;;; typescript-ts-mode.el --- tree sitter support for TypeScript  -*- lexical-binding: t; -*-

;; Copyright (C) 2022 Free Software Foundation, Inc.

;; Author     : Theodor Thornhill <theo@thornhill.no>
;; Maintainer : Theodor Thornhill <theo@thornhill.no>
;; Created    : October 2022
;; Keywords   : typescript tsx languages tree-sitter

;; This file is part of GNU Emacs.

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Code:

(require 'treesit)
(require 'rx)
(require 'js)

(declare-function treesit-parser-create "treesit.c")

(defcustom typescript-ts-mode-indent-offset 2
  "Number of spaces for each indentation step in `typescript-ts-mode'."
  :version "29.1"
  :type 'integer
  :safe 'integerp
  :group 'typescript)

(defcustom typescript-ts-mode-indent-style 'typescript-ts-mode--default-style
  "Style used for indentation.

The selected style could either be the default style, or a
function could be set instead.  This function is expected to
return a list that follows the form of
`treesit-simple-indent-rules'."
  :version "29.1"
  :type '(choice (symbol :tag "Default" 'typescript-ts-mode--default-style)
                 (function :tag "A function for user customized style" ignore))
  :group 'typescript)

(defun typescript-ts-mode--set-indent-style ()
  "Helper function to set indentation style."
  (if (functionp typescript-ts-mode-indent-style)
      (funcall typescript-ts-mode-indent-style)
    typescript-ts-mode--indent-rules))

(defvar typescript-ts-mode--syntax-table
  (let ((table (make-syntax-table)))
    ;; Taken from the cc-langs version
    (modify-syntax-entry ?_  "_"     table)
    (modify-syntax-entry ?$ "_"      table)
    (modify-syntax-entry ?\\ "\\"    table)
    (modify-syntax-entry ?+  "."     table)
    (modify-syntax-entry ?-  "."     table)
    (modify-syntax-entry ?=  "."     table)
    (modify-syntax-entry ?%  "."     table)
    (modify-syntax-entry ?<  "."     table)
    (modify-syntax-entry ?>  "."     table)
    (modify-syntax-entry ?&  "."     table)
    (modify-syntax-entry ?|  "."     table)
    (modify-syntax-entry ?` "\""     table)
    (modify-syntax-entry ?\240 "."   table)
    table)
  "Syntax table for `typescript-ts-mode'.")

(defvar typescript-ts-mode--indent-rules
  `((tsx
     ((parent-is "program") parent-bol 0)
     ((node-is "}") parent-bol 0)
     ((node-is ")") parent-bol 0)
     ((node-is "]") parent-bol 0)
     ((node-is ">") parent-bol 0)
     ((and (parent-is "comment") comment-end) comment-start -1)
     ((parent-is "comment") comment-start-skip 0)
     ((parent-is "ternary_expression") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "member_expression") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "named_imports") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "statement_block") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "type_arguments") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "variable_declarator") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "arguments") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "array") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "formal_parameters") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "template_substitution") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "object_pattern") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "object") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "object_type") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "enum_body") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "arrow_function") parent-bol typescript-ts-mode-indent-offset)
     ((parent-is "parenthesized_expression") parent-bol typescript-ts-mode-indent-offset)

     ;; TSX
     ((parent-is "jsx_opening_element") parent typescript-ts-mode-indent-offset)
     ((node-is "jsx_closing_element") parent 0)
     ((parent-is "jsx_element") parent typescript-ts-mode-indent-offset)
     ((node-is "/") parent 0)
     ((parent-is "jsx_self_closing_element") parent typescript-ts-mode-indent-offset)
     (no-node parent-bol 0)))
  "Tree-sitter indent rules.")

