using System.Globalization;
using System.Text.Json;
using System.Text.Json.Nodes;
using Microsoft.AspNetCore.Components;
using Microsoft.JSInterop;
using ZB.MOM.WW.ScadaBridge.CentralUI.Auth;
using ZB.MOM.WW.ScadaBridge.CentralUI.Services;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.InboundApi;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Instances;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Debugging;
using ZB.MOM.WW.ScadaBridge.Commons.Types.InboundApi;
using ZB.MOM.WW.ScadaBridge.ScriptAnalysis;

namespace ZB.MOM.WW.ScadaBridge.CentralUI.Components.Pages.Deployment;

/// <summary>
/// Flow Debugger page (design 2026-09-05 §4): pick an entry point (inbound API method or a
/// value-change trigger), see the predicted swimlane, run it live with tracing on the active
/// central node, or replay a past execution from the audit store. State machine
/// <c>Idle → Predicted → Running → Completed | Failed | TimedOut</c>. The server's
/// <c>STANDBY_NODE</c> refusal renders as an inline alert with the message verbatim.
/// </summary>
public partial class FlowDebugger : ComponentBase, IDisposable
{
    /// <summary>Entry point kinds.</summary>
    public enum EntryKind
    {
        /// <summary>An inbound API method.</summary>
        Method,
        /// <summary>A value-change trigger on an instance attribute.</summary>
        ValueChange,
    }

    /// <summary>Live vs Replay.</summary>
    public enum FlowMode
    {
        /// <summary>Run it now.</summary>
        Live,
        /// <summary>Rebuild a past flow from the audit store.</summary>
        Replay,
    }

    /// <summary>Page state.</summary>
    public enum FlowState
    {
        /// <summary>Nothing chosen.</summary>
        Idle,
        /// <summary>Predicted graph shown, not yet run.</summary>
        Predicted,
        /// <summary>A run or replay is in flight.</summary>
        Running,
        /// <summary>Run finished (or replay loaded).</summary>
        Completed,
        /// <summary>Run refused or failed.</summary>
        Failed,
        /// <summary>Run timed out / no trigger within the window.</summary>
        TimedOut,
    }

    private const string StorageEntry = "flowDebugger.entry";
    private const string StorageMethod = "flowDebugger.methodId";
    private const string StorageSite = "flowDebugger.siteId";
    private const string StorageInstance = "flowDebugger.instanceId";
    private const string StorageAttribute = "flowDebugger.attribute";
    private const string StorageInputsPrefix = "flowDebugger.inputs.";

    [Inject] private IFlowDebugService FlowDebug { get; set; } = default!;
    [Inject] private IInboundApiRepository InboundApi { get; set; } = default!;
    [Inject] private ITemplateEngineRepository TemplateEngineRepository { get; set; } = default!;
    [Inject] private ISiteRepository SiteRepository { get; set; } = default!;
    [Inject] private SiteScopeService SiteScope { get; set; } = default!;
    [Inject] private IJSRuntime JS { get; set; } = default!;

    /// <summary>Drill-in: pre-select an inbound method.</summary>
    [SupplyParameterFromQuery] public int? MethodId { get; set; }

    /// <summary>Drill-in: pre-select an instance (value-change entry).</summary>
    [SupplyParameterFromQuery] public int? InstanceId { get; set; }

    /// <summary>Drill-in: pre-select the trigger attribute (with <see cref="InstanceId"/>).</summary>
    [SupplyParameterFromQuery] public string? Attribute { get; set; }

