using System;
using System.Collections.Concurrent;
using System.IO;
using System.Linq;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Gott.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;

namespace Gott.Endpoints;

/// <summary>
/// Interne API-Endpoints für MCP-Server und andere lokale Integrationen.
/// Gesichert über einen internen Token (da Reverse-Proxy den Localhost-Check umgeht).
/// </summary>
public static class InternalEndpoint
{
    /// <summary>
    /// Interner Auth-Token – wird beim Start generiert und an MCP-Server übergeben.
    /// </summary>
    public static string InternalToken { get; } = Guid.NewGuid().ToString("N");

    /// <summary>
    /// Pending user choices – Key ist sessionId, Value wird completed wenn der User klickt.
    /// </summary>
    public static readonly ConcurrentDictionary<string, TaskCompletionSource<string>> PendingChoices = new();

    public static void MapInternalEndpoints(this IEndpointRouteBuilder app)
    {
        app.MapPost("/api/internal/remote-execute", HandleRemoteExecute);
        app.MapPost("/api/internal/ask-user-choice", HandleAskUserChoice);
        // choice-respond ist NICHT unter /api/internal/ weil es vom Frontend aufgerufen wird (normale Auth)
        app.MapPost("/api/chat/choice-respond", HandleChoiceRespond);
        app.MapPost("/api/internal/memory-read", HandleMemoryRead);
        app.MapPost("/api/internal/memory-write", HandleMemoryWrite);
        app.MapPost("/api/internal/memory-list", HandleMemoryList);
    }

    private static async Task<IResult> HandleRemoteExecute(HttpContext ctx, RemoteConnectionManager mgr)
    {
        try
        {
            // Token-Check: Header "X-Internal-Token" muss den internen Token enthalten
            var token = ctx.Request.Headers["X-Internal-Token"].FirstOrDefault() ?? "";
            if (token != InternalToken)
                return Results.StatusCode(403);

            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();

            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var command = json.TryGetProperty("command", out var cmd) ? cmd.GetString() ?? "" : "";
            var sessionId = json.TryGetProperty("sessionId", out var sid) ? sid.GetString() ?? "" : "";

            if (string.IsNullOrEmpty(command))
                return Results.BadRequest(new { error = "command erforderlich" });

            if (string.IsNullOrEmpty(sessionId))
                return Results.BadRequest(new { error = "sessionId erforderlich" });

            var conn = mgr.GetBySessionId(sessionId);
            if (conn == null)
                return Results.NotFound(new { error = "Keine Remote-Verbindung für diese Session" });

            using var cts = new CancellationTokenSource(System.TimeSpan.FromSeconds(180));
            var result = await mgr.ExecuteCommand(conn.Id, command, 180, cts.Token);

            return Results.Ok(new
            {
                exitCode = result.ExitCode,
                stdout = result.Output ?? "",
                stderr = result.Error ?? ""
            });
        }
        catch (System.Exception ex)
        {
            return Results.Json(new { error = ex.Message, stackTrace = ex.StackTrace }, statusCode: 500);
        }
    }

    /// <summary>
    /// MCP-Server ruft diesen Endpoint auf und blockiert bis der User eine Auswahl trifft.
    /// Der TCS wird vorher von AnthropicService erstellt (beim tool_use Event).
    /// </summary>
    private static async Task<IResult> HandleAskUserChoice(HttpContext ctx)
    {
        try
        {
            var denied = CheckToken(ctx);
            if (denied != null) return denied;

            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();
            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var sessionId = json.TryGetProperty("sessionId", out var sid) ? sid.GetString() ?? "" : "";
            if (string.IsNullOrEmpty(sessionId))
                return Results.BadRequest(new { error = "sessionId erforderlich" });

            // Warte auf den TCS der von AnthropicService erstellt wurde
            if (!PendingChoices.TryGetValue(sessionId, out var tcs))
            {
                // TCS noch nicht erstellt (Race Condition) – kurz warten und nochmal probieren
                for (int i = 0; i < 10; i++)
                {
                    await Task.Delay(500, ctx.RequestAborted);
                    if (PendingChoices.TryGetValue(sessionId, out tcs)) break;
                }
                if (tcs == null)
                    return Results.Json(new { error = "Keine ausstehende Auswahl für diese Session" }, statusCode: 404);
            }

            // Blockieren bis User antwortet (max 5 Minuten)
            using var cts = CancellationTokenSource.CreateLinkedTokenSource(ctx.RequestAborted);
            cts.CancelAfter(TimeSpan.FromMinutes(5));

            try
            {
                var choice = await tcs.Task.WaitAsync(cts.Token);
                PendingChoices.TryRemove(sessionId, out _);
                return Results.Ok(new { choice });
            }
            catch (OperationCanceledException)
            {
                PendingChoices.TryRemove(sessionId, out _);
                return Results.Json(new { error = "Timeout – keine Auswahl getroffen" }, statusCode: 408);
            }
        }
        catch (Exception ex)
        {
            return Results.Json(new { error = ex.Message }, statusCode: 500);
        }
    }

