#include "ptn.h"

#define ASSERT_NONEMPTY { if (ptn == 0 || *ptn == 0) return PTN_INVALID; }
#define ASSERT_MORE     { if (*ptn == 0) return PTN_INVALID; }

enum PTN_PARSE_RESULT
parse_place(const uint8_t board_size, char *ptn,
            uint8_t *out_location, enum STONE_VARIANT *out_stone) {

  if (board_size < 5 || board_size > 6) return PTN_INVALID;

  ASSERT_NONEMPTY;

  *out_stone = STONE_FLAT;
  switch (*ptn) {
    case 'C' : { ptn++; *out_stone = STONE_CAPSTONE; break; };
    case 'S' : { ptn++; *out_stone = STONE_STANDING; break; };
    case 'F' : { ptn++; break; };
  }

  ASSERT_MORE;

  if ( (*ptn < 'a') || (*ptn > '`' + board_size) ) return PTN_INVALID;
  *out_location = *ptn - 'a';

  ptn++; ASSERT_MORE;

  if ( (*ptn < '1') || (*ptn > board_size + '0') ) return PTN_INVALID;
  *out_location += board_size * (*ptn - '1');

  if (*(++ptn) > 0) return PTN_INVALID;

  return PTN_VALID;
}

enum PTN_PARSE_RESULT
parse_move(const uint8_t board_size, char *ptn,
           uint8_t *out_location, enum MOVE_DIRECTION *out_direction,
           uint8_t *out_steps, uint8_t out_drops[5]) {

  if (board_size < 5 || board_size > 6) return PTN_INVALID;

  ASSERT_NONEMPTY;

  uint8_t picked_up = 0;

  if ( (*ptn >= '1') && (*ptn <= '0' + board_size)) {
    picked_up = *ptn - '0';
    ptn++; ASSERT_MORE;
  }

  if ( (*ptn < 'a') || (*ptn > '`' + board_size) ) return PTN_INVALID;
  *out_location = *ptn - 'a';

  ptn++; ASSERT_MORE;

  if ( (*ptn < '1') || (*ptn > board_size + '0') ) return PTN_INVALID;
  *out_location += board_size * (*ptn - '1');

  ptn++; ASSERT_MORE;

  switch (*ptn) {
    case '+': { *out_direction = M_UP;    break; }
    case '-': { *out_direction = M_DOWN;  break; }
    case '<': { *out_direction = M_LEFT;  break; }
    case '>': { *out_direction = M_RIGHT; break; }
    default: return PTN_INVALID;
  }

  ptn++;
  // Handle the case '<column><row><direction>' as
  // '1<column><row><direction>1' for convenience
  if (*ptn == 0) {
    if (picked_up == 0) {
      *out_steps = 1;
      out_drops[0] = 1;
    } else {
      return PTN_INVALID;
    }
  }

  *out_steps = 0;
  uint8_t total = 0;
  while (*ptn) {
      if ( (*ptn < '1') || (*ptn > '0' + board_size) ) {
        return PTN_INVALID;
      }

      if ( (*out_steps + 1 >= board_size) && *ptn) return PTN_INVALID;

      out_drops[*out_steps] = *ptn - '0';
      total += out_drops[*out_steps];
      *out_steps += 1;
      ptn++;
  }

  if ( (picked_up > 0) && (total != picked_up) ) return PTN_INVALID;

  return PTN_VALID;
}