#include "stdio_impl.h"
#include "ringbuffer.h"
#include <errno.h>
#include <ctype.h>
#include <limits.h>
#include <string.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <inttypes.h>
#include <math.h>

/* Some useful macros */

#define MAX(a,b) ((a)>(b) ? (a) : (b))
#define MIN(a,b) ((a)<(b) ? (a) : (b))

/* Convenient bit representation for modifier flags, which all fall
 * within 31 codepoints of the space character. */

#define ALT_FORM   (1U<<'#'-' ')
#define ZERO_PAD   (1U<<'0'-' ')
#define LEFT_ADJ   (1U<<'-'-' ')
#define PAD_POS    (1U<<' '-' ')
#define MARK_POS   (1U<<'+'-' ')
#define GROUPED    (1U<<'\''-' ')

#define FLAGMASK (ALT_FORM|ZERO_PAD|LEFT_ADJ|PAD_POS|MARK_POS|GROUPED)

/* State machine to accept length modifiers + conversion specifiers.
 * Result is 0 on failure, or an argument type to pop on success. */

enum {
  BARE, LPRE, LLPRE, HPRE, HHPRE, BIGLPRE,
  ZTPRE, JPRE,
  STOP,
  PTR, INT, UINT, ULLONG,
  LONG, ULONG,
  SHORT, USHORT, CHAR, UCHAR,
  LLONG, SIZET, IMAX, UMAX, PDIFF, UIPTR,
  NOARG,
  MAXSTATE
};

#define S(x) [(x)-'A']

extern ringbuffer *comm_out_buf;

static const unsigned char states[]['z'-'A'+1] = {
  { /* 0: bare types */
    S('d') = INT, S('i') = INT,
    S('o') = UINT, S('u') = UINT, S('x') = UINT, S('X') = UINT,
    S('c') = CHAR, S('C') = INT,
    S('s') = PTR, S('S') = PTR, S('p') = UIPTR, S('n') = PTR,
    S('m') = NOARG,
    S('l') = LPRE, S('h') = HPRE, S('L') = BIGLPRE,
    S('z') = ZTPRE, S('j') = JPRE, S('t') = ZTPRE,
  }, { /* 1: l-prefixed */
    S('d') = LONG, S('i') = LONG,
    S('o') = ULONG, S('u') = ULONG, S('x') = ULONG, S('X') = ULONG,
    S('c') = INT, S('s') = PTR, S('n') = PTR,
    S('l') = LLPRE,
  }, { /* 2: ll-prefixed */
    S('d') = LLONG, S('i') = LLONG,
    S('o') = ULLONG, S('u') = ULLONG,
    S('x') = ULLONG, S('X') = ULLONG,
    S('n') = PTR,
  }, { /* 3: h-prefixed */
    S('d') = SHORT, S('i') = SHORT,
    S('o') = USHORT, S('u') = USHORT,
    S('x') = USHORT, S('X') = USHORT,
    S('n') = PTR,
    S('h') = HHPRE,
  }, { /* 4: hh-prefixed */
    S('d') = CHAR, S('i') = CHAR,
    S('o') = UCHAR, S('u') = UCHAR,
    S('x') = UCHAR, S('X') = UCHAR,
    S('n') = PTR,
  }, { /* 5: L-prefixed */
    S('n') = PTR,
  }, { /* 6: z- or t-prefixed (assumed to be same size) */
    S('d') = PDIFF, S('i') = PDIFF,
    S('o') = SIZET, S('u') = SIZET,
    S('x') = SIZET, S('X') = SIZET,
    S('n') = PTR,
  }, { /* 7: j-prefixed */
    S('d') = IMAX, S('i') = IMAX,
    S('o') = UMAX, S('u') = UMAX,
    S('x') = UMAX, S('X') = UMAX,
    S('n') = PTR,
  }
};

#define OOB(x) ((unsigned)(x)-'A' > 'z'-'A')

union arg
{
  uintmax_t i;
  long double f;
  void *p;
};

