;;; init-completion.el --- Completion Configuration File -*- lexical-binding: t -*-
;;; Commentary:
;; Config for completion-at-point (corfu), as well as orderless (see also init-minibuffer.el)
;; Most of it is taken from the READMEs and wikis of those packages
;;; Code:

(use-package dabbrev
  :diminish)

(use-package hippie-expand
  :ensure nil
  :init
  (setq hippie-expand-try-functions-list
      '(;yas-hippie-try-expand
        try-expand-dabbrev
        try-expand-all-abbrevs
        try-expand-dabbrev-all-buffers
        try-expand-dabbrev-from-kill
        try-complete-file-name-partially
        try-complete-file-name
        try-expand-list
        try-expand-line
        try-complete-lisp-symbol-partially
        try-complete-lisp-symbol))
  :bind
  ("M-/" . hippie-expand))

(use-package fancy-dabbrev
  :diminish
  :config
  (global-fancy-dabbrev-mode))

(use-package emacs
  :init
  (setq completion-cycle-threshold 3)
  (setq tab-always-indent 'complete))

(use-package orderless
  :bind (:map minibuffer-local-completion-map
              ("C-l" . my/orderless-match-components-literally))
  :custom (orderless-component-separator 'orderless-escapable-split-on-space)
  :init
  (setq completion-styles '(orderless basic)
        completion-category-defaults nil
        completion-category-overrides '((file (styles . (partial-completion orderless)))))

  (defun my/orderless-match-components-literally ()
    "Components match literally for the rest of the session."
    (interactive)
    (setq-local orderless-matching-styles '(orderless-literal)
                orderless-style-dispatchers nil))
  :config
  ;; Recognizes the following patterns:
  ;; * ~flex flex~
  ;; * =literal literal=
  ;; * %char-fold char-fold%
  ;; * `initialism initialism`
  ;; * !without-literal without-literal!
  ;; * .ext (file extension)
  ;; * regexp$ (regexp matching at end)
  (defun my/orderless-dispatch (pattern _index _total)
    (cond
     ;; Ensure that $ works with Consult commands, which add disambiguation suffixes
     ((string-suffix-p "$" pattern) `(orderless-regexp . ,(concat (substring pattern 0 -1) "[\x100000-\x10FFFD]*$")))
     ;; File extensions
     ((string-match-p "\\`\\.." pattern) `(orderless-regexp . ,(concat "\\." (substring pattern 1) "[\x100000-\x10FFFD]*$")))
     ;; Ignore single !
     ((string= "!" pattern) `(orderless-literal . ""))
     ;; Character folding
     ((string-prefix-p "%" pattern) `(char-fold-to-regexp . ,(substring pattern 1)))
     ((string-suffix-p "%" pattern) `(char-fold-to-regexp . ,(substring pattern 0 -1)))
     ;; Without literal
     ((string-prefix-p "!" pattern) `(orderless-without-literal . ,(substring pattern 1)))
     ((string-suffix-p "!" pattern) `(orderless-without-literal . ,(substring pattern 0 -1)))
     ;; Initialism matching
     ((string-prefix-p "`" pattern) `(orderless-initialism . ,(substring pattern 1)))
     ((string-suffix-p "`" pattern) `(orderless-initialism . ,(substring pattern 0 -1)))
     ;; Literal matching
     ((string-prefix-p "=" pattern) `(orderless-literal . ,(substring pattern 1)))
     ((string-suffix-p "=" pattern) `(orderless-literal . ,(substring pattern 0 -1)))
     ;; Flex matching
     ((string-prefix-p "~" pattern) `(orderless-flex . ,(substring pattern 1)))
     ((string-suffix-p "~" pattern) `(orderless-flex . ,(substring pattern 0 -1)))))
  (setq orderless-matching-styles '(orderless-literal orderless-regexp orderless-strict-leading-initialism)
        orderless-style-dispatchers '(my/orderless-dispatch)))

;; code completion - corfu
(use-package corfu
  ;; Optional customizations
  :custom
  (corfu-cycle t)            ;; Enable cycling for `corfu-next/previous'
  :bind (:map corfu-map
         ("TAB" . corfu-next)
         ([tab] . corfu-next)
         ("S-TAB" . corfu-previous)
         ([backtab] . corfu-previous))
  :init
  (corfu-global-mode))

(provide 'init-completion)
;;; init-completion.el ends here