/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import type { languages } from '../../fillers/monaco-editor-core';

export const conf: languages.LanguageConfiguration = {
	comments: {
		lineComment: '#'
	},
	brackets: [
		['{', '}'],
		['[', ']'],
		['(', ')']
	],
	surroundingPairs: [
		{ open: '{', close: '}' },
		{ open: '[', close: ']' },
		{ open: '(', close: ')' },
		{ open: "'", close: "'" },
		{ open: '"', close: '"' }
	],
	autoClosingPairs: [
		{ open: "'", close: "'", notIn: ['string', 'comment'] },
		{ open: '"', close: '"', notIn: ['comment'] },
		{ open: '"""', close: '"""' },
		{ open: '`', close: '`', notIn: ['string', 'comment'] },
		{ open: '(', close: ')' },
		{ open: '{', close: '}' },
		{ open: '[', close: ']' },
		{ open: '<<', close: '>>' }
	],
	indentationRules: {
		increaseIndentPattern: /^\s*(after|else|catch|rescue|fn|[^#]*(do|<\-|\->|\{|\[|\=))\s*$/,
		decreaseIndentPattern: /^\s*((\}|\])\s*$|(after|else|catch|rescue|end)\b)/
	}
};

/**
 * A Monarch lexer for the Elixir language.
 *
 * References:
 *
 * * Monarch documentation - https://microsoft.github.io/monaco-editor/monarch.html
 * * Elixir lexer - https://github.com/elixir-makeup/makeup_elixir/blob/master/lib/makeup/lexers/elixir_lexer.ex
 * * TextMate lexer (elixir-tmbundle) - https://github.com/elixir-editors/elixir-tmbundle/blob/master/Syntaxes/Elixir.tmLanguage
 * * TextMate lexer (vscode-elixir-ls) - https://github.com/elixir-lsp/vscode-elixir-ls/blob/master/syntaxes/elixir.json
 */
export const language = <languages.IMonarchLanguage>{
	defaultToken: 'source',
	tokenPostfix: '.elixir',

	brackets: [
		{ open: '[', close: ']', token: 'delimiter.square' },
		{ open: '(', close: ')', token: 'delimiter.parenthesis' },
		{ open: '{', close: '}', token: 'delimiter.curly' },
		{ open: '<<', close: '>>', token: 'delimiter.angle.special' }
	],

	// Below are lists/regexps to which we reference later.

	declarationKeywords: [
		'def',
		'defp',
		'defn',
		'defnp',
		'defguard',
		'defguardp',
		'defmacro',
		'defmacrop',
		'defdelegate',
		'defcallback',
		'defmacrocallback',
		'defmodule',
		'defprotocol',
		'defexception',
		'defimpl',
		'defstruct'
	],
	operatorKeywords: ['and', 'in', 'not', 'or', 'when'],
	namespaceKeywords: ['alias', 'import', 'require', 'use'],
	otherKeywords: [
		'after',
		'case',
		'catch',
		'cond',
		'do',
		'else',
		'end',
		'fn',
		'for',
		'if',
		'quote',
		'raise',
		'receive',
		'rescue',
		'super',
		'throw',
		'try',
		'unless',
		'unquote_splicing',
		'unquote',
		'with'
	],
	constants: ['true', 'false', 'nil'],
	nameBuiltin: ['__MODULE__', '__DIR__', '__ENV__', '__CALLER__', '__STACKTRACE__'],

	// Matches any of the operator names:
	// <<< >>> ||| &&& ^^^ ~~~ === !== ~>> <~> |~> <|> == != <= >= && || \\ <> ++ -- |> =~ -> <- ~> <~ :: .. = < > + - * / | . ^ & !
	operator:
		/-[->]?|!={0,2}|\*{1,2}|\/|\\\\|&{1,3}|\.\.?|\^(?:\^\^)?|\+\+?|<(?:-|<<|=|>|\|>|~>?)?|=~|={1,3}|>(?:=|>>)?|\|~>|\|>|\|{1,3}|~>>?|~~~|::/,

	// See https://hexdocs.pm/elixir/syntax-reference.html#variables
	variableName: /[a-z_][a-zA-Z0-9_]*[?!]?/,