    /// <summary>Drill-in: replay this execution on first render.</summary>
    [SupplyParameterFromQuery] public Guid? ExecutionId { get; set; }

    private EntryKind _entry = EntryKind.Method;
    private FlowMode _mode = FlowMode.Live;
    private FlowState _state = FlowState.Idle;

    private List<ApiMethod> _methods = [];
    private List<Site> _sites = [];
    private List<Instance> _instances = [];
    private List<string> _attributes = [];

    private int _selectedMethodId;
    private int _selectedSiteId;
    private int _selectedInstanceId;
    private string _selectedAttribute = string.Empty;
    private string _valueChangeValue = string.Empty;
    private string _replayExecutionIdText = string.Empty;

    private List<InboundApiSchemaField> _inputFields = [];
    private readonly Dictionary<string, string> _inputs = new(StringComparer.Ordinal);

    private PredictedFlow? _predicted;
    private FlowGraph? _graph;
    private FlowDebugRunResult? _raw;
    private FlowStep? _selected;
    private string? _error;
    private string? _errorCode;
    private int _runNumber;
    private double _zoom = 1.0;
    private bool _running;
    private bool _storageRestored;

    // Outbound calls (plan 2026-09-06 D5): after a Live run whose graph still has Pending
    // outbound steps, re-read the tree through the Replay command until every step is terminal
    // or the window closes. Page constants, not options — nothing operational depends on them.
    internal static readonly TimeSpan PendingRefreshInterval = TimeSpan.FromSeconds(5);
    internal static readonly TimeSpan PendingRefreshWindow = TimeSpan.FromMinutes(2);
    private CancellationTokenSource? _refreshCts;
    private bool _refreshing;

    /// <summary>Delay seam for the pending-refresh loop (tests inject an immediate delay).</summary>
    internal Func<TimeSpan, CancellationToken, Task> Delay { get; set; } = Task.Delay;

    private int PendingCount => _graph?.Steps.Count(s => s.Outcome == FlowStepOutcome.Pending) ?? 0;

    private bool CanRefresh => !_running && _raw is not null;

    private bool CanRun => !_running && _mode == FlowMode.Live && (
        _entry == EntryKind.Method ? _selectedMethodId > 0
        : _selectedInstanceId > 0 && !string.IsNullOrWhiteSpace(_selectedAttribute));

    private string StateLabel => _state switch
    {
        FlowState.Idle => "Not run",
        FlowState.Predicted => "Predicted",
        FlowState.Running => "Running",
        FlowState.Completed => "Completed",
        FlowState.Failed => "Failed",
        FlowState.TimedOut => "Timed out",
        _ => _state.ToString(),
    };

    private string StateCss => _state switch
    {
        FlowState.Idle => "idle",
        FlowState.Predicted => "predicted",
        FlowState.Running => "running",
        FlowState.Completed => "completed",
        FlowState.Failed => "failed",
        FlowState.TimedOut => "timed-out",
        _ => "idle",
    };

    /// <summary>
    /// True when a run produced a route call whose site leg came back untraced — no Site-lane
    /// steps and no child execution id on the route call (older site build / untraced call).
    /// </summary>
    private bool SiteNotTraced
        => _graph is { Steps.Count: > 0 }
           && _graph.Steps.All(s => s.Lane != FlowLane.Site)
           && _graph.Steps.Any(s => s.Kind == FlowStepKind.RouteCall && s.Extra?.ChildExecutionId == null);

    /// <inheritdoc/>
    protected override async Task OnInitializedAsync()
    {
        _methods = (await InboundApi.GetAllApiMethodsAsync()).OrderBy(m => m.Name, StringComparer.OrdinalIgnoreCase).ToList();
        _sites = await SiteScope.FilterSitesAsync(await SiteRepository.GetAllSitesAsync());

        if (InstanceId is int iid && iid > 0)
        {
            _entry = EntryKind.ValueChange;
            var inst = await TemplateEngineRepository.GetInstanceByIdAsync(iid);
            if (inst != null && await SiteScope.IsSiteAllowedAsync(inst.SiteId))
            {
                _selectedSiteId = inst.SiteId;
                await LoadInstancesAsync();
                _selectedInstanceId = inst.Id;
                await LoadAttributesAsync();
                if (!string.IsNullOrEmpty(Attribute) && _attributes.Contains(Attribute))
                {
                    _selectedAttribute = Attribute;
                    await PredictAsync();
                }
            }
        }
        else if (MethodId is int mid && mid > 0 && _methods.Any(m => m.Id == mid))
        {
            _entry = EntryKind.Method;
            _selectedMethodId = mid;
            await OnMethodChangedAsync();
        }

