using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;
using NozCli.Repl;
using Spectre.Console;

namespace NozCli.Commands;

public class EditCommand : ICommand
{
    public string Name        => "edit";
    public string Description => "Open a note in your default editor, then offer to push";
    public string Usage       => "edit <slug>";

    public async Task ExecuteAsync(string[] args, ReplContext ctx)
    {
        var slug = args.FirstOrDefault();
        if (slug is null) { AnsiConsole.MarkupLine("[red]Usage: edit <slug>[/]"); return; }

        slug = ctx.ResolveSlug(slug);

        // 1. Fetch note from server
        NozCli.Core.Models.NoteContent note = default!;
        await AnsiConsole.Status().StartAsync("Fetching…", async _ =>
            note = await ctx.Api.GetNoteAsync(slug));

        // 2. Write to temp file
        var tmp = Path.Combine(Path.GetTempPath(), $"noz-{slug.Replace('/', '-')}.md");
        await File.WriteAllTextAsync(tmp, note.Markdown);

        // 3. Open editor
        var editor = ResolveEditor();
        AnsiConsole.MarkupLine($"[dim]Opening {editor} …[/]");
        var proc = Process.Start(new ProcessStartInfo
        {
            FileName  = editor,
            Arguments = $"\"{tmp}\"",
            UseShellExecute = !OperatingSystem.IsWindows(),
        });
        proc?.WaitForExit();

        // 4. Compare hashes
        var edited = await File.ReadAllTextAsync(tmp);
        var newHash = HashContent(edited);

        File.Delete(tmp);

        if (newHash == note.Hash)
        {
            AnsiConsole.MarkupLine("[dim]No changes.[/]");
            return;
        }

        // 5. Ask to push
        AnsiConsole.MarkupLine("[green]Changes detected.[/]");
        var push = AnsiConsole.Confirm("Push changes to server?");
        if (!push) { AnsiConsole.MarkupLine("[dim]Discarded.[/]"); return; }

        await AnsiConsole.Status().StartAsync("Pushing…", async _ =>
            await ctx.Api.PutNoteAsync(slug, edited));

        AnsiConsole.MarkupLine($"[green]✓[/] {slug} updated");
    }

    private static string ResolveEditor()
    {
        // Priority: $EDITOR → $VISUAL → VS Code → nano → vi
        var env = Environment.GetEnvironmentVariable("EDITOR")
               ?? Environment.GetEnvironmentVariable("VISUAL");
        if (env is not null) return env;

        foreach (var candidate in new[] { "code", "nano", "vi", "notepad" })
            if (IsOnPath(candidate)) return candidate;

        return "nano";
    }

    private static bool IsOnPath(string name)
    {
        try
        {
            var result = Process.Start(new ProcessStartInfo
            {
                FileName        = OperatingSystem.IsWindows() ? "where" : "which",
                Arguments       = name,
                RedirectStandardOutput = true,
                UseShellExecute = false,
            });
            result?.WaitForExit();
            return result?.ExitCode == 0;
        }
        catch { return false; }
    }

    private static string HashContent(string content) =>
        Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(content))).ToLower();
}