using System.Text.Json;
using ClawdDotNet.Core.Tools;
using MailKit;
using MailKit.Net.Imap;
using MailKit.Net.Smtp;
using MailKit.Search;
using Microsoft.Extensions.Logging;
using MimeKit;

using ClawdDotNet.Core.State;

namespace ClawdDotNet.Tools.Mail;

public sealed class MailTool : IAgentTool, IToolJobProvider
{
    public string Name => "Mail";

    /// <summary>#715: Brings text from outside into the context — mails from anyone.</summary>
    public bool ReadsForeignContent => true;

    public string Description => "Allows sending and receiving emails via SMTP and IMAP. read_message lists a message's attachments; read_attachment returns an attachment's text (Word, Excel, text and CSV files); save_attachment stores it in your workspace.";

    public JsonElement InputSchema { get; } = JsonDocument.Parse("""
        {
            "type": "object",
            "properties": {
                "action": {
                    "type": "string",
                    "enum": ["send", "read_inbox", "read_message", "mark_read", "read_attachment", "save_attachment"],
                    "description": "The action to perform"
                },
                "to": {
                    "type": "string",
                    "description": "Recipient email (only for send)"
                },
                "subject": {
                    "type": "string",
                    "description": "Subject (only for send)"
                },
                "body": {
                    "type": "string",
                    "description": "Body of the email (only for send)"
                },
                "limit": {
                    "type": "integer",
                    "description": "Maximum number of emails to retrieve (only for read_inbox)"
                },
                "messageId": {
                    "type": "string",
                    "description": "The message ID (for read_message, mark_read, read_attachment, save_attachment)"
                },
                "attachment": {
                    "type": "string",
                    "description": "read_attachment, save_attachment: the attachment's number from read_message, or its file name"
                },
                "fileName": {
                    "type": "string",
                    "description": "save_attachment: the file name in your workspace (default: the attachment's name)"
                }
            },
            "required": ["action"]
        }
        """).RootElement.Clone();

    public async Task<ToolResult> ExecuteAsync(
        JsonElement input,
        AgentToolContext context,
        CancellationToken ct)
    {
        var action = input.GetProperty("action").GetString()
            ?? throw new ArgumentException("'action' is required");

        try
        {
            return action switch
            {
                "send" => await HandleSendAsync(input, context, ct),
                "read_inbox" => await HandleReadInboxAsync(input, context, ct),
                "read_message" => await HandleReadMessageAsync(input, context, ct),
                "mark_read" => await HandleMarkReadAsync(input, context, ct),
                "read_attachment" or "save_attachment" => await HandleAttachmentAsync(action, input, context, ct),
                _ => ToolResult.Fail($"Unknown action: {action}")
            };
        }
        catch (Exception ex)
        {
            context.Logger.LogError(ex, "Error during Mail action {Action}", action);
            return ToolResult.Fail($"Error: {ex.Message}");
        }
    }

    private async Task<ToolResult> HandleSendAsync(JsonElement input, AgentToolContext context, CancellationToken ct)
    {
        var to = input.TryGetProperty("to", out var t) ? t.GetString() : null;
        var subject = (input.TryGetProperty("subject", out var s) ? s.GetString() : null) ?? "(No Subject)";
        var body = (input.TryGetProperty("body", out var b) ? b.GetString() : null) ?? "";

        if (string.IsNullOrWhiteSpace(to)) return ToolResult.Fail("'to' is required.");

        // Sicherheitsprüfung: Erlaubte Empfänger
        if (!IsRecipientAllowed(to, context))
        {
            return ToolResult.Fail($"Security error: Sending to '{to}' is not allowed.");
        }

        if (!TryReadAccess(context, "smtpHost", "smtpPort", 587, out var access, out var fehlt))
            return ToolResult.Fail(fehlt);

        var message = new MimeMessage();
        message.From.Add(new MailboxAddress("ClawdDotNet", access.UserName));
        message.To.Add(MailboxAddress.Parse(to));
        message.Subject = subject;
        message.Body = new TextPart("plain") { Text = body };

        using var client = new SmtpClient();
        await client.ConnectAsync(access.Host, access.Port, true, ct);
        await client.AuthenticateAsync(access.UserName, access.Password, ct);
        await client.SendAsync(message, ct);
        await client.DisconnectAsync(true, ct);

        return ToolResult.Ok($"Email successfully sent to {to}.");
    }

    private async Task<ToolResult> HandleReadInboxAsync(JsonElement input, AgentToolContext context, CancellationToken ct)
    {
        var limit = input.TryGetProperty("limit", out var l) ? l.GetInt32() : 10;

        if (!TryReadAccess(context, "imapHost", "imapPort", 993, out var access, out var fehlt))
            return ToolResult.Fail(fehlt);

