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

namespace Gott.Endpoints;

public static class SessionEndpoint
{
    public static void MapSessionEndpoints(this IEndpointRouteBuilder app)
    {
        app.MapGet("/api/sessions", HandleList);
        app.MapGet("/api/sessions/{sessionId}", HandleGet);
        app.MapPost("/api/sessions", HandleCreate);
        app.MapPut("/api/sessions/{sessionId}", HandleUpdate);
        app.MapDelete("/api/sessions/{sessionId}", HandleDelete);
        app.MapGet("/api/sessions/{sessionId}/system-prompt", HandleSystemPrompt);
        app.MapGet("/api/sessions/{sessionId}/streaming", HandleStreaming);
        app.MapPost("/api/sessions/{sessionId}/exec", HandleExec);
        app.MapGet("/api/sessions/{sessionId}/git-status", HandleGitStatus);
    }

    private static async Task HandleList(HttpContext ctx, DatabaseService db)
    {
        var sessions = await db.GetSessionsWithStats();
        await ctx.Response.WriteAsJsonAsync(sessions);
    }

    private static async Task HandleGet(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }
        var session = await db.GetSession(sessionId);
        if (session == null)
        {
            ctx.Response.StatusCode = 404;
            return;
        }
        await ctx.Response.WriteAsJsonAsync(session);
    }

    private static async Task HandleCreate(HttpContext ctx, DatabaseService db, ImageService imageService)
    {
        var body = await JsonSerializer.DeserializeAsync<JsonElement>(ctx.Request.Body);

        var name = body.TryGetProperty("name", out var n) ? n.GetString() : "Neue Session";
        var description = body.TryGetProperty("description", out var d) ? d.GetString() : null;
        var imageRaw = body.TryGetProperty("image", out var img) ? img.GetString() : null;
        var image = imageService.ResizeDataUrl(imageRaw);
        var agentId = body.TryGetProperty("agentId", out var a) ? a.GetString() : null;
        var workspace = body.TryGetProperty("workspace", out var w) ? w.GetString() : null;
        var context = body.TryGetProperty("context", out var ctxEl) ? ctxEl.GetString() : null;
        var customCommands = body.TryGetProperty("customCommands", out var cc) && cc.ValueKind != JsonValueKind.Null ? cc.GetRawText() : null;

        var session = await db.CreateSession(name, description, image, agentId, workspace, context, customCommands);
        await ctx.Response.WriteAsJsonAsync(session);
    }

    private static async Task HandleUpdate(HttpContext ctx, DatabaseService db, ImageService imageService)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var body = await JsonSerializer.DeserializeAsync<JsonElement>(ctx.Request.Body);
        await db.UpdateSession(sessionId, body, imageService);

        var session = await db.GetSession(sessionId);
        await ctx.Response.WriteAsJsonAsync(session);
    }

    private static async Task HandleDelete(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId)) { ctx.Response.StatusCode = 400; return; }

        await db.DeleteSession(sessionId);
        ctx.Response.StatusCode = 204;
    }

    private static async Task HandleSystemPrompt(HttpContext ctx, DatabaseService db, MemoryService memoryService)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var session = await db.GetSession(sessionId);
        if (session == null)
        {
            ctx.Response.StatusCode = 404;
            return;
        }

        if (string.IsNullOrEmpty(session.AgentId))
        {
            ctx.Response.StatusCode = 400;
            await ctx.Response.WriteAsJsonAsync(new { error = "Kein Agent ausgewählt" });
            return;
        }

        var agent = await db.GetAgent(session.AgentId);
        if (agent == null)
        {
            ctx.Response.StatusCode = 400;
            await ctx.Response.WriteAsJsonAsync(new { error = "Agent nicht gefunden" });
            return;
        }

        var markedMessages = await db.GetMarkedMessages(sessionId);
        var agentMemoryDir = memoryService.GetAgentMemoryDir(agent.AgentId);
        var systemPrompt = SystemPromptBuilder.Build(agent, session, markedMessages, memoryService, agentMemoryDir);

        ctx.Response.ContentType = "text/plain; charset=utf-8";
        await ctx.Response.WriteAsync(systemPrompt);
    }

    private static async Task HandleStreaming(HttpContext ctx, StreamingTracker streamingTracker)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var isStreaming = streamingTracker.IsStreaming(sessionId);
        var chainId = streamingTracker.GetChainId(sessionId);
        await ctx.Response.WriteAsJsonAsync(new { streaming = isStreaming, chainId });
    }

    private static async Task HandleExec(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var session = await db.GetSession(sessionId);
        if (session == null)
        {
            ctx.Response.StatusCode = 404;
            return;
        }

        var body = await JsonSerializer.DeserializeAsync<JsonElement>(ctx.Request.Body);
        var command = body.TryGetProperty("command", out var c) ? c.GetString() : null;
        var mode = body.TryGetProperty("mode", out var m) ? m.GetString() ?? "background" : "background";

        if (string.IsNullOrWhiteSpace(command))
        {
            ctx.Response.StatusCode = 400;
            await ctx.Response.WriteAsJsonAsync(new { error = "Kein Befehl angegeben" });
            return;
        }

        var workingDir = !string.IsNullOrWhiteSpace(session.Workspace) ? session.Workspace : "/tmp";

        if (mode == "foreground")
        {
            // Synchron ausführen, auf Ergebnis warten
            try
            {
                var psi = new ProcessStartInfo
                {
                    FileName = "/bin/bash",
                    WorkingDirectory = workingDir,
                    RedirectStandardInput = true,
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    UseShellExecute = false,
                    CreateNoWindow = true
                };

                using var proc = System.Diagnostics.Process.Start(psi);
                if (proc == null)
                {
                    ctx.Response.StatusCode = 500;
                    await ctx.Response.WriteAsJsonAsync(new { error = "Prozess konnte nicht gestartet werden" });
                    return;
                }

