using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;

namespace Gott.Services;

/// <summary>
/// Service für die Kommunikation mit der Claude Code CLI.
/// Verwendet die CLI als Backend für OAuth-basierte Chats (kein API-Key nötig).
/// </summary>
public class ClaudeCliService
{
    private readonly ILogger<ClaudeCliService> _logger;
    private readonly string _cliPath;
    private readonly bool _isAvailable;

    public ClaudeCliService(ILogger<ClaudeCliService> logger)
    {
        _logger = logger;
        _cliPath = FindCliPath();
        _isAvailable = !string.IsNullOrEmpty(_cliPath) && File.Exists(_cliPath);

        if (_isAvailable)
            _logger.LogInformation("Claude CLI gefunden: {Path}", _cliPath);
        else
            _logger.LogWarning("Claude CLI nicht gefunden. CLI-basierte Chats sind nicht verfügbar.");
    }

    public bool IsAvailable => _isAvailable;
    public string CliPath => _cliPath;

    private static string FindCliPath()
    {
        var possiblePaths = new[]
        {
            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".local", "bin", "claude"),
            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".local", "bin", "claude.exe"),
            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "Programs", "claude-code", "claude.exe"),
            "/usr/local/bin/claude",
            "/usr/bin/claude"
        };

        foreach (var path in possiblePaths)
        {
            if (File.Exists(path))
                return path;
        }

        try
        {
            var pathEnv = Environment.GetEnvironmentVariable("PATH") ?? "";
            foreach (var dir in pathEnv.Split(Path.PathSeparator))
            {
                var exePath = Path.Combine(dir, "claude");
                if (File.Exists(exePath)) return exePath;

                exePath = Path.Combine(dir, "claude.exe");
                if (File.Exists(exePath)) return exePath;
            }
        }
        catch { }

        return null;
    }

    /// <summary>
    /// Streaming-Chat über die Claude CLI mit Event-basiertem Callback.
    /// Unterstützt Text-Streaming und Tool-Use Events.
    /// </summary>
    public async Task<CliChatResult> ChatStreamingAsync(
        string prompt,
        Func<CliStreamEvent, Task> onEvent,
        string modelId = null,
        string systemPrompt = null,
        string workspace = null,
        bool hasWorkspace = false,
        bool planMode = false,
        bool webSearch = false,
        CancellationToken cancellationToken = default)
    {
        if (!_isAvailable)
            return new CliChatResult { Success = false, Error = "Claude CLI nicht verfügbar" };

        var args = new List<string>
        {
            "-p",
            "--verbose",
            "--output-format", "stream-json",
            "--include-partial-messages",
            "--no-session-persistence",
            "--permission-mode", "acceptEdits",
            "--disallowed-tools", "AskUserQuestion"
        };

        // Tools konfigurieren
        var tools = new List<string>();
        if (hasWorkspace && planMode)
        {
            // Plan-Modus: nur read-only Tools
            tools.AddRange(new[] { "Read", "Glob", "Grep" });
        }
        else if (hasWorkspace)
        {
            // Normaler Modus mit Workspace: alle File-Tools
            tools.AddRange(new[] { "Bash(*)", "Read", "Write", "Edit", "Glob", "Grep" });
        }
        if (webSearch) { tools.Add("WebFetch"); tools.Add("WebSearch"); }
        args.Add("--allowed-tools");
        args.Add(tools.Count > 0 ? string.Join(" ", tools) : "\"\"");

        if (!string.IsNullOrEmpty(workspace))
        {
            args.Add("--add-dir");
            args.Add(workspace);
        }

        if (!string.IsNullOrEmpty(modelId))
        {
            args.Add("--model");
            args.Add(modelId);
        }

        if (!string.IsNullOrEmpty(systemPrompt))
        {
            args.Add("--system-prompt");
            args.Add(systemPrompt);
        }

        return await RunCliStreamingAsync(args, prompt, onEvent, cancellationToken);
    }

    private async Task<CliChatResult> RunCliStreamingAsync(
        List<string> args,
        string stdinPrompt,
        Func<CliStreamEvent, Task> onEvent,
        CancellationToken cancellationToken)
    {
        var result = new CliChatResult();
        var fullOutput = new StringBuilder();
        var error = new StringBuilder();

