using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.Json;

namespace Gott.Services;

public class SkillService
{
    private readonly string _skillsDir;

    public string SkillsDir => _skillsDir;

    public SkillService(string dataDir)
    {
        _skillsDir = Path.Combine(dataDir, "skills");
        Directory.CreateDirectory(_skillsDir);
    }

    /// <summary>
    /// Scannt den Skills-Ordner und gibt alle verfügbaren Skills zurück.
    /// </summary>
    public List<SkillInfo> GetAllSkills()
    {
        var skills = new List<SkillInfo>();
        if (!Directory.Exists(_skillsDir)) return skills;

        foreach (var dir in Directory.GetDirectories(_skillsDir))
        {
            var skill = LoadSkill(dir);
            if (skill != null) skills.Add(skill);
        }

        return skills.OrderBy(s => s.Name).ToList();
    }

    /// <summary>
    /// Lädt einen einzelnen Skill anhand seines Slugs.
    /// </summary>
    public SkillInfo GetSkill(string slug)
    {
        var dir = Path.Combine(_skillsDir, slug);
        if (!Directory.Exists(dir)) return null;
        return LoadSkill(dir);
    }

    /// <summary>
    /// Liest die PROMPT.md eines Skills. Gibt null zurück wenn nicht vorhanden.
    /// Nur Skills mit PROMPT.md können im System-Prompt verwendet werden.
    /// </summary>
    public string GetSkillPrompt(string slug)
    {
        var promptMd = Path.Combine(_skillsDir, slug, "PROMPT.md");
        if (!File.Exists(promptMd)) return null;
        return File.ReadAllText(promptMd);
    }

    private SkillInfo LoadSkill(string dir)
    {
        var slug = Path.GetFileName(dir);
        var metaFile = Path.Combine(dir, "_meta.json");
        var skillMd = Path.Combine(dir, "SKILL.md");

        var promptMd = Path.Combine(dir, "PROMPT.md");

        var info = new SkillInfo
        {
            Slug = slug,
            Path = Path.GetFullPath(dir),
            HasSkillMd = File.Exists(skillMd),
            HasPromptMd = File.Exists(promptMd)
        };

        // Name/Description aus SKILL.md Frontmatter lesen
        if (File.Exists(skillMd))
        {
            var content = File.ReadAllText(skillMd);
            var frontmatter = ParseFrontmatter(content);
            if (frontmatter.TryGetValue("name", out var name)) info.Name = name;
            if (frontmatter.TryGetValue("description", out var desc)) info.Description = desc;
            if (frontmatter.TryGetValue("version", out var ver)) info.Version = ver;
        }

        // _meta.json als Fallback/Ergänzung
        if (File.Exists(metaFile))
        {
            try
            {
                var json = File.ReadAllText(metaFile);
                using var doc = JsonDocument.Parse(json);
                var root = doc.RootElement;
                if (string.IsNullOrEmpty(info.Name) && root.TryGetProperty("name", out var n))
                    info.Name = n.GetString();
                if (string.IsNullOrEmpty(info.Version) && root.TryGetProperty("version", out var v))
                    info.Version = v.GetString();
                if (root.TryGetProperty("slug", out var s) && !string.IsNullOrEmpty(s.GetString()))
                    info.Slug = s.GetString();
            }
            catch { /* Fehler in _meta.json ignorieren */ }
        }

        // Fallback: Name = Slug
        if (string.IsNullOrEmpty(info.Name)) info.Name = slug;

        return info;
    }

    /// <summary>
    /// Parst einen einfachen YAML-Frontmatter-Block (--- ... ---) aus einer Markdown-Datei.
    /// </summary>
    private Dictionary<string, string> ParseFrontmatter(string content)
    {
        var result = new Dictionary<string, string>();
        if (!content.StartsWith("---")) return result;

        var end = content.IndexOf("---", 3, StringComparison.Ordinal);
        if (end < 0) return result;

        var frontmatter = content.Substring(3, end - 3).Trim();
        foreach (var line in frontmatter.Split('\n'))
        {
            var colon = line.IndexOf(':');
            if (colon < 0) continue;
            var key = line.Substring(0, colon).Trim();
            var value = line.Substring(colon + 1).Trim();
            result[key] = value;
        }

        return result;
    }
}

public class SkillInfo
{
    public string Slug { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string Version { get; set; }
    public string Path { get; set; }
    public bool HasSkillMd { get; set; }
    public bool HasPromptMd { get; set; }
}