        if (ExecutionId is Guid exec && exec != Guid.Empty)
        {
            _mode = FlowMode.Replay;
            _replayExecutionIdText = exec.ToString();
            await LoadReplayAsync();
        }
    }

    /// <inheritdoc/>
    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!firstRender || _storageRestored)
            return;
        _storageRestored = true;

        // Only restore from localStorage when nothing was chosen through the URL.
        if (_selectedMethodId > 0 || _selectedInstanceId > 0 || ExecutionId != null)
            return;

        try
        {
            var entry = await JS.InvokeAsync<string?>("localStorage.getItem", StorageEntry);
            if (string.Equals(entry, nameof(EntryKind.ValueChange), StringComparison.Ordinal))
            {
                _entry = EntryKind.ValueChange;
                var site = await JS.InvokeAsync<string?>("localStorage.getItem", StorageSite);
                var inst = await JS.InvokeAsync<string?>("localStorage.getItem", StorageInstance);
                var attr = await JS.InvokeAsync<string?>("localStorage.getItem", StorageAttribute);
                if (int.TryParse(site, NumberStyles.Integer, CultureInfo.InvariantCulture, out var sid) && _sites.Any(s => s.Id == sid))
                {
                    _selectedSiteId = sid;
                    await LoadInstancesAsync();
                    if (int.TryParse(inst, NumberStyles.Integer, CultureInfo.InvariantCulture, out var iid) && _instances.Any(i => i.Id == iid))
                    {
                        _selectedInstanceId = iid;
                        await LoadAttributesAsync();
                        if (!string.IsNullOrEmpty(attr) && _attributes.Contains(attr))
                        {
                            _selectedAttribute = attr;
                            await PredictAsync();
                        }
                    }
                }
            }
            else
            {
                var method = await JS.InvokeAsync<string?>("localStorage.getItem", StorageMethod);
                if (int.TryParse(method, NumberStyles.Integer, CultureInfo.InvariantCulture, out var mid) && _methods.Any(m => m.Id == mid))
                {
                    _selectedMethodId = mid;
                    await OnMethodChangedAsync();
                }
            }

            StateHasChanged();
        }
        catch (Exception)
        {
            // localStorage unavailable (prerender, test host) — start clean.
        }
    }

    private async Task SetEntryAsync(EntryKind entry)
    {
        if (_entry == entry) return;
        _entry = entry;
        ResetResult();
        _predicted = null;
        _state = FlowState.Idle;
        await PersistAsync(StorageEntry, entry.ToString());
        if (_entry == EntryKind.Method && _selectedMethodId > 0)
            await OnMethodChangedAsync();
        else if (_entry == EntryKind.ValueChange && _selectedInstanceId > 0 && _selectedAttribute != string.Empty)
            await PredictAsync();
    }

    private async Task OnMethodChangedAsync()
    {
        ResetResult();
        _inputFields = [];
        _inputs.Clear();
        _predicted = null;
        _state = FlowState.Idle;

        var method = _methods.FirstOrDefault(m => m.Id == _selectedMethodId);
        if (method == null)
            return;

        try
        {
            var schema = InboundApiSchema.Parse(method.ParameterDefinitions);
            if (schema is { Type: "object" })
                _inputFields = schema.Fields.ToList();
        }
        catch (JsonException)
        {
            _inputFields = [];
        }

        await PersistAsync(StorageEntry, EntryKind.Method.ToString());
        await PersistAsync(StorageMethod, method.Id.ToString(CultureInfo.InvariantCulture));
        await RestoreInputsAsync(method.Id);
        await PredictAsync();
    }