        // Tracking für content blocks
        string currentBlockType = null;   // "text" oder "tool_use"
        string currentToolName = null;
        string currentToolId = null;
        var currentToolInput = new StringBuilder();
        bool inTextBlock = false;

        // Tracking für ask_user_choice Marker-Erkennung
        var lineBuffer = new StringBuilder();
        bool inChoiceCapture = false;
        var choiceJsonBuffer = new StringBuilder();
        bool userChoiceDetected = false;

        try
        {
            var startInfo = new ProcessStartInfo
            {
                FileName = _cliPath,
                RedirectStandardInput = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true,
                StandardOutputEncoding = Encoding.UTF8,
                StandardErrorEncoding = Encoding.UTF8
            };

            foreach (var arg in args)
                startInfo.ArgumentList.Add(arg);

            using var process = new Process { StartInfo = startInfo };

            process.ErrorDataReceived += (s, e) =>
            {
                if (e.Data != null)
                {
                    error.AppendLine(e.Data);
                    _logger.LogDebug("CLI stderr: {Line}", e.Data);
                }
            };

            process.Start();
            process.BeginErrorReadLine();

            await process.StandardInput.WriteAsync(stdinPrompt);
            await process.StandardInput.FlushAsync();
            process.StandardInput.Close();

            using var reader = process.StandardOutput;
            string line;
            while ((line = await reader.ReadLineAsync(cancellationToken)) != null)
            {
                if (cancellationToken.IsCancellationRequested)
                {
                    try { process.Kill(entireProcessTree: true); } catch { }
                    throw new OperationCanceledException();
                }

                if (!line.StartsWith("{"))
                    continue;

                try
                {
                    var json = JsonSerializer.Deserialize<JsonElement>(line);
                    var type = json.TryGetProperty("type", out var t) ? t.GetString() : null;

                    if (type == "stream_event" && json.TryGetProperty("event", out var evt))
                    {
                        var evtType = evt.TryGetProperty("type", out var et) ? et.GetString() : null;

                        switch (evtType)
                        {
                            case "content_block_start":
                            {
                                if (evt.TryGetProperty("content_block", out var cb))
                                {
                                    var cbType = cb.TryGetProperty("type", out var cbt) ? cbt.GetString() : null;

                                    if (cbType == "text")
                                    {
                                        currentBlockType = "text";
                                        if (!inTextBlock)
                                        {
                                            inTextBlock = true;
                                            await onEvent(new CliStreamEvent { Type = CliEventType.TextStart });
                                        }
                                    }
                                    else if (cbType == "tool_use")
                                    {
                                        // Text-Block vorher abschließen
                                        if (inTextBlock)
                                        {
                                            inTextBlock = false;
                                            await onEvent(new CliStreamEvent { Type = CliEventType.TextEnd });
                                        }

                                        currentBlockType = "tool_use";
                                        currentToolName = cb.TryGetProperty("name", out var n) ? n.GetString() : "unknown";
                                        currentToolId = cb.TryGetProperty("id", out var id) ? id.GetString() : "";
                                        currentToolInput.Clear();

                                        await onEvent(new CliStreamEvent
                                        {
                                            Type = CliEventType.ToolStart,
                                            ToolName = currentToolName,
                                            ToolId = currentToolId
                                        });
                                    }
                                }
                                break;
                            }

                            case "content_block_delta":
                            {
                                if (evt.TryGetProperty("delta", out var delta))
                                {
                                    var deltaType = delta.TryGetProperty("type", out var dt) ? dt.GetString() : null;

                                    if (deltaType == "text_delta" && delta.TryGetProperty("text", out var txt))
                                    {
                                        var text = txt.GetString();
                                        if (!string.IsNullOrEmpty(text) && !userChoiceDetected)
                                        {
                                            // Zeilenbasierte Marker-Erkennung für :::ASK_USER_CHOICE:::
                                            for (int ci = 0; ci < text.Length; ci++)
                                            {
                                                var ch = text[ci];
                                                if (ch == '\n')
                                                {
                                                    var completedLine = lineBuffer.ToString().Trim();
                                                    lineBuffer.Clear();

