//! Auto-updater — checks the Gitea releases endpoint for a newer version
//! than the one currently running. Downloads are opt-in (user clicks
//! "Install Update"), not automatic.
//!
//! Port of the v1 `lib/updater.js` semver-compare + Gitea polling flow.

use semver::Version;
use serde::{Deserialize, Serialize};
use std::time::Duration;

const REPO: &str = "Administrator/Multi-Hoster-Upload-2";
const BASE: &str = "https://git.24-music.de/api/v1/repos";

#[derive(Serialize, Default, Clone, Debug)]
#[serde(rename_all = "camelCase")]
pub struct UpdateCheck {
    pub available: bool,
    pub current_version: String,
    pub latest_version: Option<String>,
    pub download_url: Option<String>,
    pub release_notes: Option<String>,
}

#[derive(Deserialize)]
struct GiteaRelease {
    tag_name: String,
    body: Option<String>,
    assets: Option<Vec<GiteaAsset>>,
}

#[derive(Deserialize)]
struct GiteaAsset {
    name: String,
    browser_download_url: String,
}

pub async fn download_and_launch(app: tauri::AppHandle) -> Result<(), String> {
    let info = check().await;
    if !info.available {
        return Err("Kein Update verfügbar".into());
    }
    let url = info.download_url.ok_or("Kein Download-URL im Release")?;
    let client = reqwest::Client::builder()
        .timeout(Duration::from_secs(5 * 60))
        .user_agent("multi-hoster-upload/2.0")
        .build().map_err(|e| e.to_string())?;
    let resp = client.get(&url).send().await.map_err(|e| e.to_string())?;
    if !resp.status().is_success() {
        return Err(format!("Download HTTP {}", resp.status().as_u16()));
    }
    let bytes = resp.bytes().await.map_err(|e| e.to_string())?;
    let tmp = std::env::temp_dir();
    let file_name = url.rsplit('/').next().unwrap_or("Multi-Hoster-Upload-Setup.exe");
    let target = tmp.join(format!("multi-hoster-update-{}-{file_name}",
        chrono::Utc::now().timestamp()));
    std::fs::write(&target, &bytes).map_err(|e| e.to_string())?;

    // Notify UI and launch the installer detached. We then exit so the NSIS
    // installer can replace the running exe.
    let _ = tauri::Emitter::emit(&app, "app:update-installing",
        &serde_json::json!({ "path": target.display().to_string() }));

    #[cfg(target_os = "windows")]
    {
        use std::os::windows::process::CommandExt;
        const DETACHED_PROCESS: u32 = 0x00000008;
        const CREATE_NEW_PROCESS_GROUP: u32 = 0x00000200;
        std::process::Command::new(&target)
            .creation_flags(DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP)
            .spawn()
            .map_err(|e| e.to_string())?;
    }
    #[cfg(not(target_os = "windows"))]
    {
        std::process::Command::new(&target).spawn().map_err(|e| e.to_string())?;
    }
    tokio::time::sleep(Duration::from_millis(500)).await;
    app.exit(0);
    Ok(())
}

pub async fn check() -> UpdateCheck {
    let current = env!("CARGO_PKG_VERSION").to_string();
    let mut out = UpdateCheck {
        available: false,
        current_version: current.clone(),
        ..Default::default()
    };

    let Ok(client) = reqwest::Client::builder()
        .timeout(Duration::from_secs(15))
        .user_agent("multi-hoster-upload/2.0")
        .build()
    else { return out };

    let url = format!("{BASE}/{REPO}/releases?limit=10");
    let Ok(resp) = client.get(&url).send().await else { return out };
    if !resp.status().is_success() { return out; }
    let Ok(list) = resp.json::<Vec<GiteaRelease>>().await else { return out };

    let Ok(current_v) = Version::parse(current.trim_start_matches('v')) else { return out };

    for r in list {
        let raw = r.tag_name.trim_start_matches('v');
        let Ok(v) = Version::parse(raw) else { continue };
        if v > current_v {
            out.available = true;
            out.latest_version = Some(r.tag_name.clone());
            out.release_notes = r.body.clone();
            // Prefer MSI > NSIS Setup > fallback.
            let assets = r.assets.unwrap_or_default();
            let url = assets.iter().find(|a| a.name.ends_with(".msi"))
                .or_else(|| assets.iter().find(|a| a.name.to_lowercase().contains("setup.exe")))
                .or_else(|| assets.iter().find(|a| a.name.ends_with(".exe")));
            out.download_url = url.map(|a| a.browser_download_url.clone());
            break;
        }
    }
    out
}