;;; java-ts-mode.el --- tree-sitter support for Java  -*- lexical-binding: t; -*-

;; Copyright (C) 2022-2025 Free Software Foundation, Inc.

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

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:
;;

;;; Code:

(require 'treesit)
(eval-when-compile (require 'rx))
(require 'c-ts-common) ; For comment indent and filling.

(declare-function treesit-parser-create "treesit.c")
(declare-function treesit-induce-sparse-tree "treesit.c")
(declare-function treesit-node-start "treesit.c")
(declare-function treesit-node-type "treesit.c")
(declare-function treesit-node-child-by-field-name "treesit.c")
(declare-function treesit-node-child-by-field-name "treesit.c")
(declare-function treesit-node-end "treesit.c")
(declare-function treesit-query-capture "treesit.c")

(defcustom java-ts-mode-indent-offset 4
  "Number of spaces for each indentation step in `java-ts-mode'."
  :version "29.1"
  :type 'integer
  :safe 'integerp
  :group 'java)

(defvar java-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 ?\240 "."   table)
    (modify-syntax-entry ?/  ". 124b" table)
    (modify-syntax-entry ?*  ". 23"   table)
    (modify-syntax-entry ?\n "> b"  table)
    (modify-syntax-entry ?\^m "> b" table)
    (modify-syntax-entry ?@ "'" table)
    table)
  "Syntax table for `java-ts-mode'.")

(defvar java-ts-mode--indent-rules
  `((java
     ((parent-is "program") column-0 0)
     ((match "}" "element_value_array_initializer")
      parent-bol 0)
     ((node-is
       ,(format "\\`%s\\'"
                (regexp-opt '("constructor_body" "class_body" "interface_body"
                              "block" "switch_block" "array_initializer"))))
      parent-bol 0)
     ((node-is "}") standalone-parent 0)
     ((node-is ")") parent-bol 0)
     ((node-is "else") parent-bol 0)
     ((node-is "]") parent-bol 0)
     ((and (parent-is "comment") c-ts-common-looking-at-star)
      c-ts-common-comment-start-after-first-star -1)
     ((parent-is "comment") prev-adaptive-prefix 0)
     ((parent-is "text_block") no-indent)
     ((parent-is "class_body") column-0 c-ts-common-statement-offset)
     ((parent-is "array_initializer") parent-bol java-ts-mode-indent-offset)
     ((parent-is "annotation_type_body") column-0 c-ts-common-statement-offset)
     ((parent-is "interface_body") column-0 c-ts-common-statement-offset)
     ((parent-is "constructor_body") standalone-parent java-ts-mode-indent-offset)
     ((parent-is "enum_body_declarations") parent-bol 0)
     ((parent-is "enum_body") column-0 c-ts-common-statement-offset)
     ((parent-is "switch_block") standalone-parent java-ts-mode-indent-offset)
     ((parent-is "record_declaration_body") column-0 c-ts-common-statement-offset)
     ((query "(method_declaration (block _ @indent))") parent-bol java-ts-mode-indent-offset)
     ((query "(method_declaration (block (_) @indent))") parent-bol java-ts-mode-indent-offset)
     ((parent-is "local_variable_declaration") parent-bol java-ts-mode-indent-offset)
     ((parent-is "expression_statement") parent-bol java-ts-mode-indent-offset)
     ((match "type_identifier" "field_declaration") parent-bol 0)
     ((parent-is "field_declaration") parent-bol java-ts-mode-indent-offset)
     ((parent-is "return_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "variable_declarator") parent-bol java-ts-mode-indent-offset)
     ((match ">" "type_arguments") parent-bol 0)
     ((parent-is "type_arguments") parent-bol java-ts-mode-indent-offset)
     ((parent-is "method_invocation") parent-bol java-ts-mode-indent-offset)
     ((parent-is "switch_rule") parent-bol java-ts-mode-indent-offset)
     ((parent-is "switch_label") parent-bol java-ts-mode-indent-offset)
     ((parent-is "ternary_expression") parent-bol java-ts-mode-indent-offset)
     ((parent-is "lambda_expression") parent-bol java-ts-mode-indent-offset)
     ((parent-is "element_value_array_initializer") parent-bol java-ts-mode-indent-offset)
     ((parent-is "function_definition") parent-bol 0)
     ((parent-is "conditional_expression") first-sibling 0)
     ((parent-is "assignment_expression") parent-bol 2)
     ((parent-is "binary_expression") parent 0)
     ((parent-is "parenthesized_expression") first-sibling 1)
     ((parent-is "argument_list") parent-bol java-ts-mode-indent-offset)
     ((parent-is "annotation_argument_list") parent-bol java-ts-mode-indent-offset)
     ((parent-is "modifiers") parent-bol 0)
     ((parent-is "formal_parameters") parent-bol java-ts-mode-indent-offset)
     ((parent-is "formal_parameter") parent-bol 0)
     ((parent-is "init_declarator") parent-bol java-ts-mode-indent-offset)
     ((parent-is "if_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "for_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "while_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "switch_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "case_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "labeled_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "do_statement") parent-bol java-ts-mode-indent-offset)
     ((parent-is "block") standalone-parent java-ts-mode-indent-offset)))
  "Tree-sitter indent rules.")

