module AccomParse

# File lib/accom_parse.rb, line 60
def extract_when_tokens(tokens, today:)
  return [nil, tokens] if tokens.empty?

  (1..[3, tokens.length].min).each do |size|
    chunk = tokens.first(size)
    joined = chunk.join(" ")
    next unless resolve_check_in(joined, today: today)

    return [chunk, tokens[size..] || []]
  end

  [nil, tokens]
end

# File lib/accom_parse.rb, line 127
def month_number(name)
  months = {
    "jan" => 1, "january" => 1,
    "feb" => 2, "february" => 2,
    "mar" => 3, "march" => 3,
    "apr" => 4, "april" => 4,
    "may" => 5,
    "jun" => 6, "june" => 6,
    "jul" => 7, "july" => 7,
    "aug" => 8, "august" => 8,
    "sep" => 9, "sept" => 9, "september" => 9,
    "oct" => 10, "october" => 10,
    "nov" => 11, "november" => 11,
    "dec" => 12, "december" => 12
  }
  months[name.downcase]
end

# File lib/accom_parse.rb, line 94
def next_weekday(target_wday, today)
  days_ahead = (target_wday - today.wday) % 7
  today + days_ahead
end

# File lib/accom_parse.rb, line 186
def nights_error(nights)
  return "Nights must be at least #{MIN_NIGHTS}." if nights.to_i < MIN_NIGHTS

  "Nights cannot exceed #{MAX_NIGHTS}."
end

# File lib/accom_parse.rb, line 145
def normalize_year(value)
  return value if value >= 100

  2000 + value
end

# File lib/accom_parse.rb, line 99
def parse_calendar_date(text, today:)
  today = today_date(today: today)

  if text.match?(/\A\d{4}-\d{2}-\d{2}\z/)
    return Date.parse(text)
  end

  if (match = text.match(/\A(\d{1,2})[\/\-](\d{1,2})(?:[\/\-](\d{2,4}))?\z/))
    day = match[1].to_i
    month = match[2].to_i
    year = match[3] ? normalize_year(match[3].to_i) : today.year
    return Date.new(year, month, day)
  end

  if (match = text.match(/\A(\d{1,2})\s+([A-Za-z]{3,9})(?:\s+(\d{4}))?\z/))
    day = match[1].to_i
    month = month_number(match[2])
    return nil unless month

    year = match[3] ? match[3].to_i : today.year
    return Date.new(year, month, day)
  end

  nil
rescue Date::Error
  nil
end

# File lib/accom_parse.rb, line 33
def parse_command(text, today: nil)
  raw = text.to_s.strip
  return { error: usage_message } if raw.empty?

  tokens = tokenize(raw)
  return { error: usage_message } if tokens.empty?

  today = today_date(today: today)
  when_tokens, remainder = extract_when_tokens(tokens, today: today)
  nights = 1
  location_tokens = remainder.dup

  if location_tokens.first.to_s.match?(/\A\d+\z/)
    nights = location_tokens.shift.to_i
  end

  return { error: nights_error(nights) } unless valid_nights?(nights)

  location = location_tokens.join(" ").strip
  location = unwrap_quotes(location)
  return { error: usage_message } if location.empty?

  when_token = when_tokens&.join(" ")
  stay = resolve_stay(when_token, nights, today: today)
  stay.merge(location: location)
end

# File lib/accom_parse.rb, line 83
def resolve_check_in(token, today: nil)
  today = today_date(today: today)
  text = token.to_s.strip
  return nil if text.empty?

  weekday = WEEKDAYS[text.downcase]
  return next_weekday(weekday, today) unless weekday.nil?

  parse_calendar_date(text, today: today)
end

# File lib/accom_parse.rb, line 74
def resolve_stay(when_token, nights, today: nil)
  today = today_date(today: today)
  check_in = when_token ? resolve_check_in(when_token, today: today) : today
  nights = nights.to_i
  check_out = check_in + nights

  { check_in: check_in, check_out: check_out, nights: nights }
end

# File lib/accom_parse.rb, line 29
def today_date(today: nil)
  today || HolidayCalendar.local_date
end

# File lib/accom_parse.rb, line 151
def tokenize(text)
  tokens = []
  current = +""
  in_quote = false

  text.each_char do |char|
    if char == '"'
      in_quote = !in_quote
      next
    end

    if char.match?(/\s/) && !in_quote
      tokens << current unless current.empty?
      current = +""
      next
    end

    current << char
  end

  tokens << current unless current.empty?
  tokens
end

# File lib/accom_parse.rb, line 175
def unwrap_quotes(text)
  value = text.to_s.strip
  return value[1..-2].strip if value.start_with?('"') && value.end_with?('"')

  value
end

# File lib/accom_parse.rb, line 25
def usage_message
  USAGE_MESSAGE
end

# File lib/accom_parse.rb, line 182
def valid_nights?(nights)
  nights.is_a?(Integer) && (MIN_NIGHTS..MAX_NIGHTS).cover?(nights)
end