(defvar typescript-ts-mode--keywords
  '("!" "abstract" "as" "async" "await" "break"
    "case" "catch" "class" "const" "continue" "debugger"
    "declare" "default" "delete" "do" "else" "enum"
    "export" "extends" "finally" "for" "from" "function"
    "get" "if" "implements" "import" "in" "instanceof" "interface"
    "keyof" "let" "namespace" "new" "of" "private" "protected"
    "public" "readonly" "return" "set" "static" "switch"
    "target" "throw" "try" "type" "typeof" "var" "void"
    "while" "with" "yield")
  "TypeScript keywords for tree-sitter font-locking.")

(defvar typescript-ts-mode--operators
  '("=" "+=" "-=" "*=" "/=" "%=" "**=" "<<=" ">>=" ">>>=" "&=" "^="
    "|=" "&&=" "||=" "??=" "==" "!=" "===" "!==" ">" ">=" "<" "<=" "+"
    "-" "*" "/" "%" "++" "--" "**" "&" "|" "^" "~" "<<" ">>" ">>>"
    "&&" "||" "!" "?.")
  "TypeScript operators for tree-sitter font-locking.")

(defvar typescript-ts-mode--font-lock-settings
  (treesit-font-lock-rules
   :language 'tsx
   :override t
   :feature 'comment
   `((comment) @font-lock-comment-face)

   :language 'tsx
   :override t
   :feature 'constant
   `(((identifier) @font-lock-constant-face
      (:match "^[A-Z_][A-Z_\\d]*$" @font-lock-constant-face))

     [(true) (false) (null)] @font-lock-constant-face)

   :language 'tsx
   :override t
   :feature 'keyword
   `([,@typescript-ts-mode--keywords] @font-lock-keyword-face
     [(this) (super)] @font-lock-keyword-face)

   :language 'tsx
   :override t
   :feature 'string
   `((regex pattern: (regex_pattern)) @font-lock-string-face
     (string) @font-lock-string-face
     (template_string) @js--fontify-template-string
     (template_substitution ["${" "}"] @font-lock-builtin-face))

   :language 'tsx
   :override t
   :feature 'declaration
   `((function
      name: (identifier) @font-lock-function-name-face)

     (function_declaration
      name: (identifier) @font-lock-function-name-face)

     (method_definition
      name: (property_identifier) @font-lock-function-name-face)

     (variable_declarator
      name: (identifier) @font-lock-variable-name-face)

     (enum_declaration (identifier) @font-lock-type-face)

     (arrow_function
      parameter: (identifier) @font-lock-variable-name-face)

     (variable_declarator
      name: (identifier) @font-lock-function-name-face
      value: [(function) (arrow_function)])

     (variable_declarator
      name: (array_pattern
             (identifier)
             (identifier) @font-lock-function-name-face)
      value: (array (number) (function))))

   :language 'tsx
   :override t
   :feature 'identifier
   `((nested_type_identifier
      module: (identifier) @font-lock-type-face)

     (type_identifier) @font-lock-type-face

     (predefined_type) @font-lock-type-face

     (new_expression
      constructor: (identifier) @font-lock-type-face)

     (enum_body (property_identifier) @font-lock-type-face)

     (enum_assignment name: (property_identifier) @font-lock-type-face)

     (assignment_expression
      left: [(identifier) @font-lock-variable-name-face
             (member_expression
              property: (property_identifier) @font-lock-variable-name-face)])

     (for_in_statement
      left: (identifier) @font-lock-variable-name-face)

     (arrow_function
      parameters:
      [(_ (identifier) @font-lock-variable-name-face)
       (_ (_ (identifier) @font-lock-variable-name-face))
       (_ (_ (_ (identifier) @font-lock-variable-name-face)))]))

   :language 'tsx
   :override t
   :feature 'expression
   '((assignment_expression
      left: [(identifier) @font-lock-function-name-face
             (member_expression
              property: (property_identifier) @font-lock-function-name-face)]
      right: [(function) (arrow_function)])

     (call_expression
      function:
      [(identifier) @font-lock-function-name-face
       (member_expression
        property: (property_identifier) @font-lock-function-name-face)]))

