fix(init): support scoped npm packages (#27128)

The naming scheme for create npm packages varies depending on whether
they are scoped or not. We only supported unscoped packages prior to
this PR. This PR adds support for all the following cases which npm
supports:

- `foo` -> `create-foo`
- `@foo/bar` -> `@foo/create-bar`
- `@foo` -> `@foo/create`
- `@foo@2.0.0` -> `@foo/create@2.0.0`
- `@foo/bar@2.0.0` -> `@foo/create-bar@2.0.0`

See https://docs.npmjs.com/cli/v8/commands/npm-init#description

Fixes https://github.com/denoland/deno/issues/27127

cli/tools/init/mod.rs

@@ -252,8 +252,46 @@ Deno.test(function addTest() {
   Ok(0)
 }
 
+fn npm_name_to_create_package(name: &str) -> String {
+  let mut s = "npm:".to_string();
+
+  let mut scoped = false;
+  let mut create = false;
+
+  for (i, ch) in name.char_indices() {
+    if i == 0 {
+      if ch == '@' {
+        scoped = true;
+      } else {
+        create = true;
+        s.push_str("create-");
+      }
+    } else if scoped {
+      if ch == '/' {
+        scoped = false;
+        create = true;
+        s.push_str("/create-");
+        continue;
+      } else if ch == '@' && !create {
+        scoped = false;
+        create = true;
+        s.push_str("/create@");
+        continue;
+      }
+    }
+
+    s.push(ch);
+  }
+
+  if !create {
+    s.push_str("/create");
+  }
+
+  s
+}
+
 async fn init_npm(name: &str, args: Vec<String>) -> Result<i32, AnyError> {
-  let script_name = format!("npm:create-{}", name);
+  let script_name = npm_name_to_create_package(name);
 
   fn print_manual_usage(script_name: &str, args: &[String]) -> i32 {
     log::info!("{}", cformat!("You can initialize project manually by running <u>deno run {} {}</> and applying desired permissions.", script_name, args.join(" ")));
@@ -336,3 +374,37 @@ fn create_file(
     Ok(())
   }
 }
+
+#[cfg(test)]
+mod test {
+  use crate::tools::init::npm_name_to_create_package;
+
+  #[test]
+  fn npm_name_to_create_package_test() {
+    // See https://docs.npmjs.com/cli/v8/commands/npm-init#description
+    assert_eq!(
+      npm_name_to_create_package("foo"),
+      "npm:create-foo".to_string()
+    );
+    assert_eq!(
+      npm_name_to_create_package("foo@1.0.0"),
+      "npm:create-foo@1.0.0".to_string()
+    );
+    assert_eq!(
+      npm_name_to_create_package("@foo"),
+      "npm:@foo/create".to_string()
+    );
+    assert_eq!(
+      npm_name_to_create_package("@foo@1.0.0"),
+      "npm:@foo/create@1.0.0".to_string()
+    );
+    assert_eq!(
+      npm_name_to_create_package("@foo/bar"),
+      "npm:@foo/create-bar".to_string()
+    );
+    assert_eq!(
+      npm_name_to_create_package("@foo/bar@1.0.0"),
+      "npm:@foo/create-bar@1.0.0".to_string()
+    );
+  }
+}