-- Copyright (c) 2017 Larry Hynes. See LICENSE.
-- Taskpaper LPeg lexer

local l = require('lexer')
local token = l.token
local P, R, S = lpeg.P, lpeg.R, lpeg.S

local M = {_NAME = 'taskpaper'}

local delimiter = P('    ') + P('\t')

-- Whitespace
local ws = token(l.WHITESPACE, l.space^1)

-- Tags
local day_tag = token('day_tag', (P('@today') + P('@tomorrow')))

local overdue_tag = token('overdue_tag', P('@overdue'))

local plain_tag = token('plain_tag', P('@') * l.word)

local extended_tag = token('extended_tag',
                           P('@') * l.word * P('(') *
                           (l.word + R('09') + P('-'))^1 * P(')'))

-- Projects
local project = token('project',
                      l.nested_pair(l.starts_line(l.alnum), ':') * l.newline)

-- Notes
local note = token('note', delimiter^1 * l.alnum * l.nonnewline^0)

-- Tasks
local task = token('task', delimiter^1 * P('-') + l.newline)

M._rules = {
  {'note', note},
  {'task', task},
  {'project', project},
  {'extended_tag', extended_tag},
  {'day_tag', day_tag},
  {'overdue_tag', overdue_tag},
  {'plain_tag', plain_tag},
  {'whitespace', ws},
}

M._tokenstyles = {
  note = l.STYLE_CONSTANT,
  task = l.STYLE_FUNCTION,
  project = l.STYLE_TAG,
  extended_tag = l.STYLE_COMMENT,
  day_tag = l.STYLE_CLASS,
  overdue_tag = l.STYLE_PREPROCESSOR,
  plain_tag = l.STYLE_COMMENT,
}

M._LEXBYLINE = true

return M