodeConfig>(&node.config))
    {
        const BitReadResult reset_read = repository.readBit(counter->resetAddress);
        if (!reset_read.succeeded)
        {
            return failure(
                LogicScanError::RegisterReadFailed,
                "读取计数器复位输入失败：" + counter->resetAddress.toString(),
                {},
                {},
                node.id);
        }
        std::int16_t preset = 0;
        LogicScanResult result = readWordOperand(
            counter->preset, repository, &preset, node.id);
        if (!result.succeeded)
        {
            return result;
        }
        const std::int32_t bounded_preset = std::max<std::int32_t>(0, preset);
        preset = static_cast<std::int16_t>(
            std::min<std::int32_t>(bounded_preset, std::numeric_limits<std::int16_t>::max()));
        const WordReadResult current_read = repository.readWord(
            counter->currentValueAddress);
        if (!current_read.succeeded)
        {
            return failure(
                LogicScanError::RegisterReadFailed,
                "读取计数当前值失败：" + counter->currentValueAddress.toString(),
                {},
                {},
                node.id);
        }
        std::int32_t current = std::max<std::int32_t>(0, current_read.value);
        current = std::min<std::int32_t>(current, std::numeric_limits<std::int16_t>::max());
        const auto runtime_key = std::make_pair(logic_id, node.id);
        const bool previous = previous_counter_inputs_[runtime_key];
        const bool rising = rung_value && !previous;
        previous_counter_inputs_[runtime_key] = rung_value;
        bool done = counter_states_[counter->address.index()].done;
        if (reset_read.value)
        {
            current = counter->mode == CounterMode::Up ? 0 : preset;
            done = counter->mode == CounterMode::Down && current == 0;
        }
        else if (rising)
        {
            if (counter->mode == CounterMode::Up)
            {
                if (current < preset)
                {
                    ++current;
                }
                done = current >= preset;
            }
            else
            {
                if (current > 0)
                {
                    --current;
                }
                done = current <= 0;
            }
        }
        if (counter->mode == CounterMode::Up && current >= preset)
        {
            done = true;
        }
        if (counter->mode == CounterMode::Down && current <= 0)
        {
            done = true;
        }
        const std::int16_t current_value = static_cast<std::int16_t>(current);
        const RegisterWriteResult write = repository.writeWord(
            counter->currentValueAddress, current_value);
        if (!write.succeeded)
        {
            return failure(
                LogicScanError::RegisterWriteFailed,
                "写入计数当前值失败：" + counter->currentValueAddress.toString(),
                {},
                {},
                node.id);
        }
        counter_states_[counter->address.index()].done = done;
        *output_value = done;
        if (trace != nullptr)
        {
            trace->counterValues[node.id] = {
                rung_value,
                reset_read.value,
                done,
                current_value,
                preset};
        }
        return success();
    }

    if (const auto *move = std::get_if<MoveNodeConfig>(&node.config))
    {
        if (!rung_value)
        {
            *output_value = false;
            return success();
        }
        std::int16_t source = 0;
        LogicScanResult result = readWordOperand(
            move->source, repository, &source, node.id);
        if (!result.succeeded)
        {
            return result;
        }
        const RegisterWriteResult write = repository.writeWord(
            move->destination, source);
        if (!write.succeeded)
        {
            return failure(
                LogicScanError::RegisterWriteFailed,
                "MOVE 写入寄存器失败：" + move->destination.toString(),
                {},
                {},
                node.id);
        }
        *output_value = true;
        if (trace != nullptr)
        {
            trace->wordValues[node.id] = {source, false};
        }
        return success();
    }

    if (const auto *arithmetic = std::get_if<ArithmeticNodeConfig>(&node.config))
    {
        if (!rung_value)
        {
            *output_value = false;
            return success();
        }
        std::int16_t left = 0;
        std::int16_t right = 0;
        LogicScanResult result = readWordOperand(
            arithmetic->left, repository, &left, node.id);
        if (!result.succeeded)
        {
            return result;
        }
        result = readWordOperand(arithmetic->right, repository, &right, node.id);
        if (!result.succeeded)
        {
            return result;
        }
        const std::int32_t raw = arithmetic->operation == ArithmeticOperation::Add
            ? static_cast<std::int32_t>(left) + right
            : static_cast<std::int32_t>(left) - right;
        const bool overflow = raw < std::numeric_limits<std::int16_t>::min()
            || raw > std::numeric_limits<std::int16_t>::max();
        const std::int32_t bounded = std::max<std::int32_t>(
            std::numeric_limits<std::int16_t>::min(),
            std::min<std::int32_t>(raw, std::numeric_limits<std::int16_t>::max()));
        const std::int16_t result_value = static_cast<std::int16_t>(bounded);
        const RegisterWriteResult write = repository.writeWord(
            arithmetic->destination, result_value);
        if (!write.succeeded)
        {
            return failure(
                LogicScanError::RegisterWriteFailed,
                "算术指令写入寄存器失败：" + arithmetic->destination.toString(),
                {},
                {},
                node.id);
        }
        *output_value = true;
        if (trace != nullptr)
        {
            trace->wordValues[node.id] = {result_value, overflow};
        }
        return success();
    }

    const auto *config = std::get_if<CoilNodeConfig>(&node.config);
    if (config == nullptr)
    {
        return failure(
            LogicScanError::InvalidLogic,
            "梯形图输出不是有效的输出指令",
            {},
            {},
            node.id);
    }

    bool should_write = true;
    bool register_value = rung_value;
    switch (config->mode)
    {
    case CoilMode::Normal:
    {
        break;
    }
    case CoilMode::Set:
    {
        should_write = rung_value;
        register_value = true;
        break;
    }
    case CoilMode::Reset:
    {
        should_write = rung_value;
        register_value = false;
        break;
    }
    default:
    {
        return failure(
            LogicScanError::InvalidLogic,
            "不支持的线圈模式",
            {},
            {},
            node.id);
    }
    }

    if (!should_write)
    {
        *output_value = rung_value;
        return success();
    }
    const RegisterWriteResult write = repository.writeBit(
        config->address, register_value);
    if (!write.succeeded)
    {
        return failure(
            LogicScanError::RegisterWriteFailed,
            "写入寄存器失败：" + config->address.toString(),
            {},
            {},
            node.id);
    }
    *output_value = rung_value;
    return success();
}