/**
  scoundrel.c: a C89 port of the Scoundrel roguelike card game
  using the official ruleset only
  See the README.md file for platform-specific build instructions
  Created by Luxferre in 2026, released into public domain
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if defined(__CC65__) || defined(__Z80__)
#define RETRO_IMPL
#endif
#ifdef RETRO_IMPL
#include <conio.h>
#else
#include <time.h>
#endif

char scanchar() {
  char c;
  scanf(" %c", &c);
  return c;
}

void randomize() {
#ifdef RETRO_IMPL
  unsigned int entropy;
#ifdef _randomize
  _randomize();
#endif
  entropy = rand();
  clrscr();
  puts("Press any key to start...");
  while(!kbhit()) entropy++;
  while(kbhit()) cgetc();
#ifdef SPECTRUM
  while(!kbhit()) entropy++;
#endif
  srand(entropy);
  clrscr();
#else
  srand(time(NULL));
#endif
}

/* UI choices */
#define CH1 0
#define CH2 1
#define CH3 2
#define CH4 3
#define CH_R 4
#define CH_Q 5
#define CH_INVAL 6

/**
Deck/room representation:
0 is empty (this value cannot be in the deck, only in the room),
1 to 13 is a monster,
14 to 22 is a weapon,
23 to 31 is a potion

Monster level: x + 1
Weapon level: x - 12
Potion level: x - 21
*/

/* Game stats */

/* main deck and room */
static char deck[44], room[] = {0, 0, 0, 0};

static short deck_idx = 0, hp = 20,
  weapon = 0, durability = 0, can_run = 1,
  engaged = 0, potion_drank = 0, last_potion_val = 0; 

/* Output method */
void print_msg(char *s) {
  puts(s);
}

/* Input method */
char get_choice() {
  char c, res;
  printf("Your choice: ");
  c = scanchar();
  switch(c) {
    case 'a':
    case 'A':
      res = CH1;
      break;
    case 'b':
    case 'B':
      res = CH2;
      break;
    case 'c':
    case 'C':
      res = CH3;
      break;
    case 'd':
    case 'D':
      res = CH4;
      break;
    case 'r':
    case 'R':
      res = CH_R;
      break;
    case 'q':
    case 'Q':
      res = CH_Q;
      break;
    default:
      res = CH_INVAL;
  }
  printf("\n");
  return res;
}

/* Confirmation method */
int confirm(char *prompt) {
  char c, d;
  printf("%s", prompt);
  c = scanchar();
  if(c == 'y' || c == 'Y') d = 1;
  else d = 0;
  printf("\n");
  return d;
}

/* Stats display method */
void display_stats() {
  printf("---------------\nHP:%02d W:%02d D:%02d\n---------------\n",
    hp, weapon, durability);
}

/* Room display method */
void display_room() {
  unsigned int i, v;
  for(i=0;i<4;i++) {
    v = room[i];
    if(v == 0) printf("    "); /* just 4 spaces */
    else if(v < 14) printf("M%02d ", v + 1);
    else if(v < 23) printf("W%02d ", v - 12);
    else printf("P%02d ", v - 21);
  }
  printf("\n a   b   c   d");
  if(can_run) printf("  r)un->");
  printf("\n");
}

/* Array shuffle method */
void shuffle(char *array, size_t n) {
  unsigned int i, j, t;
  if(n > 1) {
    for(i=n-1;i>0;i--) {
      j = (unsigned int) (rand()%(i+1));
      t = array[j];
      array[j] = array[i];
      array[i] = t;
    }
  }
}

/* Room item handling methods */

int handle_monster(int val) {
  int healthlost = val;
  printf("You fight a %d-level monster.\n", val);
  if(weapon > 0 && val <= durability) {
    int weapondiff = val - weapon;
    if(weapondiff < 0) weapondiff = 0;
    printf("Without weapon: lose %d HP.\n", val);
    printf("With weapon: lose %d HP.\n", weapondiff);
    if(confirm("Use weapon? (y/n) ")) {
      healthlost = weapondiff;
      durability = val - 1;
      if(durability < 2) {
        print_msg("You lose your weapon.");
        durability = weapon = 0;
      }
      else printf("Your weapon's durability is now %d.\n", durability);
    }
  }
  hp -= healthlost;
  if(hp < 0) hp = 0;
  printf("You lost %d HP. New HP: %d.\n", healthlost, hp);
  return val;
}

void handle_weapon(int val) {
  weapon = val;
  printf("You equip a %d-level weapon.\n", weapon);
  durability = 14; /* reset durability to max limit */
}

void handle_potion(int val) {
  if(potion_drank) {
    print_msg("You already drank a potion in this room. Discarding.");
  } else {
    potion_drank = 1;
    hp += val;
    if(hp > 20) hp = 20;
    printf("You drink a %d-level potion. New HP: %d.\n", val, hp);
    if(deck_idx >= sizeof(deck) || deck[deck_idx] == 0)
      last_potion_val = val;
  }
}