    private async Task OnSiteChangedAsync()
    {
        ResetResult();
        _predicted = null;
        _state = FlowState.Idle;
        _selectedInstanceId = 0;
        _selectedAttribute = string.Empty;
        _attributes = [];
        await LoadInstancesAsync();
        await PersistAsync(StorageSite, _selectedSiteId.ToString(CultureInfo.InvariantCulture));
    }

    private async Task OnInstanceChangedAsync()
    {
        ResetResult();
        _predicted = null;
        _state = FlowState.Idle;
        _selectedAttribute = string.Empty;
        await LoadAttributesAsync();
        await PersistAsync(StorageInstance, _selectedInstanceId.ToString(CultureInfo.InvariantCulture));
    }

    private async Task OnAttributeChangedAsync()
    {
        ResetResult();
        await PersistAsync(StorageEntry, EntryKind.ValueChange.ToString());
        await PersistAsync(StorageAttribute, _selectedAttribute);
        await PredictAsync();
    }

    private async Task LoadInstancesAsync()
    {
        _instances = _selectedSiteId > 0
            ? (await TemplateEngineRepository.GetInstancesBySiteIdAsync(_selectedSiteId)).OrderBy(i => i.UniqueName, StringComparer.OrdinalIgnoreCase).ToList()
            : [];
    }

    private async Task LoadAttributesAsync()
    {
        _attributes = [];
        var inst = _instances.FirstOrDefault(i => i.Id == _selectedInstanceId);
        if (inst == null)
            return;
        var attrs = await TemplateEngineRepository.GetAttributesByTemplateIdAsync(inst.TemplateId);
        _attributes = attrs.Select(a => a.Name).Distinct(StringComparer.Ordinal).OrderBy(n => n, StringComparer.OrdinalIgnoreCase).ToList();
    }

    private async Task PredictAsync()
    {
        try
        {
            _predicted = _entry == EntryKind.Method
                ? await FlowDebug.PredictMethodAsync(_selectedMethodId)
                : await FlowDebug.PredictValueChangeAsync(_selectedInstanceId, _selectedAttribute);
            _state = _predicted.Nodes.Count > 0 ? FlowState.Predicted : FlowState.Idle;
        }
        catch (Exception ex)
        {
            _predicted = null;
            _error = "Prediction failed: " + ex.Message;
            _errorCode = "PREDICTION_FAILED";
        }
    }

    private void SetMode(FlowMode mode)
    {
        if (_mode == mode) return;
        CancelPendingRefresh();
        _mode = mode;
    }

    private async Task RunAsync()
    {
        if (!CanRun) return;
        CancelPendingRefresh();
        _running = true;
        _state = FlowState.Running;
        _error = null;
        _errorCode = null;
        _graph = null;
        _raw = null;
        _selected = null;
        _runNumber++;

        try
        {
            FlowDebugOutcome outcome;
            if (_entry == EntryKind.Method)
            {
                await PersistInputsAsync(_selectedMethodId);
                outcome = await FlowDebug.RunMethodAsync(_selectedMethodId, BuildParameters());
            }
            else
            {
                outcome = await FlowDebug.RunValueChangeAsync(_selectedInstanceId, _selectedAttribute, _valueChangeValue);
            }

            ApplyOutcome(outcome);
        }
        catch (Exception ex)
        {
            _error = ex.Message;
            _errorCode = "RUN_FAILED";
            _state = FlowState.Failed;
        }
        finally
        {
            _running = false;
        }