static void pop_arg(union arg *arg, int type, va_list *ap)
{
  switch (type) {
         case PTR:	arg->p = va_arg(*ap, void *);
  break; case INT:	arg->i = va_arg(*ap, int);
  break; case UINT:	arg->i = va_arg(*ap, unsigned int);
  break; case LONG:	arg->i = va_arg(*ap, long);
  break; case ULONG:	arg->i = va_arg(*ap, unsigned long);
  break; case ULLONG:	arg->i = va_arg(*ap, unsigned long long);
  break; case SHORT:	arg->i = (short)va_arg(*ap, int);
  break; case USHORT:	arg->i = (unsigned short)va_arg(*ap, int);
  break; case CHAR:	arg->i = (signed char)va_arg(*ap, int);
  break; case UCHAR:	arg->i = (unsigned char)va_arg(*ap, int);
  break; case LLONG:	arg->i = va_arg(*ap, long long);
  break; case SIZET:	arg->i = va_arg(*ap, size_t);
  break; case IMAX:	arg->i = va_arg(*ap, intmax_t);
  break; case UMAX:	arg->i = va_arg(*ap, uintmax_t);
  break; case PDIFF:	arg->i = va_arg(*ap, ptrdiff_t);
  break; case UIPTR:	arg->i = (uintptr_t)va_arg(*ap, void *);
  }
}

static void out(FILE *f, const char *s, size_t l)
{
  f->f(f->arg, s, l);
}

static void pad(FILE *f, char c, int w, int l, int fl)
{
  char pad[256];
  if (fl & (LEFT_ADJ | ZERO_PAD) || l >= w) return;
  l = w - l;
  memset(pad, c, l>sizeof pad ? sizeof pad : l);
  for (; l >= sizeof pad; l -= sizeof pad)
    out(f, pad, sizeof pad);
  out(f, pad, l);
}

static const char xdigits[16] = {
  "0123456789ABCDEF"
};

static char *fmt_x(uintmax_t x, char *s, int lower)
{
  for (; x; x>>=4) *--s = xdigits[(x&15)]|lower;
  return s;
}

static char *fmt_o(uintmax_t x, char *s)
{
  for (; x; x>>=3) *--s = '0' + (x&7);
  return s;
}

static char *fmt_u(uintmax_t x, char *s)
{
  unsigned long y;
  for (   ; x>ULONG_MAX; x/=10) *--s = '0' + x%10;
  for (y=x;           y; y/=10) *--s = '0' + y%10;
  return s;
}

static int getint(char **s) {
  int i;
  for (i=0; isdigit(**s); (*s)++) {
    if (i > INT_MAX/10U || **s-'0' > INT_MAX-10*i) i = -1;
    else i = 10*i + (**s-'0');
  }
  return i;
}

static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type)
{
  char *a, *z, *s=(char *)fmt;
  unsigned l10n=0, fl;
  int w, p, xp;
  union arg arg;
  int argpos;
  unsigned st, ps;
  int cnt=0, l=0;
  size_t i;
  const char *prefix;
  int t, pl;

  for (;;) {
    /* This error is only specified for snprintf, but since it's
     * unspecified for other forms, do the same. Stop immediately
     * on overflow; otherwise %n could produce wrong results. */
    if (l > INT_MAX - cnt) goto overflow;

    /* Update output count, end loop when fmt is exhausted */
    cnt += l;
    if (!*s) break;

    /* Handle literal text and %% format specifiers */
    for (a=s; *s && *s!='%'; s++);
    for (z=s; s[0]=='%' && s[1]=='%'; z++, s+=2);
    if (z-a > INT_MAX-cnt) goto overflow;
    l = z-a;
    if (f) out(f, a, l);
    if (l) continue;

    if (isdigit(s[1]) && s[2]=='$') {
      l10n=1;
      argpos = s[1]-'0';
      s+=3;
    } else {
      argpos = -1;
      s++;
    }

    /* Read modifier flags */
    for (fl=0; (unsigned)*s-' '<32 && (FLAGMASK&(1U<<*s-' ')); s++)
      fl |= 1U<<*s-' ';

    /* Read field width */
    if (*s=='*') {
      if (isdigit(s[1]) && s[2]=='$') {
        l10n=1;
        nl_type[s[1]-'0'] = INT;
        w = nl_arg[s[1]-'0'].i;
        s+=3;
      } else if (!l10n) {
        w = f ? va_arg(*ap, int) : 0;
        s++;
      } else goto inval;
      if (w<0) fl|=LEFT_ADJ, w=-w;
    } else if ((w=getint(&s))<0) goto overflow;

    /* Read precision */
    if (*s=='.' && s[1]=='*') {
      if (isdigit(s[2]) && s[3]=='$') {
        nl_type[s[2]-'0'] = INT;
        p = nl_arg[s[2]-'0'].i;
        s+=4;
      } else if (!l10n) {
        p = f ? va_arg(*ap, int) : 0;
        s+=2;
      } else goto inval;
      xp = (p>=0);
    } else if (*s=='.') {
      s++;
      p = getint(&s);
      xp = 1;
    } else {
      p = -1;
      xp = 0;
    }

