using System.Collections.Concurrent;

namespace MiGu.Server.Ota;

public sealed class OtaJobRunner
{
    private readonly OtaStore _store;
    private readonly WatchDogClient _wd;
    private readonly OtaVehicleSource _vehicles;
    private readonly ILogger<OtaJobRunner> _log;
    private readonly ConcurrentDictionary<string, CancellationTokenSource> _running = new();

    public OtaJobRunner(OtaStore store, WatchDogClient wd, OtaVehicleSource vehicles, ILogger<OtaJobRunner> log)
    {
        _store = store;
        _wd = wd;
        _vehicles = vehicles;
        _log = log;
    }

    public OtaJob EnqueueSync(CreateSyncJobRequest req, string? user)
    {
        var target = _store.GetTarget() ?? throw new InvalidOperationException("未设置目标版本，请先在版本库激活");
        var components = (req.Components is { Count: > 0 } ? req.Components : OtaPathMap.ComponentKeys.ToList())
            .Where(c => target.Components.ContainsKey(c))
            .ToList();
        if (components.Count == 0) throw new InvalidOperationException("目标版本中无选定组件");
        if (req.CarIds.Count == 0) throw new InvalidOperationException("请选择车辆");

        var settings = _store.GetSettings();
        var job = new OtaJob
        {
            Id = _store.NextJobId(),
            Kind = "sync",
            Status = "pending",
            CreatedAt = DateTimeOffset.UtcNow,
            CreatedBy = user,
            PackageId = target.PackageId,
            CarIds = req.CarIds.ToList(),
            Components = components,
            RequireLatencyCheck = req.RequireLatencyCheck ?? settings.LatencyEnabled
        };
        foreach (var carId in job.CarIds)
        foreach (var comp in components)
            job.Steps.Add(new OtaJobStep { CarId = carId, Component = comp, Status = "pending" });
        job.TotalSteps = job.Steps.Count;
        _store.SaveJob(job);
        _ = Task.Run(() => RunAsync(job.Id));
        return job;
    }

    public OtaJob EnqueueCustomFile(CreateCustomFileJobRequest req, IReadOnlyList<OtaCustomFileItem> files, string? user)
    {
        if (req.CarIds.Count == 0) throw new InvalidOperationException("请选择车辆");
        if (files.Count == 0) throw new InvalidOperationException("请至少添加一个本地文件");
        if (string.IsNullOrWhiteSpace(req.RemotePath)) throw new InvalidOperationException("请填写小车内目标路径");
        var settings = _store.GetSettings();
        var ops = req.RestartOps is { Count: > 0 }
            ? req.RestartOps.Distinct().ToList()
            : new List<int> { req.RestartOp };
        if (ops.Count == 0) ops.Add(-1);

        var job = new OtaJob
        {
            Id = _store.NextJobId(),
            Kind = "customFile",
            Status = "pending",
            CreatedAt = DateTimeOffset.UtcNow,
            CreatedBy = user,
            CarIds = req.CarIds.ToList(),
            CustomFileName = files[0].FileName,
            CustomRemotePath = req.RemotePath,
            CustomRestartOp = ops[0],
            CustomLocalPath = files[0].LocalPath,
            CustomFiles = files.ToList(),
            CustomRestartOps = ops,
            RequireLatencyCheck = req.RequireLatencyCheck ?? settings.LatencyEnabled,
            Components = new List<string> { "custom" }
        };
        foreach (var carId in job.CarIds)
            job.Steps.Add(new OtaJobStep { CarId = carId, Component = $"custom×{files.Count}", Status = "pending" });
        job.TotalSteps = job.Steps.Count;
        _store.SaveJob(job);
        _ = Task.Run(() => RunAsync(job.Id));
        return job;
    }

