Create initial project structure

The initial project structure includes the base scaffolding of the
application as well as the ability to fetch the repo list from the
remote endpoint.

src/commands/repo.rs

@@ -0,0 +1,59 @@
+use crate::cli::{RepoArgs, RepoCommands};
+use crate::config::Config;
+use crate::error::ApiError;
+use serde::Deserialize;
+
+const BASE_CATALOG_URI: &str = "/v2/_catalog";
+
+pub async fn handler(config: &Config, args: &RepoArgs) -> Result<(), ApiError> {
+    log::trace!("handler()");
+
+    match args.command {
+        RepoCommands::List => handle_list(config, args).await?,
+    }
+
+    Ok(())
+}
+
+
+#[derive(Deserialize)]
+struct CatalogResponse {
+    repositories: Vec<String>,
+}
+
+async fn handle_list(config: &Config, _args: &RepoArgs) -> Result<(), ApiError> {
+    log::trace!("handle_list()");
+
+    let mut url = config.registry_url.join(BASE_CATALOG_URI)?;
+    let mut responses = Vec::new();
+
+    loop {
+        log::debug!("Using url {url}");
+        let response = reqwest::get(url.clone()).await?;
+        let headers = response.headers().to_owned();
+        let body: CatalogResponse = response.json().await?;
+
+        responses.push(body);
+
+        if let Some(link_value) = headers.get(http::header::LINK) {
+            let link_str = link_value.to_str()?;
+            let parts:Vec<&str> = link_str.split(';').collect();
+            if let Some(url_part) = parts.first() {
+                if let Some(uri) = url_part.trim().strip_prefix('<').and_then(|s| s.strip_suffix('>')) {
+                    url = config.registry_url.join(uri)?;
+                }
+            }
+        } else {
+            break;
+        }
+    }
+
+    let repo_list: Vec<&str> = responses.iter().flat_map(|r| r.repositories.iter().map(String::as_str)).collect();
+    
+    for repo in repo_list {
+        println!("{repo}");
+    }
+
+    Ok(())
+
+}