	// See https://hexdocs.pm/elixir/syntax-reference.html#atoms
	atomName: /[a-zA-Z_][a-zA-Z0-9_@]*[?!]?|@specialAtomName|@operator/,
	specialAtomName: /\.\.\.|<<>>|%\{\}|%|\{\}/,

	aliasPart: /[A-Z][a-zA-Z0-9_]*/,
	moduleName: /@aliasPart(?:\.@aliasPart)*/,

	// Sigil pairs are: """ """, ''' ''', " ", ' ', / /, | |, < >, { }, [ ], ( )
	sigilSymmetricDelimiter: /"""|'''|"|'|\/|\|/,
	sigilStartDelimiter: /@sigilSymmetricDelimiter|<|\{|\[|\(/,
	sigilEndDelimiter: /@sigilSymmetricDelimiter|>|\}|\]|\)/,
	sigilModifiers: /[a-zA-Z0-9]*/,

	decimal: /\d(?:_?\d)*/,
	hex: /[0-9a-fA-F](_?[0-9a-fA-F])*/,
	octal: /[0-7](_?[0-7])*/,
	binary: /[01](_?[01])*/,

	// See https://hexdocs.pm/elixir/master/String.html#module-escape-characters
	escape: /\\u[0-9a-fA-F]{4}|\\x[0-9a-fA-F]{2}|\\./,

	// The keys below correspond to tokenizer states.
	// We start from the root state and match against its rules
	// until we explicitly transition into another state.
	// The `include` simply brings in all operations from the given state
	// and is useful for improving readability.
	tokenizer: {
		root: [
			{ include: '@whitespace' },
			{ include: '@comments' },
			// Keywords start as either an identifier or a string,
			// but end with a : so it's important to match this first.
			{ include: '@keywordsShorthand' },
			{ include: '@numbers' },
			{ include: '@identifiers' },
			{ include: '@strings' },
			{ include: '@atoms' },
			{ include: '@sigils' },
			{ include: '@attributes' },
			{ include: '@symbols' }
		],

		// Whitespace

		whitespace: [[/\s+/, 'white']],

		// Comments

		comments: [[/(#)(.*)/, ['comment.punctuation', 'comment']]],

		// Keyword list shorthand

		keywordsShorthand: [
			[/(@atomName)(:)(\s+)/, ['constant', 'constant.punctuation', 'white']],
			// Use positive look-ahead to ensure the string is followed by :
			// and should be considered a keyword.
			[
				/"(?=([^"]|#\{.*?\}|\\")*":)/,
				{ token: 'constant.delimiter', next: '@doubleQuotedStringKeyword' }
			],
			[
				/'(?=([^']|#\{.*?\}|\\')*':)/,
				{ token: 'constant.delimiter', next: '@singleQuotedStringKeyword' }
			]
		],

		doubleQuotedStringKeyword: [
			[/":/, { token: 'constant.delimiter', next: '@pop' }],
			{ include: '@stringConstantContentInterpol' }
		],

		singleQuotedStringKeyword: [
			[/':/, { token: 'constant.delimiter', next: '@pop' }],
			{ include: '@stringConstantContentInterpol' }
		],

		// Numbers

		numbers: [
			[/0b@binary/, 'number.binary'],
			[/0o@octal/, 'number.octal'],
			[/0x@hex/, 'number.hex'],
			[/@decimal\.@decimal([eE]-?@decimal)?/, 'number.float'],
			[/@decimal/, 'number']
		],

