using System;
using System.Diagnostics;

namespace Aivfo.OperationLog
{
    /// <summary>
    /// 操作日志组件门面（14§9）。
    /// 用法：
    ///   启动时一次：OperationLogger.Init(o =&gt; { o.Project="operate"; o.KafkaBootstrapServers="localhost:9092"; });
    ///   记一条：     OperationLogger.Log("串口", "打开端口", input: new{port="COM3"}, result:"成功");
    ///   计时 scope： using (OperationLogger.Begin("串口","打开端口")) { ... } // 自动耗时 + 成功/失败 + 异常→error
    /// 所有 API 全 try 兜底：日志失败绝不影响业务。
    /// </summary>
    public static class OperationLogger
    {
        private static OperationLogOptions _options;
        private static OperationLogPipeline _pipeline;
        private static LocalFileWriter _local;
        private static OperationLogConfigWatcher _configWatcher; // G3-3：配置热加载 watcher（ConfigFilePath 非空才起）
        private static readonly object _initLock = new object();
        private static volatile bool _initialized;

        /// <summary>当前配置（运行时可改模块开关：OperationLogger.Options.SetModule(...)）。</summary>
        public static OperationLogOptions Options => _options;

        /// <summary>是否已初始化。</summary>
        public static bool Initialized => _initialized;

        /// <summary>用默认 Kafka 传输初始化。</summary>
        public static void Init(Action<OperationLogOptions> configure)
        {
            lock (_initLock)
            {
                if (_initialized) return;
                var opts = new OperationLogOptions();
                configure?.Invoke(opts);
                var local = new LocalFileWriter(opts.LocalLogDir);
                IOplogTransport transport;
                try
                {
                    // G3-3 / 14§11：投递失败（broker 宕/超时/队列满）把整条 JSON 落本地兜底，
                    // 由 pipeline 的补送定时器在 Kafka 恢复后补回，不静默丢。
                    transport = new KafkaOplogTransport(opts.KafkaBootstrapServers, opts.Topic,
                        onError: local.WriteSelfError, onDeliveryFailed: local.WriteFallback);
                }
                catch (Exception ex)
                {
                    // Kafka 客户端建不起来：降级为只写本地，不抛。
                    local.WriteSelfError("Kafka transport init failed, fallback to local-only: " + ex.Message);
                    transport = new NullTransport();
                }
                InitCore(opts, transport, local);
            }
        }

        /// <summary>用自定义传输初始化（测试/离线降级用）。</summary>
        public static void Init(OperationLogOptions opts, IOplogTransport transport)
        {
            lock (_initLock)
            {
                if (_initialized) return;
                var local = new LocalFileWriter(opts.LocalLogDir);
                InitCore(opts, transport ?? new NullTransport(), local);
            }
        }

        private static void InitCore(OperationLogOptions opts, IOplogTransport transport, LocalFileWriter local)
        {
            _options = opts;
            _local = local;
            _pipeline = new OperationLogPipeline(opts, transport, local);

            // G3-3 / 14§10：配置集中下发——指定了 ConfigFilePath 才起后台热加载 watcher
            // （日志微服务/运维把统一配置文件下发覆盖到该路径即热生效，无需重编）。
            if (!string.IsNullOrWhiteSpace(opts.ConfigFilePath))
            {
                try { _configWatcher = new OperationLogConfigWatcher(opts, local.WriteSelfError); }
                catch (Exception ex) { local.WriteSelfError("ConfigWatcher init failed: " + ex.Message); }
            }

            _initialized = true;
        }

        /// <summary>
        /// 记一条操作日志。input/output 任意对象，内部安全序列化。
        /// level 默认 Info（操作级，发 Kafka）；Debug 走本地文件、不入 Kafka。
        /// </summary>
        public static void Log(
            string module,
            string operation,
            object input = null,
            object output = null,
            string result = null,
            string error = null,
            long? elapsedMs = null,
            OpLogLevel level = OpLogLevel.Info,
            string operatorName = null,
            int? houseSn = null,
            int? wellSn = null,
            string tlSn = null)
        {
            try
            {
                if (!_initialized) return;
                // 模块整体关闭则什么都不记（含调试级本地文件）。
                if (!_options.IsModuleEnabled(module)) return;

                var msg = new OperationLogMessage
                {
                    TraceId = OperationLogContext.TraceId ?? OperationLogContext.NewTraceId(),
                    ParentId = OperationLogContext.ParentId,
                    Time = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                    Project = _options.Project,
                    Module = module,
                    Operation = operation,
                    Operator = operatorName ?? OperationLogContext.Operator,
                    Input = SafeSerializer.Serialize(input),
                    Output = SafeSerializer.Serialize(output),
                    Result = result,
                    Error = error,
                    ElapsedMs = elapsedMs,
                    Level = level == OpLogLevel.Debug ? "DEBUG" : "INFO",
                    HouseSn = houseSn ?? OperationLogContext.HouseSn,
                    WellSn = wellSn ?? OperationLogContext.WellSn,
                    TlSn = tlSn ?? _options.TlSn,
                    Host = _options.Host
                };

                if (level == OpLogLevel.Debug)
                {
                    // 调试级（14§4）：写本地文件、不入 Kafka（除非该模块 MinLevel 显式调到 Debug）。
                    _local.WriteDebug(msg);
                    if (_options.ShouldSendKafka(module, level))
                        _pipeline.Enqueue(msg);
                }
                else
                {
                    // 操作级：达到 Kafka 门槛才发；否则也落本地兜底，避免静默丢失。
                    if (_options.ShouldSendKafka(module, level))
                        _pipeline.Enqueue(msg);
                    else
                        _local.WriteDebug(msg);
                }
            }
            catch (Exception ex)
            {
                try { _local?.WriteSelfError("Log() failed: " + ex.Message); } catch { }
            }
        }