        using var client = new ImapClient();
        await client.ConnectAsync(access.Host, access.Port, true, ct);
        await client.AuthenticateAsync(access.UserName, access.Password, ct);

        await client.Inbox!.OpenAsync(FolderAccess.ReadOnly, ct);
        var messages = new List<object>();

        for (int i = client.Inbox!.Count - 1; i >= Math.Max(0, client.Inbox!.Count - limit); i--)
        {
            var msg = await client.Inbox!.GetMessageAsync(i, ct);
            messages.Add(new
            {
                Id = i.ToString(),
                Date = msg.Date,
                From = msg.From.ToString(),
                Subject = msg.Subject
            });
        }

        await client.DisconnectAsync(true, ct);
        return ToolResult.Ok(JsonSerializer.Serialize(messages, new JsonSerializerOptions { WriteIndented = true }));
    }

    private async Task<ToolResult> HandleReadMessageAsync(JsonElement input, AgentToolContext context, CancellationToken ct)
    {
        if (!input.TryGetProperty("messageId", out var mi) || !int.TryParse(mi.GetString(), out var index))
        {
            return ToolResult.Fail("'messageId' (index) is required.");
        }

        if (!TryReadAccess(context, "imapHost", "imapPort", 993, out var access, out var fehlt))
            return ToolResult.Fail(fehlt);

        using var client = new ImapClient();
        await client.ConnectAsync(access.Host, access.Port, true, ct);
        await client.AuthenticateAsync(access.UserName, access.Password, ct);

        await client.Inbox!.OpenAsync(FolderAccess.ReadOnly, ct);
        var msg = await client.Inbox!.GetMessageAsync(index, ct);
        
        var result = new
        {
            Id = index.ToString(),
            Date = msg.Date,
            From = msg.From.ToString(),
            Subject = msg.Subject,
            Body = msg.TextBody,
            // #692: what came with it — read with read_attachment, kept with save_attachment.
            Attachments = Attachments(msg).Select((a, i) => new
            {
                Number = i + 1,
                Name = a.FileName ?? $"attachment-{i + 1}",
                Type = a.ContentType.MimeType,
                Readable = ClawdDotNet.Core.Documents.DocumentText.Supports(a.FileName ?? "")
            }).ToList()
        };

        await client.DisconnectAsync(true, ct);
        return ToolResult.Ok(JsonSerializer.Serialize(result, new JsonSerializerOptions { WriteIndented = true }));
    }

    /// <summary>The largest attachment that is read or saved.</summary>
    private const long MaxAttachmentBytes = 25L * 1024 * 1024;

    /// <summary>The longest text an attachment hands to the model.</summary>
    private const int MaxAttachmentChars = 60_000;

    private static List<MimePart> Attachments(MimeMessage msg)
        => msg.Attachments.OfType<MimePart>().ToList();

    /// <summary>
    /// #692: The text of what really comes in — an order confirmation as a Word file, a price list
    /// as a spreadsheet — or the file itself in the workspace. The text is a supplier's text:
    /// the engine frames it as foreign content like every tool result.
    /// </summary>
    private async Task<ToolResult> HandleAttachmentAsync(string action, JsonElement input, AgentToolContext context, CancellationToken ct)
    {
        if (!input.TryGetProperty("messageId", out var mi) || !int.TryParse(mi.GetString(), out var index))
            return ToolResult.Fail("'messageId' (index) is required.");
        var wanted = input.TryGetProperty("attachment", out var at) ? at.ToString().Trim() : "";
        if (wanted.Length == 0)
            return ToolResult.Fail("'attachment' is required — its number from read_message, or its file name.");

        if (!TryReadAccess(context, "imapHost", "imapPort", 993, out var access, out var fehlt))
            return ToolResult.Fail(fehlt);

        using var client = new ImapClient();
        await client.ConnectAsync(access.Host, access.Port, true, ct);
        await client.AuthenticateAsync(access.UserName, access.Password, ct);
        await client.Inbox!.OpenAsync(FolderAccess.ReadOnly, ct);
        var msg = await client.Inbox!.GetMessageAsync(index, ct);
        await client.DisconnectAsync(true, ct);

        var attachments = Attachments(msg);
        var part = int.TryParse(wanted, out var number) && number >= 1 && number <= attachments.Count
            ? attachments[number - 1]
            : attachments.FirstOrDefault(a => string.Equals(a.FileName, wanted, StringComparison.OrdinalIgnoreCase));
        if (part is null)
            return ToolResult.Fail($"Message {index} has no attachment '{wanted}' — it has {attachments.Count}.");

        using var buffer = new MemoryStream();
        await part.Content.DecodeToAsync(buffer, ct);
        if (buffer.Length > MaxAttachmentBytes)
            return ToolResult.Fail($"The attachment is {buffer.Length / 1024 / 1024} MB — more than {MaxAttachmentBytes / 1024 / 1024} MB are not taken.");
        var name = part.FileName ?? $"attachment-{index}";

