-- 15/09/2k7: algorithms for Nomignolov's Intervalo's script, Jean M. Morales
-- 15/09/2k7: start
-- 15/09/2k7: added Oscillator, Halver and Filler
-- 16/09/2k7: added Center and Borders (Mari), Median (Mari)
--          : Random, Bodyguard, Inner Oscillator (Mari), Primer (Mari)
-- 30/09/2k7: added Mirror, Uneven

-- Situation: string to array
situation_to_board =
  function (situation)
    local board = {};

    for i = 1,64 do
      board[i] = string.sub(situation, i, i);
    end

    return board;

  end

stb = situation_to_board;

ALG = function (n, situation)
  res = 0;

  if (n == 1) then res = ALG_01(situation); end
  if (n == 2) then res = ALG_02(situation); end
  if (n == 3) then res = ALG_03(situation); end
  if (n == 4) then res = ALG_04(situation); end
  if (n == 5) then res = ALG_05(situation); end
  if (n == 6) then res = ALG_06(situation); end
  if (n == 7) then res = ALG_07(situation); end
  if (n == 8) then res = ALG_08(situation); end
  if (n == 9) then res = ALG_09(situation); end
  if (n == 10) then res = ALG_10(situation); end
  if (n == 11) then res = ALG_11(situation); end

  return res;
  end


-- Oscillator
-- - A = 1, ..., 32; B = 33, ..., 64
-- - p(X) = number of player's piece in set
-- - play in B if p(B) < p(A), else in A
-- - play in the empty cell farther from the center
ALG_01 =
  function (situation)

    local res = 0;
    local pA = 0; local pB = 0;
    local S = stb(situation);

    for i = 1,32 do
      if (S[i] == "p") then
        pA = pA + 1;
      end
      if (S[32 + i] == "p") then
        pB = pB + 1;
      end
    end

    if (pB < pA) then
      for i = 1,64 do
        if (S[65 - i] == ".") then
          res = 65 - i;
          break;
        end
      end
    else
      for i = 1,64 do
        if (S[i] == ".") then
          res = i;
          break;
        end
      end
    end

    if (res == 0) then
      print("Error in algorithm Oscillator!!!");
    end

    return res;
    
  end

-- Halver
-- - find the longest run of empty cells
--   (take the one in case of draw)
-- - place a piece in the middle of it
--   (if there are n cells, n even, put in the middle of n=1)
ALG_02 =
  function (situation)

    local res = 0; local S = stb(situation);
    local s1 = 0; local s2 = 0; local started = 0;
    local m1 = 0; local m2 = -1;

    for i = 1,64 do
      if (S[i] == ".") then
        if (started == 0) then
          s1 = i; s2 = i; started = 1;
        else
          s2 = i;
        end
      else
        if (started == 1) then -- just finished
          if ((s2 - s1 + 1) > (m2 - m1 + 1)) then
            m1 = s1; m2 = s2;
          end
          started = 0;
        end
      end
    end
    if (started == 1) then
      if ((s2 - s1 + 1) > (m2 - m1 + 1)) then
        m1 = s1; m2 = s2;
      end
      started = 0;
    end

    local n = m2 - m1 + 1;

    if (math.mod(n, 2) == 0) then
      res = m1 + n/2;
    else
      res = m1 + (n-1)/2;
    end

    if (res == 0) then
      print("Error in algorithm Halver!!!");
    end

    return res;

  end

-- Filler
-- - Play in the first empty cell starting from 1
ALG_03 =
  function (situation)

    local res = 0; local S = stb(situation);

    for i = 1,64 do
      if (S[i] == ".") then
        res = i;
        break;
      end
    end

    if (res == 0) then
      print("Error in algorithm Filler!!!");
    end

    return res;

  end

-- Center and borders (Mari 16/09/2k7)
-- - Count pieces to tell what turn is it.
-- - Play with the following order:
--  - Center most from the right
--  - Farther to the left
--  - Center most from the left
--  - Farther to the right
-- - If half board is filled, oscillate in the other half
ALG_04 =
  function (situation)

    local res = 0; local S = stb(situation);
    local n_turns = 0;

    for i = 1,64 do
      if (S[i] == "n") then
	n_turns = n_turns + 1;
      else
	if ((S[i] == "a") or (S[i] == "p")) then
	  n_turns = n_turns + 0.5;
	end
      end
    end

    -- n_turns should be integer
    -- CR, BL, CL, BR
    local found = 0;

    while (found == 0) do
      if (math.mod(n_turns, 4) == 0) then
	for i = 33,64 do -- CR
	  if (S[i] == ".") then
	    res = i; found = 1;
	    break;
	  end
	end
	n_turns = 2; --> so CL
      end
      if (math.mod(n_turns, 4) == 1) then
	for i = 1,32 do -- BL
	  if (S[i] == ".") then
	    res = i; found = 1;
	    break;
	  end
	end
	n_turns = 3; --> so BS
      end
      if (math.mod(n_turns, 4) == 2) then
	for i = 1,32 do -- CL
	  if (S[33-i] == ".") then
	    res = 33-i; found = 1;
	    break;
	  end
	end
	n_turns = 0; --> so CR
      end
      if (math.mod(n_turns, 4) == 3) then
	for i = 33,64 do -- BR
	  if (S[64+33-i] == ".") then
	    res = 64+33-i; found = 1;
	    break;
	  end
	end
	n_turns = 1; --> so BR
      end
    end