    public OtaJob EnqueueConfigPush(CreateConfigPushRequest req, string? user)
    {
        if (req.CarIds.Count == 0) throw new InvalidOperationException("请选择车辆");
        var app = req.App.Trim().ToLowerInvariant();
        if (app is not ("medulla" or "detour" or "clumsy"))
            throw new InvalidOperationException("app 须为 medulla|detour|clumsy");
        var settings = _store.GetSettings();
        var job = new OtaJob
        {
            Id = _store.NextJobId(),
            Kind = "configPush",
            Status = "pending",
            CreatedAt = DateTimeOffset.UtcNow,
            CreatedBy = user,
            CarIds = req.CarIds.ToList(),
            ConfigApp = app,
            ConfigJson = req.Json,
            RequireLatencyCheck = req.RequireLatencyCheck ?? settings.LatencyEnabled,
            Components = new List<string> { $"config:{app}" }
        };
        foreach (var carId in job.CarIds)
            job.Steps.Add(new OtaJobStep { CarId = carId, Component = $"config:{app}", Status = "pending" });
        job.TotalSteps = job.Steps.Count;
        _store.SaveJob(job);
        _ = Task.Run(() => RunAsync(job.Id));
        return job;
    }

    public bool Cancel(string jobId)
    {
        var job = _store.GetJob(jobId);
        if (job == null) return false;
        if (job.Status is "succeeded" or "failed" or "partial" or "cancelled") return false;
        // 正在运行：只发取消信号，由 RunAsync 统一收尾，避免与运行线程并发写同一 job 文件。
        if (_running.TryGetValue(jobId, out var cts))
        {
            cts.Cancel();
            return true;
        }
        // 尚未开始（Task.Run 排队中）：直接落盘取消；RunAsync 启动时有 status 守卫会跳过执行。
        foreach (var step in job.Steps.Where(s => s.Status == "pending"))
        {
            step.Status = "skipped";
            step.Error = "已取消";
        }
        job.Status = "cancelled";
        job.FinishedAt = DateTimeOffset.UtcNow;
        job.DoneSteps = job.Steps.Count(s => s.Status is "succeeded" or "failed" or "skipped");
        _store.SaveJob(job);
        return true;
    }

    public OtaJob? RetryFailed(string jobId, string? user)
    {
        var old = _store.GetJob(jobId);
        if (old == null) return null;
        var failedCars = old.Steps.Where(s => s.Status == "failed").Select(s => s.CarId).Distinct().ToList();
        if (failedCars.Count == 0) throw new InvalidOperationException("没有失败项可重试");

        return old.Kind switch
        {
            "sync" => EnqueueSync(new CreateSyncJobRequest
            {
                CarIds = failedCars,
                Components = old.Components,
                RequireLatencyCheck = old.RequireLatencyCheck
            }, user),
            "customFile" when ResolveCustomFiles(old).Count > 0 =>
                EnqueueCustomFile(new CreateCustomFileJobRequest
                {
                    CarIds = failedCars,
                    RemotePath = old.CustomRemotePath ?? "",
                    RestartOps = old.CustomRestartOps is { Count: > 0 }
                        ? old.CustomRestartOps
                        : new List<int> { old.CustomRestartOp ?? -1 },
                    RequireLatencyCheck = old.RequireLatencyCheck
                }, ResolveCustomFiles(old), user),
            "configPush" => EnqueueConfigPush(new CreateConfigPushRequest
            {
                CarIds = failedCars,
                App = old.ConfigApp ?? "",
                Json = old.ConfigJson ?? "",
                RequireLatencyCheck = old.RequireLatencyCheck
            }, user),
            _ => throw new InvalidOperationException("无法重试该任务类型或文件已丢失")
        };
    }

    private async Task RunAsync(string jobId)
    {
        var cts = new CancellationTokenSource();
        if (!_running.TryAdd(jobId, cts)) return;
        // 单一内存实例贯穿全程；所有「改状态 + 落盘」都在 jobLock 下串行，杜绝并发车批次的丢更新。
        var jobLock = new object();
        try
        {
            var job = _store.GetJob(jobId);
            if (job == null) return;
            // 守卫：排队期间被取消 / 已终结的任务不再执行。
            if (job.Status is "cancelled" or "succeeded" or "failed" or "partial") return;
            var settings = _store.GetSettings();
            var cars = await _vehicles.ListCarsAsync(cts.Token);
            var byId = cars.ToDictionary(c => c.Id, StringComparer.OrdinalIgnoreCase);

            job.Status = job.RequireLatencyCheck ? "probing" : "running";
            _store.SaveJob(job);

