#include "aoc.h"
#include <map>

namespace aoc2022 {

static line_view moves;
static size_t index = 0;

static bool at(uint8_t r, int p) {
  // p 0..7
  uint8_t m = 0x01;
  while (p-- > 0)
    m <<= 1;
  return m & r;
}

char next() {
  int x = index++ % (moves.length - 1);
  const char* p = moves.line;
  // printf("%c at %d\n", *(p + x), x);
  return *(p + x);
}

void print(std::vector<uint8_t>& rs) {
  for (size_t i = rs.size(); i > 0; i--) {
    uint8_t x = rs[i - 1];
    printf("%05ld| ", i - 1);
    int c{6};
    while (c >= 0) {
      printf("%c", at(x, c) ? '#' : '.');
      c--;
    }
    printf("\n");
  }
}

rock17 make_rock(size_t i) {
  rock17 r;
  r.type = (rock_type)(i % 5);
  switch (r.type) {
  case r1:
    r.rs = {0x1E};
    break;
  case r2:
    r.rs = {0x08, 0x1C, 0x08};
    break;
  case r3:
    r.rs = {0x1C, 0x04, 0x04};
    break;
  case r4:
    r.rs = {0x10, 0x10, 0x10, 0x10};
    break;
  case r5:
    r.rs = {0x18, 0x18};
    break;
  default:
    break;
  }
  /*
  case chamber:
    r.rs = {0x7F};
    break;
  case three:
    r.rs = {0x00, 0x00, 0x00};
    break;
  */
  return r;
}

rock17 right(rock17 r) {
  for (auto& rx : r.rs) {
    rx >>= 1;
  }
  return r;
}

rock17 left(rock17 r) {
  for (auto& rx : r.rs) {
    rx <<= 1;
  }
  return r;
}

bool collide(uint8_t r1, uint8_t r2) { return r1 & r2; }

bool collide_left(std::vector<uint8_t>& rs1, std::vector<uint8_t>& rs2) {
  for (size_t j = 0; j < rs1.size(); j++) {
    for (int i = 6; i >= 0; i--) {
      if (at(rs1[j], i)) {
        if (i == 6)
          return true;
        if (at(rs2[j + 1], i + 1)) {
          return true;
        } else {
          break;
        }
      }
    }
  }
  return false;
}

bool collide_right(std::vector<uint8_t>& rs1, std::vector<uint8_t>& rs2) {
  for (size_t j = 0; j < rs1.size(); j++) {
    for (int i = 0; i <= 6; i++) {
      if (at(rs1[j], i)) {
        if (i == 0)
          return true;
        if (at(rs2[j + 1], i - 1)) {
          return true;
        } else {
          break;
        }
      }
    }
  }
  return false;
}

bool collide_down(std::vector<uint8_t>& rs1, std::vector<uint8_t>& rs2) {
  for (size_t i = 0; i < rs1.size(); i++) {
    if (collide(rs1[i], rs2[i]))
      return true;
  }
  return false;
}

void merge(rock17& floor, rock17 r, int n) {
  std::vector<uint8_t> room;
  for (size_t i = floor.rs.size() - n - 1; room.size() < r.rs.size() + 1 && i < floor.rs.size(); i++) {
    room.push_back(floor.rs[i]);
  }

  while (room.size() < r.rs.size() + 1) {
    room.push_back(0x00);
  }

  auto m = next();
  if (m == '>' && !collide_right(r.rs, room)) {
    // printf("%c %d\n", m, r.type);
    r = right(r);
  }
  if (m == '<' && !collide_left(r.rs, room)) {
    // printf("%c %d\n", m, r.type);
    r = left(r);
  }

  if (!collide_down(r.rs, room)) {
    merge(floor, r, n + 1);
  } else { // merge from n to last with r
    size_t m{0};
    // 1. merge
    for (size_t i = floor.rs.size() - n; m < r.rs.size() && i < floor.rs.size(); i++) {
      floor.rs[i] |= r.rs[m];
      m++;
    }
    // 2. push if necessary
    while (m < r.rs.size()) {
      floor.rs.push_back(r.rs[m++]);
    }
  }
}

int merge(std::vector<uint8_t>& rs1, std::vector<uint8_t>& rs2, int n) {
  if (collide(rs1[rs1.size() - 1 - n], rs2[0]))
    return n;
  else
    return merge(rs1, rs2, n + 1);
}

int check_three(std::vector<uint8_t>& rs) {
  auto n = 0;
  while (rs[rs.size() - n - 1] == 0x00) {
    n++;
  }

  auto needed = 3 - n;
  while (needed-- > 0) {
    rs.push_back(0x00);
  }
  return n;
}

std::vector<uint8_t> get_pattern(rock17& r) {
  auto n = 0;
  while (r.rs[r.rs.size() - n - 1] == 0x00) {
    n++;
  }
  return {r.rs.begin() + 1, r.rs.end() - n};
}

std::pair<size_t, size_t> day17(line_view file) {
  moves = file;
  rock17 floor{chamber, {0x7F}};

  // size_t p = (file.length - 1) * 5;
  // size_t n = 8602 + 8576;
  size_t n = 2022;
  // sample 17(29) 35(53)/35/35
  // input  8602 8575/8575/8575
  for (size_t i = 0; i < n; i++) {
    rock17 r = make_rock(i);
    check_three(floor.rs);
    // auto x = check_three(floor.rs);
    // if (x == 0) {
    //   printf("%ld, %ld\n", i, index % p);
    // }
    merge(floor, r, 0);
    // printf("%ld, %ld %ld\n", i, index % p, floor.rs.size() - 1);
    // 8601, 6 13526
    // 8602, 11 13529
    // 8603, 17 13531
    // 15450, 40309 24274
    // 15451, 40313 24275
    // 15452, 40318 24278
    // 17177, 11 26979
    // 8602 + 116618074 * 8575 + 6848
    // 13526 + 116618074 * 13450 + (24274 - 13529)
  }
  return {floor.rs.size() - 1, 1568513119571};
}
} // namespace aoc2022