#include "map.hpp"
#include "dbc.hpp"
#include <vector>
#include <fmt/core.h>
#include <random>
#include <utility>

std::random_device g_rng;
std::mt19937 g_generator(g_rng());

using std::vector, std::pair;
using namespace fmt;

void dump_map(const std::string &msg, Matrix &map) {
  println("----------------- {}", msg);
  for(auto row : map) {
    for(auto col : row) {
      print("{} ", col);
    }
    print("\n");
  }
}

inline void add_neighbors(PointList &neighbors, Matrix &closed, size_t y, size_t x) {
  size_t h = closed.size();
  size_t w = closed[0].size();
  vector<size_t> rows{y - 1, y, y + 1};
  vector<size_t> cols{x - 1, x, x + 1};

  for(size_t row : rows) {
    for(size_t col : cols) {
      if((0 <= row && row < h) &&
          (0 <= col && col < w) &&
          closed[row][col] == 0)
      {
        closed[row][col] = 1;
        neighbors.push_back({.x=col, .y=row});
      }
    }
  }
}

/**
 * This will create an _inverted_ map that you
 * can run make_rooms and generate on. It will
 * NOT be valid until you actually run generate.
 */
Map::Map(size_t width, size_t height) : m_limit(1000) {
  m_walls = Matrix(height, MatrixRow(width, INV_WALL));
  m_input_map = Matrix(height, MatrixRow(width, 1));
}

void Map::make_paths() {
  size_t h = m_input_map.size();
  size_t w = m_input_map[0].size();

  // Initialize the new array with every pixel at limit distance
  // NOTE: this is normally ones() * limit
  int limit = m_limit == 0 ? h * w : m_limit;
  Matrix new_arr = Matrix(h, MatrixRow(w, limit));
  Matrix closed = m_walls;
  PointList starting_pixels;
  PointList open_pixels;

  // First pass: Add starting pixels and put them in closed
 for(size_t counter = 0; counter < h * w; counter++) {
    size_t x = counter % w;
    size_t y = counter / w;
    if(m_input_map[y][x] == 0) {
      new_arr[y][x] = 0;
      closed[y][x] = 1;
      starting_pixels.push_back({.x=x,.y=y});
    }
  }

  // Second pass: Add border to open
  for(auto sp : starting_pixels) {
    add_neighbors(open_pixels, closed, sp.y, sp.x);
  }

  // Third pass: Iterate filling in the open list
  int counter = 1; // leave this here so it's available below
  for(; counter < limit && !open_pixels.empty(); ++counter) {
    PointList next_open;
    for(auto sp : open_pixels) {
      new_arr[sp.y][sp.x] = counter;
      add_neighbors(next_open, closed, sp.y, sp.x);
    }
    open_pixels = next_open;
  }

  // Last pass: flood last pixels
  for(auto sp : open_pixels) {
    new_arr[sp.y][sp.x] = counter;
  }

  m_paths = new_arr;
}

void Map::make_room(size_t origin_x, size_t origin_y, size_t w, size_t h) {
  dbc::pre("x out of bounds", origin_x < width());
  dbc::pre("y out of bounds", origin_y < height());
  dbc::pre("w out of bounds", w <= width());
  dbc::pre("h out of bounds", h <= height());

  for(size_t y = origin_y; y < origin_y + h; ++y) {
    dbc::check(y < m_walls.size(), "y is out of bounds");
    for(size_t x = origin_x; x < origin_x + w; ++x) {
      dbc::check(x < m_walls[y].size(), "x is out of bounds");
      m_walls[y][x] = INV_SPACE;
    }
  }
}

inline int make_split(Room &cur, bool horiz) {
  size_t dimension = horiz ? cur.height : cur.width;
  int min = dimension / 4;
  int max = dimension - min;
  std::uniform_int_distribution<int> rand_dim(min, max);
  return rand_dim(g_generator);
}

void Map::partition_map(Room &cur, int depth) {
  if(cur.width >= 5 && cur.width <= 10 &&
      cur.height >= 5 && cur.height <= 10) {
    m_rooms.push_back(cur);
    return;
  }

  std::uniform_int_distribution<int> rsplit(0, 1);
  bool horiz = cur.width > cur.height ? false : true;
  int split = make_split(cur, horiz);
  Room left = cur;
  Room right = cur;

  if(horiz) {
    dbc::check(split > 0, "split is not > 0");
    dbc::check(split < int(cur.height), "split is too big!");
    left.height = size_t(split - 1);
    right.y = cur.y + split;
    right.height = size_t(cur.height - split);
  } else {
    dbc::check(split > 0, "split is not > 0");
    dbc::check(split < int(cur.width), "split is too big!");

    left.width = size_t(split-1);
    right.x = cur.x + split,
    right.width = size_t(cur.width - split);
  }

  if(depth > 0  && left.width > 5 && left.height > 5) {
    partition_map(left, depth-1);
  }