            // 解析 IP
            foreach (var step in job.Steps)
            {
                if (byId.TryGetValue(step.CarId, out var car))
                    step.Ip = car.Ip;
            }

            if (job.RequireLatencyCheck)
            {
                var threshold = settings.RttThresholdMs;
                var overMode = settings.OverThreshold;
                foreach (var carId in job.CarIds.Distinct())
                {
                    var ip = job.Steps.FirstOrDefault(s => s.CarId == carId)?.Ip;
                    if (string.IsNullOrEmpty(ip))
                    {
                        SkipCar(job, carId, "无 IP");
                        continue;
                    }
                    var rtt = await _wd.MeasureRttMsAsync(ip, cts.Token);
                    if (rtt == null || rtt > threshold)
                    {
                        if (string.Equals(overMode, "skip", StringComparison.OrdinalIgnoreCase) || rtt == null)
                            SkipCar(job, carId, rtt == null ? "延迟探测失败" : $"RTT {rtt}ms > {threshold}ms");
                    }
                }
                _store.SaveJob(job);
            }

            job.Status = "running";
            _store.SaveJob(job);

            var maxCar = Math.Max(1, settings.MaxCar);
            var carGroups = job.CarIds.Distinct()
                .Where(id => job.Steps.Any(s => s.CarId == id && s.Status == "pending"))
                .Chunk(maxCar);

            foreach (var batch in carGroups)
            {
                if (cts.IsCancellationRequested) break;
                var tasks = batch.Select(carId => RunCarAsync(job, jobLock, carId, settings.BandwidthKbps, cts.Token));
                await Task.WhenAll(tasks);
            }

            lock (jobLock)
            {
                if (cts.IsCancellationRequested)
                {
                    foreach (var s in job.Steps.Where(s => s.Status is "pending" or "running"))
                    {
                        s.Status = "skipped";
                        s.Error ??= "已取消";
                    }
                    job.Status = "cancelled";
                    job.FinishedAt = DateTimeOffset.UtcNow;
                    Recalc(job);
                }
                else
                {
                    Finalize(job);
                }
                _store.SaveJob(job);
            }
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "OTA job {Id} crashed", jobId);
            var job = _store.GetJob(jobId);
            if (job != null)
            {
                job.Status = "failed";
                job.Message = ex.Message;
                job.FinishedAt = DateTimeOffset.UtcNow;
                _store.SaveJob(job);
            }
        }
        finally
        {
            _running.TryRemove(jobId, out _);
            cts.Dispose();
        }
    }

    private static void SkipCar(OtaJob job, string carId, string reason)
    {
        foreach (var step in job.Steps.Where(s => s.CarId == carId && s.Status == "pending"))
        {
            step.Status = "skipped";
            step.Error = reason;
        }
    }

    private static List<OtaCustomFileItem> ResolveCustomFiles(OtaJob job)
    {
        if (job.CustomFiles is { Count: > 0 })
            return job.CustomFiles.Where(f => File.Exists(f.LocalPath)).ToList();
        if (!string.IsNullOrEmpty(job.CustomLocalPath) && File.Exists(job.CustomLocalPath))
        {
            return new List<OtaCustomFileItem>
            {
                new()
                {
                    LocalPath = job.CustomLocalPath,
                    FileName = job.CustomFileName ?? Path.GetFileName(job.CustomLocalPath)
                }
            };
        }
        return new();
    }

    private async Task UploadCustomFilesForCarAsync(OtaJob job, string ip, int bandwidth, CancellationToken ct)
    {
        var files = ResolveCustomFiles(job);
        if (files.Count == 0) throw new InvalidOperationException("自定义文件已丢失");
        var remote = job.CustomRemotePath ?? "";
        var ops = job.CustomRestartOps is { Count: > 0 }
            ? job.CustomRestartOps
            : new List<int> { job.CustomRestartOp ?? -1 };