(defvar java-ts-mode--keywords
  '("abstract" "assert" "break" "case" "catch"
    "class" "continue" "default" "do" "else"
    "enum" "exports" "extends" "final" "finally"
    "for" "if" "implements" "import" "instanceof"
    "interface" "module" "native" "new" "non-sealed"
    "open" "opens" "package" "private" "protected"
    "provides" "public" "requires" "return" "sealed"
    "static" "strictfp" "switch" "synchronized"
    "throw" "throws" "to" "transient" "transitive"
    "try" "uses" "volatile" "while" "with" "record"
    "@interface")
  "Java keywords for tree-sitter font-locking.")

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

(defun java-ts-mode--string-highlight-helper ()
  "Return, for strings, a query based on what is supported by
the available version of Tree-sitter for Java."
  (condition-case nil
      (progn (treesit-query-capture 'java '((text_block) @font-lock-string-face))
	     `((string_literal) @font-lock-string-face
	       (text_block) @font-lock-string-face))
    (error
     `((string_literal) @font-lock-string-face))))

(defun java-ts-mode--fontify-constant (node override start end &rest _)
  "Fontify a Java constant.
In Java the names of variables declared class constants and of ANSI
constants should be all uppercase with words separated by underscores.
This function also prevents annotations from being highlighted as if
they were constants.
For NODE, OVERRIDE, START, and END, see `treesit-font-lock-rules'."
  (let ((node-start (treesit-node-start node))
	(case-fold-search nil))
    (when (and
	   (not (equal (char-before node-start) ?@)) ;; skip annotations
	   (string-match "\\`[A-Z_][0-9A-Z_]*\\'" (treesit-node-text node)))
      (treesit-fontify-with-override
       node-start (treesit-node-end node)
       'font-lock-constant-face override
       start end))))

(defvar java-ts-mode--font-lock-settings
  (treesit-font-lock-rules
   :language 'java
   :override t
   :feature 'comment
   `((line_comment) @font-lock-comment-face
     (block_comment) @font-lock-comment-face)
   :language 'java
   :override t
   :feature 'constant
   `((identifier) @java-ts-mode--fontify-constant
     [(true) (false)] @font-lock-constant-face)
   :language 'java
   :override t
   :feature 'keyword
   `([,@java-ts-mode--keywords
      (this)
      (super)] @font-lock-keyword-face
      (labeled_statement
       (identifier) @font-lock-keyword-face))
   :language 'java
   :override t
   :feature 'operator
   `([,@java-ts-mode--operators] @font-lock-operator-face
     "@" @font-lock-constant-face)
   :language 'java
   :override t
   :feature 'annotation
   `((annotation
      name: (identifier) @font-lock-constant-face)

     (marker_annotation
      name: (identifier) @font-lock-constant-face))
   :language 'java
   :override t
   :feature 'string
   (java-ts-mode--string-highlight-helper)
   :language 'java
   :override t
   :feature 'literal
   `((null_literal) @font-lock-constant-face
     (binary_integer_literal)  @font-lock-number-face
     (decimal_integer_literal) @font-lock-number-face
     (hex_integer_literal) @font-lock-number-face
     (octal_integer_literal) @font-lock-number-face
     (decimal_floating_point_literal) @font-lock-number-face
     (hex_floating_point_literal) @font-lock-number-face)
   :language 'java
   :override t
   :feature 'type
   '((annotation_type_declaration
      name: (identifier) @font-lock-type-face)

     (interface_declaration
      name: (identifier) @font-lock-type-face)

     (class_declaration
      name: (identifier) @font-lock-type-face)

     (record_declaration
      name: (identifier) @font-lock-type-face)

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

     (constructor_declaration
      name: (identifier) @font-lock-type-face)

     (compact_constructor_declaration
      name: (identifier) @font-lock-type-face)

     (field_access
      object: (identifier) @font-lock-type-face)

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

     (scoped_identifier (identifier) @font-lock-constant-face)

     ((scoped_identifier name: (identifier) @font-lock-type-face)
      (:match "\\`[A-Z]" @font-lock-type-face))