		// Identifiers

		identifiers: [
			// Tokenize identifier name in function-like definitions.
			// Note: given `def a + b, do: nil`, `a` is not a function name,
			// so we use negative look-ahead to ensure there's no operator.
			[
				/\b(defp?|defnp?|defmacrop?|defguardp?|defdelegate)(\s+)(@variableName)(?!\s+@operator)/,
				[
					'keyword.declaration',
					'white',
					{
						cases: {
							unquote: 'keyword',
							'@default': 'function'
						}
					}
				]
			],
			// Tokenize function calls
			[
				// In-scope call - an identifier followed by ( or .(
				/(@variableName)(?=\s*\.?\s*\()/,
				{
					cases: {
						// Tokenize as keyword in cases like `if(..., do: ..., else: ...)`
						'@declarationKeywords': 'keyword.declaration',
						'@namespaceKeywords': 'keyword',
						'@otherKeywords': 'keyword',
						'@default': 'function.call'
					}
				}
			],
			[
				// Referencing function in a module
				/(@moduleName)(\s*)(\.)(\s*)(@variableName)/,
				['type.identifier', 'white', 'operator', 'white', 'function.call']
			],
			[
				// Referencing function in an Erlang module
				/(:)(@atomName)(\s*)(\.)(\s*)(@variableName)/,
				['constant.punctuation', 'constant', 'white', 'operator', 'white', 'function.call']
			],
			[
				// Piping into a function (tokenized separately as it may not have parentheses)
				/(\|>)(\s*)(@variableName)/,
				[
					'operator',
					'white',
					{
						cases: {
							'@otherKeywords': 'keyword',
							'@default': 'function.call'
						}
					}
				]
			],
			[
				// Function reference passed to another function
				/(&)(\s*)(@variableName)/,
				['operator', 'white', 'function.call']
			],
			// Language keywords, builtins, constants and variables
			[
				/@variableName/,
				{
					cases: {
						'@declarationKeywords': 'keyword.declaration',
						'@operatorKeywords': 'keyword.operator',
						'@namespaceKeywords': 'keyword',
						'@otherKeywords': 'keyword',
						'@constants': 'constant.language',
						'@nameBuiltin': 'variable.language',
						'_.*': 'comment.unused',
						'@default': 'identifier'
					}
				}
			],
			// Module names
			[/@moduleName/, 'type.identifier']
		],

		// Strings

		strings: [
			[/"""/, { token: 'string.delimiter', next: '@doubleQuotedHeredoc' }],
			[/'''/, { token: 'string.delimiter', next: '@singleQuotedHeredoc' }],
			[/"/, { token: 'string.delimiter', next: '@doubleQuotedString' }],
			[/'/, { token: 'string.delimiter', next: '@singleQuotedString' }]
		],

		doubleQuotedHeredoc: [
			[/"""/, { token: 'string.delimiter', next: '@pop' }],
			{ include: '@stringContentInterpol' }
		],

		singleQuotedHeredoc: [
			[/'''/, { token: 'string.delimiter', next: '@pop' }],
			{ include: '@stringContentInterpol' }
		],

		doubleQuotedString: [
			[/"/, { token: 'string.delimiter', next: '@pop' }],
			{ include: '@stringContentInterpol' }
		],

		singleQuotedString: [
			[/'/, { token: 'string.delimiter', next: '@pop' }],
			{ include: '@stringContentInterpol' }
		],

		// Atoms

		atoms: [
			[/(:)(@atomName)/, ['constant.punctuation', 'constant']],
			[/:"/, { token: 'constant.delimiter', next: '@doubleQuotedStringAtom' }],
			[/:'/, { token: 'constant.delimiter', next: '@singleQuotedStringAtom' }]
		],

		doubleQuotedStringAtom: [
			[/"/, { token: 'constant.delimiter', next: '@pop' }],
			{ include: '@stringConstantContentInterpol' }
		],

		singleQuotedStringAtom: [
			[/'/, { token: 'constant.delimiter', next: '@pop' }],
			{ include: '@stringConstantContentInterpol' }
		],

		// Sigils

		// See https://elixir-lang.org/getting-started/sigils.html
		// Sigils allow for typing values using their textual representation.
		// All sigils start with ~ followed by a letter indicating sigil type
		// and then a delimiter pair enclosing the textual representation.
		// Optional modifiers are allowed after the closing delimiter.
		// For instance a regular expressions can be written as:
		// ~r/foo|bar/ ~r{foo|bar} ~r/foo|bar/g
		//
		// In general lowercase sigils allow for interpolation
		// and escaped characters, whereas uppercase sigils don't
		//
		// During tokenization we want to distinguish some
		// specific sigil types, namely string and regexp,
		// so that they cen be themed separately.
		//
		// To reasonably handle all those combinations we leverage
		// dot-separated states, so if we transition to @sigilStart.interpol.s.{.}
		// then "sigilStart.interpol.s" state will match and also all
		// the individual dot-separated parameters can be accessed.

