//! Self-update via GitHub Releases: find a newer `*-setup.exe`, download
//! it and hand over to the installer.

use crate::state::build;
use anyhow::{anyhow, Context, Result};
use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize)]
pub struct UpdateInfo {
    pub version: String,
    pub notes: String,
    pub url: String,
    pub size: u64,
}

#[derive(Deserialize)]
struct Release {
    tag_name: String,
    #[serde(default)]
    body: String,
    #[serde(default)]
    draft: bool,
    #[serde(default)]
    prerelease: bool,
    assets: Vec<Asset>,
}

#[derive(Deserialize)]
struct Asset {
    name: String,
    browser_download_url: String,
    size: u64,
}

fn parse(v: &str) -> Vec<u64> {
    v.trim_start_matches('v').split(['.', '-', '+']).map_while(|p| p.parse().ok()).collect()
}

pub fn is_newer(candidate: &str, current: &str) -> bool {
    parse(candidate) > parse(current)
}

pub async fn check(http: &reqwest::Client) -> Result<Option<UpdateInfo>> {
    let Some(repo) = build::REPO.filter(|r| !r.is_empty()) else { return Ok(None) };
    let release: Release = http
        .get(format!("https://api.github.com/repos/{repo}/releases/latest"))
        .header("Accept", "application/vnd.github+json")
        .send()
        .await?
        .error_for_status()?
        .json()
        .await?;
    if release.draft || release.prerelease || !is_newer(&release.tag_name, env!("CARGO_PKG_VERSION")) {
        return Ok(None);
    }
    let asset = release
        .assets
        .iter()
        .find(|a| a.name.to_lowercase().ends_with("-setup.exe"))
        .ok_or_else(|| anyhow!("release {} has no installer", release.tag_name))?;
    Ok(Some(UpdateInfo {
        version: release.tag_name.trim_start_matches('v').to_string(),
        notes: release.body,
        url: asset.browser_download_url.clone(),
        size: asset.size,
    }))
}

/// Download the installer and start it. The caller exits the app afterwards.
pub async fn download_and_run(http: &reqwest::Client, url: &str) -> Result<()> {
    if !url.starts_with("https://github.com/") && !url.starts_with("https://objects.githubusercontent.com/") {
        anyhow::bail!("refusing to download an update from an unexpected host");
    }
    let dest = std::env::temp_dir().join("scopenet-launcher-setup.exe");
    let dl = scopenet_core::http::Download::new(url, dest.clone(), None, None);
    scopenet_core::http::download_one(http, &dl, &|_| {}).await.context("downloading update")?;
    // /P = passive (progress only), /R = relaunch when done (Tauri NSIS).
    std::process::Command::new(&dest).args(["/P", "/R"]).spawn().context("starting the installer")?;
    Ok(())
}

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

    #[test]
    fn versions() {
        assert!(is_newer("v0.2.0", "0.1.9"));
        assert!(is_newer("1.0.0", "0.9.12"));
        assert!(!is_newer("v0.1.0", "0.1.0"));
        assert!(!is_newer("0.1.0-beta", "0.1.0"));
    }
}