  if(depth > 0 && right.width > 5 && right.height > 5) {
    partition_map(right, depth-1);
  }
}

void Map::place_rooms(Room &cur) {
  for(auto &cur : m_rooms) {
    cur.x += 2;
    cur.y += 2;
    cur.width -= 4;
    cur.height -= 4;
    add_door(cur);
    set_door(cur, INV_SPACE);
    make_room(cur.x, cur.y, cur.width, cur.height);
  }
}

bool Map::neighbors(Point &out, bool greater) {
  std::array<Point, 4> dirs{{
      {out.x,out.y-1},
      {out.x+1,out.y},
      {out.x,out.y+1},
      {out.x-1,out.y}
  }};

  int zero_i = -1;
  int cur = m_paths[out.y][out.x];

  if(cur == 1000) {
    // BUG: sometimes the generation clips a door and we
    // start in a wall
    return false;
  }

  for(int i = 0; i < 4; ++i) {
    Point dir = dirs[i];
    int diff = inmap(dir.x, dir.y) ? cur - m_paths[dir.y][dir.x] : -1000;

    if(diff == 1) {
      out = {.x=dir.x, .y=dir.y};
      return true;
    } else if(diff == 0) {
      zero_i = i;
    }
  }

  if(zero_i != -1) {
    out = {.x=dirs[zero_i].x, .y=dirs[zero_i].y};
    return true;
  } else {
    return false;
  }
}

bool Map::inmap(size_t x, size_t y) {
  return x < width() && y < height();
}

void Map::set_door(Room &room, int value) {
  m_walls[room.entry.y][room.entry.x] = value;
  m_walls[room.exit.y][room.exit.x] = value;
}

void rand_side(Room &room, Point &door) {
  std::uniform_int_distribution<int> rand_side(0, 3);
  std::uniform_int_distribution<int> rand_x(0, room.width - 1);
  std::uniform_int_distribution<int> rand_y(0, room.height - 1);

  switch(rand_side(g_generator)) {
    case 0: // north
      door.x = room.x + rand_x(g_generator);
      door.y = room.y-1;
      break;
    case 1: // south
      door.x = room.x + rand_x(g_generator);
      door.y = room.y + room.height;
      break;
    case 2: // east
      door.x = room.x + room.width;
      door.y = room.y + rand_y(g_generator);
      break;
    case 3: // west
      door.x = room.x - 1;
      door.y = room.y + rand_y(g_generator);
      break;
    default:
      dbc::sentinel("impossible side");
  }
}

void Map::add_door(Room &room) {
  rand_side(room, room.entry);
  rand_side(room, room.exit);
}

bool Map::walk(Point &src, Point &target) {
  // this sets the target for the path
  dbc::check(m_input_map[target.y][target.x] == 0, "target point not set to 0");

  m_walls[src.y][src.x] = INV_WALL;
  m_walls[target.y][target.x] = INV_WALL;

  // for the walk this needs to be walls since it's inverted?
  dbc::check(m_walls[src.y][src.x] == INV_WALL,
      "src room has a wall at exit door");
  dbc::check(m_walls[target.y][target.x] == INV_WALL,
      "target room has a wall at entry door");

  make_paths();
  bool found = false;
  Point out{src.x, src.y};
  do {
    m_walls[out.y][out.x] = INV_SPACE;
    found = neighbors(out, true);

    if(m_paths[out.y][out.x] == 0) {
      m_walls[out.y][out.x] = INV_SPACE;
      return true;
    }
  } while(found && out.x > 0 && out.y > 0);

  return false;
}

void Map::set_target(Point &at, int value) {
  m_input_map[at.y][at.x] = 0;
}

void Map::clear_target(Point &at) {
  m_input_map[at.y][at.x] = 1;
}

void Map::generate() {
  Room root{
    .x = 0,
    .y = 0,
    .width = width(),
    .height = height()
  };

  partition_map(root, 10);
  place_rooms(root);

  for(size_t i = 0; i < m_rooms.size() - 1; i++) {
    Room &src = m_rooms[i];
    Room &target = m_rooms[i+1];
    set_target(target.entry);
    bool found = walk(src.exit, target.entry);
    if(!found) {
      println("ROOM NOT FOUND!");
    }
    clear_target(target.entry);
 }

  Room &src = m_rooms.back();
  Room &target = m_rooms.front();

  set_target(target.entry);
  walk(src.exit, target.entry);
  clear_target(target.entry);

  for(size_t y = 0; y < height(); ++y) {
    for(size_t x = 0; x < width(); ++x) {
      m_walls[y][x] = !m_walls[y][x];
    }
  }
}

bool Map::iswall(size_t x, size_t y) {
  return m_walls[y][x] == WALL_VALUE;
}


void Map::dump() {
  dump_map("PATHS", m_paths);
  dump_map("WALLS", m_walls);
  dump_map("INPUT", m_input_map);
}