#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "common.h"

char otherplayer(char player)
{
  return player^'x'^'o';  
}

void printtopbottom(Boardstate *b)
{
  long j;
  printf("  ");
  for (j=-2; j<b->maxx+2; j++)
    printf("%2ld",j+2);
  printf("\n");
}
  
void printboard(Boardstate *b)
{
#if 0
  printf("maxx=%ld  maxy=%ld  toplay=%c\n",b->maxx,b->maxy,b->toplay);
  for (long i=b->maxy-1; i>=0; i--) {
    for (long j=0; j<b->maxx; j++)
      printf("%2x ",b->board[i*b->maxx+j]);
    printf("\n");
  }
#endif
  printtopbottom(b);
  for (long i=b->maxy+1; i>=-2; i--) {
    printf("%2ld",i+2);
    for (long j=-2; j<b->maxx+2; j++)
      if (i>=0 && j>=0 && i<b->maxy && j<b->maxx)
        printf(" %c",b->board[i*b->maxx+j]);
      else
        printf("  ");
    printf("%2ld\n",i+2);
  }
  printtopbottom(b);
}

/* note: order of lines in file is reversed from what is shown in printboard */
void saveboard(Boardstate *b, char *filename)
{
  long i;
  FILE *f=fopen(filename,"w");
  if (f==NULL) {
    perror(filename);
    exit(1);
  }
  for (i=0; i<b->maxy; i++) {
    fwrite(&b->board[i*b->maxx],1,b->maxx,f);
    fputs("\n",f);
  }
  if (fclose(f)!=0) {
    perror(filename);
    exit(1);
  }
}

Boardstate *loadboard(char *filename)
{
  FILE *f=fopen(filename,"r");
  if (f==NULL) {
    perror(filename);
    exit(1);
  }
  Boardstate *b=malloc(sizeof(Boardstate));
  b->maxx=0;
  b->maxy=1;
  b->board=malloc(1);
  int c;
  for (;;) {
    c=getc(f);
    if (c=='\n')
      break;
    if (c==EOF) {
      fprintf(stderr,"%s: format error (no newline)\n",filename);
      exit(1);
    }
    b->maxx++;
    b->board = realloc(b->board,b->maxx);
    b->board[b->maxx-1]=c;
  }
  while (1) {
    b->board = realloc(b->board,b->maxx*(b->maxy+1));
    size_t len = fread(&b->board[b->maxx*(b->maxy)],1,b->maxx,f);
    if (len==0)
      break;
    b->maxy++;
    if (len!=b->maxx) {
      fprintf(stderr,"%s: format error (line too short)\n",filename);
      exit(1);
    }
    c=getc(f);
    if (c!='\n') {
      fprintf(stderr,"%s: format error (newline expected)\n",filename);
      exit(1);
    }
  }
  // printboard(b);
  /* now check the board */
  long i, countx=0, counto=0;
  for (i=0; i<b->maxx*b->maxy; i++) {
    if (b->board[i]=='x')
      countx++;
    else if (b->board[i]=='o')
      counto++;
    else if (b->board[i]!=' ') {
      fprintf(stderr,"wrong character %d in %s\n",b->board[i],filename);
      exit(1);
    }
  }
  if (countx<counto || countx>counto+1) {
    fprintf(stderr,"unbalanced: %ld xs, %ld os\n", countx, counto);
    exit(1);
  }
  b->toplay = (countx==counto)?'x':'o';
  return b;
}

int moveok(Boardstate *b, long x, long y)
{
  // printf("moveok(b,%ld,%ld)\n",x,y);
  if (x>=0 && x<b->maxx && y>=0 && y<b->maxy)
    if (b->board[y*b->maxx+x]!=' ')
      return 0;
  for (long x1=x-2; x1<=x+2; x1++)
    for (long y1=y-2; y1<=y+2; y1++)
      if (x1>=0 && x1<b->maxx && y1>=0 && y1<b->maxy)
        if (b->board[y1*b->maxx+x1]!=' ')
          return 1;
  return 0;
}

int iswin(Boardstate *b)
{
  for (long i=0; i<b->maxy; i++)
    for (long j=0; j<b->maxx; j++) {
      /* check horizontal */
      for (long k=0;; k++) {
        if (j+k >= b->maxx)
          break;
        if (b->board[i*b->maxx+j+k] != b->toplay)
          break;
        if (k==4)
          return 1;
      }
      /* check vertical */
      for (long k=0;; k++) {
        if (i+k >= b->maxy)
          break;
        if (b->board[(i+k)*b->maxx+j] != b->toplay)
          break;
        if (k==4)
          return 1;
      }
      /* check diagonal / */
      for (long k=0;; k++) {
        if (j+k >= b-> maxx || i+k >= b->maxy)
          break;
        if (b->board[(i+k)*b->maxx+j+k] != b->toplay)
          break;
        if (k==4)
          return 1;
      }
      /* check diagonal \ */
      for (long k=0;; k++) {
        if (j-k<0 || i+k >= b->maxy)
          break;
        if (b->board[(i+k)*b->maxx+j-k] != b->toplay)
          break;
        if (k==4)
          return 1;
      }
    }
  return 0;
}

/* if move outside the board, grow the board to include the move */
Boardstate *resizeboard(Boardstate *b, long *px, long *py)
{
  long omaxx=b->maxx;
  long omaxy=b->maxy;
  if (*px>=0 && *py>=0 && *px<omaxx && *py<omaxy)
    return b;
  long nmaxx=omaxx;
  long nmaxy=omaxy;
  long offx=0;
  long offy=0;
  if (*px<0) {
    offx = -*px;
    *px=0;
    nmaxx += offx;
  } else if (*px>=omaxx) {
    nmaxx = *px+1;
  }
  if (*py<0) {
    offy = -*py;
    *py=0;
    nmaxy += offy;
  } else if (*py>=omaxy) {
    nmaxy = *py+1;
  }
  char *ob=b->board;
  char *nb=malloc(nmaxy*nmaxx);
  // printf("nmaxx=%ld nmaxy=%ld\n",nmaxx,nmaxy);
  for (long i=0; i<nmaxy; i++) {
    long oi=i-offy;
    for (long j=0; j<nmaxx; j++) {
      long oj=j-offx;
      if (oi<0 || oi>=omaxy || oj<0 || oj>=omaxx) {
        // printf("space i=%ld j=%ld oi=%ld oj=%ld\n",i,j,oi,oj);
        nb[i*nmaxx+j] = ' ';
      } else {
        // printf("board i=%ld j=%ld oi=%ld oj=%ld\n",i,j,oi,oj);
        nb[i*nmaxx+j] = ob[oi*omaxx+oj];
      }
    }
  }
  b->maxx=nmaxx;
  b->maxy=nmaxy;
  b->board=nb;
  free(ob);
  return b;
}

int plyfull(Boardstate *b, long x, long y)
{
  if (moveok(b, x, y)) {
    b=resizeboard(b,&x,&y);
    assert(x>=0 && x<b->maxx && y>=0 && y<b->maxy);
    b->board[y*b->maxx+x] = b->toplay;
    if (iswin(b))
      return 1;
    else {
      b->toplay = otherplayer(b->toplay);
      return 0;
    }
  } else
    return -1;
}