#include "common/aoc.h"

namespace y2016::day21
{
  enum class Operator
  {
    Swap,
    SwapLetter,
    Rotate,
    RotatePos,
    Reverse,
    Move
  };

  struct Instruction
  {
    Operator op;
    int arg1;
    int arg2;
  };

  REGISTER_DAY(2016, Day21, std::vector<Instruction>, std::string);

  REGISTER_TEST_EXAMPLE(2016, Day21, ExampleInput, 1, "decab");
  REGISTER_TEST(2016, Day21, Input, 1, "hcdefbag");
  REGISTER_TEST(2016, Day21, Input, 2, "fbhaegdc");

  READ_INPUT(input)
  {
    std::vector<Instruction> vec;
    std::string str;
    while (getline(input, str))
    {
      Instruction instruction;
      std::stringstream ss{str};
      if (Helper::StartsWith(str, "swap position"))
      {
        instruction.op = Operator::Swap;
        ss >> "swap position " >> instruction.arg1 >> "with position " >> instruction.arg2;
      }
      else if (Helper::StartsWith(str, "swap letter"))
      {
        instruction.op = Operator::SwapLetter;
        char c1, c2;
        ss >> "swap letter " >> c1 >> "with letter " >> c2;
        instruction.arg1 = c1;
        instruction.arg2 = c2;
      }
      else if (Helper::StartsWith(str, "rotate left"))
      {
        instruction.op = Operator::Rotate;
        ss >> "rotate left" >> instruction.arg1;
        instruction.arg1 = -instruction.arg1;
      }
      else if (Helper::StartsWith(str, "rotate right"))
      {
        instruction.op = Operator::Rotate;
        ss >> "rotate right" >> instruction.arg1;
      }
      else if (Helper::StartsWith(str, "rotate based"))
      {
        instruction.op = Operator::RotatePos;
        char c;
        ss >> "rotate based on position of letter " >> c;
        instruction.arg1 = c;
      }
      else if (str[0] == 'r')
      {
        instruction.op = Operator::Reverse;
        ss >> "reverse positions " >> instruction.arg1 >> "through " >> instruction.arg2;
      }
      else
      {
        instruction.op = Operator::Move;
        ss >> "move position " >> instruction.arg1 >> "to position " >> instruction.arg2;
      }
      vec.emplace_back(instruction);
    }
    return vec;
  }

  OUTPUT1(input)
  {
    CyclicVector<char> data{isExample ? "abcde" : "abcdefgh"};
    for (const auto& instruction : input)
    {
      switch (instruction.op)
      {
        case Operator::Swap:
        {
          std::swap(data[instruction.arg1], data[instruction.arg2]);
          break;
        }
        case Operator::SwapLetter:
        {
          size_t i1 = data.Find(instruction.arg1);
          size_t i2 = data.Find(instruction.arg2);
          std::swap(data[i1], data[i2]);
          break;
        }
        case Operator::Rotate:
        {
          data.Rotate(instruction.arg1);
          break;
        }
        case Operator::RotatePos:
        {
          size_t pos = data.Find(instruction.arg1);
          int additional = pos >= 4 ? 1 : 0;
          data.Rotate(pos + 1 + additional);
          break;
        }
        case Operator::Reverse:
        {
          for (size_t i = 0; i < (instruction.arg2 - instruction.arg1 + 1) / 2; i++)
          {
            std::swap(data[instruction.arg1 + i], data[instruction.arg2 - i]);
          }
          break;
        }
        case Operator::Move:
        {
          if (instruction.arg1 < instruction.arg2)
          {
            char c = data[instruction.arg1];
            for (size_t i = instruction.arg1; i < instruction.arg2; i++)
            {
              data[i] = data[i + 1];
            }
            data[instruction.arg2] = c;
          }
          else
          {
            char c = data[instruction.arg1];
            for (size_t i = instruction.arg1; i > instruction.arg2; i--)
            {
              data[i] = data[i - 1];
            }
            data[instruction.arg2] = c;
          }
          break;
        }
      }
    }
    std::string str;
    for (size_t i = 0; i < data.size(); i++)
    {
      str.push_back(data[i]);
    }
    return str;
  }

  OUTPUT2(input)
  {
    CyclicVector<char> data{"fbgdceah"};
    std::map<int, int> rotatePosMap;
    for (int i = 0; i < data.size(); i++)
    {
      int result = (i + i + 1 + (i >= 4 ? 1 : 0)) % data.size();
      rotatePosMap.emplace(result, i - result);
    }
    for (int i = input.size() - 1; i >= 0; i--)
    {
      const auto& instruction = input[i];
      switch (instruction.op)
      {
        case Operator::Swap:
        {
          std::swap(data[instruction.arg1], data[instruction.arg2]);
          break;
        }
        case Operator::SwapLetter:
        {
          size_t i1 = data.Find(instruction.arg1);
          size_t i2 = data.Find(instruction.arg2);
          std::swap(data[i1], data[i2]);
          break;
        }
        case Operator::Rotate:
        {
          data.Rotate(-instruction.arg1);
          break;
        }
        case Operator::RotatePos:
        {
          size_t pos = data.Find(instruction.arg1);
          data.Rotate(rotatePosMap[pos]);
          break;
        }
        case Operator::Reverse:
        {
          for (size_t i = 0; i < (instruction.arg2 - instruction.arg1 + 1) / 2; i++)
          {
            std::swap(data[instruction.arg1 + i], data[instruction.arg2 - i]);
          }
          break;
        }
        case Operator::Move:
        {
          if (instruction.arg2 < instruction.arg1)
          {
            char c = data[instruction.arg2];
            for (size_t i = instruction.arg2; i < instruction.arg1; i++)
            {
              data[i] = data[i + 1];
            }
            data[instruction.arg1] = c;
          }
          else
          {
            char c = data[instruction.arg2];
            for (size_t i = instruction.arg2; i > instruction.arg1; i--)
            {
              data[i] = data[i - 1];
            }
            data[instruction.arg1] = c;
          }
          break;
        }
      }
    }
    std::string str;
    for (auto c : data)
    {
      str.push_back(c);
    }
    return str;
  }
}