using System.Collections.Concurrent;
using System.Diagnostics;
using System.Text.Json;
using System.Text.Json.Serialization;
using Poe2Trade.Core;
using Serilog;

namespace Poe2Trade.Trade;

public class TradeDaemonBridge : ITradeMonitor
{
    private static readonly JsonSerializerOptions JsonOpts = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
    };

    private Process? _proc;
    private int _reqCounter;
    private readonly ConcurrentDictionary<int, TaskCompletionSource<JsonElement>> _pending = new();
    private readonly SavedSettings _config;
    private readonly string _daemonScript;
    private readonly string _nodeExe;

    public event Action<string, List<string>>? NewListings;

    public TradeDaemonBridge(SavedSettings config)
    {
        _config = config;
        _daemonScript = Path.GetFullPath(Path.Combine("tools", "trade-daemon", "daemon.mjs"));
        _nodeExe = "node";
    }

    public async Task Start(string? dashboardUrl = null)
    {
        EnsureDaemonRunning();

        var userDataDir = Path.GetFullPath(_config.BrowserUserDataDir);
        await SendCommand("start", new
        {
            browserUserDataDir = userDataDir,
            headless = _config.Headless,
            dashboardUrl,
        });

        Log.Information("Trade daemon browser started");
    }

    public async Task AddSearch(string tradeUrl)
    {
        EnsureDaemonRunning();
        await SendCommand("addSearch", new { url = tradeUrl });
    }

    public async Task PauseSearch(string searchId)
    {
        EnsureDaemonRunning();
        await SendCommand("pauseSearch", new { searchId });
    }

    public async Task<bool> ClickTravelToHideout(string pageId, string? itemId = null)
    {
        EnsureDaemonRunning();
        var resp = await SendCommand("clickTravel", new { pageId, itemId });
        return resp.TryGetProperty("clicked", out var c) && c.GetBoolean();
    }

    public async Task<(string ScrapId, List<TradeItem> Items)> OpenScrapPage(string tradeUrl)
    {
        EnsureDaemonRunning();
        var resp = await SendCommand("openScrapPage", new { url = tradeUrl });
        var scrapId = resp.GetProperty("scrapId").GetString()!;
        var items = ParseItems(resp);
        return (scrapId, items);
    }

    public async Task<List<TradeItem>> ReloadScrapPage(string scrapId)
    {
        EnsureDaemonRunning();
        var resp = await SendCommand("reloadScrapPage", new { scrapId });
        return ParseItems(resp);
    }

    public async Task CloseScrapPage(string scrapId)
    {
        EnsureDaemonRunning();
        await SendCommand("closeScrapPage", new { scrapId });
    }

    public string ExtractSearchId(string url)
    {
        var cleaned = System.Text.RegularExpressions.Regex.Replace(url, @"/live/?$", "");
        var parts = cleaned.Split('/');
        return parts.Length > 0 ? parts[^1] : url;
    }

    public async ValueTask DisposeAsync()
    {
        if (_proc != null && !_proc.HasExited)
        {
            try
            {
                // Send stop command (best effort)
                var reqId = Interlocked.Increment(ref _reqCounter);
                var msg = JsonSerializer.Serialize(new { reqId, cmd = "stop" }, JsonOpts);
                await _proc.StandardInput.WriteLineAsync(msg);
                await _proc.StandardInput.FlushAsync();
                _proc.WaitForExit(5000);
            }
            catch { /* ignore */ }

            if (_proc != null && !_proc.HasExited)
            {
                try { _proc.Kill(); } catch { /* ignore */ }
            }
        }

        _proc?.Dispose();
        _proc = null;

        // Complete any pending requests
        foreach (var kv in _pending)
        {
            kv.Value.TrySetCanceled();
            _pending.TryRemove(kv.Key, out _);
        }

        Log.Information("Trade daemon stopped");
    }

    private async Task<JsonElement> SendCommand(string cmd, object? parameters = null)
    {
        if (_proc == null || _proc.HasExited)
            throw new InvalidOperationException("Trade daemon is not running");

        var reqId = Interlocked.Increment(ref _reqCounter);
        var tcs = new TaskCompletionSource<JsonElement>(TaskCreationOptions.RunContinuationsAsynchronously);
        _pending[reqId] = tcs;

        // Build command object: merge reqId + cmd + params
        var dict = new Dictionary<string, object?> { ["reqId"] = reqId, ["cmd"] = cmd };
        if (parameters != null)
        {
            var paramJson = JsonSerializer.SerializeToElement(parameters, JsonOpts);
            foreach (var prop in paramJson.EnumerateObject())
                dict[prop.Name] = prop.Value;
        }

        var json = JsonSerializer.Serialize(dict, JsonOpts);
        await _proc.StandardInput.WriteLineAsync(json);
        await _proc.StandardInput.FlushAsync();

        // Await response with timeout
        using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(60));
        cts.Token.Register(() => tcs.TrySetCanceled());

        try
        {
            return await tcs.Task;
        }
        finally
        {
            _pending.TryRemove(reqId, out _);
        }
    }

    private void EnsureDaemonRunning()
    {
        if (_proc != null && !_proc.HasExited)
            return;