                                                    if (inChoiceCapture)
                                                    {
                                                        if (completedLine == ":::END_ASK_USER_CHOICE:::")
                                                        {
                                                            // JSON parsen und UserChoice-Event emittieren
                                                            try
                                                            {
                                                                var choiceJson = JsonSerializer.Deserialize<JsonElement>(choiceJsonBuffer.ToString());
                                                                var question = choiceJson.TryGetProperty("question", out var cq) ? cq.GetString() ?? "" : "";
                                                                var choices = new List<string>();
                                                                if (choiceJson.TryGetProperty("choices", out var cc) && cc.ValueKind == JsonValueKind.Array)
                                                                    foreach (var cOpt in cc.EnumerateArray())
                                                                        choices.Add(cOpt.GetString() ?? "");

                                                                userChoiceDetected = true;
                                                                await onEvent(new CliStreamEvent
                                                                {
                                                                    Type = CliEventType.UserChoice,
                                                                    ChoiceQuestion = question,
                                                                    ChoiceOptions = choices
                                                                });
                                                            }
                                                            catch (JsonException)
                                                            {
                                                                // Fehlerhaftes JSON → als normalen Text weiterleiten
                                                                var fallback = $":::ASK_USER_CHOICE:::\n{choiceJsonBuffer}\n:::END_ASK_USER_CHOICE:::\n";
                                                                fullOutput.Append(fallback);
                                                                await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = fallback });
                                                            }
                                                            inChoiceCapture = false;
                                                            choiceJsonBuffer.Clear();
                                                        }
                                                        else
                                                        {
                                                            choiceJsonBuffer.AppendLine(completedLine);
                                                        }
                                                    }
                                                    else if (completedLine == ":::ASK_USER_CHOICE:::")
                                                    {
                                                        inChoiceCapture = true;
                                                        choiceJsonBuffer.Clear();
                                                    }
                                                    else if (completedLine.Length > 0 || fullOutput.Length > 0)
                                                    {
                                                        // Normale Zeile → Text weiterleiten (inkl. Newline)
                                                        // Leere Zeilen am Anfang überspringen (vor dem eigentlichen Text)
                                                        var lineText = completedLine + "\n";
                                                        fullOutput.Append(lineText);
                                                        await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = lineText });
                                                    }
                                                }
                                                else
                                                {
                                                    lineBuffer.Append(ch);
                                                }
                                            }
                                        }
                                    }
                                    else if (deltaType == "input_json_delta" && delta.TryGetProperty("partial_json", out var pj))
                                    {
                                        currentToolInput.Append(pj.GetString());
                                    }
                                }
                                break;
                            }

                            case "content_block_stop":
                            {
                                if (currentBlockType == "tool_use")
                                {
                                    await onEvent(new CliStreamEvent
                                    {
                                        Type = CliEventType.ToolEnd,
                                        ToolName = currentToolName,
                                        ToolId = currentToolId,
                                        ToolInput = currentToolInput.ToString()
                                    });
                                    currentBlockType = null;
                                    currentToolName = null;
                                    currentToolId = null;
                                    currentToolInput.Clear();
                                }
                                else if (currentBlockType == "text")
                                {
                                    currentBlockType = null;
                                    // text_end wird erst beim nächsten tool_use oder am Ende gesendet
                                }
                                break;
                            }
                        }
                    }
                    else if (type == "result")
                    {
                        // Restlichen lineBuffer flushen (nicht-abgeschlossene Zeile)
                        if (lineBuffer.Length > 0 && !userChoiceDetected)
                        {
                            var remaining = lineBuffer.ToString().Trim();
                            lineBuffer.Clear();

                            if (inChoiceCapture && remaining == ":::END_ASK_USER_CHOICE:::")
                            {
                                // End-Marker ohne trailing \n → Capture abschließen
                                try
                                {
                                    var choiceJson = JsonSerializer.Deserialize<JsonElement>(choiceJsonBuffer.ToString());
                                    var question = choiceJson.TryGetProperty("question", out var cq) ? cq.GetString() ?? "" : "";
                                    var choices = new List<string>();
                                    if (choiceJson.TryGetProperty("choices", out var cc) && cc.ValueKind == JsonValueKind.Array)
                                        foreach (var cOpt in cc.EnumerateArray())
                                            choices.Add(cOpt.GetString() ?? "");

