-- Copyright 2016-2023 Alejandro Baez (https://keybase.io/baez). See LICENSE.
-- Moonscript LPeg lexer.
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S

local lex = lexer.new('moonscript', {fold_by_indentation = true})

-- Whitespace.
lex:add_rule('whitspace', token(lexer.WHITESPACE, lexer.space ^ 1))

-- Table keys.
lex:add_rule('tbl_key', token('tbl_key', lexer.word * ':' + ':' * lexer.word))
lex:add_style('tbl_key', lexer.styles.regex)

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match {
    -- Lua.
    'and', 'break', 'do', 'else', 'elseif', 'false', 'for', 'if', 'in', 'local',
    'nil', 'not', 'or', 'return', 'then', 'true', 'while', -- Moonscript.
    'continue', 'class', 'export', 'extends', 'from', 'import', 'super',
    'switch', 'unless', 'using', 'when', 'with'
}))

-- Error words.
lex:add_rule('error', token(lexer.ERROR, word_match('function end')))

-- Self reference.
lex:add_rule('self_ref', token('self_ref', '@' * lexer.word ^ -1 + 'self'))
lex:add_style('self_ref', lexer.styles.label)

-- Functions.
lex:add_rule('function', token(lexer.FUNCTION, word_match {
    'assert', 'collectgarbage', 'dofile', 'error', 'getmetatable', 'ipairs',
    'load', 'loadfile', 'next', 'pairs', 'pcall', 'print', 'rawequal', 'rawget',
    'rawset', 'require', 'select', 'setmetatable', 'tonumber', 'tostring',
    'type', 'xpcall', -- Added in 5.2.
    'rawlen'
}))

-- Constants.
lex:add_rule('constant', token(lexer.CONSTANT, word_match {
    '_G', '_VERSION', -- Added in 5.2.
    '_ENV'
}))

-- Libraries.
lex:add_rule('library', token(lexer.FUNCTION_BUILTIN, word_match {
    -- Coroutine.
    'coroutine', 'coroutine.create', 'coroutine.resume', 'coroutine.running',
    'coroutine.status', 'coroutine.wrap', 'coroutine.yield',
    -- Coroutine added in 5.3.
    'coroutine.isyieldable', -- Module.
    'package', 'package.cpath', 'package.loaded', 'package.loadlib',
    'package.path', 'package.preload', -- Module added in 5.2.
    'package.config', 'package.searchers', 'package.searchpath',
    -- UTF-8 added in 5.3.
    'utf8', 'utf8.char', 'utf8.charpattern', 'utf8.codepoint', 'utf8.codes',
    'utf8.len', 'utf8.offset', -- String.
    'string', 'string.byte', 'string.char', 'string.dump', 'string.find',
    'string.format', 'string.gmatch', 'string.gsub', 'string.len',
    'string.lower', 'string.match', 'string.rep', 'string.reverse',
    'string.sub', 'string.upper', -- String added in 5.3.
    'string.pack', 'string.packsize', 'string.unpack', -- Table.
    'table', 'table.concat', 'table.insert', 'table.remove', 'table.sort',
    -- Table added in 5.2.
    'table.pack', 'table.unpack', -- Table added in 5.3.
    'table.move', -- Math.
    'math', 'math.abs', 'math.acos', 'math.asin', 'math.atan', 'math.ceil',
    'math.cos', 'math.deg', 'math.exp', 'math.floor', 'math.fmod', 'math.huge',
    'math.log', 'math.max', 'math.min', 'math.modf', 'math.pi', 'math.rad',
    'math.random', 'math.randomseed', 'math.sin', 'math.sqrt', 'math.tan',
    -- Math added in 5.3.
    'math.maxinteger', 'math.mininteger', 'math.tointeger', 'math.type',
    'math.ult', -- IO.
    'io', 'io.close', 'io.flush', 'io.input', 'io.lines', 'io.open',
    'io.output', 'io.popen', 'io.read', 'io.stderr', 'io.stdin', 'io.stdout',
    'io.tmpfile', 'io.type', 'io.write', -- OS.
    'os', 'os.clock', 'os.date', 'os.difftime', 'os.execute', 'os.exit',
    'os.getenv', 'os.remove', 'os.rename', 'os.setlocale', 'os.time',
    'os.tmpname', -- Debug.
    'debug', 'debug.debug', 'debug.gethook', 'debug.getinfo', 'debug.getlocal',
    'debug.getmetatable', 'debug.getregistry', 'debug.getupvalue',
    'debug.sethook', 'debug.setlocal', 'debug.setmetatable', 'debug.setupvalue',
    'debug.traceback', -- Debug added in 5.2.
    'debug.getuservalue', 'debug.setuservalue', 'debug.upvalueid',
    'debug.upvaluejoin', --- MoonScript 0.3.1 standard library.
    -- Printing functions.
    'p', -- Table functions.
    'run_with_scope', 'defaultbl', 'extend', 'copy', -- Class/object functions.
    'is_object', 'bind_methods', 'mixin', 'mixin_object', 'mixin_table',
    -- Misc functions.
    'fold', -- Debug functions.
    'debug.upvalue'
}))

-- Identifiers.
local identifier = token(lexer.IDENTIFIER, lexer.word)
local proper_ident = token('proper_ident', lexer.upper * lexer.word)
lex:add_rule('identifier', proper_ident + identifier)
lex:add_style('proper_ident', lexer.styles.class)

-- Strings.
local sq_str = lexer.range("'", false, false)
local dq_str = lexer.range('"', false, false)
local longstring = lpeg.Cmt('[' * lpeg.C(P('=') ^ 0) * '[',
                            function(input, index, eq)
    local _, e = input:find(']' .. eq .. ']', index, true)
    return (e or #input) + 1
end)
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str) +
                 token(lexer.STRING, longstring))

-- Comments.
local line_comment = lexer.to_eol('--')
local block_comment = '--' * longstring
lex:add_rule('comment', token(lexer.COMMENT, block_comment + line_comment))

-- Numbers.
lex:add_rule('number', token(lexer.NUMBER, lexer.number))

-- Function definition.
lex:add_rule('fndef', token('fndef', P('->') + '=>'))
lex:add_style('fndef', lexer.styles.preprocessor)

-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('+-*!\\/%^#=<>;:,.')))
lex:add_rule('symbol', token('symbol', S('(){}[]')))
lex:add_style('symbol', lexer.styles.embedded)

lexer.property['scintillua.comment'] = '--'

return lex
