rustic-cargo-add-missing-imports (brotzeit#161)

* Extract crate name from error message

* Build list from missing imports

* update name

* Add all missing imports in current buffer

* Let the user select one import with prefix arg

* Check for cargo-edit and handle no missing imports

* Mention function in readme

README.md

@@ -464,6 +464,7 @@ modify the parameters of a command.
 - `rustic-cargo-add`      Add crate to Cargo.toml using 'cargo add'
 - `rustic-cargo-rm`       Remove crate from Cargo.toml using 'cargo rm'
 - `rustic-cargo-upgrade`  Upgrade dependencies as specified in the local manifest file using 'cargo upgrade'
+- `rustic-cargo-add-missing-imports ` Add the missing imports for the current buffer to `cargo.toml`. This function requires `lsp-mode`.
 
 ### Test
 

rustic-cargo.el

@@ -709,6 +709,25 @@ If running with prefix command `C-u', read whole command from minibuffer."
                               (read-from-minibuffer "Crate: ")))))
       (rustic-run-cargo-command command))))
 
+(defun rustic-cargo-add-missing-imports ()
+  "Add missing imports to Cargo.toml.
+Adds all missing imports by default.
+Use with 'prefix-arg` to select imports to add."
+  (interactive)
+  (when (rustic-cargo-edit-installed-p)
+    (let ((missing-imports (delete-dups
+                            (seq-reduce (lambda (missing-crates errortable)
+                                          (if (string= "E0432" (gethash "code" errortable))
+                                              (cons (nth 3 (split-string (gethash "message" errortable) "`")) missing-crates)
+                                            missing-crates))
+                                        (gethash (buffer-file-name) (lsp-diagnostics t)) '()))))
+      (if missing-imports
+          (rustic-run-cargo-command (format  "cargo add %s"
+                                             (if current-prefix-arg
+                                                 (completing-read "Select import to add to Cargo.toml" missing-imports)
+                                               (mapconcat 'identity  missing-imports " "))))
+        (message "Couldn't find any imports to add. If this was a mistake, make sure your language server is running properly.")))))
+
 ;;;###autoload
 (defun rustic-cargo-rm (&optional arg)
   "Remove crate from Cargo.toml using 'cargo rm'.