    /* Format specifier state machine */
    st=0;
    do {
      if (OOB(*s)) goto inval;
      ps=st;
      st=states[st]S(*s++);
    } while (st-1<STOP);
    if (!st) goto inval;

    /* Check validity of argument type (nl/normal) */
    if (st==NOARG) {
      if (argpos>=0) goto inval;
    } else {
      if (argpos>=0) nl_type[argpos]=st, arg=nl_arg[argpos];
      else if (f) pop_arg(&arg, st, ap);
      else return 0;
    }

    if (!f) continue;

    prefix = "-+   0X0x";
    pl = 0;
    t = s[-1];

    /* Transform ls,lc -> S,C */
    if (ps && (t&15)==3) t&=~32;

    /* - and 0 flags are mutually exclusive */
    if (fl & LEFT_ADJ) fl &= ~ZERO_PAD;

    switch(t) {
    case 'n':
      switch(ps) {
      case BARE: *(int *)arg.p = cnt; break;
      case LPRE: *(long *)arg.p = cnt; break;
      case LLPRE: *(long long *)arg.p = cnt; break;
      case HPRE: *(unsigned short *)arg.p = cnt; break;
      case HHPRE: *(unsigned char *)arg.p = cnt; break;
      case ZTPRE: *(size_t *)arg.p = cnt; break;
      case JPRE: *(uintmax_t *)arg.p = cnt; break;
      }
      continue;
    case 'p':
      p = MAX(p, 2*sizeof(void*));
      t = 'x';
      fl |= ALT_FORM;
    case 'x': case 'X':
      a = fmt_x(arg.i, z, t&32);
      if (arg.i && (fl & ALT_FORM)) prefix+=(t>>4), pl=2;
      if (0) {
    case 'o':
      a = fmt_o(arg.i, z);
      if ((fl&ALT_FORM) && p<z-a+1) p=z-a+1;
      } if (0) {
    case 'd': case 'i':
      pl=1;
      if (arg.i>INTMAX_MAX) {
        arg.i=-arg.i;
      } else if (fl & MARK_POS) {
        prefix++;
      } else if (fl & PAD_POS) {
        prefix+=2;
      } else pl=0;
    case 'u':
      a = fmt_u(arg.i, z);
      }
      if (xp && p<0) goto overflow;
      if (xp) fl &= ~ZERO_PAD;
      if (!arg.i && !p) {
        a=z;
        break;
      }
      p = MAX(p, z-a + !arg.i);
      break;
    case 'c':
      *(a=z-(p=1))=arg.i;
      fl &= ~ZERO_PAD;
      break;
    case 's':
      a = arg.p ? arg.p : "(null)";
      z = a + strnlen(a, p<0 ? INT_MAX : p);
      if (p<0 && *z) goto overflow;
      p = z-a;
      fl &= ~ZERO_PAD;
      break;
    }

    if (p < z-a) p = z-a;
    if (p > INT_MAX-pl) goto overflow;
    if (w < pl+p) w = pl+p;
    if (w > INT_MAX-cnt) goto overflow;

    pad(f, ' ', w, pl+p, fl);
    out(f, prefix, pl);
    pad(f, '0', w, pl+p, fl^ZERO_PAD);
    pad(f, '0', p, z-a, 0);
    out(f, a, z-a);
    pad(f, ' ', w, pl+p, fl^LEFT_ADJ);

    l = w;
  }

  if (f) return cnt;
  if (!l10n) return 0;

  for (i=1; i<=NL_ARGMAX && nl_type[i]; i++)
    pop_arg(nl_arg+i, nl_type[i], ap);
  for (; i<=NL_ARGMAX && !nl_type[i]; i++);
  if (i<=NL_ARGMAX) goto inval;
  return 1;

inval:
  errno = EINVAL;
  return -1;
overflow:
  errno = EOVERFLOW;
  return -1;
}

int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
{
  va_list ap2;
  int nl_type[NL_ARGMAX+1] = {0};
  union arg nl_arg[NL_ARGMAX+1];
  int ret;

  /* the copy allows passing va_list* even if va_list is an array */
  va_copy(ap2, ap);
  if (printf_core(0, fmt, &ap2, nl_arg, nl_type) < 0) {
    va_end(ap2);
    return -1;
  }

  else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type);
  va_end(ap2);
  return ret;
}

int printf(char const *fmt, ...) {
  FILE f = {.f = (int (*)(void *, char const *, int)) & ringbuffer_add, .arg = comm_out_buf};

  va_list ap;
  size_t l = 0;
  va_start(ap, fmt);
  l = vfprintf(&f, fmt, ap);
  va_end(ap);

  return l + ringbuffer_add(comm_out_buf, "\r\n", 2);
}