   :language 'tsx
   :override t
   :feature 'pattern
   `((pair_pattern
      key: (property_identifier) @font-lock-property-face)

     (array_pattern (identifier) @font-lock-variable-name-face))

   :language 'tsx
   :override t
   :feature 'jsx
   `((jsx_opening_element
      [(nested_identifier (identifier)) (identifier)]
      @font-lock-function-name-face)

     (jsx_closing_element
      [(nested_identifier (identifier)) (identifier)]
      @font-lock-function-name-face)

     (jsx_self_closing_element
      [(nested_identifier (identifier)) (identifier)]
      @font-lock-function-name-face)

     (jsx_attribute (property_identifier) @font-lock-constant-face))

   :language 'tsx
   :feature 'number
   `((number) @font-lock-number-face
     ((identifier) @font-lock-number-face
      (:match "^\\(:?NaN\\|Infinity\\)$" @font-lock-number-face)))

   :language 'tsx
   :feature 'operator
   `([,@typescript-ts-mode--operators] @font-lock-operator-face
     (ternary_expression ["?" ":"] @font-lock-operator-face))

   :language 'tsx
   :feature 'bracket
   '((["(" ")" "[" "]" "{" "}"]) @font-lock-bracket-face)

   :language 'tsx
   :feature 'delimiter
   '((["," "." ";" ":"]) @font-lock-delimiter-face)

   :language 'tsx
   :feature 'escape-sequence
   :override t
   '((escape_sequence) @font-lock-escape-face)

   :language 'tsx
   :override t
   :feature 'property
   `(((property_identifier) @font-lock-property-face)

     (pair value: (identifier) @font-lock-variable-name-face)

     ((shorthand_property_identifier) @font-lock-property-face)

     ((shorthand_property_identifier_pattern)
      @font-lock-property-face)))
  "Tree-sitter font-lock settings.")

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.ts\\'" . typescript-ts-mode))

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.tsx\\'" . typescript-ts-mode))

;;;###autoload
(define-derived-mode typescript-ts-mode prog-mode "TypeScript"
  "Major mode for editing TypeScript."
  :group 'typescript
  :syntax-table typescript-ts-mode--syntax-table

  (cond
   ;; `typescript-ts-mode' requires tree-sitter to work, so we don't check if
   ;; user enables tree-sitter for it.
   ((treesit-ready-p 'tsx)
    ;; Tree-sitter.
    (treesit-parser-create 'tsx)

    ;; Comments.
    (setq-local comment-start "// ")
    (setq-local comment-start-skip "\\(?://+\\|/\\*+\\)\\s *")
    (setq-local comment-end "")
    (setq-local treesit-comment-start (rx "/" (or (+ "/") (+ "*"))))
    (setq-local treesit-comment-end (rx (+ (or "*")) "/"))

    ;; Electric
    (setq-local electric-indent-chars
                (append "{}():;," electric-indent-chars))

    ;; Indent.
    (setq-local treesit-simple-indent-rules
                (typescript-ts-mode--set-indent-style))

    ;; Navigation.
    (setq-local treesit-defun-type-regexp
                (rx (or "class_declaration"
                        "method_definition"
                        "function_declaration"
                        "lexical_declaration")))

    ;; Font-lock.
    (setq-local treesit-font-lock-settings typescript-ts-mode--font-lock-settings)
    (setq-local treesit-font-lock-feature-list
                '((comment declaration)
                  (constant expression identifier keyword number string)
                  (bracket delimiter jsx pattern property)))
    ;; Imenu.
    (setq-local imenu-create-index-function #'js--treesit-imenu)

    ;; Which-func (use imenu).
    (setq-local which-func-functions nil)

    (treesit-major-mode-setup))

   ;; Elisp.
   (t
    (js-mode)
    (message "Tree-sitter for TypeScript isn't available, falling back to `js-mode'"))))

(provide 'typescript-ts-mode)

;;; typescript-ts-mode.el ends here