Revert refactor: Put fetch_crate_cratesio back to drivers

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

src/drivers.rs

@@ -1,17 +1,19 @@
 use std::collections::BTreeSet;
 use std::path::{Path, PathBuf};
+use std::time::Duration;
 
+use cargo_toml::Manifest;
+use crates_io_api::AsyncClient;
 use log::debug;
 use semver::{Version, VersionReq};
+use url::Url;
 
-use crate::BinstallError;
-
-mod cratesio;
-pub use cratesio::*;
+use crate::{helpers::*, BinstallError, Meta, TarBasedFmt};
 
 mod vfs;
 
 mod visitor;
+use visitor::ManifestVisitor;
 
 fn find_version<'a, V: Iterator<Item = &'a String>>(
     requirement: &str,
@@ -55,6 +57,67 @@ fn find_version<'a, V: Iterator<Item = &'a String>>(
         .ok_or(BinstallError::VersionMismatch { req: version_req })
 }
 
+/// Fetch a crate Cargo.toml by name and version from crates.io
+pub async fn fetch_crate_cratesio(
+    name: &str,
+    version_req: &str,
+) -> Result<Manifest<Meta>, BinstallError> {
+    // Fetch / update index
+    debug!("Looking up crate information");
+
+    // Build crates.io api client
+    let api_client = AsyncClient::new(
+        "cargo-binstall (https://github.com/ryankurte/cargo-binstall)",
+        Duration::from_millis(100),
+    )
+    .expect("bug: invalid user agent");
+
+    // Fetch online crate information
+    let base_info =
+        api_client
+            .get_crate(name.as_ref())
+            .await
+            .map_err(|err| BinstallError::CratesIoApi {
+                crate_name: name.into(),
+                err,
+            })?;
+
+    // Locate matching version
+    let version_iter =
+        base_info
+            .versions
+            .iter()
+            .filter_map(|v| if !v.yanked { Some(&v.num) } else { None });
+    let version_name = find_version(version_req, version_iter)?;
+
+    // Fetch information for the filtered version
+    let version = base_info
+        .versions
+        .iter()
+        .find(|v| v.num == version_name.to_string())
+        .ok_or_else(|| BinstallError::VersionUnavailable {
+            crate_name: name.into(),
+            v: version_name.clone(),
+        })?;
+
+    debug!("Found information for crate version: '{}'", version.num);
+
+    // Download crate to temporary dir (crates.io or git?)
+    let crate_url = format!("https://crates.io/{}", version.dl_path);
+
+    debug!("Fetching crate from: {crate_url} and extracting Cargo.toml from it");
+
+    let manifest_dir_path: PathBuf = format!("{name}-{version_name}").into();
+
+    download_tar_based_and_visit(
+        Url::parse(&crate_url)?,
+        TarBasedFmt::Tgz,
+        ManifestVisitor::new(manifest_dir_path),
+    )
+    .await?
+    .load_manifest()
+}
+
 /// Fetch a crate by name and version from github
 /// TODO: implement this
 pub async fn fetch_crate_gh_releases(