        _proc?.Dispose();
        _proc = null;

        if (!File.Exists(_daemonScript))
            throw new FileNotFoundException($"Trade daemon not found at {_daemonScript}");

        Log.Information("Spawning trade daemon: {Node} {Script}", _nodeExe, _daemonScript);

        var proc = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = _nodeExe,
                Arguments = $"\"{_daemonScript}\"",
                UseShellExecute = false,
                RedirectStandardInput = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true,
            }
        };

        proc.ErrorDataReceived += (_, e) =>
        {
            if (!string.IsNullOrEmpty(e.Data))
                Log.Debug("[trade-daemon] {Line}", e.Data);
        };

        try
        {
            proc.Start();
            proc.BeginErrorReadLine();

            // Wait for ready signal (up to 15s)
            var readyTask = Task.Run(() => proc.StandardOutput.ReadLine());
            if (!readyTask.Wait(TimeSpan.FromSeconds(15)))
                throw new TimeoutException("Trade daemon did not send ready signal within 15s");

            var readyLine = readyTask.Result
                ?? throw new Exception("Trade daemon exited before ready signal");

            var readyDoc = JsonDocument.Parse(readyLine);
            if (!readyDoc.RootElement.TryGetProperty("type", out var typeProp) ||
                typeProp.GetString() != "ready")
                throw new Exception($"Trade daemon did not send ready signal: {readyLine}");
        }
        catch
        {
            try { if (!proc.HasExited) proc.Kill(); } catch { /* best effort */ }
            proc.Dispose();
            throw;
        }

        _proc = proc;

        // Start background reader thread
        _ = Task.Run(() => ReadLoop(proc));

        Log.Information("Trade daemon ready");
    }

    private void ReadLoop(Process proc)
    {
        try
        {
            while (!proc.HasExited)
            {
                var line = proc.StandardOutput.ReadLine();
                if (line == null) break;

                try
                {
                    using var doc = JsonDocument.Parse(line);
                    var root = doc.RootElement;
                    var type = root.GetProperty("type").GetString();

                    if (type == "response")
                    {
                        var reqId = root.GetProperty("reqId").GetInt32();
                        if (_pending.TryGetValue(reqId, out var tcs))
                        {
                            var ok = root.GetProperty("ok").GetBoolean();
                            if (ok)
                                tcs.TrySetResult(root.Clone());
                            else
                            {
                                var error = root.TryGetProperty("error", out var e)
                                    ? e.GetString() ?? "Unknown error"
                                    : "Unknown error";
                                tcs.TrySetException(new Exception($"Trade daemon error: {error}"));
                            }
                        }
                    }
                    else if (type == "event")
                    {
                        HandleEvent(root);
                    }
                }
                catch (Exception ex)
                {
                    Log.Debug("Failed to parse daemon output: {Line} - {Error}", line, ex.Message);
                }
            }
        }
        catch (Exception ex)
        {
            Log.Warning(ex, "Trade daemon read loop ended");
        }

        // Daemon exited — fail all pending requests
        foreach (var kv in _pending)
        {
            kv.Value.TrySetException(new Exception("Trade daemon process exited"));
            _pending.TryRemove(kv.Key, out _);
        }
    }

    private void HandleEvent(JsonElement root)
    {
        var eventName = root.GetProperty("event").GetString();
        switch (eventName)
        {
            case "newListings":
                var searchId = root.GetProperty("searchId").GetString()!;
                var itemIds = root.GetProperty("itemIds").EnumerateArray()
                    .Select(e => e.GetString()!)
                    .Where(s => s != null)
                    .ToList();
                if (itemIds.Count > 0)
                {
                    Log.Information("New listings from daemon: {SearchId} ({Count} items)", searchId, itemIds.Count);
                    NewListings?.Invoke(searchId, itemIds);
                }
                break;

            case "wsClose":
                var closedId = root.GetProperty("searchId").GetString()!;
                Log.Warning("WebSocket closed (daemon): {SearchId}", closedId);
                break;

            default:
                Log.Debug("Unknown daemon event: {Event}", eventName);
                break;
        }
    }

    private static List<TradeItem> ParseItems(JsonElement resp)
    {
        var items = new List<TradeItem>();
        if (resp.TryGetProperty("items", out var arr) && arr.ValueKind == JsonValueKind.Array)
        {
            foreach (var el in arr.EnumerateArray())
            {
                items.Add(new TradeItem(
                    el.GetProperty("id").GetString() ?? "",
                    el.TryGetProperty("w", out var w) ? w.GetInt32() : 1,
                    el.TryGetProperty("h", out var h) ? h.GetInt32() : 1,
                    el.TryGetProperty("stashX", out var sx) ? sx.GetInt32() : 0,
                    el.TryGetProperty("stashY", out var sy) ? sy.GetInt32() : 0,
                    el.TryGetProperty("account", out var acc) ? acc.GetString() ?? "" : ""
                ));
            }
        }
        return items;
    }
}