--
-- Agario Checkers - Checkers-like game with inspiration from agar.io
-- Copyright (C) 2015-2018 Delwink, LLC
--
-- Redistributions, modified or unmodified, in whole or in part, must retain
-- applicable copyright or other legal privilege notices, these conditions, and
-- the following license terms and disclaimer.  Subject to these conditions,
-- the holder(s) of copyright or other legal privileges, author(s) or
-- assembler(s), and contributors of this work hereby grant to any person who
-- obtains a copy of this work in any form:
--
-- 1. Permission to reproduce, modify, distribute, publish, sell, sublicense,
-- use, and/or otherwise deal in the licensed material without restriction.
--
-- 2. A perpetual, worldwide, non-exclusive, royalty-free, irrevocable patent
-- license to reproduce, modify, distribute, publish, sell, use, and/or
-- otherwise deal in the licensed material without restriction, for any and all
-- patents:
--
--     a. Held by each such holder of copyright or other legal privilege,
--     author or assembler, or contributor, necessarily infringed by the
--     contributions alone or by combination with the work, of that privilege
--     holder, author or assembler, or contributor.
--
--     b. Necessarily infringed by the work at the time that holder of
--     copyright or other privilege, author or assembler, or contributor made
--     any contribution to the work.
--
-- NO WARRANTY OF ANY KIND IS IMPLIED BY, OR SHOULD BE INFERRED FROM, THIS
-- LICENSE OR THE ACT OF DISTRIBUTION UNDER THE TERMS OF THIS LICENSE,
-- INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR
-- A PARTICULAR PURPOSE, AND NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS,
-- ASSEMBLERS, OR HOLDERS OF COPYRIGHT OR OTHER LEGAL PRIVILEGE BE LIABLE FOR
-- ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN ACTION OF CONTRACT, TORT,
-- OR OTHERWISE ARISING FROM, OUT OF, OR IN CONNECTION WITH THE WORK OR THE USE
-- OF OR OTHER DEALINGS IN THE WORK.
--

require 'board'
require 'gui'
require 'geom'
require 'piece'

local mainfont = love.graphics.getFont()
local winfont = love.graphics.newFont(25)

local function spaceisdown()
   return love.keyboard.isDown(' ') or love.keyboard.isDown('space')
end

local function resetgamestate()
   if activestate:is_a(GameState) then
      activestate:_resetgame()
   end
end

local function entermainmenustate()
   setstate(MainMenuState())
end

GameState = class(State)

function GameState:__init()
   self._base.__init(self)

   self:_resetgame()

   local resetbutton = Button(5, 5, 50, 18, {245, 245, 245}, {0, 0, 0})
   resetbutton:settext('Reset')
   resetbutton:setvisible(true)
   resetbutton:addclicklistener(resetgamestate)

   self._gui:addcomponent(resetbutton)
end

function GameState:_initrow(start, y)
   local board_dim = BOARD_SIZE / boardsqsize()
   for i=0,3 do
      local x = start + i * 2
      table.insert(self._pieces, Piece(x, y, 1))
      table.insert(self._pieces, Piece(board_dim - (x - 1),
				       board_dim - (y - 1),
				       2))
   end
end

function GameState:_resetgame()
   self._pieces = {}
   self:_initrow(2, 1)
   self:_initrow(1, 2)
   self:_initrow(2, 3)

   self._turn = 1
   self._selected = nil
   self._targetspace = nil
   self._wantsplit = false
   self._winner = 0
end

function GameState:_checkwinner()
   local numpieces = {0, 0}
   local biggest = nil
   for _,piece in ipairs(self._pieces) do
      numpieces[piece.team] = numpieces[piece.team] + 1

      if not biggest or piece.size > biggest.size then
	 biggest = piece
      end
   end

   if numpieces[1] == 0 then
      self._winner = 2
   elseif numpieces[2] == 0 then
      self._winner = 1
   elseif (numpieces[1] == 1 and numpieces[2] == 1
	   and self._pieces[1].size ~= self._pieces[2].size) then
      self._winner = biggest.team
   else
      self._winner = 0
   end
end

function GameState:_trymove(quad, distance)
   if distance == 2 and not self:_trymove(quad, 1) then
      return nil
   end

   local x, y

   if quad == 1 then
      x = self._selected.x + distance
      y = self._selected.y + distance
   elseif quad == 2 then
      x = self._selected.x - distance
      y = self._selected.y + distance
   elseif quad == 3 then
      x = self._selected.x - distance
      y = self._selected.y - distance
   else
      x = self._selected.x + distance
      y = self._selected.y - distance
   end

   if not self._selected:canmove(x, y) then
      return nil
   end

   return {x=x, y=y}
end

function GameState:_getmove()
   local start = getcenter(self._selected.x, self._selected.y)
   local mx, my = love.mouse.getX(), love.mouse.getY()
   local quad = getquadrant(mx - start.x, my - start.y)
   if not quad then
      return nil
   end

   if self._wantsplit then
      if self._selected.size < 10 then
         return nil
      end

      local move = self:_trymove(quad, 2)
      if move then
	 return move
      end
   end

   return self:_trymove(quad, 1)
end

function GameState:update(dt)
   self:_checkwinner()
   if self._winner ~= 0 then
      return
   end

   if self._selected then
      self._wantsplit = spaceisdown()
      self._targetspace = self:_getmove()
   end
end

function GameState:draw()
   self._base.draw(self)

