;;; 401-rust.el --- handle rust code

;;; Commentary:

;;  using rust-mode with rust-analyzer via lsp

;;; Code:

;; load rustic -> IDE like for rust
;; it superseeds rust-mode
;; reference: https://robert.kra.hn/posts/2021-02-07_rust-with-emacs/
(use-package rustic
  :ensure t
  :bind (:map rustic-mode-map
	      ("M-j" . lsp-ui-imenu)
	      ("M-?" . lsp-find-references)
	      ("C-c C-c l" . flycheck-list-errors)
	      ("C-c C-c a" . lsp-execute-code-action)
	      ("C-c C-c r" . lsp-rename)
	      ("C-c C-c q" . lsp-workspace-restart)
	      ("C-c C-c Q" . lsp-workspace-shutdown)
	      ("C-c C-c s" . lsp-rust-analyzer-status))
  :custom
  (global-linum-mode)
  (rustic-lsp-server 'rust-analyzer)
  (rustic-lsp-format t)
  (setq rustic-format-on-save t)
  ;;(linum-relative-mode 0)
  ;;(linum-relative-toggle)
  ;;(hs-minor-mode t)
  ;;(lsp-origami-try-enable)
  ;;(linum-relative-mode 1)
  ;;(setq-default indent-tabs-mode nil)

  :config
  ;; recommended: use spaces instead of tabs
  (add-hook 'rust-mode-hook
	    (lambda () (setq indent-tabs-mode nil)))
    ;; enable code folding und line numbering rust buffers
  (add-hook 'prog-mode-hook
	    ;;'lsp-origami-mode
	    'hs-minor-mode
	    ;;'linum-relative-mode
	    'tmp/rustic-mode-hook)
  ;; (remove-hook 'rustic-mode-hook 'flycheck-mode)
  ;; (setq lsp-eldoc-hook nil)
  ;; (setq lsp-enable-symbol-highlighting nil)
  ;; (setq lsp-signature-auto-activate nil)

  (defun tmp/rustic-mode-hook ()
  ;; so that run C-c C-c C-r works without having to confirm, but don't try to
  ;; save rust buffers that are not file visiting. Once
  ;; https://github.com/brotzeit/rustic/issues/253 has been resolved this should
  ;; no longer be necessary.
  (when buffer-file-name
    (setq-local buffer-save-without-query t)))

  ;; use the lsp package
  ;; https://emacs-lsp.github.io/lsp-mode
  (use-package lsp-mode
    :ensure
    :commands lsp
    :custom
    ;; what to use when checking on-save. "check" is default, I prefer clippy
    (lsp-rust-analyzer-cargo-watch-command "clippy")
    (lsp-eldoc-render-all t)
    (lsp-idle-delay 0.6)
    (lsp-rust-analyzer-server-display-inlay-hints t)
    :config
    (add-hook 'lsp-mode-hook 'lsp-ui-mode))

  (use-package lsp-ivy
    :ensure t)

  (use-package lsp-ui
    :ensure t
    :commands lsp-ui-mode
    :custom
    (lsp-ui-peek-always-show t)
    (lsp-ui-sideline-show-hover t)
    (lsp-ui-doc-enable nil))

  ;; use the company package
  ;; a completion framework for emacs
  (use-package company
    :ensure
    :custom
    (company-idle-delay 2.5) ;; how long to wait until popup
    ;; (company-begin-commands nil) ;; uncomment to disable popup
    :bind
    (:map company-active-map
	  ("C-n". company-select-next)
	  ("C-p". company-select-previous)
	  ("M-<". company-select-first)
	  ("M->". company-select-last))
    (:map company-mode-map
	  ("<tab>". tab-indent-or-complete)
	  ("TAB". tab-indent-or-complete)))

  ;; use the yasnippet
  (use-package yasnippet
    :ensure t
    ;; YASnippet is a template system for Emacs.
    ;; It allows you to type an abbreviation and automatically expand it into function templates
    ;; use YASnippet as a non-global minor mode
    :config
    (yas-reload-all))

  ;; company-capf.el from load-path
  ;;(use-package linum-relative
  ;;  :config
  ;;  (setq linum-relative-backend 'display-line-numbers-mode))

  ) ;; end use-package rustic

(defun company-yasnippet-or-completion ()
  (interactive)
  (or (do-yas-expand)
      (company-complete-common)))

(defun check-expansion ()
  (save-excursion
    (if (looking-at "\\_>") t
      (backward-char 1)
      (if (looking-at "\\.") t
	(backward-char 1)
	(if (looking-at "::") t nil)))))

(defun do-yas-expand ()
  (let ((yas/fallback-behavior 'return-nil))
    (yas/expand)))

(defun tab-indent-or-complete ()
  (interactive)
  (if (minibufferp)
      (minibuffer-complete)
    (if (or (not yas/minor-mode)
	    (null (do-yas-expand)))
	(if (check-expansion)
	    (company-complete-common)
	  (indent-for-tab-command)))))

(provide '401-rust)
;; Local Variables:
;; no-byte-compile: t
;; End
;;; 401-rust.el ends here