/*
  date_strptime.c: Coded by Tadayoshi Funaba 2011,2012
*/

#include "ruby.h"
#include "ruby/encoding.h"
#include "ruby/re.h"
#include <ctype.h>

static const char *day_names[] = {
    "Sunday", "Monday", "Tuesday", "Wednesday",
    "Thursday", "Friday", "Saturday",
    "Sun", "Mon", "Tue", "Wed",
    "Thu", "Fri", "Sat"
};

static const char *month_names[] = {
    "January", "February", "March", "April",
    "May", "June", "July", "August", "September",
    "October", "November", "December",
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static const char *merid_names[] = {
    "am", "pm",
    "a.m.", "p.m."
};

static const char *extz_pats[] = {
    ":z",
    "::z",
    ":::z"
};

#define sizeof_array(o) (sizeof o / sizeof o[0])

#define f_negate(x) rb_funcall(x, rb_intern("-@"), 0)
#define f_add(x,y) rb_funcall(x, '+', 1, y)
#define f_sub(x,y) rb_funcall(x, '-', 1, y)
#define f_mul(x,y) rb_funcall(x, '*', 1, y)
#define f_div(x,y) rb_funcall(x, '/', 1, y)
#define f_idiv(x,y) rb_funcall(x, rb_intern("div"), 1, y)
#define f_mod(x,y) rb_funcall(x, '%', 1, y)
#define f_expt(x,y) rb_funcall(x, rb_intern("**"), 1, y)

#define f_lt_p(x,y) rb_funcall(x, '<', 1, y)
#define f_gt_p(x,y) rb_funcall(x, '>', 1, y)
#define f_le_p(x,y) rb_funcall(x, rb_intern("<="), 1, y)
#define f_ge_p(x,y) rb_funcall(x, rb_intern(">="), 1, y)

#define f_match(r,s) rb_funcall(r, rb_intern("match"), 1, s)
#define f_aref(o,i) rb_funcall(o, rb_intern("[]"), 1, i)
#define f_end(o,i) rb_funcall(o, rb_intern("end"), 1, i)

#define issign(c) ((c) == '-' || (c) == '+')

static int
num_pattern_p(const char *s)
{
    if (isdigit(*s))
	return 1;
    if (*s == '%') {
	s++;
	if (*s == 'E' || *s == 'O')
	    s++;
	if (*s &&
	    (strchr("CDdeFGgHIjkLlMmNQRrSsTUuVvWwXxYy", *s) || isdigit(*s)))
	    return 1;
    }
    return 0;
}

#define NUM_PATTERN_P() num_pattern_p(&fmt[fi + 1])

static long
read_digits(const char *s, VALUE *n, size_t width)
{
    size_t l;

    l = strspn(s, "0123456789");

    if (l == 0)
	return 0;

    if (width < l)
	l = width;

    if ((4 * l * sizeof(char)) <= (sizeof(long)*CHAR_BIT)) {
	const char *os = s;
	long v;

	v = 0;
	while ((size_t)(s - os) < l) {
	    v *= 10;
	    v += *s - '0';
	    s++;
	}
	if (os == s)
	    return 0;
	*n = LONG2NUM(v);
	return l;
    }
    else {
	char *s2 = ALLOCA_N(char, l + 1);
	memcpy(s2, s, l);
	s2[l] = '\0';
	*n = rb_cstr_to_inum(s2, 10, 0);
	return l;
    }
}

#define set_hash(k,v) rb_hash_aset(hash, ID2SYM(rb_intern(k)), v)
#define ref_hash(k) rb_hash_aref(hash, ID2SYM(rb_intern(k)))
#define del_hash(k) rb_hash_delete(hash, ID2SYM(rb_intern(k)))

#define fail() \
{ \
    set_hash("_fail", Qtrue); \
    return 0; \
}

#define fail_p() (!NIL_P(ref_hash("_fail")))

#define READ_DIGITS(n,w) \
{ \
    size_t l; \
    l = read_digits(&str[si], &n, w); \
    if (l == 0) \
	fail();	\
    si += l; \
}