/* Main gameplay */
int game() {
  unsigned int i;
  int score = -208; /* score storage */
  int item, room_sum; /* true item value */
  int last_room = 0, last_room_clr = 0; /* last room markers */
  char ch;
  deck_idx = 0; /* reset the deck index */
  /* Prefill the deck */
  for(i=0;i<13;i++) deck[i] = deck[i+13] = i+1;
  for(i=26;i<44;i++) deck[i] = i - 12;
  /* Shuffle the deck */
  shuffle(deck, sizeof(deck));
  /* prepare all other parameters */
  hp = 20;
  can_run = 1;
  weapon = durability = engaged = 0;
  potion_drank = last_potion_val = 0;
  for(i=0;i<sizeof(room);i++) room[i] = 0; /* reset the room */
  
  while(hp > 0 && !last_room_clr) {
    /* fill in the new room unless engaged */
    if(!engaged) {
      for(i=0;i<sizeof(room);i++) {
        /* fill only if empty */
        if(!room[i]) {
          /* Check if deck is empty or exhausted */
          if(deck_idx >= sizeof(deck) || deck[deck_idx] == 0) {
            last_room = 1;
            can_run = 0;
          } else {
            room[i] = deck[deck_idx];
            deck[deck_idx] = 0; /* remove from deck */
            deck_idx++;
            /* Check immediately if that was the last card */
            if(deck_idx >= sizeof(deck) || deck[deck_idx] == 0) {
               last_room = 1;
               can_run = 0;
            }
          }
        }
      }
    }

    /* display the stats and room */
    display_stats();
    display_room();
    ch = get_choice();
    
    /* Logic validation */
    if(ch == CH_R) {
        if(!can_run || engaged) ch = CH_INVAL; /* Cannot run if disabled or engaged */
    } else if(ch < CH_R && !room[(int)ch]) {
        ch = CH_INVAL; /* empty item */
    }

    if(ch == CH_Q) {
      hp = 0;
      print_msg("Quitting...");
      break;
    } else if(ch == CH_INVAL) {
      print_msg("Invalid input!");
      continue;
    } else if(ch == CH_R) { /* run mechanics */
      /* Compact and rearrange the deck */
      char temp_deck[sizeof(deck)];
      int t_idx = 0;

      /* 1. Collect all valid remaining cards from deck */
      for(i=0; i<sizeof(deck); i++) {
        if(deck[i] != 0) temp_deck[t_idx++] = deck[i];
      }

      /* 2. Shuffle room cards and append to the end */
      shuffle(room, sizeof(room));
      for(i=0; i<sizeof(room); i++) {
        if(room[i] != 0) {
          temp_deck[t_idx++] = room[i];
          room[i] = 0; /* Clear room */
        }
      }

      /* 3. Rebuild deck */
      memset(deck, 0, sizeof(deck));
      for(i=0; i<t_idx; i++) deck[i] = temp_deck[i];

      /* 4. Reset state */
      deck_idx = 0; /* Reset index to start of compacted deck */
      can_run = 0; /* can't run twice in a row */
      engaged = 0;
      last_room = 0; /* Since we added cards, it's not the last room anymore */
      
    } else { /* engagement mechanics */
      engaged++; /* increase the amount of engaged cards */
      can_run = 0; /* Cannot run once engaged */
      
      item = room[(int)ch]; /* get the item from the room */
      room[(int)ch] = 0; /* mark the room slot as empty */
      /* Note: We do NOT put the item back in deck. It is consumed. */

      if(item < 14) { /* monster */
        score += handle_monster(item + 1);
      } else if(item < 23) { /* weapon */
        handle_weapon(item - 12);
      } else { /* potion */
        handle_potion(item - 21);
      }
      
      /* condition to move to the next room */
      room_sum = 0;
      for(i=0;i<sizeof(room);i++) room_sum += room[i];
      
      if(hp > 0) {
        if(room_sum == 0) {
          if(last_room) last_room_clr = 1;
          else {
            print_msg("Room clear, moving on...");
            engaged = 0;
            potion_drank = 0;
            can_run = 1;
          }
        } else if(!last_room && engaged == 3) {
          print_msg("Room clear, moving on...");
          engaged = 0;
          potion_drank = 0;
          can_run = 1;
        }
      }
    }
  }
  /* Score the result */
  if(hp > 0) { /* win */
    score = hp;
    if(hp == 20) score += last_potion_val;
  }
  return score;
}

/* Entry point */
int main() {
  int score;
  randomize();
  while(1) {
    print_msg("\n===============\nScoundrel--2026\n  by Luxferre\n===============\n  Good  luck!");
    score = game();
    if(score > 0) {
      printf("You win! Your score: %d\n", score);
    } else {
      printf("You lose! Your score: %d\n", score);
    }
    if(!confirm("Play again? (y/n) ")) break;
  }
  return 0;
}