		sigils: [
			[/~[a-z]@sigilStartDelimiter/, { token: '@rematch', next: '@sigil.interpol' }],
			[/~[A-Z]@sigilStartDelimiter/, { token: '@rematch', next: '@sigil.noInterpol' }]
		],

		sigil: [
			[/~([a-zA-Z])\{/, { token: '@rematch', switchTo: '@sigilStart.$S2.$1.{.}' }],
			[/~([a-zA-Z])\[/, { token: '@rematch', switchTo: '@sigilStart.$S2.$1.[.]' }],
			[/~([a-zA-Z])\(/, { token: '@rematch', switchTo: '@sigilStart.$S2.$1.(.)' }],
			[/~([a-zA-Z])\</, { token: '@rematch', switchTo: '@sigilStart.$S2.$1.<.>' }],
			[
				/~([a-zA-Z])(@sigilSymmetricDelimiter)/,
				{ token: '@rematch', switchTo: '@sigilStart.$S2.$1.$2.$2' }
			]
		],

		// The definitions below expect states to be of the form:
		//
		// sigilStart.<interpol-or-noInterpol>.<sigil-letter>.<start-delimiter>.<end-delimiter>
		// sigilContinue.<interpol-or-noInterpol>.<sigil-letter>.<start-delimiter>.<end-delimiter>
		//
		// The sigilStart state is used only to properly classify the token (as string/regex/sigil)
		// and immediately switches to the sigilContinue sate, which handles the actual content
		// and waits for the corresponding end delimiter.

		'sigilStart.interpol.s': [
			[
				/~s@sigilStartDelimiter/,
				{
					token: 'string.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.interpol.s': [
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'string.delimiter', next: '@pop' },
						'@default': 'string'
					}
				}
			],
			{ include: '@stringContentInterpol' }
		],

		'sigilStart.noInterpol.S': [
			[
				/~S@sigilStartDelimiter/,
				{
					token: 'string.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.noInterpol.S': [
			// Ignore escaped sigil end
			[/(^|[^\\])\\@sigilEndDelimiter/, 'string'],
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'string.delimiter', next: '@pop' },
						'@default': 'string'
					}
				}
			],
			{ include: '@stringContent' }
		],

		'sigilStart.interpol.r': [
			[
				/~r@sigilStartDelimiter/,
				{
					token: 'regexp.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.interpol.r': [
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'regexp.delimiter', next: '@pop' },
						'@default': 'regexp'
					}
				}
			],
			{ include: '@regexpContentInterpol' }
		],

		'sigilStart.noInterpol.R': [
			[
				/~R@sigilStartDelimiter/,
				{
					token: 'regexp.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.noInterpol.R': [
			// Ignore escaped sigil end
			[/(^|[^\\])\\@sigilEndDelimiter/, 'regexp'],
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'regexp.delimiter', next: '@pop' },
						'@default': 'regexp'
					}
				}
			],
			{ include: '@regexpContent' }
		],

		// Fallback to the generic sigil by default
		'sigilStart.interpol': [
			[
				/~([a-zA-Z])@sigilStartDelimiter/,
				{
					token: 'sigil.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.interpol': [
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'sigil.delimiter', next: '@pop' },
						'@default': 'sigil'
					}
				}
			],
			{ include: '@sigilContentInterpol' }
		],

		'sigilStart.noInterpol': [
			[
				/~([a-zA-Z])@sigilStartDelimiter/,
				{
					token: 'sigil.delimiter',
					switchTo: '@sigilContinue.$S2.$S3.$S4.$S5'
				}
			]
		],

		'sigilContinue.noInterpol': [
			// Ignore escaped sigil end
			[/(^|[^\\])\\@sigilEndDelimiter/, 'sigil'],
			[
				/(@sigilEndDelimiter)@sigilModifiers/,
				{
					cases: {
						'$1==$S5': { token: 'sigil.delimiter', next: '@pop' },
						'@default': 'sigil'
					}
				}
			],
			{ include: '@sigilContent' }
		],

