#include "moves.h"
#include "help.h"
#include "types.h"
#include <stddef.h>
#include <stdlib.h>

int rookScan(game *g, move *moves, long long w, long long b);
int bishopScan(game *g, move *moves, long long w, long long b);
int kingScan(game *g, move *moves, long long w, long long b);

int pawnMove(game *g, move *moves) {
  long long pawns = g->whiteToMove ? g->white.pawns : g->black.pawns;
  long long enemy = g->whiteToMove ? fullSet(&g->black) : fullSet(&g->white);
  long long occupied = fullSetBoth(g);
  long long promo = (0xFFULL) << (g->whiteToMove ? 56 : 0);

  int movdir = g->whiteToMove ? 8 : -8;
  int capLeft = g->whiteToMove ? 7 : -9;
  int capRight = g->whiteToMove ? 9 : -7;

  size_t index = 0;

  for (int i = 0; i < 64; ++i) {
    long long bit = 1ULL << i;
    char p = 0;
    if (!(pawns & bit))
      continue;

    // forword
    int to = i + movdir;
    p = (promo & (1ULL << to)) ? 'q' : 0;
    if (to >= 0 && to < 64 && !(occupied & (1ULL << to))) {
      moves[index++] = (move){.From = i, .To = to, .Promo = p};
    }

    // left
    to = i + capLeft;
    p = (promo & (1ULL << to)) ? 'q' : 0;
    if (i % 8 > 0 && (to >= 0 && to < 64) && (enemy & (1ULL << to))) {
      moves[index++] = (move){.From = i, .To = to, .Promo = p};
    }

    // right
    to = i + capRight;
    p = (promo & (1ULL << to)) ? 'q' : 0;
    if (i % 8 < 7 && (to >= 0 && to < 64) && (enemy & (1ULL << to))) {
      moves[index++] = (move){.From = i, .To = to, .Promo = p};
    }
  }
  return index;
}

int knightMove(game *g, move *moves) {
  long long knights = g->whiteToMove ? g->white.knights : g->black.knights;
  long long occupied = g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);

  int kMoves[] = {-17, -15, -10, -6, 6, 10, 15, 17};
  int index = 0;

  for (int i = 0; i < 64; i++) {
    long long bit = 1ULL << i;
    if (!(knights & bit))
      continue;

    for (int j = 0; j < 8; ++j) {
      int to = i + kMoves[j];
      if (to < 0 || to > 64)
        continue;

      int fromFile = i % 8;
      int toFile = to % 8;
      int fromRank = i / 8;
      int toRank = to / 8;

      int fileDiff = abs(fromFile - toFile);
      int rankDiff = abs(fromRank - toRank);
      if (!((fileDiff == 1 && rankDiff == 2) ||
            (fileDiff == 2 && rankDiff == 1)))
        continue;

      long long destBit = 1ULL << to;
      if (occupied & destBit)
        continue;

      moves[index++] = (move){.From = i, .To = to, .Promo=0};
    }
  }
  return index;
}

int rookMove(game *g, move *moves) {
  return rookScan(g, moves, g->white.rooks, g->black.rooks);
}

int rookScan(game *g, move *moves, long long w, long long b) {
  long long rooks = g->whiteToMove ? w : b;
  long long occupied = g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);
  long long occupiedE =
    !g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);
  int index = 0;

  for (int i = 0; i < 64; i++) {
    long long bit = 1ULL << i;
    int x = i % 8;
    int y = i / 8;
    if (!(rooks & bit))
      continue;

    // fwd
    for (int j = y + 1; j < 8; j++) {
      int to = (j * 8) + x;
      long long lbit = 1ULL << to;
      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // bck
    for (int j = y - 1; j >= 0; j--) {
      int to = (j * 8) + x;
      long long lbit = 1ULL << to;
      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // rht
    for (int j = x + 1; j < 8; j++) {
      int to = (y * 8) + j;
      long long lbit = 1ULL << to;
      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // lft
    for (int j = x - 1; j >= 0; j--) {
      int to = (y * 8) + j;
      long long lbit = 1ULL << to;
      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }
  }
  return index;
}

int bishopMove(game *g, move *moves) {
  return bishopScan(g, moves, g->white.bishops, g->black.bishops);
}

int bishopScan(game *g, move *moves, long long w, long long b) {
  unsigned long long bishops = g->whiteToMove ? w : b;
  unsigned long long occupied = g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);
  unsigned long long occupiedE =
      !g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);
  int index = 0;

  for (int i = 0; i < 64; i++) {
    unsigned long long bit = 1ULL << i;
    int x = i % 8;
    int y = i / 8;

    if (!(bishops & bit))
      continue;

    // ur
    for (int j = 1;; j++) {
      int xTo = x + j;
      int yTo = y + j;
      if (xTo >= 8 || yTo >= 8)
        break;

      int to = (yTo * 8) + xTo;
      unsigned long long lbit = 1ULL << to;

      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // ul
    for (int j = 1;; j++) {
      int xTo = x - j;
      int yTo = y + j;
      if (xTo < 0 || yTo >= 8)
        break;

      int to = (yTo * 8) + xTo;
      unsigned long long lbit = 1ULL << to;

      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // dr
    for (int j = 1;; j++) {
      int xTo = x + j;
      int yTo = y - j;
      if (xTo >= 8 || yTo < 0)
        break;

      int to = (yTo * 8) + xTo;
      unsigned long long lbit = 1ULL << to;

      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }

    // dl
    for (int j = 1;; j++) {
      int xTo = x - j;
      int yTo = y - j;
      if (xTo < 0 || yTo < 0)
        break;

      int to = (yTo * 8) + xTo;
      unsigned long long lbit = 1ULL << to;

      if (occupied & lbit)
        break;
      moves[index++] = (move){.From = i, .To = to, .Promo=0};
      if (occupiedE & lbit)
        break;
    }
  }
  return index;
}

int queenMove(game *g, move *moves){
  int size = 0;
  unsigned long long w,b;
  w = g->white.queen;
  b = g->black.queen;
  size += rookScan(g,moves,w,b);
  size += bishopScan(g,(moves+size),w,b);
  return size;
}


int kingMove(game *g, move *moves){
  unsigned long long king = g->whiteToMove ? g->white.king : g->black.king;
  unsigned long long occupied = g->whiteToMove ? fullSet(&g->white) : fullSet(&g->black);
  int index = 0;

  for (int i = 0; i < 64; i++){
    unsigned long long bit = 1ULL << i;
    int x = i % 8;
    int y = i / 8;
    int movesX[] = {-1, 0, 1, -1, 1, -1, 0, 1};
    int movesY[] = {-1, -1, -1, 0, 0, 1, 1, 1};

    if(!(king & bit))
      continue;

    for (int j = 0; j < 8; ++j) {
      int toX = x + movesX[j];
      int toY = y + movesY[j];
      int to = (toY * 8) + toX;
      if(to > 63 || to < 1)
	continue;
      unsigned long long destBit = 1ULL << to;

      if (toX >= 0 && toX < 8 && toY >= 0 && toY < 8) {
        if (!(occupied & destBit)) {
          moves[index++] = (move){.From = i, .To = to, .Promo=0};
        }
      }
    }
  }
  return index;
}