--
-- Agario Checkers - Checkers-like game with inspiration from agar.io
-- Copyright (C) 2017 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 'class'
require 'geom'
require 'piece'
require 'util'

local socket = require 'socket'
local finished = false

local AFFIRMATIVE = 'Y\nEND\n'
local NEGATIVE = 'N\nEND\n'
local ERR_ARGNUM = 'ERR ARGNUM\nEND\n'
local ERR_SYNTAX = 'ERR SYNTAX\nEND\n'

Server = class()

function Server:__init(server, socks, comm)
   self._srv = server
   self._socks = socks
   self._names = { 'Player 1', 'Player 2' }
   self._rooms = { 1, 0 }
   self._queue = { {}, {} }
   self._updatequeue = { {}, {} }
   self._comm = comm
   self._done = false

   self:_resetgame()
end

function Server:_cleanup()
   for _,sock in ipairs(self._socks) do
      sock:send('SHUTDOWN\nEND\n')
      sock:close()
   end

   self._srv:close()
end

function Server:_updateall(lines)
   for _,queue in ipairs(self._updatequeue) do
      for __,line in ipairs(lines) do
         table.insert(queue, line)
      end
   end
end

function Server:_addpiece(new)
   for i,piece in ipairs(self._pieces) do
      if not piece then
         new.id = i
         self._pieces[i] = new
         self:_updateall({'PIECE ' .. i,
                          'SIZE ' .. i .. ' ' .. new.size,
                          'TEAM ' .. i .. ' ' .. new.team,
                          'MOVE ' .. i .. ' ' .. new.x .. ' ' .. new.y})
         return
      end
   end
end

function Server:_initrow(start, y)
   local board_dim = 8
   for i=0,3 do
      local x = start + i * 2
      self:_addpiece(Piece(x, y, 1))
      self:_addpiece(Piece(board_dim - (x - 1), board_dim - (y - 1), 2))
   end
end

function Server:_resetgame()
   self._pieces = {}
   for _ = 1,32 do
      table.insert(self._pieces, nil)
   end

   self._updatequeue[1] = { 'CLEARBOARD' }
   self._updatequeue[2] = { 'CLEARBOARD' }
   self:_initrow(2, 1)
   self:_initrow(1, 2)
   self:_initrow(2, 3)

   self._turn = 1
   self._selected = nil
   self._targetspace = nil
   self._winner = nil
end

function Server:_toggleturn()
   if self._turn == 1 then
      self._turn = 2
   else
      self._turn = 1
   end
end

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

function Server:_trymove(quad, distance, sizemod)
   if not sizemod then
      sizemode = 1
   end

   local step1
   if distance == 2 then
      step1 = self._trymove(quad, 1, sizemod)
      if not step1 then
         return nil
      end
   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

   local newsize = self._selected.size + sizemod
   if distance == 2 then
      local o = self._getoccupying(step1.x, step1.y)
      if o then
         newsize = newsize + o.size
      end
   end

   local o = self:_getoccupying(x, y)
   if o and o.team ~= self._selected.team and o.size >= newsize then
      return nil
   end

   return {x=x, y=y, dist=distance, step1=step1}
end

function Server:_getmove(dx, dy, wantsplit)
   local quad = getquadrant(dx, dy)
   if not quad then
      return nil
   end

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

      return self:_trymove(quad, 2, -self._selected.size / 2)
   end

   return self:_trymove(quad, 1)
end

function Server:_king(piece)
   self:_updateall({'KING ' .. piece.id})
   piece.king = true
end

function Server:_singlemove(move, piece)
   local o = self:_getoccupying(move.x, move.y)
   if o then
      piece.size = piece.size + o.size
      self:_updateall({'ABSORB ' .. piece.id .. ' ' .. o.id,
                       'SIZE ' .. piece.id .. ' ' .. piece.size})

      if o.team == piece.team and o.king then
         self:_king(piece)
      end

      self._pieces[o.id] = nil
   end

   self:_updateall({'MOVE ' .. piece.id .. ' ' .. move.x .. ' ' .. move.y})
   piece:move(move.x, move.y)

   if ((piece.y == 1 and piece.team == 2)
      or (piece.y == 8 and piece.team == 1)) then
      self:_king(piece)
   end
end

function Server:_move(move, wantsplit)
   local piece = self._selected

   self:_updateall({'DESELECTED'})
   self._selected = nil

   if wantsplit then
      local prev = piece
      piece = Piece(piece.x, piece.y, piece.team)
      prev.size = prev.size / 2
      piece.size = prev.size
      self:_addpiece(piece)

      if move.dist == 2 then
         self:_singlemove(move.step1, piece)
      end
   end

   self:_singlemove(move, piece)
end

function Server:_sendall(msg)
   for _,sock in ipairs(self._socks) do
      sock:send(msg)
   end
end

function Server:_process()
   local other = 2
   for this,queue in ipairs(self._queue) do
      for _,line in ipairs(queue) do
         if line == 'DC' then
            table.insert(self._updatequeue[other], 'DC')
            self._done = true
            return
         elseif line:startswith('SETNAME') then
            line = line:split(' ')
            if #line < 2 then
               self._socks[this]:send(ERR_ARGNUM)
               break
            end