        if (action == "read_attachment")
        {
            var text = ClawdDotNet.Core.Documents.DocumentText.Extract(buffer.ToArray(), name, MaxAttachmentChars);
            if (!text.Ok)
                return ToolResult.Fail($"{name}: {text.Problem} Keep it with save_attachment if a human should look at it.");
            return ToolResult.Ok($"Attachment '{name}' ({text.Kind}) of message {index}" +
                                 (text.Truncated ? $", first {MaxAttachmentChars} characters" : "") + ":\n" + text.Text);
        }

        if (string.IsNullOrWhiteSpace(context.WorkspacePath))
            return ToolResult.Fail("You have no workspace to keep the attachment in.");
        var requested = input.TryGetProperty("fileName", out var fn) ? fn.GetString() : null;
        var fileName = SafeFileName(string.IsNullOrWhiteSpace(requested) ? name : requested);
        Directory.CreateDirectory(context.WorkspacePath);
        var target = Path.Combine(context.WorkspacePath, fileName);
        // Never over an existing file: name.pdf, name (2).pdf, ...
        for (var n = 2; File.Exists(target); n++)
            target = Path.Combine(context.WorkspacePath, $"{Path.GetFileNameWithoutExtension(fileName)} ({n}){Path.GetExtension(fileName)}");
        await File.WriteAllBytesAsync(target, buffer.ToArray(), ct);
        return ToolResult.Ok($"Attachment '{name}' of message {index} saved in your workspace as '{Path.GetFileName(target)}' ({buffer.Length} bytes).");
    }

    /// <summary>A file name only — no directory, nothing that leaves the workspace.</summary>
    public static string SafeFileName(string name)
    {
        // The same answer on every system: the last segment, and the characters any of them refuses replaced.
        var bare = name.Replace('\\', '/').Split('/').Last().Trim();
        bare = new string(bare.Select(c => c < 32 || "<>:\"|?*".Contains(c) ? '_' : c).ToArray());
        bare = bare.TrimStart('.');
        return bare.Length == 0 ? "attachment" : bare.Length > 120 ? bare[..120] : bare;
    }

    private async Task<ToolResult> HandleMarkReadAsync(JsonElement input, AgentToolContext context, CancellationToken ct)
    {
        if (!input.TryGetProperty("messageId", out var mi) || !int.TryParse(mi.GetString(), out var index))
        {
            return ToolResult.Fail("'messageId' (index) is required.");
        }

        if (!TryReadAccess(context, "imapHost", "imapPort", 993, out var access, out var fehlt))
            return ToolResult.Fail(fehlt);

        using var client = new ImapClient();
        await client.ConnectAsync(access.Host, access.Port, true, ct);
        await client.AuthenticateAsync(access.UserName, access.Password, ct);

        await client.Inbox!.OpenAsync(FolderAccess.ReadWrite, ct);
        await client.Inbox!.AddFlagsAsync(index, MessageFlags.Seen, true, ct);
        
        await client.DisconnectAsync(true, ct);
        return ToolResult.Ok($"Message {index} marked as read.");
    }

    /// <summary>Ein Zugang: Server, Port und Anmeldedaten — vollständig oder gar nicht.</summary>
    private readonly record struct MailAccess(string Host, int Port, string UserName, string Password);

    /// <summary>
    /// Liest Server und Anmeldedaten aus der Werkzeug-Konfiguration.
    ///
    /// <para>Vorher standen die Werte an vier Stellen einzeln im Aufruf:
    /// <c>config["smtpHost"]?.ToString()</c>. Das ging auf zwei Arten schief. Fehlte der
    /// Schlüssel ganz, warf der Indexer eine <c>KeyNotFoundException</c>; war er leer,
    /// ging <c>null</c> an MailKit — worauf der Compiler mit fünfzehn
    /// Nullable-Warnungen hinwies. Beim Agenten kam beides als dieselbe unbrauchbare
    /// Zeile an: „Fehler: …".</para>
    ///
    /// <para>Hier fällt stattdessen die Antwort aus, die weiterhilft: welcher Schlüssel
    /// fehlt. Der Port bleibt weich — dafür gibt es sinnvolle Vorgaben; Server und
    /// Anmeldedaten kann niemand raten.</para>
    /// </summary>
    private static bool TryReadAccess(
        AgentToolContext context, string hostKey, string portKey, int defaultPort,
        out MailAccess access, out string error)
    {
        access = default;

        var host = ReadSetting(context, hostKey);
        var user = ReadSetting(context, "username");
        var password = ReadSetting(context, "password");