    /// <summary>
    /// Frontend ruft diesen Endpoint auf wenn der User einen Choice-Button klickt (CLI-Modus).
    /// </summary>
    private static async Task<IResult> HandleChoiceRespond(HttpContext ctx)
    {
        try
        {
            // Kein Token-Check – wird über normale Auth-Middleware geschützt (Cookie-basiert)
            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();
            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var sessionId = json.TryGetProperty("sessionId", out var sid) ? sid.GetString() ?? "" : "";
            var choice = json.TryGetProperty("choice", out var c) ? c.GetString() ?? "" : "";

            if (string.IsNullOrEmpty(sessionId))
                return Results.BadRequest(new { error = "sessionId erforderlich" });
            if (string.IsNullOrEmpty(choice))
                return Results.BadRequest(new { error = "choice erforderlich" });

            if (PendingChoices.TryGetValue(sessionId, out var tcs))
            {
                tcs.TrySetResult(choice);
                return Results.Ok(new { success = true });
            }

            return Results.NotFound(new { error = "Keine ausstehende Auswahl für diese Session" });
        }
        catch (Exception ex)
        {
            return Results.Json(new { error = ex.Message }, statusCode: 500);
        }
    }

    private static IResult CheckToken(HttpContext ctx)
    {
        var token = ctx.Request.Headers["X-Internal-Token"].FirstOrDefault() ?? "";
        return token != InternalToken ? Results.StatusCode(403) : null;
    }

    private static async Task<IResult> HandleMemoryRead(HttpContext ctx, MemoryService memoryService)
    {
        try
        {
            var denied = CheckToken(ctx);
            if (denied != null) return denied;

            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();
            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var agentId = json.TryGetProperty("agentId", out var a) ? a.GetString() ?? "" : "";
            var path = json.TryGetProperty("path", out var p) ? p.GetString() ?? "" : "";

            if (string.IsNullOrEmpty(agentId)) return Results.BadRequest(new { error = "agentId erforderlich" });
            if (string.IsNullOrEmpty(path)) return Results.BadRequest(new { error = "path erforderlich" });

            var content = memoryService.ReadMemoryFile(agentId, path);
            if (content == null)
                return Results.NotFound(new { error = $"Datei nicht gefunden: {path}" });

            return Results.Ok(new { content });
        }
        catch (System.Exception ex)
        {
            return Results.Json(new { error = ex.Message }, statusCode: 500);
        }
    }

    private static async Task<IResult> HandleMemoryWrite(HttpContext ctx, MemoryService memoryService)
    {
        try
        {
            var denied = CheckToken(ctx);
            if (denied != null) return denied;

            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();
            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var agentId = json.TryGetProperty("agentId", out var a) ? a.GetString() ?? "" : "";
            var path = json.TryGetProperty("path", out var p) ? p.GetString() ?? "" : "";
            var content = json.TryGetProperty("content", out var c) ? c.GetString() ?? "" : "";
            var append = json.TryGetProperty("append", out var ap) && ap.GetBoolean();

            if (string.IsNullOrEmpty(agentId)) return Results.BadRequest(new { error = "agentId erforderlich" });
            if (string.IsNullOrEmpty(path)) return Results.BadRequest(new { error = "path erforderlich" });

            if (append)
                memoryService.AppendMemoryFile(agentId, path, content);
            else
                memoryService.WriteMemoryFile(agentId, path, content);

            return Results.Ok(new { success = true, message = $"Memory-Datei {(append ? "erweitert" : "geschrieben")}: {path} ({content.Length} Zeichen)" });
        }
        catch (System.Exception ex)
        {
            return Results.Json(new { error = ex.Message }, statusCode: 500);
        }
    }

    private static async Task<IResult> HandleMemoryList(HttpContext ctx, MemoryService memoryService)
    {
        try
        {
            var denied = CheckToken(ctx);
            if (denied != null) return denied;

            using var reader = new StreamReader(ctx.Request.Body);
            var body = await reader.ReadToEndAsync();
            JsonElement json;
            try { json = JsonSerializer.Deserialize<JsonElement>(body); }
            catch { return Results.BadRequest(new { error = "Invalid JSON" }); }

            var agentId = json.TryGetProperty("agentId", out var a) ? a.GetString() ?? "" : "";
            var subPath = json.TryGetProperty("path", out var p) ? p.GetString() ?? "" : "";

            if (string.IsNullOrEmpty(agentId)) return Results.BadRequest(new { error = "agentId erforderlich" });

            var files = memoryService.ListMemoryFiles(agentId, subPath);
            return Results.Ok(new { files });
        }
        catch (System.Exception ex)
        {
            return Results.Json(new { error = ex.Message }, statusCode: 500);
        }
    }
}