-- | Internal representation of the Chu Shogi board at a given instance in time
-- Copyright 2009 Colin Adams
--
-- This file is part of chu-shogi.
--
--  Chu-shogi 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.

--  Chu-shogi 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 chu-shogi.  If not, see <http://www.gnu.org/licenses/>.

module Lighting (
                 -- * Types
                 Lighting_colour (..),
                 -- * Status report
                 is_lion_a_pair,
                 is_lion_b_pair,
                 is_capture
                ) where

import Coordinate

-- | Type of move possible onto a 'Square'. Distinguished by colour on the GUI.
data Lighting_colour = Step_lighting      -- ^ Ordinary step or ranging move
                     | Jump_lighting      -- ^ Jump move
                     | Lion_b_lighting    -- ^ Second square for lion-type moves
                     | Lion_a_lighting    -- ^ First square for Lion-type moves
                     | Step_capture       -- ^ Ordinary step or ranging capture
                     | Jump_capture       -- ^ Jump capture
                     | Lion_b_capture     -- ^ Second square for lion-type captures
                     | Lion_a_capture     -- ^ First square for Lion-type captures
                       deriving (Eq, Ord, Show)

-- | Is item a one-step lion move target?
is_lion_a_pair :: (Coordinate, Lighting_colour) -> Bool
is_lion_a_pair item = case item of
                   (_, c) | c == Lion_a_lighting || c == Lion_a_capture -> True
                   _ -> False
                   
-- | Is item a two-step lion move target?
is_lion_b_pair :: (Coordinate, Lighting_colour) -> Bool
is_lion_b_pair item = case item of
                   (_, c) | c == Lion_b_lighting || c == Lion_b_capture -> True
                   _ -> False

-- | Is item a capture?
is_capture :: (Coordinate, Lighting_colour) -> Bool
is_capture (_, l) = case l of
                      Step_capture -> True
                      Jump_capture -> True
                      Lion_b_capture -> False
                      Lion_a_capture -> False