using System.Diagnostics;
using MeetingAssistant.Workflow;
using Microsoft.Extensions.Options;

namespace MeetingAssistant.MacOs;

public sealed class MacOsWorkflowRulesEditorWindowService : IWorkflowRulesEditorWindowService
{
    private readonly IOptions<MeetingAssistantOptions> options;
    private readonly Func<MacOsWorkflowRulesEditorSessions> getSessions;

    public MacOsWorkflowRulesEditorWindowService(
        IOptions<MeetingAssistantOptions> options,
        Func<MacOsWorkflowRulesEditorSessions> getSessions)
    {
        this.options = options;
        this.getSessions = getSessions;
    }

    public void Show()
    {
        if (!OperatingSystem.IsMacOS())
        {
            return;
        }

        var url = $"{options.Value.Api.PublicBaseUrl.TrimEnd('/')}/diagnostics/settings-and-logs";
        Process.Start(new ProcessStartInfo
        {
            FileName = "/usr/bin/open",
            ArgumentList = { url },
            UseShellExecute = false
        });
    }

    public void ShowWithPrompt(string initialPrompt)
    {
        getSessions().OpenWithPrompt(initialPrompt);
    }
}

public sealed class MacOsWorkflowRulesEditorSession
{
    private readonly WorkflowRulesEditorChatViewModel viewModel;
    private readonly CancellationToken applicationStopping;
    private readonly SemaphoreSlim sendLock = new(1, 1);
    private MacOsWorkflowRulesEditorChatResponse snapshot = new([], false);

    public MacOsWorkflowRulesEditorSession(
        WorkflowRulesEditorChatViewModel viewModel,
        CancellationToken applicationStopping = default)
    {
        this.viewModel = viewModel;
        this.applicationStopping = applicationStopping;
    }

    public Task<MacOsWorkflowRulesEditorChatResponse> SendAsync(
        string? message,
        CancellationToken cancellationToken)
    {
        cancellationToken.ThrowIfCancellationRequested();
        if (string.IsNullOrWhiteSpace(message))
        {
            return Task.FromResult(GetSnapshot());
        }

        // The response connection controls only its wait; accepted agent work belongs to the application.
        return SendCoreAsync(message.Trim()).WaitAsync(cancellationToken);
    }

    public MacOsWorkflowRulesEditorChatResponse GetSnapshot() => Volatile.Read(ref snapshot);

    private async Task<MacOsWorkflowRulesEditorChatResponse> SendCoreAsync(string message)
    {
        await sendLock.WaitAsync(applicationStopping);
        try
        {
            applicationStopping.ThrowIfCancellationRequested();
            var messages = GetSnapshot().Messages
                .Append(new MacOsWorkflowRulesEditorMessage("user", message))
                .ToArray();
            Volatile.Write(ref snapshot, new MacOsWorkflowRulesEditorChatResponse(
                Array.AsReadOnly(messages), true));
            try
            {
                // Dispatch the agent away from the caller so opening a window or processing a decision stays responsive.
                await Task.Run(() => viewModel.SendPromptAsync(message, applicationStopping), applicationStopping);
            }
            finally
            {
                var completedMessages = viewModel.Messages
                    .Where(item => item.Kind == WorkflowRulesEditorConversationItemKind.Message)
                    .Select(item => new MacOsWorkflowRulesEditorMessage(
                        item.Message!.Role.ToString().ToLowerInvariant(),
                        item.Message.Content))
                    .ToArray();
                Volatile.Write(ref snapshot, new MacOsWorkflowRulesEditorChatResponse(
                    Array.AsReadOnly(completedMessages), false));
            }
            return GetSnapshot();
        }
        finally
        {
            sendLock.Release();
        }
    }
}

public sealed record MacOsWorkflowRulesEditorChatRequest(string? Message);

public sealed record MacOsWorkflowRulesEditorChatResponse(
    IReadOnlyList<MacOsWorkflowRulesEditorMessage> Messages,
    bool IsThinking = false);

public sealed record MacOsWorkflowRulesEditorMessage(string Role, string Content);