                                    userChoiceDetected = true;
                                    await onEvent(new CliStreamEvent
                                    {
                                        Type = CliEventType.UserChoice,
                                        ChoiceQuestion = question,
                                        ChoiceOptions = choices
                                    });
                                }
                                catch (JsonException)
                                {
                                    var fallback = $":::ASK_USER_CHOICE:::\n{choiceJsonBuffer}\n{remaining}\n";
                                    fullOutput.Append(fallback);
                                    await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = fallback });
                                }
                                inChoiceCapture = false;
                                choiceJsonBuffer.Clear();
                            }
                            else if (!inChoiceCapture)
                            {
                                fullOutput.Append(remaining);
                                await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = remaining });
                            }
                        }

                        // Offenen Text-Block abschließen
                        if (inTextBlock)
                        {
                            inTextBlock = false;
                            await onEvent(new CliStreamEvent { Type = CliEventType.TextEnd });
                        }

                        if (json.TryGetProperty("usage", out var usage))
                        {
                            result.InputTokens = usage.TryGetProperty("input_tokens", out var it) ? it.GetInt64() : 0;
                            result.OutputTokens = usage.TryGetProperty("output_tokens", out var ot) ? ot.GetInt64() : 0;
                            result.CacheReadTokens = usage.TryGetProperty("cache_read_input_tokens", out var cr) ? cr.GetInt64() : 0;
                            result.CacheCreationTokens = usage.TryGetProperty("cache_creation_input_tokens", out var cc) ? cc.GetInt64() : 0;
                        }
                        if (json.TryGetProperty("total_cost_usd", out var cost))
                            result.CostUsd = cost.GetDouble();
                        if (json.TryGetProperty("duration_api_ms", out var dur))
                            result.DurationApiMs = dur.GetInt64();
                        if (json.TryGetProperty("session_id", out var sid))
                            result.SessionId = sid.GetString();
                        if (json.TryGetProperty("num_turns", out var nt))
                            result.NumTurns = nt.GetInt32();

                        var isError = json.TryGetProperty("is_error", out var ie) && ie.GetBoolean();
                        if (isError)
                            result.Error = json.TryGetProperty("result", out var errMsg) ? errMsg.GetString() : "CLI error";
                    }
                }
                catch (JsonException ex)
                {
                    _logger.LogDebug("CLI JSON parse error: {Error} for line: {Line}", ex.Message, line.Length > 200 ? line[..200] : line);
                }
            }

            // Restlichen lineBuffer flushen
            if (lineBuffer.Length > 0 && !userChoiceDetected)
            {
                var remaining = lineBuffer.ToString().Trim();
                lineBuffer.Clear();

                if (inChoiceCapture && remaining == ":::END_ASK_USER_CHOICE:::")
                {
                    try
                    {
                        var choiceJson = JsonSerializer.Deserialize<JsonElement>(choiceJsonBuffer.ToString());
                        var question = choiceJson.TryGetProperty("question", out var cq) ? cq.GetString() ?? "" : "";
                        var choices = new List<string>();
                        if (choiceJson.TryGetProperty("choices", out var cc) && cc.ValueKind == JsonValueKind.Array)
                            foreach (var cOpt in cc.EnumerateArray())
                                choices.Add(cOpt.GetString() ?? "");

                        userChoiceDetected = true;
                        await onEvent(new CliStreamEvent
                        {
                            Type = CliEventType.UserChoice,
                            ChoiceQuestion = question,
                            ChoiceOptions = choices
                        });
                    }
                    catch (JsonException)
                    {
                        var fallback = $":::ASK_USER_CHOICE:::\n{choiceJsonBuffer}\n{remaining}\n";
                        fullOutput.Append(fallback);
                        await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = fallback });
                    }
                    inChoiceCapture = false;
                    choiceJsonBuffer.Clear();
                }
                else if (!inChoiceCapture)
                {
                    fullOutput.Append(remaining);
                    await onEvent(new CliStreamEvent { Type = CliEventType.TextDelta, Text = remaining });
                }
            }