   -- checkerboard squares
   drawboard()

   -- draw idle pieces in position
   for _,piece in ipairs(self._pieces) do
      piece:draw()
   end

   -- draw box around selected piece
   if self._selected then
      love.graphics.setColor(teamcolor(self._selected.team))

      local spos = getsqpos(self._selected.x, self._selected.y)
      local sqsize = boardsqsize()
      drawbox(spos.x, spos.y, sqsize, sqsize)

      -- draw arrow to attempted move
      if self._targetspace then
	 local from = getcenter(self._selected.x, self._selected.y)
	 local to = getcenter(self._targetspace.x, self._targetspace.y)
	 drawarrow(from.x, from.y, to.x, to.y)
      end
   end

   -- indicate winner
   if self._winner ~= 0 then
      local winstr = string.format('Player %d wins!', self._winner)
      local bpos = getboardpos()
      local y = winfont:getHeight() + 12
      love.graphics.setFont(winfont)
      love.graphics.setColor(0, 0, 0)
      love.graphics.printf(winstr, bpos.x, bpos.y - y, BOARD_SIZE, 'center')
      love.graphics.setFont(mainfont)
   end
end

function GameState:keypressed(key, isrepeat)
   if key == 'escape' then
      entermainmenustate()
   end
end

function GameState:_selectpiece(x, y)
   local space = getspace(x, y)
   for _,piece in ipairs(self._pieces) do
      if (piece.team == self._turn
	  and space.x == piece.x and space.y == piece.y) then
	 return piece
      end
   end

   return nil
end

function GameState:_getoccupying(x, y)
   for i,piece in ipairs(self._pieces) do
      if piece.x == x and piece.y == y then
	 return i
      end
   end
end

function GameState:_canabsorb(o, sizemod)
   if not sizemod then
      sizemod = 1
   end

   if o and not (self._selected.team == self._pieces[o].team
		 or self._selected.size / sizemod > self._pieces[o].size) then
      return false
   end

   return true
end

function GameState:_absorb(o)
   self._selected:move(self._pieces[o].x, self._pieces[o].y)
   self._selected.size = self._selected.size + self._pieces[o].size

   if self._pieces[o].team == self._selected.team and self._pieces[o].king then
      self._selected.king = true
   end

   table.remove(self._pieces, o)
end

function GameState:_singlemove(o)
   if not o then
      o = self:_getoccupying(self._targetspace.x, self._targetspace.y)
   end

   if o then
      if self:_canabsorb(o) then
	 self:_absorb(o)
      else
	 return false
      end
   else
      self._selected:move(self._targetspace.x, self._targetspace.y)
   end

   return true
end

function GameState:_split()
   local new = Piece(self._selected.x, self._selected.y, self._selected.team)
   self._selected.size = self._selected.size / 2
   new.size = self._selected.size
   table.insert(self._pieces, new)
   self._selected = new
end

function GameState:_makemove()
   if self._wantsplit then
      local o = self:_getoccupying(self._targetspace.x, self._targetspace.y)
      if math.abs(self._targetspace.x - self._selected.x) == 2 then
	 if not self:_canabsorb(o, 2) then
	    return
	 end

	 local space = {x = self._targetspace.x, y = self._targetspace.y}
	 local orig = {x = space.x, y = space.y}
	 if space.x < self._selected.x then
	    space.x = space.x + 1
	 else
	    space.x = space.x - 1
	 end

	 if space.y < self._selected.y then
	    space.y = space.y + 1
	 else
	    space.y = space.y - 1
	 end

	 o = self:_getoccupying(space.x, space.y)
	 if not self:_canabsorb(o, 2) then
	    return
	 end

	 self:_split()
	 self._targetspace = space
	 self:_singlemove()
	 self._targetspace = orig
      elseif not self:_canabsorb(o, 2) then
	 return
      else
	 self:_split()
      end
   end

   if not self:_singlemove() then
      return
   end

   if ((self._selected.y == 1 and self._selected.team == 2)
      or (self._selected.y == 8 and self._selected.team == 1)) then
      self._selected.king = true
   end

   self._selected = nil
   if self._turn == 1 then
      self._turn = 2
   else
      self._turn = 1
   end
end

function GameState:mousepressed(x, y, button)
   if self._base.mousepressed(self, x, y, button) then
      return true
   end

   if button == 1 then
      if self._winner ~= 0 then
	 return true
      end

      if not self._selected then
	 self._selected = self:_selectpiece(x, y)
      elseif self._targetspace then
	 self:_makemove()
      end

      return true
   elseif button == 2 then
      self._selected = nil
      self._targetspace = nil
      return true
   end

   return false
end

function GameState:mousereleased(x, y, button)
   if self._base.mousereleased(self, x, y, button) then
      return true
   end

   return false
end