package com.battery.device.api.registry;

import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Function;
import com.battery.device.api.DeviceAdapter;
import com.battery.device.api.TestDataObservationAdapter;

/** 管理启用设备适配器的运行时实例及其会话生命周期。 */
public final class DeviceAdapterRegistry implements AutoCloseable
{
    private final Map<String, DeviceAdapterFactory> factories = new HashMap<>();
    private final Map<String, RegisteredAdapter> adapters = new HashMap<>();

    public DeviceAdapterRegistry(List<DeviceAdapterFactory> factories)
    {
        Objects.requireNonNull(factories, "factories").forEach(factory -> {
            String type = normalizeType(factory.adapterType());
            if (this.factories.put(type, factory) != null)
                throw new IllegalArgumentException("Duplicate device adapter factory: " + type);
        });
    }

    /** 按数据库或代码配置注册、替换或移除运行时实例。 */
    public void synchronize(AdapterInstanceConfig config)
    {
        Objects.requireNonNull(config, "config");
        if (!config.enabled())
        {
            remove(config.adapterCode());
            return;
        }

        synchronized (this)
        {
            RegisteredAdapter current = adapters.get(config.adapterCode());
            if (current != null && current.config.equals(config)) return;
            if (!factories.containsKey(normalizeType(config.adapterType())))
                throw new AdapterRegistryException("Unsupported device adapter type: " + config.adapterType());
        }

        DeviceAdapterFactory factory = factories.get(normalizeType(config.adapterType()));
        register(config, factory.create(config));
    }

    /**
     * 注册已构造的运行时实例。代码装配实例与数据库配置实例共用同一份实例表，
     * 使发现与取数按同一适配器编码解析，避免同编码出现两个实例。
     */
    public void register(AdapterInstanceConfig config, DeviceAdapter adapter)
    {
        Objects.requireNonNull(config, "config");
        Objects.requireNonNull(adapter, "adapter");
        if (!config.enabled())
        {
            remove(config.adapterCode());
            return;
        }

        RegisteredAdapter previous;
        synchronized (this)
        {
            previous = adapters.put(config.adapterCode(), new RegisteredAdapter(config, adapter));
        }
        closeWhenIdle(previous);
    }

    /** 在实例级串行边界内执行一次适配器操作；未注册时给出可识别失败。 */
    public <T> T execute(String adapterCode, Function<DeviceAdapter, T> operation)
    {
        Objects.requireNonNull(operation, "operation");
        RegisteredAdapter registered = acquire(adapterCode);
        try
        {
            return operation.apply(registered.adapter);
        }
        finally
        {
            registered.operationLock.unlock();
        }
    }

    /**
     * 在实例级串行边界内按测试数据观测契约执行。
     * 实例缺失或未提供该契约时明确失败，不回退到其他实例。
     */
    public <T> T executeTestData(String adapterCode, Function<TestDataObservationAdapter, T> operation)
    {
        Objects.requireNonNull(operation, "operation");
        RegisteredAdapter registered = acquire(adapterCode);
        try
        {
            if (!(registered.adapter instanceof TestDataObservationAdapter observation))
                throw new AdapterRegistryException(
                        "Device adapter does not expose test data observation: " + adapterCode);
            return operation.apply(observation);
        }
        finally
        {
            registered.operationLock.unlock();
        }
    }

    /** 取用实例并持有其串行锁；调用方必须在 finally 中释放。 */
    private RegisteredAdapter acquire(String adapterCode)
    {
        RegisteredAdapter registered;
        synchronized (this)
        {
            registered = adapters.get(adapterCode);
            if (registered == null)
                throw new AdapterRegistryException("Device adapter is not enabled: " + adapterCode);
            registered.operationLock.lock();
        }
        return registered;
    }

    /** 返回指定编码的适配器实例当前是否已注册。 */
    public synchronized boolean contains(String adapterCode)
    {
        return adapters.containsKey(adapterCode);
    }

    /** 关闭全部已注册实例并清空实例表；逐个等待在途操作结束。 */
    @Override
    public void close()
    {
        List<RegisteredAdapter> registered;
        synchronized (this)
        {
            registered = List.copyOf(adapters.values());
            adapters.clear();
        }
        registered.forEach(this::closeWhenIdle);
    }

    private void remove(String adapterCode)
    {
        RegisteredAdapter previous;
        synchronized (this)
        {
            previous = adapters.remove(adapterCode);
        }
        closeWhenIdle(previous);
    }

    private void closeWhenIdle(RegisteredAdapter registered)
    {
        if (registered == null) return;
        registered.operationLock.lock();
        try
        {
            registered.adapter.close();
        }
        finally
        {
            registered.operationLock.unlock();
        }
    }

    private static String normalizeType(String value)
    {
        return Objects.requireNonNull(value, "adapterType").trim().toUpperCase(Locale.ROOT);
    }

    private static final class RegisteredAdapter
    {
        private final AdapterInstanceConfig config;
        private final DeviceAdapter adapter;
        private final ReentrantLock operationLock = new ReentrantLock(true);

        private RegisteredAdapter(AdapterInstanceConfig config, DeviceAdapter adapter)
        {
            this.config = config;
            this.adapter = adapter;
        }
    }
}