        // 非末文件一律 -1；末文件按所选重启项依次再传（对齐 CarOTA.App）
        for (var i = 0; i < files.Count; i++)
        {
            var f = files[i];
            var isLast = i == files.Count - 1;
            if (!isLast)
            {
                await _wd.UploadCustomFileAsync(ip, f.LocalPath, f.FileName, remote, -1, bandwidth, ct);
                continue;
            }

            if (ops.Count == 1 && ops[0] == -1)
            {
                await _wd.UploadCustomFileAsync(ip, f.LocalPath, f.FileName, remote, -1, bandwidth, ct);
            }
            else
            {
                foreach (var op in ops.Where(o => o != -1).DefaultIfEmpty(-1))
                    await _wd.UploadCustomFileAsync(ip, f.LocalPath, f.FileName, remote, op, bandwidth, ct);
            }
        }
    }

    private async Task RunCarAsync(OtaJob job, object jobLock, string carId, int bandwidth, CancellationToken ct)
    {
        // 只处理本车 step；同批其他车任务并行修改各自 step，共享同一 job 实例，写盘统一在 jobLock 下串行。
        var steps = job.Steps.Where(s => s.CarId == carId && s.Status == "pending").ToList();
        if (steps.Count == 0) return;
        var ip = steps[0].Ip;
        if (string.IsNullOrEmpty(ip))
        {
            lock (jobLock)
            {
                foreach (var s in steps) { s.Status = "failed"; s.Error = "无 IP"; }
                Recalc(job);
                _store.SaveJob(job);
            }
            return;
        }

        foreach (var step in steps)
        {
            if (ct.IsCancellationRequested)
            {
                lock (jobLock)
                {
                    step.Status = "skipped";
                    step.Error = "已取消";
                    Recalc(job);
                    _store.SaveJob(job);
                }
                continue;
            }
            lock (jobLock)
            {
                step.Status = "running";
                Recalc(job);
                _store.SaveJob(job);
            }
            try
            {
                switch (job.Kind)
                {
                    case "sync":
                    {
                        var target = _store.GetTarget() ?? throw new InvalidOperationException("目标版本丢失");
                        if (!target.Components.TryGetValue(step.Component, out var art))
                            throw new InvalidOperationException($"组件 {step.Component} 不在目标中");
                        await _wd.UploadComponentAsync(ip, step.Component, art.Path, art.FileName, bandwidth, ct);
                        break;
                    }
                    case "customFile":
                        await UploadCustomFilesForCarAsync(job, ip, bandwidth, ct);
                        break;
                    case "configPush":
                        await _wd.PutJsonAsync(ip, job.ConfigApp!, job.ConfigJson!, ct);
                        break;
                }
                lock (jobLock)
                {
                    step.Status = "succeeded";
                    step.Error = null;
                    Recalc(job);
                    _store.SaveJob(job);
                }
            }
            catch (Exception ex)
            {
                lock (jobLock)
                {
                    step.Status = ct.IsCancellationRequested ? "skipped" : "failed";
                    step.Error = ct.IsCancellationRequested ? "已取消" : ex.Message;
                    Recalc(job);
                    _store.SaveJob(job);
                }
                _log.LogWarning(ex, "OTA step fail {Job} {Car} {Comp}", job.Id, carId, step.Component);
            }
        }
    }

    private static void Recalc(OtaJob job)
    {
        job.DoneSteps = job.Steps.Count(s => s.Status is "succeeded" or "failed" or "skipped");
    }

    private static void Finalize(OtaJob job)
    {
        Recalc(job);
        job.FinishedAt = DateTimeOffset.UtcNow;
        var anyFail = job.Steps.Any(s => s.Status == "failed");
        var anyOk = job.Steps.Any(s => s.Status == "succeeded");
        var anyPending = job.Steps.Any(s => s.Status is "pending" or "running");
        if (job.Status == "cancelled") return;
        if (anyPending) job.Status = "partial";
        else if (anyFail && anyOk) job.Status = "partial";
        else if (anyFail) job.Status = "failed";
        else if (anyOk) job.Status = "succeeded";
        else job.Status = "cancelled";
    }
}