		// Attributes

		attributes: [
			// Module @doc* attributes - tokenized as comments
			[
				/\@(module|type)?doc (~[sS])?"""/,
				{
					token: 'comment.block.documentation',
					next: '@doubleQuotedHeredocDocstring'
				}
			],
			[
				/\@(module|type)?doc (~[sS])?'''/,
				{
					token: 'comment.block.documentation',
					next: '@singleQuotedHeredocDocstring'
				}
			],
			[
				/\@(module|type)?doc (~[sS])?"/,
				{
					token: 'comment.block.documentation',
					next: '@doubleQuotedStringDocstring'
				}
			],
			[
				/\@(module|type)?doc (~[sS])?'/,
				{
					token: 'comment.block.documentation',
					next: '@singleQuotedStringDocstring'
				}
			],
			[/\@(module|type)?doc false/, 'comment.block.documentation'],
			// Module attributes
			[/\@(@variableName)/, 'variable']
		],

		doubleQuotedHeredocDocstring: [
			[/"""/, { token: 'comment.block.documentation', next: '@pop' }],
			{ include: '@docstringContent' }
		],

		singleQuotedHeredocDocstring: [
			[/'''/, { token: 'comment.block.documentation', next: '@pop' }],
			{ include: '@docstringContent' }
		],

		doubleQuotedStringDocstring: [
			[/"/, { token: 'comment.block.documentation', next: '@pop' }],
			{ include: '@docstringContent' }
		],

		singleQuotedStringDocstring: [
			[/'/, { token: 'comment.block.documentation', next: '@pop' }],
			{ include: '@docstringContent' }
		],

		// Operators, punctuation, brackets

		symbols: [
			// Code point operator (either with regular character ?a or an escaped one ?\n)
			[/\?(\\.|[^\\\s])/, 'number.constant'],
			// Anonymous function arguments
			[/&\d+/, 'operator'],
			// Bitshift operators (must go before delimiters, so that << >> don't match first)
			[/<<<|>>>/, 'operator'],
			// Delimiter pairs
			[/[()\[\]\{\}]|<<|>>/, '@brackets'],
			// Triple dot is a valid name (must go before operators, so that .. doesn't match instead)
			[/\.\.\./, 'identifier'],
			// Punctuation => (must go before operators, so it's not tokenized as = then >)
			[/=>/, 'punctuation'],
			// Operators
			[/@operator/, 'operator'],
			// Punctuation
			[/[:;,.%]/, 'punctuation']
		],

		// Generic helpers

		stringContentInterpol: [
			{ include: '@interpolation' },
			{ include: '@escapeChar' },
			{ include: '@stringContent' }
		],

		stringContent: [[/./, 'string']],

		stringConstantContentInterpol: [
			{ include: '@interpolation' },
			{ include: '@escapeChar' },
			{ include: '@stringConstantContent' }
		],

		stringConstantContent: [[/./, 'constant']],

		regexpContentInterpol: [
			{ include: '@interpolation' },
			{ include: '@escapeChar' },
			{ include: '@regexpContent' }
		],

		regexpContent: [
			// # may be a regular regexp char, so we use a heuristic
			// assuming a # surrounded by whitespace is actually a comment.
			[/(\s)(#)(\s.*)$/, ['white', 'comment.punctuation', 'comment']],
			[/./, 'regexp']
		],

		sigilContentInterpol: [
			{ include: '@interpolation' },
			{ include: '@escapeChar' },
			{ include: '@sigilContent' }
		],

		sigilContent: [[/./, 'sigil']],

		docstringContent: [[/./, 'comment.block.documentation']],

		escapeChar: [[/@escape/, 'constant.character.escape']],

		interpolation: [[/#{/, { token: 'delimiter.bracket.embed', next: '@interpolationContinue' }]],

		interpolationContinue: [
			[/}/, { token: 'delimiter.bracket.embed', next: '@pop' }],
			// Interpolation brackets may contain arbitrary code,
			// so we simply match against all the root rules,
			// until we reach interpolation end (the above matches).
			{ include: '@root' }
		]
	}
};