add proper help text

src/cli/self_update.rs

@@ -0,0 +1,117 @@
+use std::io::Write;
+
+use miette::IntoDiagnostic;
+use reqwest::Client;
+use serde::Deserialize;
+
+/// Update pixi to the latest version
+#[derive(Debug, clap::Parser)]
+pub struct Args {
+    /// The desired version (to downgrade or upgrade to)
+    #[clap(long)]
+    version: Option<String>,
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Deserialize)]
+struct GithubRelease {
+    tag_name: String,
+    name: String,
+    body: String,
+    html_url: String,
+    assets: Vec<GithubReleaseAsset>,
+}
+
+#[derive(Debug, Deserialize)]
+struct GithubReleaseAsset {
+    name: String,
+    browser_download_url: String,
+}
+
+fn user_agent() -> String {
+    format!("pixi {}", env!("CARGO_PKG_VERSION"))
+}
+
+fn default_name() -> Option<String> {
+    if cfg!(target_os = "macos") {
+        if cfg!(target_arch = "x86_64") {
+            Some("pixi-x86_64-apple-darwin".to_string())
+        } else {
+            Some("pixi-aarch64-apple-darwin".to_string())
+        }
+    } else if cfg!(target_os = "windows") && cfg!(target_arch = "x86_64") {
+        Some("pixi-x86_64-pc-windows-msvc.exe".to_string())
+    } else if cfg!(target_os = "linux") {
+        if cfg!(target_arch = "x86_64") {
+            Some("pixi-x86_64-unknown-linux-musl".to_string())
+        } else if cfg!(target_arch = "aarch64") {
+            Some("pixi-aarch64-unknown-linux-musl".to_string())
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+pub async fn execute(args: Args) -> miette::Result<()> {
+    // fetch latest version from github
+    let url = if let Some(version) = args.version {
+        format!(
+            "https://api.github.com/repos/prefix-dev/pixi/releases/tags/v{}",
+            version
+        )
+    } else {
+        "https://api.github.com/repos/prefix-dev/pixi/releases/latest".to_string()
+    };
+
+    let client = Client::new();
+
+    let res = client
+        .get(url)
+        .header("User-Agent", user_agent())
+        .send()
+        .await
+        .unwrap();
+    let body = res.text().await.unwrap();
+
+    // compare latest version with current version
+    let json = serde_json::from_str::<GithubRelease>(&body).unwrap();
+
+    let version = json.tag_name.trim_start_matches('v');
+
+    // if latest version is newer, download and replace binary
+    if version != env!("CARGO_PKG_VERSION") {
+        println!("A newer version is available: {}", version);
+    } else {
+        println!("You are already using the latest version: {}", version);
+    }
+
+    let name = default_name().unwrap();
+
+    let url = json
+        .assets
+        .iter()
+        .find(|asset| asset.name == name)
+        .unwrap()
+        .browser_download_url
+        .clone();
+
+    // if latest version is newer, download and replace binary (using self_replace)
+    let tempfile = tempfile::NamedTempFile::new().into_diagnostic()?;
+
+    let mut res = client
+        .get(&url)
+        .header("User-Agent", user_agent())
+        .send()
+        .await
+        .unwrap();
+
+    while let Some(chunk) = res.chunk().await.into_diagnostic()? {
+        tempfile.as_file().write_all(&chunk).into_diagnostic()?;
+    }
+
+    self_replace::self_replace(&tempfile).into_diagnostic()?;
+
+    Ok(())
+}