public static class MacOsWorkflowRulesEditorPage
{
    public const string Html = """
        <!doctype html>
        <html lang="en">
        <head>
          <meta charset="utf-8">
          <meta name="viewport" content="width=device-width,initial-scale=1">
          <title>Meeting Summary Agent</title>
          <style>
            :root { color-scheme: dark; font: 15px -apple-system, BlinkMacSystemFont, sans-serif; }
            * { box-sizing: border-box; }
            body { margin: 0; background: #171719; color: #f5f5f7; }
            main { height: 100vh; display: grid; grid-template-rows: auto 1fr auto; padding: 18px; gap: 14px; }
            h1 { margin: 0; font-size: 18px; }
            #messages { overflow: auto; display: flex; flex-direction: column; gap: 10px; }
            .message { max-width: 82%; padding: 10px 12px; border: 1px solid #414147; border-radius: 10px; white-space: pre-wrap; }
            .user { align-self: flex-end; background: #293650; }
            .agent { align-self: flex-start; background: #232326; }
            form { display: grid; grid-template-columns: 1fr auto; gap: 10px; }
            textarea { min-height: 78px; resize: vertical; border-radius: 9px; border: 1px solid #55555d; background: #222225; color: inherit; padding: 10px; font: inherit; }
            button { min-width: 96px; border: 0; border-radius: 9px; background: #0a84ff; color: white; font-weight: 600; }
            button:disabled { opacity: .55; }
          </style>
        </head>
        <body>
          <main>
            <h1>Meeting Summary Agent</h1>
            <section id="messages"></section>
            <form id="chat">
              <textarea id="prompt" placeholder="ask me what I can do for you"></textarea>
              <button id="send">Send</button>
            </form>
          </main>
          <script>
            const form = document.querySelector('#chat');
            const prompt = document.querySelector('#prompt');
            const send = document.querySelector('#send');
            const messages = document.querySelector('#messages');
            const session = new URLSearchParams(location.search).get('session');
            const chatUrl = '/diagnostics/settings-and-logs/chat' + (session ? '?session=' + encodeURIComponent(session) : '');
            let submitting = false;
            let thinking = false;
            let refreshing = false;
            let available = true;
            let refreshTimer;
            const render = items => {
              messages.replaceChildren(...items.map(item => {
                const card = document.createElement('div');
                card.className = `message ${item.role}`;
                card.textContent = item.content;
                return card;
              }));
              messages.scrollTop = messages.scrollHeight;
            };
            const update = body => {
              render(body.messages);
              thinking = !!body.isThinking;
              send.disabled = submitting || thinking;
            };
            const showError = text => {
              const card = document.createElement('div');
              card.className = 'message agent';
              card.textContent = text;
              messages.append(card);
            };
            const refresh = async () => {
              if (refreshing || !available) return;
              clearTimeout(refreshTimer);
              refreshing = true;
              try {
                const response = await fetch(chatUrl, {cache: 'no-store'});
                if (!response.ok) throw new Error('This conversation is no longer available.');
                update(await response.json());
              } catch (error) {
                available = false;
                send.disabled = true;
                showError(error.message);
              } finally {
                refreshing = false;
                if (available && (thinking || submitting)) refreshTimer = setTimeout(refresh, 300);
              }
            };
            form.addEventListener('submit', async event => {
              event.preventDefault();
              const message = prompt.value.trim();
              if (!message || submitting || thinking || !available) return;
              prompt.value = '';
              submitting = true;
              send.disabled = true;
              try {
                const responseTask = fetch(chatUrl, {
                  method: 'POST',
                  headers: {'content-type': 'application/json'},
                  body: JSON.stringify({message})
                });
                void refresh();
                const response = await responseTask;
                if (!response.ok) throw new Error('The message could not be sent.');
                update(await response.json());
              } catch (error) {
                showError(error.message);
              } finally {
                submitting = false;
                send.disabled = !available || thinking;
                void refresh();
                prompt.focus();
              }
            });
            prompt.addEventListener('keydown', event => {
              if (event.key === 'Enter' && !event.shiftKey) {
                event.preventDefault();
                form.requestSubmit();
              }
            });
            void refresh();
          </script>
        </body>
        </html>
        """;
}