        StartPendingRefresh();
    }

    /// <summary>Begins polling when a completed Live run left outbound work in flight. Never in Replay mode.</summary>
    private void StartPendingRefresh()
    {
        if (_mode != FlowMode.Live || _raw is null || _graph is null || PendingCount == 0)
            return;
        var cts = new CancellationTokenSource();
        _refreshCts = cts;
        _ = RefreshPendingLoopAsync(_raw.RootExecutionId, cts);
    }

    private async Task RefreshPendingLoopAsync(Guid root, CancellationTokenSource cts)
    {
        var ct = cts.Token;
        _refreshing = true;
        var deadline = DateTime.UtcNow + PendingRefreshWindow;
        try
        {
            while (!ct.IsCancellationRequested && DateTime.UtcNow < deadline)
            {
                await Delay(PendingRefreshInterval, ct);
                var outcome = await FlowDebug.ReplayAsync(root, ct);
                if (ct.IsCancellationRequested) return;
                MergeRefreshedGraph(outcome);
                await InvokeAsync(StateHasChanged);
                if (PendingCount == 0) return;
            }
        }
        catch (OperationCanceledException)
        {
            // New run, mode switch or dispose — the loop is simply abandoned.
        }
        catch (Exception)
        {
            // Best-effort: the manual Refresh button stays available.
        }
        finally
        {
            if (ReferenceEquals(_refreshCts, cts))
            {
                _refreshing = false;
                _refreshCts = null;
                cts.Dispose();
                try { await InvokeAsync(StateHasChanged); } catch (ObjectDisposedException) { }
            }
        }
    }

    /// <summary>Manual refresh — one Replay read of the run's tree; works in both modes.</summary>
    private async Task RefreshOutcomesAsync()
    {
        if (!CanRefresh) return;
        var root = _raw!.RootExecutionId;
        _running = true;
        try
        {
            MergeRefreshedGraph(await FlowDebug.ReplayAsync(root));
        }
        catch (Exception ex)
        {
            _error = "Refresh failed: " + ex.Message;
            _errorCode = "REFRESH_FAILED";
        }
        finally
        {
            _running = false;
        }
    }

    /// <summary>
    /// Replaces the graph with the re-read tree and keeps the selection by event id. The run's own
    /// <c>_raw</c> (timing, root) and the state chip are deliberately left alone: pending outbound
    /// work is not a failed run, and the run's Started/Total are the truthful numbers.
    /// </summary>
    private void MergeRefreshedGraph(FlowDebugOutcome outcome)
    {
        if (!outcome.Success || outcome.Graph == null || _graph == null)
            return;
        var selectedId = _selected?.EventId;
        _graph = outcome.Graph;
        _selected = selectedId is { } id ? _graph.Steps.FirstOrDefault(s => s.EventId == id) ?? _selected : _selected;
    }

    private void CancelPendingRefresh()
    {
        var cts = _refreshCts;
        if (cts is null) return;
        _refreshCts = null;
        _refreshing = false;
        try { cts.Cancel(); } catch (ObjectDisposedException) { }
    }

    /// <inheritdoc/>
    public void Dispose() => CancelPendingRefresh();

    private async Task LoadReplayAsync()
    {
        if (!Guid.TryParse(_replayExecutionIdText, out var exec)) return;
        CancelPendingRefresh();
        _running = true;
        _state = FlowState.Running;
        _error = null;
        _errorCode = null;
        _graph = null;
        _raw = null;
        _selected = null;
        _predicted = null;

        try
        {
            ApplyOutcome(await FlowDebug.ReplayAsync(exec));
        }
        catch (Exception ex)
        {
            _error = ex.Message;
            _errorCode = "REPLAY_FAILED";
            _state = FlowState.Failed;
        }
        finally
        {
            _running = false;
        }
    }

    private void ApplyOutcome(FlowDebugOutcome outcome)
    {
        if (!outcome.Success || outcome.Graph == null)
        {
            _error = outcome.Error ?? "The run failed.";
            _errorCode = outcome.ErrorCode;
            _state = FlowState.Failed;
            return;
        }

