%{

#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cassert>

FILE* yyin = stdin;

#define YY_INPUT(buf, result, max_size) { \
    int yyc = getc(yyin); \
    result = (EOF == yyc) ? 0 : (*(buf) = yyc, 1); \
  }

#define STATCHECK_GT 1
#define STATCHECK_LT 2

struct statcheck_t {
  char *stat;
  int value;
  int rel;
};

struct statchange_t {
  char *stat;
  int addend;
};

struct Choice {
  int option;
  char *flavor;
  statcheck_t *statcheck;
  char *id;
  statchange_t *statchange;

  Choice(char*, statcheck_t *statcheck, statchange_t *statchange);
};

enum class FooterType {
  End,
  Goto,
  Choices
};

struct Footer {
  FooterType type;
  union {
    std::vector<Choice*> *choices;
    char *link;
  };

  Footer();
  ~Footer();
};

struct Page {
  char *id;
  char *body;
  Footer footer;

  Page();
  ~Page();
};

std::vector<Page*> pages;

Page *emit_ending();
Page *emit_goto(char*);
Page *emit_choices(std::vector<Choice*>*);

void append_body(Page *page, char *str);

union value {
  Page *page;
  char *string;
  Choice *choice;
  std::vector<Choice*> *choices;
  int num;
  statcheck_t *statcheck;
  statchange_t *statchange;
};

#define YYSTYPE union value

%}


Story =        BlankLine* (p:Page { pages.push_back(p.page); })+ EndOfFile

Page =         h:Header b:Body { $$.page = b.page; $$.page->id = h.string}
     	       BlankLine*

Header =       < i:Identifier > Newline BlankLine* { $$ = i; }
               
Identifier =   < [A-Z][A-Z0-9_]+ > - { $$.string = strndup(yytext, yyleng); }

Body =         Footer | t:TextLine b:Body { $$ = b; append_body(b.page, t.string);}

TextLine =     < (!Newline .)* Newline > { $$.string = strndup(yytext, yyleng); }

Footer =       Ending { $$.page = emit_ending(); }
	       | g:Goto { $$.page = emit_goto(g.string); }
	       | c:ChoiceList { $$.page = emit_choices(c.choices); }

Goto =         'GOTO' - < i:Identifier > Newline
     	       { $$.string = strndup(yytext, yyleng); }

Ending =       'THE END' Newline

ChoiceList =   c:Choice l:ChoiceList { $$ = l; $$.choices->push_back(c.choice); }
	       | c:Choice { $$.choices = new std::vector<Choice*>(); $$.choices->push_back(c.choice); }
	       
Choice =       b:Bullet f:Freetext r:Redirect
       	       {
	       $$ = r;
	       $$.choice->option = b.num;
	       $$.choice->flavor = f.string;
	       }

Bullet =       < [0-9]+ > ')' - { $$.num = atoi(yytext); }

Freetext =     < ([^[<])+ > { $$.string = strndup(yytext, yyleng); }

Redirect =     ck:StatCheck? '[' i:Identifier ']' - cg:StatChange? Newline
	       { $$.choice = new Choice(i.string, ck.statcheck, cg.statchange); }

StatCheck =    '<' n:StatName v:StatVal r:StatRel '>' -
	       { $$.statcheck = new statcheck_t{n.string, v.num, r.num}; }

StatChange =   '(' ('+' | '-') v:StatVal n:StatName ')'
	       { $$.statchange = new statchange_t{n.string, v.num}; }

StatName =     < [A-Za-z]+ > - { $$.string = strdup(yytext); }

StatVal =      < [0-9]+ > - { $$.num = atoi(yytext); }

StatRel =      < ('+'|'-')? > { $$.num = 0x0 } -

EndOfFile =    !.

BlankLine =    - Newline

- =            (' ' | '\t')*

Newline =      '\r\n' | '\r' | '\n'

%%

Choice::Choice(char *id, statcheck_t *statcheck, statchange_t *statchange) {
  this->id = id;
  this->statcheck = statcheck;
  this->statchange = statchange;
}

Footer::Footer() {
}

Footer::~Footer() {
}

Page::Page() {
  id = NULL;
  body = NULL;
}

Page::~Page() {
  if (id) {
    free(id);
  }
  if (body) {
    free(body);
  }
}

Page *emit_goto(char *id) {
  Page *mypage = new Page;
  mypage->footer.type = FooterType::Goto;
  mypage->footer.link = id;
  return mypage;
}

Page *emit_ending() {
  Page *mypage = new Page;
  mypage->footer.type = FooterType::End;
  return mypage;
}

Page *emit_choices(std::vector<Choice*> *choices) {
  Page *mypage = new Page;
  mypage->footer.type = FooterType::Choices;
  mypage->footer.choices = choices;
  return mypage;
}

void append_body(Page *page, char *str) {
  if (page->body) {
    int size = strlen(page->body) + strlen(str) + 1;
    char *newstring = (char*) calloc(size, sizeof(char));
    strcpy(newstring, str);
    strcat(newstring, page->body);
    free(page->body);
    page->body = newstring;
  } else {
    page->body = str;
  }
}

void print_page(Page *page) {
  printf("HEADER: %s\nBODY: %s\n", page->id, page->body);
  switch (page->footer.type) {
  case FooterType::End:
    printf("THE END\n");
    break;
  case FooterType::Goto:
    printf("GOTO %s\n", page->footer.link);
    break;
  case FooterType::Choices:
    printf("CHOICES:\n");
    for (Choice *c : *page->footer.choices) {
      printf("%d) %s\n", c->option, c->flavor);
    }
  }
}

std::vector<Page*> CyoaParse(FILE *file) {
  yyin = file;
  yyparse();
  yyin = stdin;
  return pages;
}
  
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