            local name = table.concat(line, ' ', 2)
            if name == self._names[other] then
               self._socks[this]:send('ERR NAMETAKEN\nEND\n')
            elseif #name > 16 then
               self._socks[this]:send('ERR NAMELEN\nEND\n')
            elseif name:find('"') then
               self._socks[this]:send('ERR NAMECHAR\nEND\n')
            elseif self._rooms[this] == 1 then
               self._socks[this]:send('ERR INGAME\nEND\n')
            else
               self._names[this] = name
               self._socks[this]:send(AFFIRMATIVE)
            end
         elseif line == 'GETROOMS' then
            local players = 1
            if self._rooms[2] == 1 then
               players = 2
            end

            self._socks[this]:send('1 "' .. self._names[1] .. '" '
                                      .. players .. '\nEND\n')
         elseif line:startswith('JOIN') then
            line = line:split(' ')
            if #line ~= 2 then
               self._socks[this]:send(ERR_ARGNUM)
               break
            end

            if line[2] ~= '1' then
               self._socks[this]:send('ERR ROOMNUM\nEND\n')
            else
               self._rooms[this] = 1
               self._socks[this]:send('FOE "' .. self._names[other]
                                         .. '"\nEND\n')
               self._socks[other]:send('FOE "' .. self._names[this]
                                          .. '"\nEND\n')
            end
         elseif line == 'MAKEROOM' then
            self._socks[this]:send(NEGATIVE)
         elseif line == 'TEAM' then
            self._socks[this]:send(this .. '\nEND\n')
         elseif line:startswith('SELECT') then
            if self._turn ~= this then
               self._socks[this]:send(NEGATIVE)
               break
            end

            line = line:split(' ')
            if #line ~= 2 then
               self._socks[this]:send(ERR_ARGNUM)
               break
            end

            local i = tonumber(line[2])
            if not i then
               self._socks[this]:send(ERR_SYNTAX)
            elseif self._pieces[i].team ~= this then
               self._socks[this]:send(NEGATIVE)
            else
               self._selected = self._pieces[i]
               self._socks[this]:send(AFFIRMATIVE)

               self:_updateall({'SELECTED ' .. i})
            end
         elseif line == 'DESELECT' then
            if self._turn ~= this then
               self._socks[this]:send(NEGATIVE)
            else
               self._selected = nil
               self._socks[this]:send(AFFIRMATIVE)

               self:_updateall({'DESELECTED'})
            end
         elseif (line:startswith('TRYMOVE')
                    or line:startswith('TRYSPLIT')
                    or line:startswith('MOVE')
                    or line:startswith('SPLIT')) then
            line = line:split(' ')
            if self._turn ~= this or not self._selected then
               self._socks[this]:send(NEGATIVE)
            elseif #line ~= 3 then
               self._socks[this]:send(ERR_ARGNUM)
            else
               local dx = tonumber(line[2])
               local dy = tonumber(line[3])

               if not dx or not dy then
                  self._socks[this]:send(ERR_SYNTAX)
               else
                  local split = line[1] == 'TRYSPLIT' or line[1] == 'SPLIT'
                  local move = self:_getmove(dx, dy, split)
                  if not move then
                     self._socks[this]:send(NEGATIVE)
                     self:_updateall({'UNPOINT'})
                     break
                  end

                  self._socks[this]:send(AFFIRMATIVE)

                  if line[1]:startswith('TRY') then
                     self:_updateall({'POINT ' .. move.x .. ' ' .. move.y})
                  else
                     self:_move(move, split)
                  end
               end
            end
         elseif line == 'FORFEIT' then
            self._sendall('FORFEIT ' .. this .. '\nSHUTDOWN\nEND\n')
            self._done = true
            return
         elseif line == 'UPDATE' then
            table.insert(self._updatequeue[this], 'END')
            self._socks[this]:send(table.concat(self._updatequeue, '\n')
                                      .. '\n')
            self._updatequeue[this] = {}
         else
            self._socks[this]:send('ERR COMMAND\nEND\n')
         end
      end

      self._queue[i] = {}
      other = 1
   end
end

function Server:run()
   local err = nil

   while not self._done do
      local recvable, _, err = socket.select(self._socks, {}, 1000)

      for _,r in ipairs(recvable) do
         if r == self._socks[1] then
            table.insert(self._queue[1], r:recv())
         else
            table.insert(self._queue[2], r:recv())
         end
      end

      self:_process()
   end

   self:_cleanup()
   return err
end

local function respondlocal(str, comm, server, socks)
   if str == 'quit' then
      for _,sock in ipairs(socks) do
         sock:send('SHUTDOWN\nEND\n')
         sock:close()
      end

      server:close()
      finished = true
   end
end

local function servermain()
   local comm = love.thread.getChannel('server')
   comm:supply('ready')

   local server = socket.bind('*', comm:demand())
   if not server then
      comm:supply('fail bind')
      return
   end

   local ip, port = server:getsockname()
   comm:supply(string(ip) .. ' ' .. string(port))

   server:settimeout(1000)
   local socks = {}
   while #socks < 2 do
      local sock = server:accept()
      if sock then
         sock:settimeout(1000)
         local line, err = sock:receive()
         if line then
            if line == 'AGARIO CHECKERS CLIENT' then
               sock:send('AGARIO CHECKERS SERVER\n')
            else
               err = 'protocol'
            end
         end

         if err then
            for _,sock in ipairs(socks) do
               sock:send('SHUTDOWN\nEND\n')
               sock:close()
            end

            server:close()
            comm:supply('err ' .. err)
            return
         end
      end

      local str = comm:pop()
      if str then
         respondlocal(str, comm, server, socks)
         if finished then
            return
         end
      end
   end

   server = Server(server, socks, comm)
   local err = server:run()

   if err then
      comm:supply('err ' .. err)
   else
      comm:supply('done')
   end
end

servermain()