            // Sicherstellen, dass offene Blöcke geschlossen werden
            if (inTextBlock)
                await onEvent(new CliStreamEvent { Type = CliEventType.TextEnd });

            await process.WaitForExitAsync(cancellationToken);

            result.ExitCode = process.ExitCode;
            result.Output = fullOutput.ToString().Trim();
            result.Success = process.ExitCode == 0 && (fullOutput.Length > 0 || userChoiceDetected);
            result.UserChoiceDetected = userChoiceDetected;

            if (!result.Success && string.IsNullOrEmpty(result.Error))
                result.Error = error.Length > 0 ? error.ToString().Trim() : $"CLI exit code: {process.ExitCode}";
        }
        catch (OperationCanceledException)
        {
            result.Success = false;
            result.Error = "Abgebrochen";
            throw;
        }
        catch (Exception ex)
        {
            result.Success = false;
            result.Error = ex.Message;
            _logger.LogError(ex, "Fehler beim Streaming der Claude CLI");
        }

        return result;
    }

    /// <summary>
    /// Prüft ob die CLI funktioniert und authentifiziert ist.
    /// </summary>
    public async Task<CliStatusResult> GetStatusAsync()
    {
        var result = new CliStatusResult { IsAvailable = _isAvailable };

        if (!_isAvailable)
        {
            result.Error = "Claude CLI nicht gefunden";
            return result;
        }

        try
        {
            var versionResult = await RunSimpleAsync(["--version"], CancellationToken.None);
            if (versionResult.Success)
                result.Version = versionResult.Output.Trim();

            var doctorResult = await RunSimpleAsync(["doctor"], CancellationToken.None);
            result.IsAuthenticated = doctorResult.Success;

            if (!doctorResult.Success)
                result.Error = doctorResult.Error ?? doctorResult.Output;
        }
        catch (Exception ex)
        {
            result.Error = ex.Message;
        }

        return result;
    }

    private async Task<CliChatResult> RunSimpleAsync(List<string> args, CancellationToken cancellationToken)
    {
        var result = new CliChatResult();
        var output = new StringBuilder();
        var error = new StringBuilder();

        try
        {
            var startInfo = new ProcessStartInfo
            {
                FileName = _cliPath,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true,
                StandardOutputEncoding = Encoding.UTF8,
                StandardErrorEncoding = Encoding.UTF8
            };

            foreach (var arg in args)
                startInfo.ArgumentList.Add(arg);

            using var process = new Process { StartInfo = startInfo };
            process.OutputDataReceived += (s, e) => { if (e.Data != null) output.AppendLine(e.Data); };
            process.ErrorDataReceived += (s, e) => { if (e.Data != null) error.AppendLine(e.Data); };

            process.Start();
            process.BeginOutputReadLine();
            process.BeginErrorReadLine();

            await process.WaitForExitAsync(cancellationToken);

            result.ExitCode = process.ExitCode;
            result.Output = output.ToString().Trim();
            result.Success = process.ExitCode == 0;

            if (!result.Success)
                result.Error = error.Length > 0 ? error.ToString().Trim() : $"Exit code: {process.ExitCode}";
        }
        catch (OperationCanceledException)
        {
            result.Success = false;
            result.Error = "Abgebrochen";
            throw;
        }
        catch (Exception ex)
        {
            result.Success = false;
            result.Error = ex.Message;
            _logger.LogError(ex, "Fehler beim Ausführen der Claude CLI");
        }

        return result;
    }
}

public enum CliEventType
{
    TextStart,
    TextDelta,
    TextEnd,
    ToolStart,
    ToolEnd,
    UserChoice
}

public class CliStreamEvent
{
    public CliEventType Type { get; set; }
    public string Text { get; set; }
    public string ToolName { get; set; }
    public string ToolId { get; set; }
    public string ToolInput { get; set; }
    public string ChoiceQuestion { get; set; }
    public List<string> ChoiceOptions { get; set; }
}

public class CliChatResult
{
    public bool Success { get; set; }
    public string Output { get; set; }
    public string Error { get; set; }
    public int ExitCode { get; set; }
    public long InputTokens { get; set; }
    public long OutputTokens { get; set; }
    public long CacheReadTokens { get; set; }
    public long CacheCreationTokens { get; set; }
    public double CostUsd { get; set; }
    public long DurationApiMs { get; set; }
    public string SessionId { get; set; }
    public int NumTurns { get; set; }
    public bool UserChoiceDetected { get; set; }
}

public class CliStatusResult
{
    public bool IsAvailable { get; set; }
    public bool IsAuthenticated { get; set; }
    public string Version { get; set; }
    public string Error { get; set; }
}