using System.Diagnostics;
using System.Net;
using System.Reflection;
using System.Text.Json;
using System.Windows.Forms;
using Markdig;
using Microsoft.Web.WebView2.Core;
using Microsoft.Web.WebView2.WinForms;

// Host sottile: l'interfaccia vive in ui.html (embedded). Protocollo messaggi: docs/MVP.md.
class Gui : Form
{
    record Model(string Label, string Id);
    static readonly Model[] Models =
    [
        new("Fable 5.1", "claude-fable-5-1"),
        new("Opus 5.5", "claude-opus-5-5"),
        new("Sonnet 5.5", "claude-sonnet-5-5"),
        new("Haiku 5.5", "claude-haiku-5-5"),
    ];

    static readonly MarkdownPipeline Md = new MarkdownPipelineBuilder().UseAdvancedExtensions().DisableHtml().Build();

    readonly WebView2 view = new()
    {
        Dock = DockStyle.Fill,
        // evita il lampo bianco all'avvio in tema scuro (stesso --bg di ui.html)
        DefaultBackgroundColor = Application.IsDarkModeEnabled ? Color.FromArgb(0x0F, 0x17, 0x2A) : Color.White,
    };

    string sessionId = Guid.NewGuid().ToString();
    bool started; // true dopo il primo messaggio riuscito: da lì in poi --resume
    bool busy;

    public Gui()
    {
        Text = "LlmRun";
        var area = Screen.PrimaryScreen!.WorkingArea;
        StartPosition = FormStartPosition.CenterScreen;
        // proporzioni 16:10 orizzontali: 75% della larghezza utile (max 1440), altezza max 90%
        var w = Math.Min(1440, area.Width * 3 / 4);
        var h = Math.Min(w * 10 / 16, area.Height * 9 / 10);
        Size = new Size(h * 16 / 10, h);
        MinimumSize = new Size(900, 600);
        Controls.Add(view);

        Load += async (_, _) =>
        {
            var dir = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "LlmRun");
            await view.EnsureCoreWebView2Async(await CoreWebView2Environment.CreateAsync(null, dir));
            var web = view.CoreWebView2;
            web.Settings.AreDevToolsEnabled = Debugger.IsAttached;
            web.NavigationStarting += (_, e) => { if (IsWeb(e.Uri)) { e.Cancel = true; Open(e.Uri); } };
            web.NewWindowRequested += (_, e) => { e.Handled = true; if (IsWeb(e.Uri)) Open(e.Uri); };
            web.WebMessageReceived += (_, e) => OnMessage(e.WebMessageAsJson);
            view.NavigateToString(LoadPage());
        };
    }

    static bool IsWeb(string uri) => uri.StartsWith("http", StringComparison.OrdinalIgnoreCase);
    static void Open(string uri) => Process.Start(new ProcessStartInfo(uri) { UseShellExecute = true });

    static string LoadPage()
    {
        var asm = Assembly.GetExecutingAssembly();
        using var s = asm.GetManifestResourceStream(asm.GetManifestResourceNames().First(n => n.EndsWith("ui.html")))!;
        var html = new StreamReader(s).ReadToEnd();
        var options = string.Concat(Models.Select(m => $"<option value=\"{m.Id}\">{WebUtility.HtmlEncode(m.Label)}</option>"));
        return html.Replace("{{MODELS}}", "<option value=\"\">Predefinito</option>" + options);
    }

    void Post(object message) => view.CoreWebView2.PostWebMessageAsJson(JsonSerializer.Serialize(message));

    void OnMessage(string json)
    {
        using var doc = JsonDocument.Parse(json);
        var r = doc.RootElement;
        switch (r.GetProperty("type").GetString())
        {
            case "reset":
                sessionId = Guid.NewGuid().ToString(); started = false;
                break;
            case "send" when !busy:
                _ = HandleSend(r.GetProperty("text").GetString()!, r.GetProperty("model").GetString()!, r.GetProperty("effort").GetString()!);
                break;
        }
    }

    async Task HandleSend(string text, string model, string effort)
    {
        busy = true;
        try
        {
            var (code, stdout, stderr) = await RunClaude(text, model, effort);
            if (code == 0) { started = true; Post(new { type = "ai", html = Markdown.ToHtml(stdout, Md), md = stdout }); }
            else Post(new { type = "err", text = $"claude è uscito con codice {code}\n{stderr}".Trim() });
        }
        catch (System.ComponentModel.Win32Exception) { Post(new { type = "err", text = "'claude' non trovato nel PATH." }); }
        catch (Exception ex) { Post(new { type = "err", text = ex.Message }); }
        finally { busy = false; Post(new { type = "done" }); }
    }

    async Task<(int Code, string Out, string Err)> RunClaude(string prompt, string model, string effort)
    {
        var psi = new ProcessStartInfo("claude")
        {
            WorkingDirectory = AppContext.BaseDirectory,
            UseShellExecute = false,
            RedirectStandardInput = true, RedirectStandardOutput = true, RedirectStandardError = true,
            CreateNoWindow = true,
        };
        psi.ArgumentList.Add("-p");
        psi.ArgumentList.Add(prompt);
        psi.ArgumentList.Add(started ? "--resume" : "--session-id");
        psi.ArgumentList.Add(sessionId);
        foreach (var (flag, value) in new[] { ("--model", model), ("--effort", effort) })
            if (value != "") { psi.ArgumentList.Add(flag); psi.ArgumentList.Add(value); }

        using var p = Process.Start(psi)!;
        p.StandardInput.Close(); // evita l'attesa di stdin di claude
        var o = p.StandardOutput.ReadToEndAsync();
        var e = p.StandardError.ReadToEndAsync();
        await p.WaitForExitAsync();
        return (p.ExitCode, (await o).Trim(), (await e).Trim());
    }
}