        _graph = outcome.Graph;
        _raw = outcome.Raw;
        if (_raw is { Completed: false })
        {
            _error = _raw.Error;
            _errorCode = _raw.ErrorCode;
            _state = _raw.ErrorCode is "NO_TRIGGER_WITHIN_WINDOW" or "TIMEOUT" ? FlowState.TimedOut : FlowState.Failed;
        }
        else
        {
            _state = _graph.Steps.Any(s => s.Outcome == FlowStepOutcome.TimedOut) ? FlowState.TimedOut
                : _graph.Steps.Any(s => s.Outcome == FlowStepOutcome.Failed) ? FlowState.Failed
                : FlowState.Completed;
        }

        _selected = _graph.Steps.FirstOrDefault();
    }

    private void ResetResult()
    {
        CancelPendingRefresh();
        _graph = null;
        _raw = null;
        _selected = null;
        _error = null;
        _errorCode = null;
    }

    private void OnSelectStep(FlowStep step) => _selected = step;

    private string InputValue(string name) => _inputs.TryGetValue(name, out var v) ? v : string.Empty;

    private void SetInput(string name, string? value)
    {
        if (value == null) _inputs.Remove(name);
        else _inputs[name] = value;
    }

    /// <summary>
    /// Builds the request body from the typed inputs, coercing by the schema's declared field
    /// type (integers/numbers/booleans become JSON scalars; objects/lists are parsed as JSON;
    /// everything else is a string). Empty inputs are omitted so a non-required field is not
    /// sent as an empty string.
    /// </summary>
    internal JsonElement? BuildParameters()
    {
        if (_inputFields.Count == 0)
            return null;

        var obj = new JsonObject();
        foreach (var f in _inputFields)
        {
            if (!_inputs.TryGetValue(f.Name, out var raw) || string.IsNullOrEmpty(raw))
                continue;
            obj[f.Name] = Coerce(f.Schema.Type, raw);
        }

        return JsonSerializer.SerializeToElement(obj);
    }

    private static JsonNode? Coerce(string? type, string raw)
    {
        switch (InboundApiSchema.NormalizeType(type))
        {
            case "integer":
                return long.TryParse(raw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var l) ? JsonValue.Create(l) : JsonValue.Create(raw);
            case "number":
                return double.TryParse(raw, NumberStyles.Float, CultureInfo.InvariantCulture, out var d) ? JsonValue.Create(d) : JsonValue.Create(raw);
            case "boolean":
                return bool.TryParse(raw, out var b) ? JsonValue.Create(b) : JsonValue.Create(raw);
            case "object":
            case "array":
            case "list":
                try
                {
                    return JsonNode.Parse(raw);
                }
                catch (JsonException)
                {
                    return JsonValue.Create(raw);
                }
            default:
                return JsonValue.Create(raw);
        }
    }

    private async Task PersistAsync(string key, string value)
    {
        try
        {
            await JS.InvokeVoidAsync("localStorage.setItem", key, value);
        }
        catch (Exception)
        {
            // Best-effort convenience only.
        }
    }

    private async Task PersistInputsAsync(int methodId)
    {
        try
        {
            await JS.InvokeVoidAsync("localStorage.setItem", StorageInputsPrefix + methodId.ToString(CultureInfo.InvariantCulture),
                JsonSerializer.Serialize(_inputs));
        }
        catch (Exception)
        {
        }
    }

    private async Task RestoreInputsAsync(int methodId)
    {
        try
        {
            var json = await JS.InvokeAsync<string?>("localStorage.getItem", StorageInputsPrefix + methodId.ToString(CultureInfo.InvariantCulture));
            if (string.IsNullOrEmpty(json)) return;
            var saved = JsonSerializer.Deserialize<Dictionary<string, string>>(json);
            if (saved == null) return;
            foreach (var (k, v) in saved)
                if (_inputFields.Any(f => f.Name == k))
                    _inputs[k] = v;
        }
        catch (Exception)
        {
        }
    }
}