    if (res == 0) then
      print("Error in algorithm Center and Borders!!!");
    end

    return res;

  end

-- Median (Mari 16/09/2k7)
-- - In a situation with n empty cells, play
--   in the n/2 (or (n+1)/2)
ALG_05 =
  function (situation)

    local res = 0; local S = stb(situation);
    local n_empty = 0;
    local pos = 0;

    for i = 1,64 do
      if (S[i] == ".") then
        n_empty = n_empty + 1;
      end
    end

    if (math.mod(n_empty, 2) == 0) then
      pos = n_empty/2;
    else
      pos = (n_empty+1)/2;
    end

    for i = 1,64 do
      if (S[i] == ".") then
	pos = pos - 1;
	if (pos == 0) then
	  res = i;
	  break;
	end
      end
    end

    if (res == 0) then
      print("Error in algorithm Median!!!");
    end

    return res;

  end

-- Random (16/09/2k7)
-- - Play at random...
ALG_06 =
  function (situation)

    local res = 0; local S = stb(situation);
    local n_empty = 0;
    local pos = 0;

    for i = 1,64 do
      if (S[i] == ".") then
        n_empty = n_empty + 1;
      end
    end

    pos = math.random(n_empty);

    for i = 1,64 do
      if (S[i] == ".") then
	pos = pos - 1;
	if (pos == 0) then
	  res = i;
	  break;
	end
      end
    end

    if (res == 0) then
      print("Error in algorithm Random!!!");
    end

    return res;

  end

-- Bodyguard (16/09/2k7)
-- - Put a piece in a cell next to an opponent's
--   piece, else random.
ALG_07 =
  function (situation)

    local res = 0; local S = stb(situation);

    for i = 1,64 do
      if (S[i] == "a") then
	if ((i > 1) and (S[i-1] == ".")) then
	    res = i-1; break;
	end
	if ((i < 64) and (S[i+1] == ".")) then
	  res = i+1; break;
	end
      end
    end

    if (res == 0) then
      res = ALG_06(situation);
    end

    if (res == 0) then
      print("Error in algorithm Bodyguard!!!");
    end

    return res;

  end

-- Inner Oscillator (Marisa - 16/09/2k7)
-- - Put a piece nearer to the center
ALG_08 =
  function (situation)

    local res = 0; local S = stb(situation);

    for i = 1,32 do
      if (S[32 + i] == ".") then
	res = 32 + i; break;
      else
	if (S[33 - i] == ".") then
	  res = 33 - i; break;
	end
      end
    end

    if (res == 0) then
      print("Error in algorithm Inner Oscillator!!!");
    end

    return res;

  end

-- Primer (Marisa - 16/09/2k7)
-- - Put a piece in a prime numbered position, else random
ALG_09 =
  function (situation)

    local res = 0; local S = stb(situation);


    if (S[61] == ".") then res = 61; end
    if (S[59] == ".") then res = 59; end
    if (S[53] == ".") then res = 53; end
    if (S[47] == ".") then res = 47; end
    if (S[43] == ".") then res = 43; end
    if (S[41] == ".") then res = 41; end
    if (S[37] == ".") then res = 37; end
    if (S[31] == ".") then res = 31; end
    if (S[29] == ".") then res = 29; end
    if (S[23] == ".") then res = 23; end
    if (S[19] == ".") then res = 19; end
    if (S[17] == ".") then res = 17; end
    if (S[13] == ".") then res = 13; end
    if (S[11] == ".") then res = 11; end
    if (S[7] == ".") then res = 7; end
    if (S[5] == ".") then res = 5; end
    if (S[3] == ".") then res = 3; end
    if (S[2] == ".") then res = 2; end

    if (res == 0) then
      res = ALG_06(situation);
    end

    if (res == 0) then
      print("Error in algorithm Primer!!!");
    end

    return res;

  end

-- Mirror (30/09/2k7)
-- - Put a piece in the first i with 65-i empty, else random.
ALG_10 =
  function (situation)

    local res = 0; local S = stb(situation);

    for i = 1,32 do
      if ((S[i] ~= ".") and (S[65-i] == ".")) then
	res = 65 - i; break;
      end
    end

    if (res == 0) then
      res = ALG_06(situation);
    end

    if (res == 0) then
      print("Error in algorithm Mirror!!!");
    end

    return res;

  end

-- Uneven (30/09/2k7)
-- - Put a piece in the first empty i when in 1,i there are
-- more friendly pieces than opponent's pieces (> 0).
ALG_11 =
  function (situation)

    local res = 0; local S = stb(situation);
    local n_my = 0; local n_opp = 0;

    for i = 1,64 do
      if (S[i] == "p") then
	n_my = n_my + 1;
      end
      if (S[i] == "a") then
	n_opp = n_opp + 1;
      end
      if ((S[i] == ".") and (n_opp > 0) and (n_my > n_opp)) then
	res = i; break;
      end
    end

    if (res == 0) then
      res = ALG_06(situation);
    end

    if (res == 0) then
      print("Error in algorithm Uneven!!!");
    end

    return res;

  end