     (type_identifier) @font-lock-type-face

     [(boolean_type)
      (integral_type)
      (floating_point_type)
      (void_type)] @font-lock-type-face)
   :language 'java
   :override t
   :feature 'definition
   `((annotation_type_element_declaration
      name: (identifier) @font-lock-function-name-face)

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

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

     (element_value_pair
      key: (identifier) @font-lock-property-use-face)

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

     (catch_formal_parameter
      name: (identifier) @font-lock-variable-name-face))
   :language 'java
   :override t
   :feature 'expression
   '((method_invocation
      object: (identifier) @font-lock-variable-use-face)

     (method_invocation
      name: (identifier) @font-lock-function-call-face)

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

     (expression_statement (identifier) @font-lock-variable-use-face))

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

   :language 'java
   :feature 'delimiter
   '((["," ":" ";"]) @font-lock-delimiter-face))
  "Tree-sitter font-lock settings for `java-ts-mode'.")

(defun java-ts-mode--defun-name (node)
  "Return the defun name of NODE.
Return nil if there is no name or if NODE is not a defun node."
  (pcase (treesit-node-type node)
    ((or "method_declaration"
         "class_declaration"
         "record_declaration"
         "interface_declaration"
         "enum_declaration"
         "import_declaration"
         "package_declaration"
         "module_declaration")
     (treesit-node-text
      (treesit-node-child-by-field-name node "name")
      t))))


(defvar java-ts-mode--feature-list
  '(( comment definition )
    ( constant keyword string type)
    ( annotation expression literal)
    ( bracket delimiter operator)))

;;;###autoload
(define-derived-mode java-ts-mode prog-mode "Java"
  "Major mode for editing Java, powered by tree-sitter."
  :group 'java
  :syntax-table java-ts-mode--syntax-table

  (unless (treesit-ready-p 'java)
    (error "Tree-sitter for Java isn't available"))

  (treesit-parser-create 'java)

  ;; Comments.
  (c-ts-common-comment-setup)

  ;; Indent.
  (setq-local c-ts-common-indent-type-regexp-alist
              `((block . ,(rx (or "class_body"
                                  "array_initializer"
                                  "constructor_body"
                                  "annotation_type_body"
                                  "interface_body"
                                  "lambda_expression"
                                  "enum_body"
                                  "switch_block"
                                  "record_declaration_body"
                                  "block")))
                (close-bracket . "}")
                (if . "if_statement")
                (else . ("if_statement" . "alternative"))
                (for . "for_statement")
                (while . "while_statement")
                (do . "do_statement")))
  (setq-local c-ts-common-indent-offset 'java-ts-mode-indent-offset)
  (setq-local treesit-simple-indent-rules java-ts-mode--indent-rules)

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

  ;; Navigation.
  (setq-local treesit-defun-type-regexp
              (regexp-opt '("method_declaration"
                            "class_declaration"
                            "record_declaration"
                            "interface_declaration"
                            "enum_declaration"
                            "import_declaration"
                            "package_declaration"
                            "module_declaration"
                            "constructor_declaration")))
  (setq-local treesit-defun-name-function #'java-ts-mode--defun-name)

  (setq-local treesit-thing-settings
              `((java
                (sexp ,(rx (or "annotation"
                               "parenthesized_expression"
                               "argument_list"
                               "identifier"
                               "modifiers"
                               "block"
                               "body"
                               "literal"
                               "access"
                               "reference"
                               "_type"
                               "true"
                               "false")))
                (sentence ,(rx (or "statement"
                                   "local_variable_declaration"
                                   "field_declaration"
                                   "module_declaration"
                                   "package_declaration"
                                   "import_declaration")))
                (text ,(regexp-opt '("line_comment"
                                     "block_comment"
                                     "text_block"))))))

  ;; Font-lock.
  (setq-local treesit-font-lock-settings java-ts-mode--font-lock-settings)
  (setq-local treesit-font-lock-feature-list java-ts-mode--feature-list)

  ;; Imenu.
  (setq-local treesit-simple-imenu-settings
              '(("Class" "\\`class_declaration\\'" nil nil)
                ("Interface" "\\`interface_declaration\\'" nil nil)
                ("Enum" "\\`record_declaration\\'" nil nil)
                ("Method" "\\`method_declaration\\'" nil nil)))
  (treesit-major-mode-setup))

(derived-mode-add-parents 'java-ts-mode '(java-mode))

(if (treesit-ready-p 'java)
    (add-to-list 'auto-mode-alist '("\\.java\\'" . java-ts-mode)))

(provide 'java-ts-mode)

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