        var missing = new List<string>();
        if (string.IsNullOrWhiteSpace(host)) missing.Add(hostKey);
        if (string.IsNullOrWhiteSpace(user)) missing.Add("username");
        if (string.IsNullOrWhiteSpace(password)) missing.Add("password");

        if (missing.Count > 0)
        {
            error = "The mail tool is not fully configured. " +
                    $"Missing in tool configuration: {string.Join(", ", missing)}.";
            return false;
        }

        access = new MailAccess(host!, ReadPort(context, portKey, defaultPort), user!, password!);
        error = "";
        return true;
    }

    private static string? ReadSetting(AgentToolContext context, string key)
        => context.ToolConfig.TryGetValue(key, out var value) ? value?.ToString() : null;

    private static int ReadPort(AgentToolContext context, string key, int fallback)
        => context.ToolConfig.TryGetValue(key, out var value)
           && value is JsonElement { ValueKind: JsonValueKind.Number } je
           && je.TryGetInt32(out var port)
            ? port
            : fallback;

    private bool IsRecipientAllowed(string email, AgentToolContext context)
    {
        if (!context.ToolConfig.TryGetValue("allowedRecipients", out var val) || val is not JsonElement je)
        {
            return false;
        }

        var allowed = je.EnumerateArray().Select(x => x.GetString()?.ToLowerInvariant()).ToList();
        return allowed.Contains(email.ToLowerInvariant());
    }

    public IReadOnlyList<ToolJobDefinition> GetJobDefinitions() =>
    [
        new("mail_check_unread", "Mail Check", "Periodically checks for new unread emails")
    ];

    public async Task<ToolJobResult> ExecuteJobAsync(
        string jobTypeId,
        IReadOnlyDictionary<string, object?> toolConfig,
        IStateStore stateStore,
        ILogger logger,
        CancellationToken ct,
        string? agentId = null,
        string? workspacePath = null)
    {
        if (jobTypeId != "mail_check_unread")
            return ToolJobResult.NoAction($"Unknown job: {jobTypeId}");

        try
        {
            using var client = new ImapClient();
            var imapHost = toolConfig.TryGetValue("imapHost", out var h) ? h?.ToString() : null;
            var imapPort = toolConfig.TryGetValue("imapPort", out var p) ? (p is long l ? (int)l : (p is int i ? i : 993)) : 993;
            var username = toolConfig.TryGetValue("username", out var u) ? u?.ToString() : null;
            var password = toolConfig.TryGetValue("password", out var pw) ? pw?.ToString() : null;

            if (string.IsNullOrWhiteSpace(imapHost) || string.IsNullOrWhiteSpace(username))
                return ToolJobResult.NoAction("Mail configuration incomplete");

            await client.ConnectAsync(imapHost, imapPort, true, ct);
            await client.AuthenticateAsync(username ?? "", password ?? "", ct);

            await client.Inbox!.OpenAsync(FolderAccess.ReadOnly, ct);
            
            // Wir suchen nach ungelesenen Nachrichten
            var uids = await client.Inbox!.SearchAsync(SearchQuery.NotSeen, ct);
            
            if (uids.Count == 0)
            {
                await client.DisconnectAsync(true, ct);
                return ToolJobResult.NoAction("No new unread emails");
            }

            // Um zu vermeiden, dass wir bei jedem Tick für die gleichen Mails wecken,
            // speichern wir die höchste UID, die wir bereits gemeldet haben.
            var lastUidStr = await stateStore.GetAsync("mail_last_notified_uid", ct);
            uint lastUid = uint.TryParse(lastUidStr, out var lu) ? lu : 0;

            var newUids = uids.Where(uid => uid.Id > lastUid).OrderBy(uid => uid.Id).ToList();

            if (newUids.Count == 0)
            {
                await client.DisconnectAsync(true, ct);
                return ToolJobResult.NoAction("No new emails since last check");
            }

            // Die neuesten Nachrichten abrufen für die Zusammenfassung
            var summary = new List<string>();
            foreach (var uid in newUids.Take(5))
            {
                var msg = await client.Inbox!.GetMessageAsync(uid, ct);
                summary.Add($"- From: {msg.From}, Subject: {msg.Subject}");
            }

            if (newUids.Count > 5) summary.Add($"- ... and {newUids.Count - 5} more");

            // Höchste UID speichern
            var maxUid = newUids.Max(u => u.Id);
            await stateStore.SetAsync("mail_last_notified_uid", maxUid.ToString(), ct);

            await client.DisconnectAsync(true, ct);

            return ToolJobResult.Wake(
                $"You have received {newUids.Count} new unread email(s):\n" + string.Join("\n", summary),
                logSummary: $"{newUids.Count} new email(s) found"
            );
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "Error in Mail background job");
            return ToolJobResult.NoAction($"Error: {ex.Message}");
        }
    }
}