        /// <summary>
        /// 开启一次带计时的操作 scope。释放时自动记录（耗时、成功/失败、异常→error）。
        /// using (var op = OperationLogger.Begin("串口","打开端口")) { op.Input(x); ...; op.Output(y); }
        /// 块内抛异常时自动记 result=失败 + error=异常摘要，再向上抛。
        /// </summary>
        public static OperationScope Begin(
            string module,
            string operation,
            OpLogLevel level = OpLogLevel.Info,
            string operatorName = null,
            int? houseSn = null,
            int? wellSn = null,
            string tlSn = null)
        {
            return new OperationScope(module, operation, level, operatorName, houseSn, wellSn, tlSn);
        }

        /// <summary>flush（测试/退出用）。</summary>
        public static void Flush(TimeSpan? timeout = null)
        {
            try { _pipeline?.Flush(timeout ?? TimeSpan.FromSeconds(5)); } catch { }
        }

        /// <summary>
        /// 包装执行一个操作：自动计时 + 异常自动记 result=失败/error，然后向上抛。
        /// 这是带异常捕获的推荐写法（Dispose 无法探测异常）。
        /// </summary>
        public static void Run(string module, string operation, Action body,
            object input = null, OpLogLevel level = OpLogLevel.Info)
        {
            var sw = Stopwatch.StartNew();
            using (OperationLogContext.BeginScope())
            {
                try
                {
                    body?.Invoke();
                    sw.Stop();
                    Log(module, operation, input: input, result: "成功", elapsedMs: sw.ElapsedMilliseconds, level: level);
                }
                catch (Exception ex)
                {
                    sw.Stop();
                    Log(module, operation, input: input, result: "失败",
                        error: ex.GetType().Name + ": " + ex.Message,
                        elapsedMs: sw.ElapsedMilliseconds, level: level);
                    throw;
                }
            }
        }

        /// <summary>Run 的有返回值版本。</summary>
        public static T Run<T>(string module, string operation, Func<T> body,
            object input = null, OpLogLevel level = OpLogLevel.Info)
        {
            var sw = Stopwatch.StartNew();
            using (OperationLogContext.BeginScope())
            {
                try
                {
                    var r = body != null ? body() : default;
                    sw.Stop();
                    Log(module, operation, input: input, output: r, result: "成功", elapsedMs: sw.ElapsedMilliseconds, level: level);
                    return r;
                }
                catch (Exception ex)
                {
                    sw.Stop();
                    Log(module, operation, input: input, result: "失败",
                        error: ex.GetType().Name + ": " + ex.Message,
                        elapsedMs: sw.ElapsedMilliseconds, level: level);
                    throw;
                }
            }
        }

        /// <summary>关停（退出时调用，flush + 释放 Kafka）。</summary>
        public static void Shutdown()
        {
            lock (_initLock)
            {
                if (!_initialized) return;
                try { _configWatcher?.Dispose(); } catch { }
                try { _pipeline?.Dispose(); } catch { }
                _initialized = false;
            }
        }

        /// <summary>空传输：纯本地降级时用，Send 直接落兜底由调用方决定（这里丢弃，已在 init 记错误）。</summary>
        private sealed class NullTransport : IOplogTransport
        {
            public void Send(string json) { }
            public void Flush(TimeSpan timeout) { }
            public void Dispose() { }
        }
    }

    /// <summary>
    /// 一次操作的计时 scope。Dispose 时落一条日志。块内异常自动记失败。
    /// </summary>
    public sealed class OperationScope : IDisposable
    {
        private readonly string _module;
        private readonly string _operation;
        private readonly OpLogLevel _level;
        private readonly string _operator;
        private readonly int? _houseSn;
        private readonly int? _wellSn;
        private readonly string _tlSn;
        private readonly Stopwatch _sw;
        private readonly IDisposable _ctxScope;

        private object _input;
        private object _output;
        private string _result;
        private string _error;
        private bool _disposed;

        internal OperationScope(string module, string operation, OpLogLevel level,
            string operatorName, int? houseSn, int? wellSn, string tlSn)
        {
            _module = module;
            _operation = operation;
            _level = level;
            _operator = operatorName;
            _houseSn = houseSn;
            _wellSn = wellSn;
            _tlSn = tlSn;
            // 进入 scope 即建立/继承 traceId（父子链）。
            _ctxScope = OperationLogContext.BeginScope();
            _sw = Stopwatch.StartNew();
        }

        /// <summary>记录入参。</summary>
        public OperationScope Input(object input) { _input = input; return this; }

        /// <summary>记录出参。</summary>
        public OperationScope Output(object output) { _output = output; return this; }

        /// <summary>显式标记成功。</summary>
        public OperationScope Success(object output = null)
        {
            _result = "成功";
            if (output != null) _output = output;
            return this;
        }

        /// <summary>显式标记失败 + 错误信息。</summary>
        public OperationScope Fail(string error)
        {
            _result = "失败";
            _error = error;
            return this;
        }

        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;
            try
            {
                _sw.Stop();

                // .NET 无法在 Dispose 内可靠探测正在传播的异常。
                // 异常路径请用 Fail()（或 Run/RunAsync 包装自动捕获）；未显式标记则默认成功。
                if (_result == null) _result = "成功";

                OperationLogger.Log(
                    _module, _operation,
                    input: _input, output: _output,
                    result: _result, error: _error,
                    elapsedMs: _sw.ElapsedMilliseconds,
                    level: _level,
                    operatorName: _operator,
                    houseSn: _houseSn, wellSn: _wellSn, tlSn: _tlSn);
            }
            catch { /* 兜底 */ }
            finally
            {
                try { _ctxScope?.Dispose(); } catch { }
            }
        }
    }
}