#define READ_DIGITS_MAX(n) READ_DIGITS(n, LONG_MAX)

static int
valid_range_p(VALUE v, int a, int b)
{
    if (FIXNUM_P(v)) {
	int vi = FIX2INT(v);
	return !(vi < a || vi > b);
    }
    return !(f_lt_p(v, INT2NUM(a)) || f_gt_p(v, INT2NUM(b)));
}

#define recur(fmt) \
{ \
    size_t l; \
    l = date__strptime_internal(&str[si], slen - si, \
				fmt, sizeof fmt - 1, hash); \
    if (fail_p()) \
	return 0; \
    si += l; \
}

VALUE date_zone_to_diff(VALUE);

static size_t
date__strptime_internal(const char *str, size_t slen,
			const char *fmt, size_t flen, VALUE hash)
{
    size_t si, fi;
    int c;

    si = fi = 0;

    while (fi < flen) {

	switch (fmt[fi]) {
	  case '%':

	  again:
	    fi++;
	    c = fmt[fi];

	    switch (c) {
	      case 'E':
		if (fmt[fi + 1] && strchr("cCxXyY", fmt[fi + 1]))
		    goto again;
		fi--;
		goto ordinal;
	      case 'O':
		if (fmt[fi + 1] && strchr("deHImMSuUVwWy", fmt[fi + 1]))
		    goto again;
		fi--;
		goto ordinal;
	      case ':':
		{
		    int i;

		    for (i = 0; i < (int)sizeof_array(extz_pats); i++)
			if (strncmp(extz_pats[i], &fmt[fi],
					strlen(extz_pats[i])) == 0) {
			    fi += i;
			    goto again;
			}
		    fail();
		}

	      case 'A':
	      case 'a':
		{
		    int i;

		    for (i = 0; i < (int)sizeof_array(day_names); i++) {
			size_t l = strlen(day_names[i]);
			if (strncasecmp(day_names[i], &str[si], l) == 0) {
			    si += l;
			    set_hash("wday", INT2FIX(i % 7));
			    goto matched;
			}
		    }
		    fail();
		}
	      case 'B':
	      case 'b':
	      case 'h':
		{
		    int i;

		    for (i = 0; i < (int)sizeof_array(month_names); i++) {
			size_t l = strlen(month_names[i]);
			if (strncasecmp(month_names[i], &str[si], l) == 0) {
			    si += l;
			    set_hash("mon", INT2FIX((i % 12) + 1));
			    goto matched;
			}
		    }
		    fail();
		}

	      case 'C':
		{
		    VALUE n;

		    if (NUM_PATTERN_P())
			READ_DIGITS(n, 2)
		    else
			READ_DIGITS_MAX(n)
		    set_hash("_cent", n);
		    goto matched;
		}

	      case 'c':
		recur("%a %b %e %H:%M:%S %Y");
		goto matched;

	      case 'D':
		recur("%m/%d/%y");
		goto matched;

	      case 'd':
	      case 'e':
		{
		    VALUE n;

		    if (str[si] == ' ') {
			si++;
			READ_DIGITS(n, 1);
		    } else {
			READ_DIGITS(n, 2);
		    }
		    if (!valid_range_p(n, 1, 31))
			fail();
		    set_hash("mday", n);
		    goto matched;
		}

	      case 'F':
		recur("%Y-%m-%d");
		goto matched;

	      case 'G':
		{
		    VALUE n;

		    if (NUM_PATTERN_P())
			READ_DIGITS(n, 4)
		    else
			READ_DIGITS_MAX(n)
		    set_hash("cwyear", n);
		    goto matched;
		}

	      case 'g':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 0, 99))
			fail();
		    set_hash("cwyear",n);
		    set_hash("_cent",
			     INT2FIX(f_ge_p(n, INT2FIX(69)) ? 19 : 20));
		    goto matched;
		}

	      case 'H':
	      case 'k':
		{
		    VALUE n;

		    if (str[si] == ' ') {
			si++;
			READ_DIGITS(n, 1);
		    } else {
			READ_DIGITS(n, 2);
		    }
		    if (!valid_range_p(n, 0, 24))
			fail();
		    set_hash("hour", n);
		    goto matched;
		}

	      case 'I':
	      case 'l':
		{
		    VALUE n;

		    if (str[si] == ' ') {
			si++;
			READ_DIGITS(n, 1);
		    } else {
			READ_DIGITS(n, 2);
		    }
		    if (!valid_range_p(n, 1, 12))
			fail();
		    set_hash("hour", n);
		    goto matched;
		}

	      case 'j':
		{
		    VALUE n;