                await proc.StandardInput.WriteAsync(command);
                proc.StandardInput.Close();

                using var cts = new System.Threading.CancellationTokenSource(TimeSpan.FromSeconds(30));
                try
                {
                    await proc.WaitForExitAsync(cts.Token);
                }
                catch (OperationCanceledException)
                {
                    proc.Kill(entireProcessTree: true);
                    await ctx.Response.WriteAsJsonAsync(new { status = "timeout", output = "Timeout nach 30 Sekunden", exitCode = -1 });
                    return;
                }

                var stdout = await proc.StandardOutput.ReadToEndAsync();
                var stderr = await proc.StandardError.ReadToEndAsync();

                var output = new System.Text.StringBuilder();
                if (!string.IsNullOrEmpty(stdout)) output.Append(stdout);
                if (!string.IsNullOrEmpty(stderr))
                {
                    if (output.Length > 0) output.Append("\n--- stderr ---\n");
                    output.Append(stderr);
                }

                await ctx.Response.WriteAsJsonAsync(new { status = "completed", output = output.ToString(), exitCode = proc.ExitCode });
            }
            catch (Exception ex)
            {
                ctx.Response.StatusCode = 500;
                await ctx.Response.WriteAsJsonAsync(new { error = ex.Message });
            }
        }
        else
        {
            // Fire-and-forget via systemd-run
            try
            {
                var scriptPath = $"/tmp/gott-exec-{Guid.NewGuid():N}.sh";
                await System.IO.File.WriteAllTextAsync(scriptPath, $"#!/bin/bash\ncd {workingDir}\n{command}\nrm -f {scriptPath}\n");

                var psi = new ProcessStartInfo
                {
                    FileName = "systemd-run",
                    Arguments = $"--scope --quiet bash {scriptPath}",
                    WorkingDirectory = workingDir,
                    UseShellExecute = false,
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    CreateNoWindow = true
                };

                var process = Process.Start(psi);
                if (process != null)
                {
                    process.WaitForExit(500);
                }

                ctx.Response.StatusCode = 202;
                await ctx.Response.WriteAsJsonAsync(new { status = "started", command = command });
            }
            catch (Exception ex)
            {
                ctx.Response.StatusCode = 500;
                await ctx.Response.WriteAsJsonAsync(new { error = ex.Message });
            }
        }
    }

    private static async Task HandleGitStatus(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.RouteValues["sessionId"]?.ToString();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var session = await db.GetSession(sessionId);
        if (session == null)
        {
            ctx.Response.StatusCode = 404;
            return;
        }

        var workingDir = !string.IsNullOrWhiteSpace(session.Workspace) ? session.Workspace : null;
        if (string.IsNullOrEmpty(workingDir))
        {
            ctx.Response.StatusCode = 400;
            await ctx.Response.WriteAsJsonAsync(new { error = "Kein Workspace konfiguriert" });
            return;
        }

        try
        {
            var psi = new ProcessStartInfo
            {
                FileName = "git",
                Arguments = "status --porcelain",
                WorkingDirectory = workingDir,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true
            };

            using var proc = Process.Start(psi);
            if (proc == null)
            {
                ctx.Response.StatusCode = 500;
                await ctx.Response.WriteAsJsonAsync(new { error = "Git-Prozess konnte nicht gestartet werden" });
                return;
            }

            var stdout = await proc.StandardOutput.ReadToEndAsync();
            var stderr = await proc.StandardError.ReadToEndAsync();
            await proc.WaitForExitAsync();

            if (proc.ExitCode != 0)
            {
                ctx.Response.StatusCode = 500;
                await ctx.Response.WriteAsJsonAsync(new { error = stderr.Trim() });
                return;
            }

            var add = new List<string>();
            var edit = new List<string>();
            var delete = new List<string>();

            var lines = stdout.Split('\n', StringSplitOptions.RemoveEmptyEntries);
            foreach (var line in lines)
            {
                if (line.Length < 4) continue;

                var x = line[0]; // index status
                var y = line[1]; // working tree status
                var file = line.Substring(3);

                // Bei Renames: "R  old -> new" => nur den neuen Namen nehmen
                var arrowIdx = file.IndexOf(" -> ", StringComparison.Ordinal);
                if (arrowIdx >= 0)
                    file = file.Substring(arrowIdx + 4);

                if (x == '?' && y == '?')
                {
                    add.Add(file);
                }
                else if (x == 'D' || y == 'D')
                {
                    delete.Add(file);
                }
                else if (x == 'A')
                {
                    add.Add(file);
                }
                else
                {
                    edit.Add(file);
                }
            }

            // Outgoing commits zählen (nur wenn Remote existiert)
            int outgoing = 0;
            try
            {
                var outPsi = new ProcessStartInfo
                {
                    FileName = "git",
                    Arguments = "rev-list --count @{u}..HEAD",
                    WorkingDirectory = workingDir,
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    UseShellExecute = false,
                    CreateNoWindow = true
                };

                using var outProc = Process.Start(outPsi);
                if (outProc != null)
                {
                    var outResult = (await outProc.StandardOutput.ReadToEndAsync()).Trim();
                    await outProc.WaitForExitAsync();
                    if (outProc.ExitCode == 0 && int.TryParse(outResult, out var count))
                        outgoing = count;
                }
            }
            catch
            {
                // Kein Remote oder kein Upstream – outgoing bleibt 0
            }

            await ctx.Response.WriteAsJsonAsync(new { add, edit, delete, outgoing });
        }
        catch (Exception ex)
        {
            ctx.Response.StatusCode = 500;
            await ctx.Response.WriteAsJsonAsync(new { error = ex.Message });
        }
    }
}