// Claude Desktop — Auto-Update System
// Prüft Forgejo-Releases und aktualisiert das AppImage

use serde::{Deserialize, Serialize};
use std::path::PathBuf;
use tauri::{AppHandle, Manager, Emitter};

/// Forgejo API Konfiguration
const FORGEJO_URL: &str = "https://git.data-it-solution.de";
const REPO_OWNER: &str = "data";
const REPO_NAME: &str = "claude-desktop";

/// Aktuelle App-Version (aus Cargo.toml)
const CURRENT_VERSION: &str = env!("CARGO_PKG_VERSION");

/// Release-Info von Forgejo
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReleaseInfo {
    pub id: i64,
    pub tag_name: String,
    pub name: String,
    pub body: Option<String>,
    pub draft: bool,
    pub prerelease: bool,
    pub created_at: String,
    pub published_at: Option<String>,
    pub assets: Vec<ReleaseAsset>,
}

/// Release-Asset (z.B. AppImage)
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReleaseAsset {
    pub id: i64,
    pub name: String,
    pub size: i64,
    pub download_count: i64,
    pub browser_download_url: String,
}

/// Update-Status für Frontend
#[derive(Debug, Clone, Serialize)]
pub struct UpdateStatus {
    pub available: bool,
    pub current_version: String,
    pub latest_version: Option<String>,
    pub release_notes: Option<String>,
    pub download_url: Option<String>,
    pub download_size: Option<i64>,
}

/// Prüft ob ein Update verfügbar ist
#[tauri::command]
pub async fn check_for_update() -> Result<UpdateStatus, String> {
    let url = format!(
        "{}/api/v1/repos/{}/{}/releases?limit=1",
        FORGEJO_URL, REPO_OWNER, REPO_NAME
    );

    let client = reqwest::Client::new();
    let response = client
        .get(&url)
        .header("Accept", "application/json")
        .send()
        .await
        .map_err(|e| format!("Netzwerkfehler: {}", e))?;

    if !response.status().is_success() {
        return Ok(UpdateStatus {
            available: false,
            current_version: CURRENT_VERSION.to_string(),
            latest_version: None,
            release_notes: None,
            download_url: None,
            download_size: None,
        });
    }

    let releases: Vec<ReleaseInfo> = response
        .json()
        .await
        .map_err(|e| format!("JSON-Fehler: {}", e))?;

    let latest = match releases.into_iter().find(|r| !r.draft && !r.prerelease) {
        Some(r) => r,
        None => {
            return Ok(UpdateStatus {
                available: false,
                current_version: CURRENT_VERSION.to_string(),
                latest_version: None,
                release_notes: None,
                download_url: None,
                download_size: None,
            });
        }
    };

    // Version vergleichen (tag_name ohne 'v' Prefix)
    let latest_version = latest.tag_name.trim_start_matches('v').to_string();
    let is_newer = version_compare(&latest_version, CURRENT_VERSION);

    // AppImage-Asset finden
    let appimage = latest.assets.iter().find(|a| a.name.ends_with(".AppImage"));

    Ok(UpdateStatus {
        available: is_newer,
        current_version: CURRENT_VERSION.to_string(),
        latest_version: Some(latest_version),
        release_notes: latest.body,
        download_url: appimage.map(|a| a.browser_download_url.clone()),
        download_size: appimage.map(|a| a.size),
    })
}

/// Download-Fortschritt
#[derive(Debug, Clone, Serialize)]
pub struct DownloadProgress {
    pub downloaded: u64,
    pub total: u64,
    pub percent: f32,
}

/// Lädt das Update herunter
#[tauri::command]
pub async fn download_update(
    app: AppHandle,
    download_url: String,
) -> Result<PathBuf, String> {
    use std::io::Write;

    let client = reqwest::Client::new();
    let response = client
        .get(&download_url)
        .send()
        .await
        .map_err(|e| format!("Download-Fehler: {}", e))?;

    let total_size = response.content_length().unwrap_or(0);

