// Slash-Command Registry — scannt ~/.claude/commands/ und ~/.claude/skills/
// und liefert eine kombinierte Liste inkl. Built-in-Commands an das Frontend.

use serde::Serialize;
use std::fs;
use std::path::PathBuf;

/// Ein Slash-Command mit Metadaten
#[derive(Debug, Clone, Serialize)]
pub struct SlashCommand {
    /// Name des Commands (ohne führenden Slash)
    pub name: String,
    /// Beschreibung (erste Zeile der .md-Datei oder fest hinterlegt)
    pub description: String,
    /// Kategorie: "builtin", "custom", "skill"
    pub category: String,
    /// Herkunft: Dateipfad oder "builtin"
    pub source: String,
}

/// Liest die erste nicht-leere Zeile einer Datei als Beschreibung.
/// Entfernt dabei führende Markdown-Header-Zeichen (#).
fn read_first_line(path: &PathBuf) -> String {
    match fs::read_to_string(path) {
        Ok(content) => {
            content
                .lines()
                .find(|line| !line.trim().is_empty())
                .map(|line| line.trim().trim_start_matches('#').trim().to_string())
                .unwrap_or_else(|| "Keine Beschreibung".into())
        }
        Err(_) => "Datei nicht lesbar".into(),
    }
}

/// Scannt alle verfügbaren Slash-Commands aus verschiedenen Quellen
fn scan_commands() -> Vec<SlashCommand> {
    let mut commands: Vec<SlashCommand> = Vec::new();

    // 1. Built-in-Commands (hardcoded)
    let builtins = vec![
        ("help", "Hilfe und verfügbare Commands anzeigen"),
        ("clear", "Chat-Verlauf leeren"),
        ("compact", "Konversation kompaktieren (Token sparen)"),
        ("model", "KI-Modell wechseln (Sonnet/Opus/Haiku)"),
        ("cost", "Aktuelle Token-Kosten anzeigen"),
        ("doctor", "System-Diagnose und Health-Check"),
        ("review", "Code-Review für aktuelles Projekt"),
    ];

    for (name, desc) in builtins {
        commands.push(SlashCommand {
            name: name.to_string(),
            description: desc.to_string(),
            category: "builtin".to_string(),
            source: "builtin".to_string(),
        });
    }

    // Home-Verzeichnis ermitteln (ohne externe Dependency)
    let home = match std::env::var("HOME") {
        Ok(h) => PathBuf::from(h),
        Err(_) => {
            eprintln!("⚠️ HOME-Umgebungsvariable nicht gesetzt");
            return commands;
        }
    };

    // 2. Custom Commands aus ~/.claude/commands/*.md
    let commands_dir = home.join(".claude").join("commands");
    if commands_dir.is_dir() {
        if let Ok(entries) = fs::read_dir(&commands_dir) {
            for entry in entries.flatten() {
                let path = entry.path();
                if path.extension().map_or(false, |ext| ext == "md") {
                    let name = path
                        .file_stem()
                        .unwrap_or_default()
                        .to_string_lossy()
                        .to_string();
                    let description = read_first_line(&path);
                    commands.push(SlashCommand {
                        name,
                        description,
                        category: "custom".to_string(),
                        source: path.to_string_lossy().to_string(),
                    });
                }
            }
        }
    }

    // 3. Skills aus ~/.claude/skills/*/SKILL.md
    let skills_dir = home.join(".claude").join("skills");
    if skills_dir.is_dir() {
        if let Ok(entries) = fs::read_dir(&skills_dir) {
            for entry in entries.flatten() {
                let skill_dir = entry.path();
                if skill_dir.is_dir() {
                    let skill_md = skill_dir.join("SKILL.md");
                    if skill_md.exists() {
                        let name = skill_dir
                            .file_name()
                            .unwrap_or_default()
                            .to_string_lossy()
                            .to_string();
                        let description = read_first_line(&skill_md);
                        commands.push(SlashCommand {
                            name,
                            description,
                            category: "skill".to_string(),
                            source: skill_md.to_string_lossy().to_string(),
                        });
                    }
                }
            }
        }
    }

    // Alphabetisch sortieren (Built-ins zuerst, dann Custom, dann Skills)
    commands.sort_by(|a, b| {
        let cat_order = |c: &str| match c {
            "builtin" => 0,
            "custom" => 1,
            "skill" => 2,
            _ => 3,
        };
        cat_order(&a.category)
            .cmp(&cat_order(&b.category))
            .then_with(|| a.name.cmp(&b.name))
    });

    commands
}

/// Tauri-Command: Gibt alle verfügbaren Slash-Commands zurück
#[tauri::command]
pub fn get_slash_commands() -> Vec<SlashCommand> {
    scan_commands()
}