local state = runtime.import("state")
local board = runtime.import("board")

local rules = {}

local function piece_index(piece_id)
  return piece_id:sub(-1) == "2" and 2 or 1
end

function rules.next_player()
  for index, player in ipairs(state.players) do
    if player == state.current_player then
      local next_index = index + 1
      if next_index > #state.players then
        next_index = 1
      end
      return state.players[next_index]
    end
  end
  return state.players[1]
end

function rules.next_dice()
  state.dice_index = state.dice_index + 1
  if state.dice_index > #state.dice_values then
    state.dice_index = 1
  end
  return state.dice_values[state.dice_index]
end

function rules.can_move(piece, dice)
  if piece == nil or piece.status == "finished" then
    return false
  end
  if piece.status == "home" then
    return dice == 6
  end
  return true
end

function rules.movable_pieces()
  local result = {}
  for id, piece in pairs(state.pieces) do
    if piece.owner == state.current_player and rules.can_move(piece, state.dice) then
      table.insert(result, id)
    end
  end
  return result
end

function rules.all_piece_ids()
  local result = {}
  for id, _ in pairs(state.pieces) do
    table.insert(result, id)
  end
  return result
end

function rules.piece_position(piece)
  return board.position(piece)
end

function rules.plan_move(piece, dice)
  local path = {}
  local final_status = "route"
  local final_progress = piece.progress

  if piece.status == "home" then
    final_progress = 1
    table.insert(path, board.route_position(piece.owner, final_progress))
  else
    for step = 1, dice do
      local progress = piece.progress + step
      if progress >= board.finish_progress then
        final_status = "finished"
        final_progress = board.finish_progress
        table.insert(path, board.finish_position(piece))
        break
      end
      table.insert(path, board.route_position(piece.owner, progress))
      final_progress = progress
    end
  end

  local captures = {}
  if final_status == "route" then
    local landing_index = board.route_index(piece.owner, final_progress)
    for id, other in pairs(state.pieces) do
      if id ~= piece.id and other.owner ~= piece.owner and other.status == "route" then
        if board.route_index(other.owner, other.progress) == landing_index then
          table.insert(captures, id)
        end
      end
    end
  end

  return {
    piece_id = piece.id,
    final_status = final_status,
    final_progress = final_progress,
    path = path,
    captures = captures
  }
end

function rules.commit_move(plan)
  local piece = state.pieces[plan.piece_id]
  piece.status = plan.final_status
  piece.progress = plan.final_progress

  for _, captured_id in ipairs(plan.captures) do
    local captured = state.pieces[captured_id]
    captured.status = "home"
    captured.progress = 0
  end
end

function rules.player_finished(owner)
  for _, piece in pairs(state.pieces) do
    if piece.owner == owner and piece.status ~= "finished" then
      return false
    end
  end
  return true
end

function rules.status_text()
  if state.winner ~= nil then
    return "胜利者: " .. state.winner
  end
  if state.phase == "waiting_roll" then
    return "请 " .. state.current_player .. " 掷骰子"
  end
  if state.phase == "waiting_piece" then
    return "请选择 " .. state.current_player .. " 的飞机"
  end
  if state.phase == "animating" then
    return "飞机移动中..."
  end
  return "准备中"
end

function rules.piece_label(piece)
  if piece.status == "home" then
    return "待飞"
  end
  if piece.status == "finished" then
    return "到达"
  end
  return tostring(piece.progress)
end

return rules