    // Temp-Verzeichnis für Download
    let cache_dir = app.path().app_cache_dir()
        .map_err(|e| format!("Cache-Verzeichnis nicht gefunden: {}", e))?;
    std::fs::create_dir_all(&cache_dir).ok();

    let file_name = download_url.split('/').last().unwrap_or("update.AppImage");
    let download_path = cache_dir.join(file_name);

    let mut file = std::fs::File::create(&download_path)
        .map_err(|e| format!("Datei erstellen fehlgeschlagen: {}", e))?;

    let mut downloaded: u64 = 0;
    let mut stream = response.bytes_stream();

    use futures_util::StreamExt;
    while let Some(chunk) = stream.next().await {
        let chunk = chunk.map_err(|e| format!("Download-Chunk-Fehler: {}", e))?;
        file.write_all(&chunk)
            .map_err(|e| format!("Schreibfehler: {}", e))?;

        downloaded += chunk.len() as u64;

        // Fortschritt an Frontend senden
        let progress = DownloadProgress {
            downloaded,
            total: total_size,
            percent: if total_size > 0 {
                (downloaded as f32 / total_size as f32) * 100.0
            } else {
                0.0
            },
        };
        app.emit("update-progress", &progress).ok();
    }

    // Ausführbar machen
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        let mut perms = std::fs::metadata(&download_path)
            .map_err(|e| format!("Metadata-Fehler: {}", e))?
            .permissions();
        perms.set_mode(0o755);
        std::fs::set_permissions(&download_path, perms)
            .map_err(|e| format!("Permissions-Fehler: {}", e))?;
    }

    println!("✅ Update heruntergeladen: {:?}", download_path);
    Ok(download_path)
}

/// Wendet das Update an (ersetzt AppImage und startet neu)
#[tauri::command]
pub async fn apply_update(app: AppHandle, update_path: PathBuf) -> Result<(), String> {
    // Prüfen ob wir in einem AppImage laufen
    let appimage_path = std::env::var("APPIMAGE").ok();

    if let Some(appimage) = appimage_path {
        let appimage_path = PathBuf::from(&appimage);

        // Backup erstellen
        let backup_path = appimage_path.with_extension("AppImage.backup");
        std::fs::rename(&appimage_path, &backup_path)
            .map_err(|e| format!("Backup fehlgeschlagen: {}", e))?;

        // Neues AppImage verschieben
        std::fs::rename(&update_path, &appimage_path)
            .map_err(|e| {
                // Backup wiederherstellen bei Fehler
                std::fs::rename(&backup_path, &appimage_path).ok();
                format!("Update-Installation fehlgeschlagen: {}", e)
            })?;

        // Backup löschen
        std::fs::remove_file(&backup_path).ok();

        println!("✅ Update installiert, starte neu...");

        // App neustarten (kehrt nicht zurück)
        app.restart();
    }

    // Nicht in AppImage — Entwicklungsmodus
    Err("Update nur für AppImage-Builds verfügbar. In Entwicklung: manuell `git pull` und neu bauen.".to_string())
}

/// Gibt aktuelle Version zurück
#[tauri::command]
pub fn get_current_version() -> String {
    CURRENT_VERSION.to_string()
}

/// Vergleicht zwei Versionen (semver-ähnlich)
fn version_compare(new: &str, current: &str) -> bool {
    let parse = |v: &str| -> Vec<u32> {
        v.split('.')
            .filter_map(|s| s.parse().ok())
            .collect()
    };

    let new_parts = parse(new);
    let current_parts = parse(current);

    for i in 0..3 {
        let n = new_parts.get(i).copied().unwrap_or(0);
        let c = current_parts.get(i).copied().unwrap_or(0);
        if n > c {
            return true;
        }
        if n < c {
            return false;
        }
    }
    false
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_version_compare() {
        assert!(version_compare("1.0.1", "1.0.0"));
        assert!(version_compare("1.1.0", "1.0.9"));
        assert!(version_compare("2.0.0", "1.9.9"));
        assert!(!version_compare("1.0.0", "1.0.0"));
        assert!(!version_compare("1.0.0", "1.0.1"));
        assert!(!version_compare("0.9.0", "1.0.0"));
    }
}