		    READ_DIGITS(n, 3);
		    if (!valid_range_p(n, 1, 366))
			fail();
		    set_hash("yday", n);
		    goto matched;
		}

	      case 'L':
	      case 'N':
		{
		    VALUE n;
		    int sign = 1;
		    size_t osi;

		    if (issign(str[si])) {
			if (str[si] == '-')
			    sign = -1;
			si++;
		    }
		    osi = si;
		    if (NUM_PATTERN_P())
			READ_DIGITS(n, c == 'L' ? 3 : 9)
		    else
			READ_DIGITS_MAX(n)
		    if (sign == -1)
			n = f_negate(n);
		    set_hash("sec_fraction",
			     rb_rational_new2(n,
					      f_expt(INT2FIX(10),
						     ULONG2NUM(si - osi))));
		    goto matched;
		}

	      case 'M':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 0, 59))
			fail();
		    set_hash("min", n);
		    goto matched;
		}

	      case 'm':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 1, 12))
			fail();
		    set_hash("mon", n);
		    goto matched;
		}

	      case 'n':
	      case 't':
		recur(" ");
		goto matched;

	      case 'P':
	      case 'p':
		{
		    int i;

		    for (i = 0; i < 4; i++) {
			size_t l = strlen(merid_names[i]);
			if (strncasecmp(merid_names[i], &str[si], l) == 0) {
			    si += l;
			    set_hash("_merid", INT2FIX((i % 2) == 0 ? 0 : 12));
			    goto matched;
			}
		    }
		    fail();
		}

	      case 'Q':
		{
		    VALUE n;
		    int sign = 1;

		    if (str[si] == '-') {
			sign = -1;
			si++;
		    }
		    READ_DIGITS_MAX(n);
		    if (sign == -1)
			n = f_negate(n);
		    set_hash("seconds",
			     rb_rational_new2(n,
					      f_expt(INT2FIX(10),
						     INT2FIX(3))));
		    goto matched;
		}

	      case 'R':
		recur("%H:%M");
		goto matched;

	      case 'r':
		recur("%I:%M:%S %p");
		goto matched;

	      case 'S':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 0, 60))
			fail();
		    set_hash("sec", n);
		    goto matched;
		}

	      case 's':
		{
		    VALUE n;
		    int sign = 1;

		    if (str[si] == '-') {
			sign = -1;
			si++;
		    }
		    READ_DIGITS_MAX(n);
		    if (sign == -1)
			n = f_negate(n);
		    set_hash("seconds", n);
		    goto matched;
		}

	      case 'T':
		recur("%H:%M:%S");
		goto matched;

	      case 'U':
	      case 'W':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 0, 53))
			fail();
		    set_hash(c == 'U' ? "wnum0" : "wnum1", n);
		    goto matched;
		}

	      case 'u':
		{
		    VALUE n;

		    READ_DIGITS(n, 1);
		    if (!valid_range_p(n, 1, 7))
			fail();
		    set_hash("cwday", n);
		    goto matched;
		}

	      case 'V':
		{
		    VALUE n;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 1, 53))
			fail();
		    set_hash("cweek", n);
		    goto matched;
		}

	      case 'v':
		recur("%e-%b-%Y");
		goto matched;

	      case 'w':
		{
		    VALUE n;

