using NozCli.Core.Models;
using NozCli.Repl;
using Spectre.Console;

namespace NozCli.Commands;

public class TreeCommand : ICommand
{
    public string Name        => "tree";
    public string Description => "Show notes hierarchy as a tree";
    public string Usage       => "tree";

    public Task ExecuteAsync(string[] args, ReplContext ctx, CancellationToken ct = default)
    {
        AnsiConsole.WriteLine();

        if (ctx.CurrentTopic is null)
            RenderRoot(ctx);
        else
            RenderTopic(ctx);

        AnsiConsole.WriteLine();
        return Task.CompletedTask;
    }

    // ── Root view: one branch per topic ─────────────────────────────────────────

    private static void RenderRoot(ReplContext ctx)
    {
        var root = new Tree($"[bold white]~[/]")
            .Style(new Style(new Color(80, 80, 100)));

        var topics = ctx.NoteCache
            .Select(n => n.Topic)
            .Where(t => !string.IsNullOrEmpty(t))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order()
            .ToList();

        foreach (var topic in topics)
        {
            var topicNotes = ctx.NoteCache
                .Where(n => string.Equals(n.Topic, topic, StringComparison.OrdinalIgnoreCase))
                .ToList();

            var count    = topicNotes.Count;
            var countStr = $"[dim grey]{count} {(count == 1 ? "note" : "notes")}[/]";
            var topicNode = root.AddNode($"[grey46]▸[/]  [bold white]{Markup.Escape(topic)}/[/]  {countStr}");

            AddNotesRecursive(topicNode, topicNotes, topic, null);
        }

        AnsiConsole.Write(root);
    }

    // ── Topic view: subtree of current topic / subpath ──────────────────────────

    private static void RenderTopic(ReplContext ctx)
    {
        var label = ctx.CurrentSubPath is null
            ? $"[bold white]~/{ctx.CurrentTopic}/[/]"
            : $"[bold white]~/{ctx.CurrentTopic}/{ctx.CurrentSubPath}/[/]";

        var root = new Tree(label)
            .Style(new Style(new Color(80, 80, 100)));

        var notes = ctx.NotesInView().ToList();
        AddNotesRecursive(root, notes, ctx.CurrentTopic!, ctx.CurrentSubPath);

        AnsiConsole.Write(root);
    }

    // ── Recursive builder ────────────────────────────────────────────────────────

    private static void AddNotesRecursive(
        IHasTreeNodes parent,
        List<NoteInfo> notes,
        string topic,
        string? subPath)
    {
        var depth       = subPath is null ? 0 : subPath.Split('/').Length;
        var topicPrefix = topic + "/";

        // Slug relative to the topic root
        string Relative(string slug) =>
            slug.StartsWith(topicPrefix, StringComparison.OrdinalIgnoreCase)
                ? slug[topicPrefix.Length..]
                : slug;

        // Notes directly at this level
        var directNotes = notes
            .Where(n =>
            {
                var rel  = Relative(n.Slug);
                var segs = rel.Split('/');
                // must be exactly at current depth, and sub-path must match
                if (segs.Length != depth + 1) return false;
                if (subPath is null) return true;
                return rel.StartsWith(subPath + "/") || rel == subPath;
            })
            .OrderBy(n => Relative(n.Slug).Split('/')[depth])
            .ToList();

        // Sub-folders at this level
        var subFolders = notes
            .Where(n =>
            {
                var rel  = Relative(n.Slug);
                var segs = rel.Split('/');
                if (segs.Length <= depth + 1) return false;
                if (subPath is null) return true;
                return rel.StartsWith(subPath + "/");
            })
            .Select(n => Relative(n.Slug).Split('/')[depth])
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order()
            .ToList();

        // Render folders first
        foreach (var folder in subFolders)
        {
            var folderSub   = subPath is null ? folder : $"{subPath}/{folder}";
            var folderNotes = notes
                .Where(n =>
                {
                    var rel = Relative(n.Slug);
                    return rel.StartsWith(folderSub + "/") || rel == folderSub;
                })
                .ToList();

            var count      = folderNotes.Count;
            var countStr   = $"[dim grey]{count} {(count == 1 ? "note" : "notes")}[/]";
            var folderNode = parent.AddNode($"[grey46]▸[/]  [white]{Markup.Escape(folder)}/[/]  {countStr}");

            AddNotesRecursive(folderNode, folderNotes, topic, folderSub);
        }

        // Then direct notes
        foreach (var note in directNotes)
        {
            var (color, dot) = Style(note.Status);
            var name = Relative(note.Slug).Split('/')[depth];
            parent.AddNode($"[{color}]{dot}[/]  [white]{Markup.Escape(name)}[/]  [dim]{Markup.Escape(note.Title)}[/]");
        }
    }

    private static (string color, string dot) Style(string status) => status switch
    {
        "seed"      => ("yellow",  "◦"),
        "budding"   => ("magenta", "◈"),
        "evergreen" => ("cyan",    "◉"),
        _           => ("grey",    "○"),
    };
}