		    READ_DIGITS(n, 1);
		    if (!valid_range_p(n, 0, 6))
			fail();
		    set_hash("wday", n);
		    goto matched;
		}

	      case 'X':
		recur("%H:%M:%S");
		goto matched;

	      case 'x':
		recur("%m/%d/%y");
		goto matched;

	      case 'Y':
		  {
		      VALUE n;
		      int sign = 1;

		      if (issign(str[si])) {
			  if (str[si] == '-')
			      sign = -1;
			  si++;
		      }
		      if (NUM_PATTERN_P())
			  READ_DIGITS(n, 4)
		      else
			  READ_DIGITS_MAX(n)
		    if (sign == -1)
			n = f_negate(n);
		      set_hash("year", n);
		      goto matched;
		  }

	      case 'y':
		{
		    VALUE n;
		    int sign = 1;

		    READ_DIGITS(n, 2);
		    if (!valid_range_p(n, 0, 99))
			fail();
		    if (sign == -1)
			n = f_negate(n);
		    set_hash("year", n);
		    set_hash("_cent",
			     INT2FIX(f_ge_p(n, INT2FIX(69)) ? 19 : 20));
		    goto matched;
		}

	      case 'Z':
	      case 'z':
		{
		    static const char pat_source[] =
			"\\A("
			"(?:gmt|utc?)?[-+]\\d+(?:[,.:]\\d+(?::\\d+)?)?"
			"|[[:alpha:].\\s]+(?:standard|daylight)\\s+time\\b"
			"|[[:alpha:]]+(?:\\s+dst)?\\b"
			")";
		    static VALUE pat = Qnil;
		    VALUE m, b;

		    if (NIL_P(pat)) {
			pat = rb_reg_new(pat_source, sizeof pat_source - 1,
					 ONIG_OPTION_IGNORECASE);
			rb_gc_register_mark_object(pat);
		    }

		    b = rb_backref_get();
		    rb_match_busy(b);
		    m = f_match(pat, rb_usascii_str_new2(&str[si]));

		    if (!NIL_P(m)) {
			VALUE s, l, o;

			s = rb_reg_nth_match(1, m);
			l = f_end(m, INT2FIX(0));
			o = date_zone_to_diff(s);
			si += NUM2LONG(l);
			set_hash("zone", s);
			set_hash("offset", o);
			rb_backref_set(b);
			goto matched;
		    }
		    rb_backref_set(b);
		    fail();
		}

	      case '%':
		if (str[si] != '%')
		    fail();
		si++;
		goto matched;

	      case '+':
		recur("%a %b %e %H:%M:%S %Z %Y");
		goto matched;

	      default:
		if (str[si] != '%')
		    fail();
		si++;
		if (fi < flen)
		    if (str[si] != fmt[fi])
			fail();
		si++;
		goto matched;
	    }
	  case ' ':
	  case '\t':
	  case '\n':
	  case '\v':
	  case '\f':
	  case '\r':
	    while (isspace(str[si]))
		si++;
	    fi++;
	    break;
	  default:
	  ordinal:
	    if (str[si] != fmt[fi])
		fail();
	    si++;
	    fi++;
	    break;
	  matched:
	    fi++;
	    break;
	}
    }

    return si;
}

VALUE
date__strptime(const char *str, size_t slen,
	       const char *fmt, size_t flen, VALUE hash)
{
    size_t si;
    VALUE cent, merid;

    si = date__strptime_internal(str, slen, fmt, flen, hash);

    if (slen > si) {
	VALUE s;

	s = rb_usascii_str_new(&str[si], slen - si);
	set_hash("leftover", s);
    }

    if (fail_p())
	return Qnil;

    cent = ref_hash("_cent");
    if (!NIL_P(cent)) {
	VALUE year;

	year = ref_hash("cwyear");
	if (!NIL_P(year))
	    set_hash("cwyear", f_add(year, f_mul(cent, INT2FIX(100))));
	year = ref_hash("year");
	if (!NIL_P(year))
	    set_hash("year", f_add(year, f_mul(cent, INT2FIX(100))));
	del_hash("_cent");
    }

    merid = ref_hash("_merid");
    if (!NIL_P(merid)) {
	VALUE hour;

	hour = ref_hash("hour");
	if (!NIL_P(hour)) {
	    hour = f_mod(hour, INT2FIX(12));
	    set_hash("hour", f_add(hour, merid));
	}
	del_hash("_merid");
    }

    return hash;
}

/*
Local variables:
c-file-style: "ruby"
End:
*/
